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Nanocellulose as a Negative
Calorie and Cholesterol
Controlling Food Additive
Matthew Stewart
Michael Fenwick-Nevin
Australian Pulp and Paper Institute
Chemical Engineering Department
Monash University
Executive Summary
Lifestyle diseases such as type II diabetes, cardiovascular disease and obesity are growing issues
amongst the global population. Obesity is currently one of the most serious worldwide health issues,
affecting more than a billion people globally. Current treatments for lifestyle diseases include exercise
and dietary modifications such as decreasing portion sizes and decreasing high-calorie food and drinks.
The objective of this research project is to assess the feasibility of creating a nanocellulose based food
additive capable of preventing energy and cholesterol absorption from foods, which not only could
help prevent and treat obesity and other lifestyle diseases, but could also allow individuals to indulge
in foods they normally wouldn’t eat, avoiding weight gain and negative health effects.
In order to achieve the objectives of this project and determine if nanocellulose can be used as a
negative calorie and cholesterol controlling food additive, a systematic methodology was used in order
to determine the interaction of nanocellulose with various food constituents. The figure below
highlights the way in which this project was broken down.
Figure 1: Project Flow Chart
It was hypothesised prior to the commencement of this project that glucose and starch oligomers can
be adsorbed onto nanocellulose fibres. It was also hypothesised that nanocellulose in the diet can
reduce blood cholesterol levels. In order to prove these hypothesis, both experimental work and an
extensive review of literature were conducted.
A literature review relating to glucose interaction with cellulose yielded no results to suggest that
glucose had previously been found to adsorb to cellulose. Experimental work was conducted using
glucometry to measure glucose concentration before and after the addition of nanocellulose. These
experiments confirmed that glucose does not adsorb to nanocellulose.
Cellulose
Energy
Monosaccharides
Glucose
Disaccharides
Sucrose
Polysaccharides
Starch
Fats
Cholesterol Triglycerides
An extensive review of literature found previous works had concluded that sucrose does not bind to
cellulose, and given that this had been previously determined experimental work was not conducted in
order to investigate the adsorption of sucrose to nanocellulose. The conclusion that glucose and
sucrose do not bind to nanocellulose was based on experiments using native forms of nanocellulose,
therefore one recommendation from this project was to conduct future experiments with chemically
modified nanocellulose and test the adsorption of glucose and sucrose to these chemically modified
molecules.
Previously published literature was found that concluded starch adsorbs to the surface of cellulose.
We used the sulphuric acid-phenol method of starch content determination in order to test whether
this result is also achieved with nanocellulose. The results of our experimental work investigating the
adsorption of starch to nanocellulose concluded that starch does bind to nanocellulose, as was
hypothesised. Further experiments were conducted investigating how the action of α-amylase impacts
upon the starch adsorbed to nanocellulose, however unfortunately the results of these experiments
were inconclusive due to the lack of sensitivity of the glucometry method used for sample analysis. As
a result another recommendation for future works is to repeat these experiments, however using a
more sensitive analytical method such as high performance liquid chromatography.
A review of literature found that increasing nanocellulose in the diet results in a reduction of
cholesterol levels in the blood, as well as reducing the likelihood of developing colon cancer. It was
also determined through reviewing literature that fructans can reduce the levels of cholesterol and
triglycerides in the blood. These concepts were only investigated on a theoretical level and therefore
it is recommended that future works confirm experimentally that nanocellulose and fructans can
reduce blood cholesterol and triglyceride levels.
In conducting this research project we were able to achieve our objective of investigating the use of
nanocellulose as a negative calorie and cholesterol controlling food additive. Although not all of our
results supported our hypothesis, many did, and those that didn’t based on these preliminary
experiments, may prove to align better with our hypothesis if further experiments are conducted.
Therefore, overall our project was a success and the use of nanocellulose as a negative calorie and
cholesterol controlling food additive still remains a valid proposal, however requires further
investigation.
Table of Contents
Executive Summary ........................................................................................................................................... 1
1. Introduction................................................................................................................................................... 4
2. Project Definition........................................................................................................................................... 5
2.1. Problem Statement ................................................................................................................................ 5
2.2. Hypothesis.............................................................................................................................................. 5
2.3. Project Objectives................................................................................................................................... 5
3. Literature Review .......................................................................................................................................... 7
3.1. Glucose ................................................................................................................................................... 7
3.2. Sucrose ................................................................................................................................................... 7
3.3. Starch...................................................................................................................................................... 8
3.4. α-Amylase............................................................................................................................................... 9
3.5. Cellulose ................................................................................................................................................. 9
3.6. Interactions between Starch, Cellulose and Amylase .......................................................................... 10
3.7. Fructans................................................................................................................................................ 11
3.8. Cholesterol............................................................................................................................................ 12
3.9. Bile Acids............................................................................................................................................... 13
3.10. Significance of the Relationship between Bile Acids and Cholesterol ............................................... 13
3.11. Overview of the Human Gastrointestinal System .............................................................................. 13
3.12. Glucometry......................................................................................................................................... 15
3.13. Starch Quantification Techniques ...................................................................................................... 16
3.14. Kinetics ............................................................................................................................................... 17
4. Methodology ............................................................................................................................................... 18
4.1. Glucose to Nanocellulose Binding Experiments................................................................................... 18
4.2. Starch to Nanocellulose Binding Experiments...................................................................................... 21
4.3. Effect of Starch Binding to Nanocellulose on α-Amylase Action Experiments..................................... 22
4.4. Literature Review ................................................................................................................................. 24
5. Key Results and Findings ............................................................................................................................. 25
5.1. Glucose Binding to Nanocellulose........................................................................................................ 25
5.2. Sucrose Binding to Nanocellulose ........................................................................................................ 33
5.3. Starch Binding to Nanocellulose........................................................................................................... 33
5.4. Effect of Starch Binding to Nanocellulose on α-Amylase Action.......................................................... 35
6. Conclusions and Recommendations............................................................................................................ 36
7. Acknowledgements ..................................................................................................................................... 37
8. References................................................................................................................................................... 38
1. Introduction
Obesity is currently one of the most serious worldwide health issues, affecting more than a billion
people globally (1). It is quickly growing in the younger generations with more than 22 million of
the world’s children under 5 years old being either overweight or obese. There are a variety of
severe health conditions that are associated with being overweight or obese. These include; sleep
apnea, type II diabetes, hypertension, hyperlipidaemia and increased risk of developing
cardiovascular disease (CVD) (2). CVD is a major health risk that has a high mortality rate and has
been the leading cause of death in the United States since the early 1900’s (3). Due to these
factors obesity can have a large impact on expected life span, particularly in younger children,
reducing their life expectancy by up to as many as 20 years (2).
These rising risk factors create the need to implement and devise solutions to combat the growing
obesity pandemic. Current treatments include exercise and dietary modifications such as
decreasing portion sizes and decreasing high-calorie food and drinks (2). The basis of this research
project is to assess the feasibility of creating a nanocellulose based food additive capable of
preventing energy and cholesterol absorption from the food. If this end product is realized, not
only will this help prevent and treat obesity and other diseases associated with being overweight,
but it will also allow individuals to indulge in foods they normally wouldn’t eat, avoiding weight
gain and negative health effects.
2. Project Definition
2.1. Problem Statement
To research the capability of nanocellulose to adsorb carbohydrates (monosaccharides,
disaccharides and polysaccharides), as well as investigating the capability of nanocellulose and
other dietary fibres (e.g. fructans) to regulate cholesterol levels. This research will aid in the
development of nanocellulose as a negative calorie and cholesterol controlling food additive.
2.2. Hypothesis
It is hypothesised that glucose and starch oligomers can be adsorbed onto nanocellulose fibres.
The inability of the human gastrointestinal tract to absorb cellulose will cause the glucose and
starch oligomers bound to the nanocellulose to be expelled rather than absorbed, hence removing
potential calories from foods consumed. It is also hypothesised that nanocellulose has the
potential to control the levels of cholesterol related elements in the human digestive tract. The
performance of different nanocellulose varieties is hypothesised to be primarily determined by the
surface area available for binding to glucose, starch and cholesterol.
2.3. Project Objectives
The objectives of this project were initially broadly defined as follows:
1. To design and investigate the effectiveness of an experimental system used to measure and
analyse the adsorption of glucose and starch onto nanocellulose.
2. To conduct a review of literature relating to the digestion of carbohydrates and cholesterol in
the human gastrointestinal tract.
As the project progressed, the main objective of the project was refined and can be defined as
follows:
- Through the review of literature and conducting laboratory experiments, investigate the
validity of the concept that nanocellulose can be used as a negative calorie and cholesterol
controlling food additive.
In conducting a literature review relating to the digestion of carbohydrates and cholesterol in the
human digestive system, we aimed to determine multiple characteristics of the system. Of specific
interest were the conditions under which glucose, starch and cholesterol are digested and
absorbed. Such conditions include the temperature, pH, enzymes required and location of
digestion and absorption in the gastrointestinal tract for the different components of ingested
food. We also aimed through our literature review to determine the retention time of glucose,
starch and cholesterol in regions of the gastrointestinal tract such as the stomach and the small
intestine. The primary outcome of achieving the objectives of this literature review were to
provide specific details of the conditions to which glucose, starch and cholesterol are subjected in
the human digestive system. This will allow for further experiments investigating the adsorption
of these molecules to nanocellulose to be analogous to reactions occurring in the human
gastrointestinal tract.
Through conducting laboratory experiments we aimed to gather data that was concordant with
literature and previous experiments, as well as determining and proving on a practical level, that
the concept of nanocellulose being used as a negative calorie food additive is valid. The results of
such experiments, whether proving or disproving the concept, will provide a basis for future
research in this area, saving time and money for future projects. The results of these experiments
will also provide insight into potential changes that could be made to the methodologies used in
this project, allowing for recommendations regarding the specifics of future works relating to
using nanocellulose as a negative calorie food additive.
The figure below illustrates a break down of the various areas that were researched in order to
achieve the objectives of this project as stated above.
Figure 2-3-1: Project Flow Chart
Cellulose
Energy
Monosaccharides
Glucose
Disaccharides
Sucrose
Polysaccharides
Starch
Fats
Cholesterol Triglycerides
3. Literature Review
Due to time constraints placed on this project it is difficult to investigate the entirety of the scope
experimentally. Therefore a literature review is necessary to give sufficient background to the
experimental work as well as explore avenues that would be too time intensive to conduct in the
laboratory.
3.1. Glucose
Glucose is essential to human life, providing energy to sustain physiological functions. It is readily
broken down to create ATP, an energy molecule, by either aerobic or anaerobic respiration. The
diet is the crucial source of glucose, where it is either directly absorbed from the food in the small
intestine or synthesised via the gluconeogenesis pathway from precursors obtained from the diet
(4).
Glucose is the only fuel used to any significant extent and is the sole energy source used by the
brain. Glycolysis, the process used to extract the chemical energy contained within the glucose
molecules, is an extremely important function within the body and malfunctions in this process
can lead to a variety of serious diseases. However, when too much glucose is ingested in the diet
it can also lead to the development of disorders like insulin resistance and diseases associated
with severe weight gain (5).
Diabetes has been linked with hyperglycemia, which has seen a recent increase due to the
increasing popularity of high energy density Western-style diets (6).
Although glucose is the building block of carbohydrates, there are also many other sources of
carbohydrates from which the body can gain energy.
3.2. Sucrose
Sucrose is a disaccharide consisting of two monosaccharides, glucose and fructose. These two
monosaccharides are condensed at their glycosidic groups and form a bond known as a glycosidic
bond, forming the disaccharide sucrose. Sucrose is commonly found around the house as table
sugar and is digested in the gastrointestinal tract by the enzyme sucrase, which catalyses the
hydrolysis of the glycosidic linkage of the sucrose molecule, breaking it down into its monomeric
components (7).
Figure 3-2-1: Sucrose, a Disaccharide of Glucose and Fructose (8)
Sucrose was used by Fernandez et al. in an investigation into the retention of fatty acid soaps
during paper recycling. In this experiment sucrose was used as a tracer molecule for a packed bed
experiment. The packed bed was filled with pulp fibres and sucrose was selected as a tracer
molecule due to the fact that it is unable to bind to cellulose (9).
3.3. Starch
Starch consists of two glucose polymers, amylose (a long, unbranched molecule) and amylopectin
(a highly branched molecule) (10). The structures of these polymers are depicted in Figure 3-3-1
and Figure 3-3-2 below. Starch is typically ingested in our diet in the following forms (11):
 Cereals: corn, oats and flour
 Root vegetables: potatoes, carrots, parsnips
 Rice and pasta
Figure 3-3-1: Structure of the Amylopectin Component of Starch (12)
Figure 3-3-2: Structure of the Amylose Component of Starch (12)
There is much energy to be gained from the ingestion of starch in the diet. However, unmodified
it is insoluble and requires the action of certain catalysts before it can be properly utilised by the
body.
3.4. α-Amylase
Complex carbohydrates, including starch, cannot be absorbed in the intestine in their native
states. Nearly all of the carbohydrates ingested must be first hydrolysed into their corresponding
monosaccharides (with the exception of a few disaccharides) before they can be absorbed. There
are hydrolytic enzymes that are present in the saliva and pancreatic secretions that are capable of
achieving this. The most abundant of these is 𝛼-amylase, which breaks links in the starch
molecule 𝛼-(1-4) bonds, in a random fashion to break down the starch constituents of amylose
and amylopectin (13) (14) (11) (10). Salivary 𝛼-amylase hydrolyses approximately 50% of starch in
the diet, however it has an optimum pH of around 7.0, causing it to be inactive once it reaches the
stomach. After the food passes through the stomach, pancreatic 𝛼-amylase is released in a much
larger quantity compared to the salivary 𝛼-amylase, which acts to break down the remaining
starch (11) (13). From previous research, 𝛼-amylase is the most commonly used hydrolytic
enzyme to mimic the break down of starch in vitro, which was the basis of investigating its activity
in this research project (14).
Even though there are many enzymes that facilitate digestion within the gastrointestinal tract,
there are some carbohydrates that are unable to be hydrolysed within the body to gain energy, a
property that this project aims to take advantage of.
3.5. Cellulose
Similar to starch, cellulose is a polysaccharide also consisting of glucose monomers and is the most
abundant polysaccharide produced in nature (12). Based on the fact that both starch and
cellulose are formed from the common building block of glucose monomers, we construct our
hypothesis that starch will actively bind to cellulose in the human gastrointestinal tract (15).
Cellulose is the fibre that supports plants, mostly found in cell walls. The glucose monomers that
make up cellulose are configured in such a way that cellulose is resistant to hydrolysis via the
hydrolytic enzymes present in the gastrointestinal tract, unlike starch (16). This means that
cellulose isn’t actually digested, but still plays an important role in providing bulk to stimulate
intestinal motility, preventing constipation (13). This property of cellulose is what allows us to
predict that starch or glucose bound to the cellulose will be excreted rather than digested.
Figure 3-5-1: Structure and Hydrogen Bond Interactions of Cellulose (12)
The previous sections of the literature review outline the underlying roles of starch, cellulose and
𝛼-amylase. We wish to analyse whether interactions between these molecules will affect the
outcomes of the project.
3.6. Interactions between Starch, Cellulose and Amylase
It is known that starch has the capacity to bind to cellulose. As starch and cellulose are both
polymers sharing a common monomer in glucose, it is thought that the binding mechanism is due
to surface interaction between the molecules. The amylose contained within starch has a very
similar structure to cellulose, it is characterised by 𝛼-1,4 linkages between glucose units whereas
cellulose is characterised by 𝛽-1,4 linkages between glucose monomers. This results in amylose
being a more flexible molecule, forming natural helical twists which can form a collapsed helix
under certain conditions while cellulose is more rigid and flat, giving strength properties to the
cellulose fibres (17).
As explained previously, starch consists of amylose and amylopectin. Van de Steeg et al. showed
that amylose binds preferentially to cellulose due to its smaller size and more linear structure.
Amylopectin was unable to penetrate the pores of the microcrystalline cellulose as it is a larger,
highly-branched molecule (18).
From experimental analysis of the kinetics of starch adsorption onto cellulose it has been found
that the adsorption mechanism follows Langmuir kinetics further confirming the importance of
surface interaction between the two molecules (19) (18).
As 𝛼-amylase is the main enzyme for breakdown of starch, there is particular focus on this enzyme
in this report. An important factor involved in the interaction of starch and 𝛼-amylase is the
surface area to volume ratio of the starch molecules (as it is much larger than the enzyme) and
therefore particle size (10). Another key variable affecting the starch and 𝛼-amylase interaction is
the degree or order of 𝛼-glucan chains of the starch, with 𝛼-amylase binding most readily to the
exposed/available amorphous 𝛼-glucan chains (20).
An objective of this project is to assess the use of cellulose to prevent the digestion of starch via a
surface binding mechanism. It is currently unknown how the interaction between 𝛼-amylase and
starch will affect the capacity of cellulose to maintain the bound starch on its surface, which will
require further investigation.
Although the experimental scope of this project is to evaluate the use of nanocellulose as a food
additive, in this literature review we have also investigated the use of alternative dietary
substances, which have positive health effects, performing a similar function to that of cellulose.
3.7. Fructans
Fructans are polysaccharides of fructose molecules and can be classified under two main types;
fructooligosaccharides and inulins. Fructooligosaccharides are fructan polymers of shorter chain
length, whilst the inulin types are of longer chain length. Typical foods that contain fructans
include wheat, onion, banana and leek (21).
Fructans are non-digestible carbohydrates and act as dietary fibres; they have been shown to have
positive health benefits, being classified as a prebiotic (22).
Unlike starch, they do not bind to other carbohydrates, however studies on inulin-type fructans in
animals and man have shown that they have the potential to reduce plasma levels of
triacylglycerols (TG). Inulin has also been linked to reducing levels of cholesterol in the
bloodstream. Inulin-type fructans have been shown to have a greater positive effect on the
reduction of TG levels than oligofructose (23).
Because fructans are non-digestible carbohydrates, they pass through the small intestine and
undergo the fermentation process within the large intestine, producing propionic acid. Increased
levels of propionic acid cause a reduction in liver lipogenesis, resulting in a lower hepatic secretion
rate of TG. It is thought that through this mechanism, fructans have the ability to reduce TG and
cholesterol levels as well as through the propionic induced inhibition of cholesterol synthesis and
modifications to bile acid metabolism (23).
The use of fructans were investigated in this report due to their functional characteristics of being
non-digestible, therefore not contributing to dietary energy intake, and their ability to reduce
plasma TG and cholesterol levels. Cholesterol is a focus point of this report due to the strong links
between high blood-cholesterol and serious health issues.
3.8. Cholesterol
High blood-cholesterol is an important risk factor for obesity and CVD (3) (2). Cholesterol is
transported around the body via the bloodstream in complexes known as lipoproteins, due to the
fact that cholesterol is a lipid and is therefore insoluble in water. There are two main forms of
lipoproteins, high-density lipoproteins (HDL) and low-density lipoproteins (LDL) (24). LDL’s carry
cholesterol to areas of the body where they are required, while HDL’s transport cholesterol back
to the liver and have a higher proportion of proteins. High LDL cholesterol levels are a health risk
associated with coronary heart disease and CVD, with build-up of LDL cholesterol in arteries being
a major cause of heart attack and stroke (25) (26) (24) (27). Although dietary cholesterol intake
should be regulated, the majority of dietary cholesterol is passed through the gastrointestinal
system with only approximately 20-50% being absorbed (25) (13). High blood-cholesterol levels
are mainly attributed to a high dietary intake of saturated fats, which are then synthesised into
cholesterol (25) (24).
Figure 3-8-1: Structure of the Sterol Cholesterol (13)
The major pathway for excretion of cholesterol from the body takes place in the liver and is via the
bile acid synthesis pathway (16) (26). Of the approximate 1 gram of cholesterol consumed by the
body each day, half of this is degraded to bile acids while biliary cholesterol excretion is
responsible for the loss of the remainder (26).
3.9. Bile Acids
Bile acids have several functions (16):
 Triglyceride assimilation
 Induction of bile flow
 Lipid transport
 Bile acid synthesis
 Water and electrolyte secretion
There are two classes of bile acids in the body; primary and secondary bile acids. Primary bile
acids (cholic acid and chenodeoxycholic acid) are synthesised by hepatocytes in the liver, while
secondary bile acids (deoxycholic acid and lithocholic acid) are formed by bacterial
dehydroxylation of primary bile acids in the intestines (13). Literature exists which suggests that
increased levels of secondary bile acids are a risk factor associated with colon cancer (28).
3.10. Significance of the Relationship between Bile Acids and Cholesterol
Experiments have determined that cellulose can aid in binding to secondary bile acids, allowing
them to be excreted as well as accelerating intestinal transit (due to higher faecal weight). This
minimises the time available for primary bile acids to be converted to secondary bile acids, thus
decreasing the risk of developing colon cancer (29).
Previous research has also suggested that added cellulose in the diet increases bile acid
production and excretion and therefore decreased cholesterol levels in the blood as well as
reducing lipid and TG levels (30) (31) (29) (32). For these reasons we have decided to analyse the
relationship between cellulose and cholesterol in conjunction with the glucose and starch
experiments (33).
3.11. Overview of the Human Gastrointestinal System
In this research project we will primarily focus on 3 major sections of the gastrointestinal system;
the stomach, the small intestine and the large intestine. However a larger focus will be on the
stomach and small intestine as the absorption of a majority of compounds occurs in the small
intestine (34).
3.11.1. Stomach
The stomach receives and can temporarily store food, its function is to partially digest food and
pump it through to the duodenum region of the small intestine. While food is contained in the
stomach, parietal juice (an acidic solution) and an alkaline solution are released from the mucous
cells of the stomach (16) (13). Hydrochloric acid is released as part of the acidic secretions.
Although hydrochloric acid can aid in breaking down muscle fibres and connective tissue, the main
purpose of its secretion is to lower the pH of the stomach. This allows for the enzymatic activation
of pepsin and more importantly kills harmful organisms, protecting the body from infection (16).
The pH of the stomach changes depending on what stage of the digestion cycle it is in. Typically
when there is food present within the stomach, the secretion of hydrochloric acid will lower the
pH down to around 1-2. However, after the food has been digested the stomach pH may increase
to 3-5. As the stomach is very flexible, the volume usually depends on the amount of material
present. The stomach can have a volume anywhere between 0.5-5 litres (16) (13). The retention
time of material within the stomach is highly dependent on many factors including the type and
amount of food. Food can remain in the stomach anywhere between 1-2 hours after which it is
pumped via muscular contractions into the duodenum. The rate of gastric emptying is dependent
on the volume of materials within the stomach, with a higher stomach volume corresponding to a
higher rate of gastric emptying (16). It should be noted that very few substances are absorbed in
the stomach and it is virtually impermeable to water. Some of the few substances that are
absorbed from the stomach are aspirin and ethyl alcohol (13).
3.11.2. Small Intestine
The small intestine is approximately 3.5 cm in diameter and about 6 metres long, of which the
duodenum occupies the first 25 cm (13). The duodenum is where the mixing of digestive juices
from the liver and the pancreas occurs and is also where bile acids are excreted. However,
intestinal juices are secreted along the entire length of the small intestine. Approximately 95% of
the water which enters the gastrointestinal tract is absorbed in the small intestine, as are glucose
and cholesterol (16) (13). The retention time of the small intestine is slightly longer than that of
the stomach, with typical times ranging between 105-135 minutes (16). Unlike the stomach, the
typical pH range of the small intestine is more neutral to alkaline, rather than acidic. This is
because the action of pancreatic enzymes and lipid absorption require alkaline pH (13).
After the food mass has passed through the small intestine where water and nutrients are
absorbed it continues on and enters the large intestine or colon.
3.11.3. Large Intestine
Compared to the small intestine the large intestine is relatively short, being only 1.5 metres in
length. However, it has a larger diameter of around 6 cm and spans from the end of the small
intestine (ileum) to the rectum where the material that remains is expelled from the body (16)
(13). The main function of the large intestine is to store faecal matter and regulate its release
from the body. The large intestine also acts to absorb water and electrolytes from the chyme, as
well as lubricating the passage for waste material to move through with ease (13). The retention
time of the large intestine is long when compared to that of the stomach and small intestine.
Although food can pass through the stomach and small intestine in less than 12 hours, remnants
of the food can remain in the large intestine for up to a week. However, the majority of it is
expelled by the 4th day after ingestion (13). Although the large intestine is still of interest in this
project, it will not be a major focus as the compounds we are placing emphasis on are not
absorbed in this region of the gastrointestinal tract.
3.12. Glucometry
Various methods exist for the quantification of glucose concentration, with common techniques
including High Performance Liquid Chromatography (HPLC), the Fehling test and enzymatic assays
(35). These methods, though effective in quantifying glucose concentration, are hindered by
disadvantages in that they can be expensive, time-consuming and technically difficult. Ideally
glucose concentration determination in a laboratory setting (as well as in a clinical setting) should
be inexpensive, fast, convenient and reliable.
Blood glucose monitors were developed in order to provide a method of glucometry for diabetics
that achieves an inexpensive, fast and convenient means of determining blood glucose
concentration. In recent studies these glucometers have been used in a laboratory setting in order
to measure glucose concentration in solutions other than blood. The Accu-Chek Performa Blood
Glucose Monitor was used by Sopade and Gidley (36) during their research into the kinetics of
starch digestion, and was also used by Blazek and Gilbert (14) when investigating the enzymatic
digestion of starch by α-amylase.
Two enzymes are commonly used for blood glucose monitors, namely glucose oxidase and glucose
dehydrogenase (35). These enzymes oxidise glucose molecules to gluconic acid and
gluconolactone respectively. The Accu-Chek Performa Blood Glucose Monitor is an example of a
glucometer that uses glucose dehydrogenase enzymes in order to determine the glucose
concentration of a sample. This glucometer uses test strips upon which glucose dehydrogenase is
immobilised. In the presence of the coenzyme pyrroloquinoline quinine, glucose dehydrogenase
oxidises glucose to gluconolactone which creates a DC signal that is converted to a digital display
of the glucose concentration in the solution on the glucometer screen. The Accu-Chek Performa
test strips require approximately 0.6 µL of solution and produce a response in approximately 5
seconds. The glucometer has a glucose concentration range of 0.6-33.3 mM, a temperature range
of 6-44oC and can be used at relative humidity ranging from 10-90% (36).
A comparison of blood glucose monitors in Australia (37) found that the glucometers available in
Australia all show acceptable precision when determining the glucose concentration in blood. The
accuracy and precision of some monitors was found to at times be compromised for glucose
standard solutions, suggesting that researchers need to be careful when using glucometry as a
method of determining glucose concentration in solutions which are not blood-based. A study
which examined the utility of blood glucose monitors in biotechnological applications (35)
determined that when using glucometers it is important to consider the pH, expected
concentration range and presence of other sugars when selecting a glucometer for the
determination of glucose concentration for biotechnological studies. The research of Sopade and
Gidley suggests that the use of glucometry can be extended to analysing the kinetics of starch
digestion (36).
3.13. Starch Quantification Techniques
The quantification of the amount of starch in solution has been conducted by various researchers
in the past (38) (39). Determination of the amount of starch that can adsorb to various materials,
such as glass and pulp fibres for example, has been investigated by determining the amount of
free starch in solution before and after introduction of the material to which the starch adsorbs.
The difference in the free starch levels quantifies the amount of starch that is bound to the
material.
Simple sugars, oligosaccharides and polysaccharides (such as starch) produce an orange-yellow
colour when they are exposed to phenol and concentrated sulphuric acid (40). By measuring the
absorbance of starch samples that have been exposed to the phenol-sulphuric acid technique at
490 nm, the concentration of the total starch in the sample can be determined using the Beer-
Lambert Law. This method for determining starch concentration is simple, rapid and sensitive,
using reagents which are stable and relatively cheap. The method requires only one standard
curve and the colours that are produced by the reaction of starch with phenol and sulphuric acid
are stable and permanent (40).
As previously discussed, starch contains two different branched molecules, namely amylose and
amylopectin. The phenol-sulphuric acid technique only quantifies the total starch concentration
of a solution and does not determine the amount of amylose or amylopectin in a sample. The
amount of amylose in solution can be determined by quantifying the iodine binding capacity of the
starch. When amylose in aqueous solution is exposed to iodine it forms a blue coloured helical
complex. By measuring the absorbance of this blue solution the Beer-Lambert Law can be used in
order to determine the concentration of amylose in the solution. By combining the iodine
technique and the phenol-sulphuric acid technique, the amylopectin concentration in solution can
also be determined as this is equal to the difference in concentration of starch and amylose (41).
3.14. Kinetics
The kinetics of adsorption and desorption of materials onto pulp fibres have been investigated by
other researchers. During their research into the adsorption and desorption kinetics of calcium
carbonate onto pulp fibres, Kamiti and Van De Ven modelled these kinetics with a modified
Langmuir equation (42). The same model equation was used by Saint-Cyr, Van De Ven and Garnier
when investigating the kinetics of paper yellowing inhibitors onto pulp fibres (43). The model
equation is shown below:
𝑑𝜃
𝑑𝑡
= 𝑘1(𝑛0 − 𝜃) − 𝑘2 𝜃 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 1
In the equation above, θ represents the fractional coverage of fibres by the adsorbed particles, k1
represents the rate of adsorption, k2 represents the rate of desorption and n0 represents the initial
concentration of adsorbing particles, divided by the maximum amount that can deposit in a unit
volume of suspension (42) (43).
The kinetics relating to the binding of starch by α-amylase have also previously been researched.
Warren, Butterworth and Ellis found in their study into the surface structure of starch that the
kinetics of pancreatic α-amylase binding to granular starch molecules could be modelled by
Freundlich enzyme kinetics (10).
4. Methodology
In order to achieve the objectives of this research project, the methodology detailed in the
following sections was carried out over a twelve week period.
4.1. Glucose to Nanocellulose Binding Experiments
In order to investigate the potential of glucose to adsorb to nanocellulose, we initially conducted a
literature search in order to determine if previous published works had found evidence of glucose
binding to nanocellulose. After conducting this literature review we carried out a series of
experiments using glucometry in order to measure glucose concentration and determine if glucose
adsorbs to nanocellulose. These experiments are briefly described below.
The glucometer used during these experiments was the Accu-Chek Performa Blood Glucose
Meter. As discussed previously in the Section 3.12, this glucometer uses test strips upon which
glucose dehydrogenase is immobilised. In the presence of the coenzyme pyrroloquinoline quinine,
glucose dehydrogenase oxidises glucose to gluconolactone which creates a DC signal which is then
converted to a digital display of the glucose concentration in the solution on the glucometer
screen. The Accu-Chek Performa test strips require approximately 0.6 µL of solution and produce
a response in approximately 5 seconds. The glucometer has a glucose concentration range of 0.6-
33.3 mM, a temperature range of 6-44oC and can be used at relative humidity ranging from 10-
90%.
Prior to conducting experiments investigating the adsorption capability of glucose onto
nanocellulose we first conducted a calibration experiment in order to find a correlation between
the glucose concentration reported by the glucometer and the known glucose concentration. In
order to conduct this experiment we first created a 15.07 mM glucose solution in 100 mL of
deionised water. We then measured the concentration of this solution with the Accu-Chek
Performa, taking repeated measurements approximately every 5 minutes for a duration of
approximately 30 minutes. The measurements were conducted by dipping the test strip of the
glucometer into the beaker containing the glucose solution. We repeated this experiment using a
2.02 mM glucose solution. The results of these experiments are discussed in Section 5.1.
Due to unexpected results produced from our calibration experiment, we repeated the calibration
experiment changing the methodology slightly each time. In all instances we made a 15 mM
glucose solution in 100 mL of deionised water. The first variation we made to the methodology
was to extract the glucose sample from the beaker using a clean syringe and then transferring the
sample by syringe to the glucometer test strip. This was conducted with the aim of collecting a
sample likely to be more indicative of the entire glucose solution, rather than only testing the
glucose solution at the surface. Unfortunately this did not eliminate the unexpected results
produced by the glucometer, which as explained in more detail in Section 5.1, was reporting a
continuous increase in glucose concentration with time, exceeding the known glucose
concentration.
Another modification to the method involved collecting the glucose solution from different
locations within the beaker of solution. This aimed to eliminate concentration spacial variation.
We also measured the concentration of the glucose solution in the presence and absence of the
magnetic stirrer, immediately after stirring, after waiting for the solution to settle after stirring and
when mixed with Bovine Serum Albumin (BSA). None of these methods were successful in
eliminating the increase in measured glucose concentration with time. We also attempted mixing
the 15 mM glucose solution with blood samples provided by APPI in an attempt to eliminate the
time variation.
Having attempted all of the above variations to the calibration experiment method, a 15 mM
glucose solution was created in 100 mL of deionised water and allowed to mix overnight. The
Accu-Chek Performa was then used to measure the glucose concentration and the increase in
glucose concentration was found to have been eliminated, allowing for a calibration curve to be
created as shown in Section 5.1.
Having successfully conducted the calibration experiment, the capability of glucose to bind to
nanocellulose was tested by again creating a 15 mM glucose solution and allowing it to mix
overnight. Once this mixing was complete, 3.726 g of VTT nanocellulose was added to the 15 mM
glucose solution and mixed overnight. 4 mL of the glucose and nanocellulose solution was then
transferred by syringe to a microtube, allowing for a titre experiment to be carried out.
This experiment involved taking 2 mL out of the “neat” microtube (i.e. the tube containing 4 mL of
the master solution) and adding it to a microtube containing 2 mL of deionised water. Once this 2
mL of the glucose and nanocellulose solution mixed with the water (making a diluted 4 mL
solution) 2 mL of this new solution was extracted and added to another microtube containing 2 mL
of deionised water. This procedure of dilutions was continued until a dilution which was one part
nanocellulose/15 mM glucose solution and 63 parts deionised water was created. The diluted
solutions in the microtubes were then analysed by the glucometer for glucose concentration.
These concentrations were then compared to the measured concentration of the 15 mM glucose
standard solution in order to determine if the addition of 3.726 g of VTT resulted in a reduction in
glucose concentration.
Having conducted the titre experiment with the solution containing 15 mM of glucose and 3.726 g
of VTT nanocellulose, another 15 mM glucose solution was created and 9.117 g of VTT added to it.
Having mixed this solution sufficiently the titre experiment outlined above was repeated for this
solution containing 9.117 g of VTT.
The experiments involving the addition of VTT to 15 mM glucose solutions were repeated, this
time using a 5 mM glucose master solution. To the 5 mM master solutions two different amounts
of VTT (namely 11.425 g and 22.94 g) were added in order to determine if at this lower glucose
concentration, the glucose would bind to the high volume of VTT.
At this point in time it was determined that the moisture content of the nanocellulose could be
impacting on the results, producing false positive readings in relation to the reduction of glucose
concentration. As a result the moisture content of VTT and Daicel nanocellulose, as well as the
moisture content of Tapioca Starch were determined. This was achieved by measuring a known
mass of each substance into a small aluminium plate and then placing the plate in an oven for
approximately two hours. During this time the materials became dried and were reweighed at the
end of the two hours. This allowed the determination of how much moisture the “un-dried” state
of each material contained. The results of this moisture content determination are reported in
Table 5-1-3 in Section 5.1.
Having determined the moisture content of various substances as described above, the titre
experiment previously conducted using the 15 mM and 5 mM master solutions was repeated for a
2 mM glucose master solution. In this instance 7.995 g of Daicel nanocellulose was added to the
glucose solution rather than VTT nanocellulose, due to the lower moisture content of Daicel. As a
control, 7.995 g of Daicel was also added to deionised water. The results of this experiment are
discussed in Section 5.1.
4.2. Starch to Nanocellulose Binding Experiments
From the literature review it is apparent that starch has the capacity to adsorb onto the surface of
cellulose. It was desired to design an experimental methodology to test these findings with
nanocellulose, having a much higher surface area.
As starch is insoluble in water at room temperature, to make a starch solution the starch must be
“cooked” or heated to weaken hydrogen bonds, allowing the starch molecules to swell and take
on water, allowing them to be dissolved. To prepare a stock starch solution for the following
experiments, 9 g of tapioca starch was added to 191 mL of deionised water in a heated vessel. The
temperature of the heated vessel was set at 80°C and a mixer was applied to the water-starch
solution to facilitate dissolution. The solution was left to mix and be heated until the viscosity
visually increased, and then decreased. Following this the solution was mixed for an additional 10
minutes before the heat and mixer were turned off.
Following preparation of the stock starch solution, the exact concentration of this solution needed
to be calculated. This was achieved following the procedure for moisture content determination
outlined in Section 4.1.
The method employed in order to determine the starch concentration was the sulphuric acid-
phenol method. When sulphuric acid and phenol are added to a starch solution, a brown colour is
created when starch is present. The higher the concentration of starch in solution the darker the
colour. Therefore spectrophotometry can be used to determine the concentration of starch in a
solution, however a calibration curve must first be constructed.
To construct the calibration curve for starch concentration using the sulphuric acid – phenol
method, the stock starch solution was used to make 10 different concentrations of starch by
dilution across the range 0-10 g/L. This range was chosen as it was found to have been used in
similar previous experiments. However, when these solutions were tested for absorbance at 490
nm in the spectrophotometer, it was observed that the maximum absorbance was reached at a
starch concentration of approximately 0.5 g/L. Therefore the method for constructing the
calibration curve was repeated for a concentration range of 0-0.5 g/L.
To make up the solutions required for use in the spectrophotometer, the following were added to
a 15 mL centrifuge tube:
 2mL starch solution
 125μL 80% Phenol solution
 5mL 98% Sulphuric acid
These solutions were allowed to sit for 10 minutes before being shaken vigorously and placed in a
water bath at 30°C for 10 minutes. An eppendorf tube was used to transfer approximately 3 mL of
the sulphuric acid – phenol assays into cuvettes to be analysed in the spectrophotometer at 490
nm. From the data gained from the spectrophotometer and the known concentration of starch
solutions a calibration curve was constructed.
To verify starch adsorption onto nanocellulose, four beakers were prepared with each containing
different starch concentrations according to Table 4-2-1 below:
Table 4-2-1: Various Starch Concentrations for Sulphuric Acid - Phenol Method
Beaker Starch Deionised water Daicel nanocellulose Starch concentration
1 0 mL 300 mL 1.207 g 0 g/L
2 0.7 mL 300 mL 1.207 g 0.1 g/L
3 1.4 mL 300 mL 1.207 g 0.2 g/L
4 2.09 mL 300 mL 1.207 g 0.3 g/L
The nanocellulose and water were added first and allowed to mix with a magnetic stirrer for
approximately 45 minutes. Following this the designated amount of stock starch solution was
added to the beakers and mixed for 45 minutes, allowing interaction between the starch and
nanocellulose. To measure the concentration of the free starch (not adsorbed onto
nanocellulose), 10 mL was taken from each beaker and placed into a centrifuge tube. These tubes
were centrifuged for 10 minutes at 5000 rpm, with the nanocellulose bound starch complexes
settling at the bottom of the tubes allowing the supernatant, or free starch, to be separated. 2 mL
of the supernatant was taken from each tube and used as the starch solution in the previously
described sulphuric acid – phenol assay. Absorbances from the spectrophotometer at 490 nm
were recorded and compared with values gained from the calibration curve data in order to
determine the starch concentration.
4.3. Effect of Starch Binding to Nanocellulose on α-Amylase Action Experiments
As mentioned previously in Section 3.6, α-amylase is the enzyme within the human body that is
responsible for the hydrolysis of starch molecules into glucose monomers. It is currently unknown
whether α-amylase has the ability to hydrolyse starch while it is bound to nanocellulose. Also if
this does indeed occur, whether the glucose monomers are released from the nanocellulose
following hydrolysis, negating the positive effects that are the basis of this project. Therefore an
experimental methodology was required to determine whether the action of α-amylase would be
an issue.
Three reactors were used to determine the effect of 𝛼-amylase on starch adsorption onto
nanocellulose, they are described in Table 4-3-1 below:
Table 4-3-1: Reactor Contents Used in α-amylase Experiments
Reactor 43g/L Starch Solution Deionised water Daicel nanocellulose
1 1.4 mL 300 mL 0 g
2 1.4 mL 300 mL 1.207 g
3 1.4 mL 300 mL 2.414 g
Starch, deionised water and nanocellulose were added to Reactors 2 & 3 according to Table 4-3-1
above and were allowed to mix overnight using a magnetic stirrer. When these were thoroughly
mixed, starch and deionised water were added to Reactor 1 and allowed to mix with a magnetic
stirrer for approximately 45 minutes. Less mixing time was required for Reactor 1 as there was no
nanocellulose present, which takes a significant amount of time for the fibres to swell in the
solution and become properly dispersed. After this, the reactors all had the same concentration of
starch, which was calculated to be 0.2 g/L.
Initial glucose measurements were taken from all three reactors using the Accu-Chek Performa
Glucose Meter described in Section 4.1. Then the reactors were placed in a water bath at 37°C to
simulate temperature within the human body. Following this, 100 μL of α-amylase was added to
all three reactors, which was determined to be an appropriate amount from reviewing relevant
literature. Glucose concentration was then measured at regular intervals to measure changes in
glucose concentration arising from starch digestion by α-amylase.
According to the hypothesis it was expected that:
- The glucose concentration in Reactor 1 will increase, as the starch won’t be bound to
any nanocellulose, leaving it free to be hydrolysed by 𝛼-amylase to release glucose
monomers.
- Reactor 2 will either show a slight increase in glucose concentration or no increase in
glucose concentration, as the starch would be bound to the nanocellulose.
- Reactor 3 having the highest concentration of nanocellulose will show the smallest
increase in glucose concentration or no rise at all due to the amount of nanocellulose in
the reactor.
4.4. Literature Review
A main component of this report is a review of current literature to determine the current state of
knowledge surrounding the binding of nanocellulose to carbohydrates and fats, as well as possible
areas for further investigation and continuation of the project. A diverse range of sources was
accessed whilst conducting the literature review with many of the Monash University Library
Databases being used. All references used in this project can be found within Section 8 of this
report.
5. Key Results and Findings
Having conducted the literature review as shown in Section 3 and carried out the experimental
work as described in Section 4, we were able to produce a large volume of results and made
multiple findings. The key results and findings from our review of literature and our experimental
work are discussed in the sections below.
5.1. Glucose Binding to Nanocellulose
In order to determine the ability of glucose to bind to nanocellulose, initially an extensive search
of literature was conducted. This research aimed to identify previous works investigating the
binding of glucose monomers to nanocellulose or similar materials, allowing us to conduct similar
experiments in order to test our hypothesis that glucose will bind to cellulose. The search of
literature yielded no results, therefore as far as we could determine this is the first documented
investigation into the adsorption of glucose monomers onto nanocellulose.
Having conducted the search of literature, we designed laboratory scale experiments as described
in Section 4.1 of this report in order to investigate the adsorption of glucose monomers to
nanocellulose. These experiments involved the use of glucometry in order to measure glucose
concentration. Specifically, the Accu-Chek Performa Blood Glucose Meter was used in order to
determine the concentration of glucose in solution. In order to conduct our experiments with the
glucometer we first attempted to create a standard curve. The first standard solution that we
attempted to measure with the glucometer was a glucose solution with a known concentration of
15 mM. Table 5-1-1 below shows the measured glucose concentration using the Accu-Chek
Performa Blood Glucose Monitor.
Table 5-1-1: Measured Glucose Concentration with Time for 15.07mM Glucose Solution
Measurement Time (Minutes) Measured Glucose Concentration (mM)
0 5.9
2 8.3
6 11
10 12.8
15 14.9
20 16.3
25 17.9
30 19.7
33 21.1
Measurements were taken over time with the hope of determining the steady-state measured
concentration. Unfortunately, as can be seen in Table 5-1-1 steady-state was not achieved in the
first 33 minutes of this experiment. In fact it can be seen that the measured concentration
continues to increase, even after having exceeded the expected steady-state value of 15.07 mM.
The results shown in Table 5-1-1 are also illustrated in graphical form in Figure 5-1-1.
Figure 5-1-1: Measured Glucose Concentration vs. Time for 15.07 mM Standard Solution
Due to the unexpected results using the 15.07 mM standard solution, we repeated the
measurements for a 2.02 mM standard glucose solution. In this instance five measurements with
the glucometer were taken for each time point, allowing for an average measured glucose
concentration to be determined. It was expected that the measured glucose concentration would
reach a steady state at approximately 2.02 mM after a given period of time, however as can be
seen in Table 5-1-2 and Figure 5-1-2 as time progressed the measured concentration continued to
increase beyond the expected value. This result was also seen for the 15.07 mM standard solution
as can be seen by referring to Figure 5-1-1.
0
5
10
15
20
25
0 5 10 15 20 25 30 35
MeasuredGlucoseConcentration(mM)
Time (mins)
Measured Glucose Concentration vs. Time - 15mM Standard Solution
Table 5-1-2: Measured Glucose Concentration vs. Time (2.02mM Glucose Standard Solution)
Time (min) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average Standard Deviation
2 Low Low Low Low Low N/A N/A
4 0.7 0.7 0.7 0.7 0.7 0.7 0
7 0.8 0.8 0.9 0.8 0.8 0.8 0.05
10 1.0 1.0 0.9 0.9 1.1 1.0 0.08
15 1.2 1.3 1.3 1.2 1.3 1.3 0.05
20 1.5 1.5 1.6 1.7 1.7 1.6 0.1
25 1.7 1.9 1.7 1.9 1.9 1.8 0.11
30 1.9 2.1 2.1 2.1 2.1 2.1 0.09
37 2.3 2.4 2.4 2.4 2.4 2.4 0.04
50 3.0 2.9 2.9 3.1 3.0 3.0 0.08
The average measured glucose concentration for each time point shown in Table 5-1-2 above is
plotted against time in Figure 5-1-2 below.
Figure 5-1-2: Average Measured Glucose Concentration vs. Time (2.02mM Glucose Standard Solution)
The variation of glucose concentration with time was unexpected, with the trends showing
measured concentration using the Accu-Chek Performa Glucose Monitor increasing well beyond
the known glucose concentration. In an attempt to rectify this unexpected result the supplier of
the glucometer was contacted and previous published works that had used glucometry for glucose
concentration determination were consulted. As a result it was determined that the unexpected
results may have arisen due to the fact that the glucometer was designed for measuring blood
glucose and therefore glucose solutions lacking the other elements of blood (i.e. cells, proteins
etc.) could yield inaccurate results.
0.0
0.5
1.0
1.5
2.0
2.5
3.0
3.5
0 10 20 30 40 50 60
MeasuredGlucoseConcentration(mM)
Time (mins)
Average Measured Glucose Concentration vs. Time - 2.02mM Standard
Solution
Further to these enquiries, we also trialled many different experiments in an attempt to stop the
variation of measured glucose concentration with time. Such experiments included modifying the
method of transferring the glucose solution to the glucometer, varying the location within the
beaker of glucose solution from which the sample was tested, taking samples with the magnetic
stirrer present and with the stirrer absent and trialling different glucose solution concentrations.
The results of these experiments all consistently displayed a continuous increase in glucose
concentration with time.
In a further attempt to eliminate the increasing measured glucose concentration with time, we
added blood to the glucose solution in order to determine if using the glucometer on a blood
solution would yield results that were consistent with expectations. This addition of blood
stabilised the variation of glucose concentration with time, suggesting that the blood glucose
meter was working as the supplier reported it should. This therefore suggested that as the
supplier stated, the unexpected results being reported by the glucometer may be due to the fact
that the meter is designed for blood samples and not for glucose solutions. This does not however
explain how previous works were successful in using blood glucose meters as a method for
determining glucose concentrations in solution.
It was hypothesised that adding Bovine Serum Albumin (BSA) to glucose solutions could eliminate
the increasing measured concentration by making the solutions closer to the composition of blood
due to the addition of proteins. BSA was therefore added to glucose solutions of varying
concentration and the glucometer was used to measure the glucose concentration over a three
hour period. The results of this experiment found that the addition of BSA did not stop the
increase in measured glucose concentration with time, with a steady-state measured
concentration not being achieved and the known concentration being well exceeded by the
glucometer concentration reading.
It was determined that if the glucose solution was left to mix overnight that a steady state
measured glucose concentration was achieved, albeit well above the known concentration. This
did however allow us to produce a standard curve for the concentration measured with the Accu-
Chek Performa Blood Glucose Meter, as is shown in Figure 5-1-3 below. Figure 5-1-3 shows the
standard curve produced having used the titre experiment outlined in Section 4.1 using a glucose
master solution with a concentration of 15 mM. This figure shows the measured concentration to
be consistently four times higher than the known glucose concentration.
Figure 5-1-3: Glucose Measured Concentration Standard Curve - 15mM Glucose Master Solution
Having determined the standard curve as shown above, we repeated the experiment as is outlined
in Section 4.1, this time making master solutions of 15 mM glucose mixed with 3.726 g and 9.117 g
of VTT nanocellulose. The measured glucose concentration in these nanocellulose/glucose
solutions could then be compared to the standard curve results, which represent the result for the
glucose solution in the absence of nanocellulose. It would therefore be hypothesised that if the
glucose had bound to the nanocellulose that the measured glucose concentration should be lower
in the solution that contains nanocellulose. Figure 5-1-4 on the following page shows the results
of this experiment.
The trends shown in Figure 5-1-4 show that when 3.726 g of VTT was added to the 15 mM glucose
solution, the glucose concentration as measured by the glucometer was very similar to that of the
standard solution (i.e. the solution containing no VTT). This was true for all known glucose
concentrations, except for higher concentrations which recorded a slightly higher measured
glucose concentration when 3.726 g of VTT was added. This result was not expected, as it was
anticipated that the addition of VTT nanocellulose would reduce the measured glucose
concentration. However, due to the lack of precision of the glucometer and the high experimental
error associated with its measurements, the increase in measured glucose concentration noted for
the solution containing 3.726 g of VTT was likely due to experimental error. Therefore it is more
likely that the glucose concentration of this solution is roughly the same as that of the glucose
standard solution. It can be concluded from this result that the addition of 3.726 g of VTT did not
result in a reduction in glucose concentration, hence suggesting that glucose did not bind to the
VTT nanocellulose.
0
5
10
15
20
25
30
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
MeasuredGlucoseConcentration(mM)
Known Glucose Concentration (mM)
Measured Glucose Concentration on Accu-Chek vs Known Glucose
Concentration
Figure 5-1-4: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 15mM Glucose
Master Solution
Figure 5-1-4 also shows that the addition of 9.117 g of VTT to the 15 mM master solution results in
a slight reduction in measured glucose concentration for most known concentrations measured.
Upon first inspection this suggests that the addition of such a mass of VTT has resulted in a
reduction in glucose concentration, hence suggesting that glucose has adsorbed onto the VTT.
However as can be seen by referring to Table 5-1-3 below, VTT has a moisture content of 96.44%
and therefore when adding 9.117 g of VTT we are in fact only adding 0.327 g of cellulose and 8.79
g of water. Given that the solution to which the VTT was added only had a volume of 100 mL
(approximately 100 g of water), this addition of 8.79 g of water would be expected to result in a
decrease in the concentration of glucose. Therefore the reduction in measured glucose
concentration seen in Figure 5-1-4 is likely due to the addition of water and therefore cannot be
conclusively linked to the binding of glucose to the added nanocellulose.
Table 5-1-3: Moisture and Solids Content of Starch and Cellulose Materials Used
Tapioca Starch VTT Cellulose Daicel Cellulose
Solid Content 88.04% 3.56% 24.86%
Moisture Content 11.96% 96.44% 75.14%
Figure 5-1-3 and Figure 5-1-4 above represent the results of the experiments using a 15 mM
glucose master solution, the methodologies of which are discussed in Section 4.1. These
experiments were repeated using a lower glucose concentration master solution of 5 mM, in order
to determine if lowering the known glucose concentration would result in measureable binding of
0
5
10
15
20
25
30
35
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
MeasuredGlucoseConcentration(mM)
Known Glucose Concentration (mM)
Measured Glucose Concentration on Accu-Chek vs Known Glucose
Concentration (15mM) - Effect of VTT Nanocellulose
15mM Glucose
Standard Solution
3.726g VTT Added to
15mM Glucose
Standard Solution
9.117g VTT Added to
15mM Glucose
Standard Solution
glucose to the VTT. The results of these experiments using a 5 mM master solution are shown in
Figure 5-1-5 below.
Figure 5-1-5: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 5mM
Glucose Master Solution
The results shown above suggest that adding VTT nanocellulose to the glucose solution resulted in
a reduction in free glucose (the glucose measured by the glucometer). However, this reduction
corresponds to the reduction in glucose concentration expected due to the amount of water
added with the VTT nanocellulose. Adding 22.94 g of “wet” VTT actually translates to adding
approximately 22.12 g of water and only 0.87 g of “dry” VTT. Therefore, as was the case for the 15
mM glucose solution experiments, these results suggest the addition of VTT to a glucose solution
does not result in a decrease in glucose concentration, hence suggesting that glucose does not
adsorb to VTT nanocellulose.
The experiments outlined above for 15 mM and 5 mM glucose master solutions were repeated for
a 2.02 mM glucose solution. For these experiments we added Daicel nanocellulose rather than
VTT due to the lower moisture content of the Daicel, as is highlighted in Table 5-1-3. The resulting
solution was very viscous and when repeating the titre experiment the glucometer was unable to
read the higher concentrations and gave “LO” results for the lower concentrations. This is
highlighted in the Table 5-1-4 on the following page.
0
2
4
6
8
10
12
14
0.0 1.0 2.0 3.0 4.0 5.0 6.0
MeasuredGlucoseConcentration(mM)
Known Glucose Concentration (mM)
Measured Glucose Concentration on Accu-Chek vs Known Glucose
Concentration in Water (5mM)
5mM Glucose
Standard Solution
11.425g VTT
Added to 5mM
Glucose Standard
Solution
22.94g VTT Added
to 5mM Glucose
Standard Solution
Table 5-1-4: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 2mM Glucose
Master Solution
Known Glucose
Concentration (mM)
Measured Glucose Concentration
(mM) - Standard Solution
Measured Glucose Concentration
(mM) - 7.995g Daicel Added
2.05 4.92 ERROR
1.03 2.38 ERROR
0.51 1.18 0.72
0.26 0.66 LO
0.13 LO LO
0.06 LO LO
0.03 LO LO
The error reported in the table above was due to the high viscosity of the solution. The figure on
the left below shows the solution of Daicel Nanocellulose and glucose. As can be seen this is a
very viscous solution. It was suggested that the viscosity could be indicative of a binding of the
nanocellulose with the Daicel, however we hypothesised that the high viscosity was merely due to
the swelling of the Daicel. In order to test this we made a solution with the same concentration of
Daicel in water, with no glucose. This solution is seen in the middle figure below. As can be seen
it has the same viscosity as the Daicel and Glucose solution shown in the figure on the left. The
figure on the right allows comparison of the two solutions. Our hypothesis was therefore
validated and it was assumed that the high viscosity is due to the swelling of the Daicel, not due to
the interaction between the Daicel and the glucose.
Figure 5-1-6: A) (Left) Daicel and Glucose Solution. B) (Middle) Daicel Solution. C) (Right) Comparison of
Daicel + Glucose Solution and Daicel Solution
Overall, our investigation into the interaction of glucose and nanocellulose found no conclusive
evidence that glucose can adsorb onto cellulose. This is however only true for cellulose and
nanocellulose in unmodified states and further research into the interaction of glucose with
modified cellulose materials needs to be conducted in order to determine if such modifications
could enable glucose to bind to cellulose materials.
5.2. Sucrose Binding to Nanocellulose
From literature it was found that sucrose does not adsorb onto cellulose fibres as it has been used
as an inert tracer in a packed bed of cellulose fibres in previous experimental work (9). Therefore
no experimental work was conducted in this area, saving time to focus on other points. It would
be advantageous to investigate chemical modification of nanocellulose to facilitate adsorption of
sucrose onto the surface.
5.3. Starch Binding to Nanocellulose
By conducting the sulphuric acid – phenol method described in Section 4.2, a calibration curve
relating absorbance and starch concentration was constructed and can be seen in Figure 5-3-1
below.
Figure 5-3-1: Calibration Curve Constructed for the Sulphuric Acid - Phenol Starch Concentration
Determination Method Using an Absorbance of 490nm
The calibration curve achieved an R2 value of 0.9834, which comparing to literature was
determined to be within the required error range. From this curve we were able to relate the
absorbance values gained from the UV-Vis spectrophotometer to starch concentration using the
equation y=13.463x+0.1066. Where y is the absorbance at 490 nm and x is the corresponding
concentration of starch in solution. This information allowed the following results to be obtained
to test starch adsorption on nanocellulose.
y = 13.463x + 0.1066
R² = 0.9834
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
0 0.05 0.1 0.15 0.2 0.25 0.3 0.35
Absorbance
Starch Concentration (g/L)
Phenol-Sulphuric Acid Determination of Starch Concentration -
Standard Curve
Figure 5-3-2: Comparison of Initial Starch Concentration and Starch Concentration after the Addition of
Daicel Nanocellulose for Initial Starch Concentrations Ranging from 0-0.3g/L
It can be seen from Figure 5-3-2 above that overall the addition of Daicel nanocellulose related to
a reduction in starch concentration. As the same amount of nanocellulose was added to each
beaker, the greatest effect was in the beaker with the highest initial starch concentration of 0.3
g/L. However a reduction was also realised in beakers 2 & 3, showing that the greatest relative
effect is noticed at higher initial starch concentrations. This suggests that the nanocellulose still
had more binding capacity and was not yet saturated with starch. However the starch was not
reduced to a concentration of zero, which suggests that nanocellulose concentration is also a
factor and a state of equilibrium between bound and free starch is achieved in the solution.
From these results we were successful in confirming the hypothesis that starch could be adsorbed
onto nanocellulose. Following on from this we wished to investigate the action of α-amylase and
whether it would have the capacity to reverse the effects that were established by the results
discussed above.
0
0.05
0.1
0.15
0.2
0.25
0.3
1
2
3
4
StarchConcentration(g/L)
Beaker
Starch Adsorption on Nanocellulose
Starch + nanocellulose
Initial Starch Solution
5.4. Effect of Starch Binding to Nanocellulose on α-Amylase Action
As can be seen in Table 5-4-1 below, there were no conclusive results achieved from the regular
glucose concentration readings taken by the Accu-Chek Performa. Before the α-amylase was
added to the reactors they showed a glucose concentration of “LO” on the glucometer, denoting a
reading below the minimum detectable concentration of 0.6 mM.
Table 5-4-1: Measured Glucose Concentrations over Time for Alpha-Amylase Experiment
Time (min) Glucose Concentration (mM)
Reactor 1 Reactor 2 Reactor 3
0 LO LO LO
30 LO LO LO
60 LO LO LO
120 LO LO LO
180 LO LO LO
240 LO LO LO
24 hours LO LO LO
After measuring the glucose concentration at regular intervals up to 24 hours after the α-amylase
was added to the reactors, it was observed that there was no apparent rise in glucose
concentration as all the readings were still “LO”. However, this does not mean that the glucose
concentration didn’t increase, as it is possibly it could have risen from 0.2 mM to 0.5 mM, for
example. However we cannot say with conviction that the glucose concentration increased due to
it being undetected by the glucometer.
It would be advantageous to conduct further investigation in this area as the interactions between
starch, nanocellulose and α-amylase are important in the context of this project.
6. Conclusions and Recommendations
Having conducted this research project we have come to multiple conclusions regarding the
potential application of nanocellulose as a negative calorie food additive.
Conducting an extensive review of literature it was determined that no literature exists on the
topic of the adsorption of the monosaccharide glucose to cellulose. The experiments that we
conducted produced results concluding that glucose does not adsorb to nanocellulose.
An extensive review of literature was also conducted regarding the adsorption of sucrose onto
cellulose. It was concluded from the previous works discovered in this investigation of published
literature that the disaccharide sucrose does not bind to nanocellulose.
A large amount of literature was found regarding the binding of starch to cellulose. Our
experiments confirmed our hypothesis that starch adsorbs to the surface of nanocellulose. We
also conducted experiments investigating the effect that α-amylase has on starch bound to
nanocellulose. We were unable to determine if α-amylase was hydrolysing the nanocellulose
bound starch from these experiments, hence these experiments were inconclusive.
A literature review of the effect of nanocellulose on cholesterol levels was also conducted, with
this review suggesting that nanocellulose can regulate blood cholesterol levels. This regulation is
not achieved through the binding of cholesterol to nanocellulose, but rather due to the fact that
increased nanocellulose levels in the diet increases faecal mass, in turn increasing bile acid
production, ultimately resulting in the breakdown of cholesterol and reduction in blood
cholesterol levels. Nanocellulose in the diet can also be linked to the prevention of colon cancer
due to the fact that it binds to secondary bile acids as well as increasing faecal mass, thus reducing
levels of secondary bile acids present in the colon, which has been linked to colon cancer.
Literature relating to the effect of fructans on blood cholesterol levels was also researched as part
of this project. From this review of literature it was concluded that fructans ferment in the colon
producing propionic acid, a chemical that inhibits cholesterol synthesis and lipogenesis in the liver.
Fructans were also found to be able to bind to triglycerides. Therefore it was concluded from this
literature review that fructans have the ability to reduce both cholesterol and triglyceride levels in
the blood.
Based on the conclusions drawn from the experiments conducted and literature reviewed
throughout this project, multiple recommendations for future works have been made.
Firstly, regarding the adsorption of glucose and sucrose onto nanocellulose, it is important to note
that the experiments that have found that glucose and sucrose do not bind to nanocellulose have
only been conducted using nanocellulose in a native form. It is therefore recommended that
nanocellulose be chemically modified in order to alter its functionality, and experiments be
conducted to determine whether glucose and sucrose will bind to this modified nanocellulose.
The experiments regarding the effect that α-amylase action has on starch binding to nanocellulose
produced inconclusive results. These results were deemed to be inconclusive due to the lack of
sensitivity of the glucometry technique used for analysis of samples. It is therefore recommended
that these experiments be repeated, however rather than using glucometry a more sensitive
analytical technique such as high performance liquid chromatography should be employed.
As previously discussed, this project found literature suggesting that nanocellulose and fructans
could, in theory, result in a reduction in cholesterol and triglyceride levels in the blood. Our
project did not however, test this experimentally and it is therefore recommended that future
works experimentally investigate the use of fructans and nanocellulose to reduce cholesterol and
triglyceride levels.
In conducting this research project we were able to achieve our objective of investigating the use
of nanocellulose as a negative calorie and cholesterol controlling food additive. Although not all of
our results supported our hypothesis, many did, and those that didn’t based on these preliminary
experiments, may prove to align better with our hypothesis if further experiments are conducted.
Therefore, overall our project was a success and the use of nanocellulose as a negative calorie and
cholesterol controlling food additive still remains a valid proposal, however requires further
investigation.
7. Acknowledgements
We would like to express our gratitude to Professor Gil Garnier, for his guidance and feedback
throughout this project. We would also like to thank Mr Scot Sharman and Dr Heather McLeish for
their continued assistance and advice while in the APPI laboratories.
8. References
1. Childhood obesity: a new pandemic of the new millenium. Kimm, S. Y. & Obarzanek, E. 2002,
Pediatrics, Vol. 110, pp. 1003-1007.
2. Childhood Obesity. Miller, J., Rosenbloom, A. & Silverstein, J. 9, s.l. : The Endocrine Society,
2004, The Journal of Clinical Endocrinology & Metabolism, Vol. 89, pp. 4211-4218.
3. Obesity and Cholesterol in Japanese, French and U.S. Children. Bingham, M. O., Harrell, J. S.,
Takada, H., Washino, K., Bradley, C., Berry, D., Park. H. & Charles, M. A. 4, August 2009, Journal
of Pediatric Nursing, Vol. 24, pp. 314-322.
4. Evolution of Glucose Utilization: Glucokinase Regulator Protein. Irwin, D. M. & Tan, H. s.l. :
Elsevier, 2014, Molecular Phylogenetics and Evolution, pp. 195-203.
5. Devlin, T. M. Textbook of Biochemistry with Clinical Correlations. 5th. New York : Wiley-Liss,
2002.
6. Glucose Homeostasis can be Differentially Modulated by Varying Individual Components of a
Western Diet. Forbes, J. M., Cowan, S. P., Andrikopoulos, S., Morley, M. L., Ward, L. C., Walker, K.
Z., Cooper, M. E. & Coughlan, M. T. 2013, Journal of Nutritional Biochemistry, pp. 1251-1257.
7. Hirschmuller, H. Principles of Sugar Technology. Principles of Sugar Technology. s.l. : Elsevier
Publishing Company, 1959, pp. 1-17.
8. Jacobsonka. [Online] 29 March 2014. http://jacobsonka.blogspot.com.au.
9. Retention of Fatty Acid Soaps During Recycling. Part I: A Study Using PAcked Beds of Pulp Fibers.
Fernandez, C. & Garnier, G. 1997, Journal of Pulp and Paper Science, pp. J143-152.
10. The surface structure of a complex substrate revealed by enzyme kinetics and Freundlich
constants for alpha-amylase interaction with the surface of starch. Warren, F. J., Butterworth, P. J.
& Ellis, P. R. 2013, Biochimica et Biophysica Acta, Vol. 1830, pp. 3095-3101.
11. McMichael, H. B. Adsorption of Carbohydrates. [book auth.] I. & Sladen, G. E. McColl.
Intestinal Absorption in Man. London : Academic Press, 1975, pp. 99-142.
12. Chemical Structure Analysis of Starch and Cellulose Derivatives. Mischnick, P. & Momcilovic, D.
2010, Advances in Carbohydrate Chemistry and Biochemistry, Vol. 64, pp. 118-184.
13. Smith, M. E. & Morton, D. G. The Digestive System: Basic Science and Clinical Conditions. 2nd
Edition. London : Elsevier, 2010. pp. 51-152.
14. Effect of Enzymatic Hydrolysis on Native Starch Granule Structure. Blazek, J. & Gilbert, E. P. 12,
2010, Biomacromolecules, Vol. 11, pp. 3275-3289.
15. Engineering a bifunctional starch-cellulose cross-bridge protein. Levy, I., Paldi, T. & Shoseyov,
O. s.l. : Elsevier, 2004, Biomaterials, Vol. 25, pp. 1841-1849.
16. Sanford, P. A. Digestive System Physiology. 2nd Edition. London : Edward Arnold, 1992.
17. Kearney, R. L. & Maurer, H. W. Starch and Starch Products in Paper Coating. Atlanta : TAPPI
Press, 1990.
18. Adsorption of Cationic Potato Starch on Microcrystalline Cellulose. van de Steeg, H. G. M., de
Keizer, A., Cohen-Stuart, M. A. & Bijsterbosch, B. H. 1993, Colloids and Surfaces A:
Physiochemical and Engineering Aspects, pp. 91-103.
19. Cationic Starch Adsorption by Cellulose: I. Nedelcheva, M. P. & Stoilkov, G. V. 1978, Journal of
Colloid and Interface Science, pp. 475-482.
20. Binding Interactions of alpha-amylase with Starch Granules: The Influence of Supramolecular
Structure and Surface Area. Warren, F.J., Royall, P. G., Gaisford, S., Butterworth, P. J. & Ellis, P. R.
2011, Carbohydrate Polymers, pp. 1038-1047.
21. Introducing Inulin-Type Fructans. Roberfroid, M. B. 2005, British Journal of Nutrition, pp. 13-
25.
22. Effects of Fructans-Type Prebiotics on Lipid Metabolism. Delzenne, N. M. & Kok, N. 2001, The
American Journal of Clinical Nutrition, pp. 456-458.
23. Effects of Inulin-Type Fructans on Lipid Metabolism in Man and Animal Models. Beylot, M.
2005, British Journal or Nutrition, pp. 163-168.
24. Freeman, M. W. & Junge, C. The Harvard Medical School Guide to Lowering Your Cholesterol.
Boston : McGraw-Hill, 2005.
25. Clark, M. L. & Harries, J. T. Absorption of lipids. [book auth.] I. & Sladen, G. E. McColl.
Intestinal Absorption in Man. London : Academic Press, 1975, pp. 187-215.
26. Pathways of cholesterol removal via bile acid synthesis and biliary cholesterol excretion in man.
Schwartz, C. C., Vlahcevic, Z. R. & Swell, L. October 1980. s.l. : MTP Press Limited, October 1980,
Bile Acids and Lipids, pp. 79-91.
27. Managing the residual cardiovascular disease risk associated with HDL-cholesterol and
triglycerides in statin-treated patients: A clinical update. Reiner, Z. 2013, Nutrition, Metabolism &
Cardiovascular Diseases, Vol. 23, pp. 799-807.
28. Effects of konjac glucomannan on putative risk factors for colon carcinogenesis in rats fed a
high-fat diet. Wu, W. T. & Chen, H. I. 2011, Journal of Agricultural and Food Chemistry, Vol. 59, pp.
989-994.
29. Cholesterol reducing and bile-acid binding properties of taioba (Xanthosoma sagittifolium) leaf
in rats fed a high-fat diet. Jackix, E. A., Monteiro, B. D., Raposo, H. F. & Amaya-Farfan, J. 2013,
Food Research International, Vol. 51, pp. 886-891.
30. Changes in cholesterol accumulation and steroid excretion in response to cellulose, alfalfa or
oats in cholesterol-fed rats. Kelley, M. J., Thomas, J. N. & Story, J. A. 1992, Nutrition Research,
Vol. 12, pp. 509-518.
31. Gallaher, D. D., Hassel, C. A. & Lee, K. J. Lowering cholesterol levels using water soluble
cellulose ethers. 5721221 24 Feb 1998.
32. Particle Size Reduction Effectively Enhances the Cholesterol-Lowering Activities of Carrot
Insoluble Fiber and Cellulose. Chou, S. Y., Chien, P. J. & Chau, C. F. 22, 2008, Journal of Agriculture
and Food Chemistry, Vol. 56, pp. 10994-10998.
33. Creating the 'dis-ease' of high cholesterol: A sociology of diagnosis reception analysis.
Jovanovic, M. 2014, Social Science & Medicine, Vol. 101, pp. 120-128.
34. In vitro human digestion models for food applications. Hur, S. J., Lim, B. O., Decker, E. A. &
McClements, D. J. 2011, Food Chemistry, Vol. 125, pp. 1-12.
35. The Utility of Blood Glucose Meters in Biotechnological Applications. FitzGerald, J and
Vermerris, W. 2005, Biotechnological Applications in Biochemistry, Vol. 41, pp. 233-239.
36. A Rapid in vitro Digestibility Assay Based on Glucometry for Investigating Kinetics of Starch
Digestion. Sopade.P.A., Gidley.M.J. 2009, Starch/Starke, Vol. 61, pp. 245-255.
37. A Comparison of Blood Glucose Meters in Australia. Cohen, M, et al. 2006, Diabetes Research
and Clinical Practice, Vol. 71, pp. 113-118.
38. Adsorption of Modified Starches on Porous Glass. Shirazi, M, Van De Ven, G and Garnier, G.
2003, Langmuir, pp. 10829-10834.
39. Adsorption of Modified Starches on Pulp Fibres. Shizari, M, Van De Ven, G and Garnier, G.
2003, Langmuir, pp. 10835-10842.
40. Colorimetric Method for Determination of Sugars and Related Substances. Dubois, M and
Gilles, A. 1956, Analytical Chemistry, pp. 350-356.
41. A Spectrophotometric Method for the Determination of Iodine Binding Capacity for Starch and
its Components. Karve, M and Kale, N. 1992, Starch/Starke, pp. 19-21.
42. Kinetics of Deposition of Calcium Carbonate Particles onto Pulp Fibres. Kamiti, M. & Van De
Ven, T.G.M. Journal of Pulp and Paper Science, pp. 199-205.
43. Adsorption of Yellowing Inhibitors on Mechanical Pulp. Saint-CYR, K., Van De Ven, T.G.M. &
Garnier, G. 2002, Journal of Pulp and Paper Science, pp. 78-84.
44. Amylose content of starch from different varieties of cassava (Manihot esculenta Crantz) in
Ghana. Dakubu, M. & Bruce-Smith, S. P. 1979, Ghana Journal of Agricultural Science, pp. 143-145.
45. Investigation into the intergranular structures of microcrystalline cellulose and pre-gelatinised
starch. Laity, P., Cassidy, A., Skepper, J., Jones, B. & Cameron, R. 2010, European Journal of
Pharmaceutics and Biopharmaceutics, pp. 377-387.
46. Villard, E. F. & Guerin, M. Reverse Cholesterol Transport in HDL Metabolism: Modulation of
Structural and Functional Features of HDL Particles. The HDL Handbook. Paris : Elsevier Inc., 2014,
pp. 66-80.
47. Effect of Various Processing Methods on the in Vitro Starch Digestibility and Resistant Starch
Content of Indian Pulses. Bravo, L., Siddhuraju, P. & Saura-Colixto, F. 1998, Journal of Agricultural
Food Chemistry, pp. 4667-4674.
48. Variations in in Vitro Starch Digestion of Glutinous Rice Flour. Zhang, Q., Abe, T., Takahashi, T.
& Sasahara T. 1996, Journal of Agricultural Food Chem, pp. 2672-2674.
49. Effects of Chemical Modification on in Vitro Rate and Extent of Food Starch Digestion: An
Attempt to Discover a Slowly Digested Starch. Wolf, B. W., Bauer, L. L. & Fahey, Jr., G. C. 1999,
Journal of Agricultural Food Chemistry, pp. 4178-4183.
50. Critical Evaluation of in Vitro Methods for Estimating Digestibility in Simple-Stomach Animals.
Boison, S. & Eggum, B. O. 1991, Nutrition Research Reviews, pp. 141-162.
51. Characterization of three different potato starches and kinetics of their enzymatic hydrolysis by
an alpha-amylase. Heitmann, T., Wenzig, E. & Mersmann, A. 1997, Enzyme and Microbial
Technology, pp. 259-267.
52. The relation of physical properties of native starch granules to the kinetics of amolysis
catalysed by porcine pancreatic alpha-amylase. Tahir, R., Ellis, P. R. & Butterworth, P. J. 2010,
Carbohydrate Polymers, pp. 57-62.
53. Study of optimum conditions and kinetics of starch hydrolysis by means of thermostable alpha-
amylase. Yankov, D., Dobreva, E., Beschkov, V. & Emanuilova, E. 1986, Enzyme and Microbial
Technology, pp. 665-667.
9. Appendices
9.1. Risk Assessment
Task / Process /
Procedure
Method 1: Risk Assessment Hazard Type
Consequence &
Likelihood
Risk
Score
Controls Currently
in Place
Controls to be
Implemented
By Who By When
In Place
(Sign)
Description of hazard
Inhalation of Sodium
Hydroxide
Chemical
(R37)
Consequence:
Minor
Likelihood:
Occasional
Medium
(D3)
Lab entry restricted to
those wearing
appropriate PPE.
Operate in fume
cupboard & wear safety
mask.
Operator
As
required
Skin Contact with Sodium
Hydroxide
Chemical
(R35)
Consequence:
Moderate
Likelihood:
Unlikely
Medium
(C4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE (lab
coat & gloves).
Operator
As
required
Eye Contact with Sodium
Hydroxide
Chemical
(R41)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE,
especially safety
glasses. Handle
carefully.
Operator
As
required
Inhalation of Hydrochloric Acid
Chemical
(R37)
Consequence:
Moderate
Likelihood:
Unlikely
Medium
(C4)
Lab entry restricted to
those wearing
appropriate PPE.
Operate in fume
cupboard & wear safety
mask.
Operator
As
required
Skin Contact with Hydrochloric
Acid
Chemical
(R35)
Consequence:
Moderate
Likelihood:
Unlikely
Medium
(C4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE (lab
coat & gloves).
Operator
As
required
Eye Contact with Hydrochloric
Acid
Chemical
(R41)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE.
Handle carefully.
Operator
As
required
Inhalation of Phenol
Chemical
(R37)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Operate in fume
cupboard & wear safety
mask.
Operator
As
required
Skin Contact with Phenol
Chemical
(R35)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE (lab
coat & gloves).
Operator
As
required
Eye Contact with Phenol
Chemical
(R41)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE.
Handle carefully.
Operator
As
required
Inhalation of Concentrated
Sulfuric Acid
Chemical
(R37)
Consequence:
Moderate
Likelihood:
Unlikely
Medium
(C4)
Lab entry restricted to
those wearing
appropriate PPE.
Operate in fume
cupboard & wear safety
mask.
Operator
As
required
Skin Contact with
Concentrated Sulfuric Acid
Chemical
(R35)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE (lab
coat & gloves).
Operator
As
required
Eye Contact with
Concentrated Sulfuric Acid
Chemical
(R41)
Consequence:
Severe
Likelihood:
Unlikely
High
(B4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE.
Handle carefully.
Operator
As
required
Inhalation of Nanocellulose
Chemical
(R20)
Consequence:
Minor
Likelihood:
Unlikely
Medium
(D4)
Fume cupboard
available.
Wear safety mask,
handle carefully.
Operator
As
required
Eye Exposure to
Nanocellulose
Chemical
(R21)
Consequence:
Minor
Likelihood:
Unlikely
Medium
(D4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE,
especially safety
glasses. Handle
carefully.
Operator
As
required
Inhalation of D(+)-Glucose
Powder
Chemical
(Irritating if
Inhaled)
Consequence:
Negligible
Likelihood:
Unlikely
Low
(E4)
Fume cupboard
available.
Wear safety mask,
handle carefully.
Operator
As
required
Eye Exposure to D(+)-Glucose
Powder
Chemical
(R36)
Consequence:
Negligible
Likelihood:
Unlikely
Low
(E4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE,
especially safety
glasses. Handle
carefully.
Operator
As
required
Inhalation of Starch Powder
Chemical
(R20)
Consequence:
Minor
Likelihood:
Highly Unlikely
Low
(D5)
Fume cupboard
available.
Wear safety mask,
handle carefully.
Operator
As
required
Eye Exposure to Starch
Powder
Chemical
(R36)
Consequence:
Negligible
Likelihood:
Unlikely
Low
(E4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE,
especially safety
glasses. Handle
carefully.
Operator
As
required
Inhalation of α-Amylase
Solution
Chemical
(R20)
Consequence:
Minor
Likelihood:
Highly Unlikely
Low
(D5)
Fume cupboard
available.
Wear safety mask,
handle carefully.
Operator
As
required
Eye Exposure to α-Amylase
Solution
Chemical
(R36)
Consequence:
Negligible
Likelihood:
Unlikely
Low
(E4)
Lab entry restricted to
those wearing
appropriate PPE.
Ensure wearing
appropriate PPE,
especially safety
glasses. Handle
carefully.
Operator
As
required
pH Monitor
Physical –
Electrical (P8)
Consequence:
Moderate
Likelihood:
Highly Unlikely
Medium
(C5)
Regular maintenance
checks.
Check equipment
condition before use and
avoid contact with
liquids. Operate only as
directed.
Operator
As
required
Magnetic Stirrer
Physical –
Electrical (P8)
Consequence:
Moderate
Likelihood:
Highly Unlikely
Medium
(C5)
Regular maintenance
checks.
Check equipment
condition before use and
avoid contact with
liquids. Operate only as
directed.
Operator
As
required
Water Bath
Physical –
Electrical (P8)
Consequence:
Moderate
Likelihood:
Highly Unlikely
Medium
(C5)
Regular maintenance
checks.
Check equipment
condition before use and
avoid contact with
liquids. Operate only as
directed.
Operator
As
required
Computer/Laptop
Physical –
Electrical (P8)
Consequence:
Moderate
Likelihood:
Highly Unlikely
Medium
(C5)
Regular maintenance
checks.
Check equipment
condition before use and
avoid contact with
liquids.
Operator
As
required
Slipping/Tripping
Physical –
Gravitational
(P3)
Consequence:
Severe
Likelihood:
Highly Unlikely
Medium
(B5)
Regulations on
storage of equipment
and cleanliness of
lab.
Ensure workspace and
lab floor is clear of
obstacles.
Operator
As
required
Broken Glass
Physical –
Machinery
(P1)
Consequence:
Moderate
Likelihood:
Unlikely
Medium
(C4)
Dust pan and glass-
specific bin provided.
Handle glassware with
care, notify appropriate
individuals and ensure
glass is completely
cleared.
Operator
As
required
Ergonomic Hazards
Associated with Desk Work
Manual
Handling
Consequence:
Minor
Likelihood:
Likely
Medium
(D2)
Adjustable chair and
computer screen.
Ensure working with
correct posture and
taking breaks when
necessary, sit in an
adjustable chair, ensure
computer screen can be
adjusted to optimum-eye
level and that
workspace is tidy and
free of obstacles
affecting posture.
Operator
As
required
Repetitive Strain Injury (RSI)
Manual
Handling
Consequence:
Negligible
Likelihood:
Occasional
Medium
(E3)
Ergonomically
designed pipettes.
Take breaks when
necessary, avoid
prolonged periods of lab
work, spread work load
between operators.
Operator
As
required

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Nanocellulose as a Negative Calorie Food Additive

  • 1. Nanocellulose as a Negative Calorie and Cholesterol Controlling Food Additive Matthew Stewart Michael Fenwick-Nevin Australian Pulp and Paper Institute Chemical Engineering Department Monash University
  • 2. Executive Summary Lifestyle diseases such as type II diabetes, cardiovascular disease and obesity are growing issues amongst the global population. Obesity is currently one of the most serious worldwide health issues, affecting more than a billion people globally. Current treatments for lifestyle diseases include exercise and dietary modifications such as decreasing portion sizes and decreasing high-calorie food and drinks. The objective of this research project is to assess the feasibility of creating a nanocellulose based food additive capable of preventing energy and cholesterol absorption from foods, which not only could help prevent and treat obesity and other lifestyle diseases, but could also allow individuals to indulge in foods they normally wouldn’t eat, avoiding weight gain and negative health effects. In order to achieve the objectives of this project and determine if nanocellulose can be used as a negative calorie and cholesterol controlling food additive, a systematic methodology was used in order to determine the interaction of nanocellulose with various food constituents. The figure below highlights the way in which this project was broken down. Figure 1: Project Flow Chart It was hypothesised prior to the commencement of this project that glucose and starch oligomers can be adsorbed onto nanocellulose fibres. It was also hypothesised that nanocellulose in the diet can reduce blood cholesterol levels. In order to prove these hypothesis, both experimental work and an extensive review of literature were conducted. A literature review relating to glucose interaction with cellulose yielded no results to suggest that glucose had previously been found to adsorb to cellulose. Experimental work was conducted using glucometry to measure glucose concentration before and after the addition of nanocellulose. These experiments confirmed that glucose does not adsorb to nanocellulose. Cellulose Energy Monosaccharides Glucose Disaccharides Sucrose Polysaccharides Starch Fats Cholesterol Triglycerides
  • 3. An extensive review of literature found previous works had concluded that sucrose does not bind to cellulose, and given that this had been previously determined experimental work was not conducted in order to investigate the adsorption of sucrose to nanocellulose. The conclusion that glucose and sucrose do not bind to nanocellulose was based on experiments using native forms of nanocellulose, therefore one recommendation from this project was to conduct future experiments with chemically modified nanocellulose and test the adsorption of glucose and sucrose to these chemically modified molecules. Previously published literature was found that concluded starch adsorbs to the surface of cellulose. We used the sulphuric acid-phenol method of starch content determination in order to test whether this result is also achieved with nanocellulose. The results of our experimental work investigating the adsorption of starch to nanocellulose concluded that starch does bind to nanocellulose, as was hypothesised. Further experiments were conducted investigating how the action of α-amylase impacts upon the starch adsorbed to nanocellulose, however unfortunately the results of these experiments were inconclusive due to the lack of sensitivity of the glucometry method used for sample analysis. As a result another recommendation for future works is to repeat these experiments, however using a more sensitive analytical method such as high performance liquid chromatography. A review of literature found that increasing nanocellulose in the diet results in a reduction of cholesterol levels in the blood, as well as reducing the likelihood of developing colon cancer. It was also determined through reviewing literature that fructans can reduce the levels of cholesterol and triglycerides in the blood. These concepts were only investigated on a theoretical level and therefore it is recommended that future works confirm experimentally that nanocellulose and fructans can reduce blood cholesterol and triglyceride levels. In conducting this research project we were able to achieve our objective of investigating the use of nanocellulose as a negative calorie and cholesterol controlling food additive. Although not all of our results supported our hypothesis, many did, and those that didn’t based on these preliminary experiments, may prove to align better with our hypothesis if further experiments are conducted. Therefore, overall our project was a success and the use of nanocellulose as a negative calorie and cholesterol controlling food additive still remains a valid proposal, however requires further investigation.
  • 4. Table of Contents Executive Summary ........................................................................................................................................... 1 1. Introduction................................................................................................................................................... 4 2. Project Definition........................................................................................................................................... 5 2.1. Problem Statement ................................................................................................................................ 5 2.2. Hypothesis.............................................................................................................................................. 5 2.3. Project Objectives................................................................................................................................... 5 3. Literature Review .......................................................................................................................................... 7 3.1. Glucose ................................................................................................................................................... 7 3.2. Sucrose ................................................................................................................................................... 7 3.3. Starch...................................................................................................................................................... 8 3.4. α-Amylase............................................................................................................................................... 9 3.5. Cellulose ................................................................................................................................................. 9 3.6. Interactions between Starch, Cellulose and Amylase .......................................................................... 10 3.7. Fructans................................................................................................................................................ 11 3.8. Cholesterol............................................................................................................................................ 12 3.9. Bile Acids............................................................................................................................................... 13 3.10. Significance of the Relationship between Bile Acids and Cholesterol ............................................... 13 3.11. Overview of the Human Gastrointestinal System .............................................................................. 13 3.12. Glucometry......................................................................................................................................... 15 3.13. Starch Quantification Techniques ...................................................................................................... 16 3.14. Kinetics ............................................................................................................................................... 17 4. Methodology ............................................................................................................................................... 18 4.1. Glucose to Nanocellulose Binding Experiments................................................................................... 18 4.2. Starch to Nanocellulose Binding Experiments...................................................................................... 21 4.3. Effect of Starch Binding to Nanocellulose on α-Amylase Action Experiments..................................... 22 4.4. Literature Review ................................................................................................................................. 24 5. Key Results and Findings ............................................................................................................................. 25 5.1. Glucose Binding to Nanocellulose........................................................................................................ 25 5.2. Sucrose Binding to Nanocellulose ........................................................................................................ 33 5.3. Starch Binding to Nanocellulose........................................................................................................... 33 5.4. Effect of Starch Binding to Nanocellulose on α-Amylase Action.......................................................... 35 6. Conclusions and Recommendations............................................................................................................ 36 7. Acknowledgements ..................................................................................................................................... 37 8. References................................................................................................................................................... 38
  • 5. 1. Introduction Obesity is currently one of the most serious worldwide health issues, affecting more than a billion people globally (1). It is quickly growing in the younger generations with more than 22 million of the world’s children under 5 years old being either overweight or obese. There are a variety of severe health conditions that are associated with being overweight or obese. These include; sleep apnea, type II diabetes, hypertension, hyperlipidaemia and increased risk of developing cardiovascular disease (CVD) (2). CVD is a major health risk that has a high mortality rate and has been the leading cause of death in the United States since the early 1900’s (3). Due to these factors obesity can have a large impact on expected life span, particularly in younger children, reducing their life expectancy by up to as many as 20 years (2). These rising risk factors create the need to implement and devise solutions to combat the growing obesity pandemic. Current treatments include exercise and dietary modifications such as decreasing portion sizes and decreasing high-calorie food and drinks (2). The basis of this research project is to assess the feasibility of creating a nanocellulose based food additive capable of preventing energy and cholesterol absorption from the food. If this end product is realized, not only will this help prevent and treat obesity and other diseases associated with being overweight, but it will also allow individuals to indulge in foods they normally wouldn’t eat, avoiding weight gain and negative health effects.
  • 6. 2. Project Definition 2.1. Problem Statement To research the capability of nanocellulose to adsorb carbohydrates (monosaccharides, disaccharides and polysaccharides), as well as investigating the capability of nanocellulose and other dietary fibres (e.g. fructans) to regulate cholesterol levels. This research will aid in the development of nanocellulose as a negative calorie and cholesterol controlling food additive. 2.2. Hypothesis It is hypothesised that glucose and starch oligomers can be adsorbed onto nanocellulose fibres. The inability of the human gastrointestinal tract to absorb cellulose will cause the glucose and starch oligomers bound to the nanocellulose to be expelled rather than absorbed, hence removing potential calories from foods consumed. It is also hypothesised that nanocellulose has the potential to control the levels of cholesterol related elements in the human digestive tract. The performance of different nanocellulose varieties is hypothesised to be primarily determined by the surface area available for binding to glucose, starch and cholesterol. 2.3. Project Objectives The objectives of this project were initially broadly defined as follows: 1. To design and investigate the effectiveness of an experimental system used to measure and analyse the adsorption of glucose and starch onto nanocellulose. 2. To conduct a review of literature relating to the digestion of carbohydrates and cholesterol in the human gastrointestinal tract. As the project progressed, the main objective of the project was refined and can be defined as follows: - Through the review of literature and conducting laboratory experiments, investigate the validity of the concept that nanocellulose can be used as a negative calorie and cholesterol controlling food additive. In conducting a literature review relating to the digestion of carbohydrates and cholesterol in the human digestive system, we aimed to determine multiple characteristics of the system. Of specific interest were the conditions under which glucose, starch and cholesterol are digested and absorbed. Such conditions include the temperature, pH, enzymes required and location of digestion and absorption in the gastrointestinal tract for the different components of ingested food. We also aimed through our literature review to determine the retention time of glucose,
  • 7. starch and cholesterol in regions of the gastrointestinal tract such as the stomach and the small intestine. The primary outcome of achieving the objectives of this literature review were to provide specific details of the conditions to which glucose, starch and cholesterol are subjected in the human digestive system. This will allow for further experiments investigating the adsorption of these molecules to nanocellulose to be analogous to reactions occurring in the human gastrointestinal tract. Through conducting laboratory experiments we aimed to gather data that was concordant with literature and previous experiments, as well as determining and proving on a practical level, that the concept of nanocellulose being used as a negative calorie food additive is valid. The results of such experiments, whether proving or disproving the concept, will provide a basis for future research in this area, saving time and money for future projects. The results of these experiments will also provide insight into potential changes that could be made to the methodologies used in this project, allowing for recommendations regarding the specifics of future works relating to using nanocellulose as a negative calorie food additive. The figure below illustrates a break down of the various areas that were researched in order to achieve the objectives of this project as stated above. Figure 2-3-1: Project Flow Chart Cellulose Energy Monosaccharides Glucose Disaccharides Sucrose Polysaccharides Starch Fats Cholesterol Triglycerides
  • 8. 3. Literature Review Due to time constraints placed on this project it is difficult to investigate the entirety of the scope experimentally. Therefore a literature review is necessary to give sufficient background to the experimental work as well as explore avenues that would be too time intensive to conduct in the laboratory. 3.1. Glucose Glucose is essential to human life, providing energy to sustain physiological functions. It is readily broken down to create ATP, an energy molecule, by either aerobic or anaerobic respiration. The diet is the crucial source of glucose, where it is either directly absorbed from the food in the small intestine or synthesised via the gluconeogenesis pathway from precursors obtained from the diet (4). Glucose is the only fuel used to any significant extent and is the sole energy source used by the brain. Glycolysis, the process used to extract the chemical energy contained within the glucose molecules, is an extremely important function within the body and malfunctions in this process can lead to a variety of serious diseases. However, when too much glucose is ingested in the diet it can also lead to the development of disorders like insulin resistance and diseases associated with severe weight gain (5). Diabetes has been linked with hyperglycemia, which has seen a recent increase due to the increasing popularity of high energy density Western-style diets (6). Although glucose is the building block of carbohydrates, there are also many other sources of carbohydrates from which the body can gain energy. 3.2. Sucrose Sucrose is a disaccharide consisting of two monosaccharides, glucose and fructose. These two monosaccharides are condensed at their glycosidic groups and form a bond known as a glycosidic bond, forming the disaccharide sucrose. Sucrose is commonly found around the house as table sugar and is digested in the gastrointestinal tract by the enzyme sucrase, which catalyses the hydrolysis of the glycosidic linkage of the sucrose molecule, breaking it down into its monomeric components (7).
  • 9. Figure 3-2-1: Sucrose, a Disaccharide of Glucose and Fructose (8) Sucrose was used by Fernandez et al. in an investigation into the retention of fatty acid soaps during paper recycling. In this experiment sucrose was used as a tracer molecule for a packed bed experiment. The packed bed was filled with pulp fibres and sucrose was selected as a tracer molecule due to the fact that it is unable to bind to cellulose (9). 3.3. Starch Starch consists of two glucose polymers, amylose (a long, unbranched molecule) and amylopectin (a highly branched molecule) (10). The structures of these polymers are depicted in Figure 3-3-1 and Figure 3-3-2 below. Starch is typically ingested in our diet in the following forms (11):  Cereals: corn, oats and flour  Root vegetables: potatoes, carrots, parsnips  Rice and pasta Figure 3-3-1: Structure of the Amylopectin Component of Starch (12)
  • 10. Figure 3-3-2: Structure of the Amylose Component of Starch (12) There is much energy to be gained from the ingestion of starch in the diet. However, unmodified it is insoluble and requires the action of certain catalysts before it can be properly utilised by the body. 3.4. α-Amylase Complex carbohydrates, including starch, cannot be absorbed in the intestine in their native states. Nearly all of the carbohydrates ingested must be first hydrolysed into their corresponding monosaccharides (with the exception of a few disaccharides) before they can be absorbed. There are hydrolytic enzymes that are present in the saliva and pancreatic secretions that are capable of achieving this. The most abundant of these is 𝛼-amylase, which breaks links in the starch molecule 𝛼-(1-4) bonds, in a random fashion to break down the starch constituents of amylose and amylopectin (13) (14) (11) (10). Salivary 𝛼-amylase hydrolyses approximately 50% of starch in the diet, however it has an optimum pH of around 7.0, causing it to be inactive once it reaches the stomach. After the food passes through the stomach, pancreatic 𝛼-amylase is released in a much larger quantity compared to the salivary 𝛼-amylase, which acts to break down the remaining starch (11) (13). From previous research, 𝛼-amylase is the most commonly used hydrolytic enzyme to mimic the break down of starch in vitro, which was the basis of investigating its activity in this research project (14). Even though there are many enzymes that facilitate digestion within the gastrointestinal tract, there are some carbohydrates that are unable to be hydrolysed within the body to gain energy, a property that this project aims to take advantage of. 3.5. Cellulose Similar to starch, cellulose is a polysaccharide also consisting of glucose monomers and is the most abundant polysaccharide produced in nature (12). Based on the fact that both starch and cellulose are formed from the common building block of glucose monomers, we construct our hypothesis that starch will actively bind to cellulose in the human gastrointestinal tract (15). Cellulose is the fibre that supports plants, mostly found in cell walls. The glucose monomers that
  • 11. make up cellulose are configured in such a way that cellulose is resistant to hydrolysis via the hydrolytic enzymes present in the gastrointestinal tract, unlike starch (16). This means that cellulose isn’t actually digested, but still plays an important role in providing bulk to stimulate intestinal motility, preventing constipation (13). This property of cellulose is what allows us to predict that starch or glucose bound to the cellulose will be excreted rather than digested. Figure 3-5-1: Structure and Hydrogen Bond Interactions of Cellulose (12) The previous sections of the literature review outline the underlying roles of starch, cellulose and 𝛼-amylase. We wish to analyse whether interactions between these molecules will affect the outcomes of the project. 3.6. Interactions between Starch, Cellulose and Amylase It is known that starch has the capacity to bind to cellulose. As starch and cellulose are both polymers sharing a common monomer in glucose, it is thought that the binding mechanism is due to surface interaction between the molecules. The amylose contained within starch has a very similar structure to cellulose, it is characterised by 𝛼-1,4 linkages between glucose units whereas cellulose is characterised by 𝛽-1,4 linkages between glucose monomers. This results in amylose being a more flexible molecule, forming natural helical twists which can form a collapsed helix under certain conditions while cellulose is more rigid and flat, giving strength properties to the cellulose fibres (17).
  • 12. As explained previously, starch consists of amylose and amylopectin. Van de Steeg et al. showed that amylose binds preferentially to cellulose due to its smaller size and more linear structure. Amylopectin was unable to penetrate the pores of the microcrystalline cellulose as it is a larger, highly-branched molecule (18). From experimental analysis of the kinetics of starch adsorption onto cellulose it has been found that the adsorption mechanism follows Langmuir kinetics further confirming the importance of surface interaction between the two molecules (19) (18). As 𝛼-amylase is the main enzyme for breakdown of starch, there is particular focus on this enzyme in this report. An important factor involved in the interaction of starch and 𝛼-amylase is the surface area to volume ratio of the starch molecules (as it is much larger than the enzyme) and therefore particle size (10). Another key variable affecting the starch and 𝛼-amylase interaction is the degree or order of 𝛼-glucan chains of the starch, with 𝛼-amylase binding most readily to the exposed/available amorphous 𝛼-glucan chains (20). An objective of this project is to assess the use of cellulose to prevent the digestion of starch via a surface binding mechanism. It is currently unknown how the interaction between 𝛼-amylase and starch will affect the capacity of cellulose to maintain the bound starch on its surface, which will require further investigation. Although the experimental scope of this project is to evaluate the use of nanocellulose as a food additive, in this literature review we have also investigated the use of alternative dietary substances, which have positive health effects, performing a similar function to that of cellulose. 3.7. Fructans Fructans are polysaccharides of fructose molecules and can be classified under two main types; fructooligosaccharides and inulins. Fructooligosaccharides are fructan polymers of shorter chain length, whilst the inulin types are of longer chain length. Typical foods that contain fructans include wheat, onion, banana and leek (21). Fructans are non-digestible carbohydrates and act as dietary fibres; they have been shown to have positive health benefits, being classified as a prebiotic (22). Unlike starch, they do not bind to other carbohydrates, however studies on inulin-type fructans in animals and man have shown that they have the potential to reduce plasma levels of triacylglycerols (TG). Inulin has also been linked to reducing levels of cholesterol in the
  • 13. bloodstream. Inulin-type fructans have been shown to have a greater positive effect on the reduction of TG levels than oligofructose (23). Because fructans are non-digestible carbohydrates, they pass through the small intestine and undergo the fermentation process within the large intestine, producing propionic acid. Increased levels of propionic acid cause a reduction in liver lipogenesis, resulting in a lower hepatic secretion rate of TG. It is thought that through this mechanism, fructans have the ability to reduce TG and cholesterol levels as well as through the propionic induced inhibition of cholesterol synthesis and modifications to bile acid metabolism (23). The use of fructans were investigated in this report due to their functional characteristics of being non-digestible, therefore not contributing to dietary energy intake, and their ability to reduce plasma TG and cholesterol levels. Cholesterol is a focus point of this report due to the strong links between high blood-cholesterol and serious health issues. 3.8. Cholesterol High blood-cholesterol is an important risk factor for obesity and CVD (3) (2). Cholesterol is transported around the body via the bloodstream in complexes known as lipoproteins, due to the fact that cholesterol is a lipid and is therefore insoluble in water. There are two main forms of lipoproteins, high-density lipoproteins (HDL) and low-density lipoproteins (LDL) (24). LDL’s carry cholesterol to areas of the body where they are required, while HDL’s transport cholesterol back to the liver and have a higher proportion of proteins. High LDL cholesterol levels are a health risk associated with coronary heart disease and CVD, with build-up of LDL cholesterol in arteries being a major cause of heart attack and stroke (25) (26) (24) (27). Although dietary cholesterol intake should be regulated, the majority of dietary cholesterol is passed through the gastrointestinal system with only approximately 20-50% being absorbed (25) (13). High blood-cholesterol levels are mainly attributed to a high dietary intake of saturated fats, which are then synthesised into cholesterol (25) (24). Figure 3-8-1: Structure of the Sterol Cholesterol (13)
  • 14. The major pathway for excretion of cholesterol from the body takes place in the liver and is via the bile acid synthesis pathway (16) (26). Of the approximate 1 gram of cholesterol consumed by the body each day, half of this is degraded to bile acids while biliary cholesterol excretion is responsible for the loss of the remainder (26). 3.9. Bile Acids Bile acids have several functions (16):  Triglyceride assimilation  Induction of bile flow  Lipid transport  Bile acid synthesis  Water and electrolyte secretion There are two classes of bile acids in the body; primary and secondary bile acids. Primary bile acids (cholic acid and chenodeoxycholic acid) are synthesised by hepatocytes in the liver, while secondary bile acids (deoxycholic acid and lithocholic acid) are formed by bacterial dehydroxylation of primary bile acids in the intestines (13). Literature exists which suggests that increased levels of secondary bile acids are a risk factor associated with colon cancer (28). 3.10. Significance of the Relationship between Bile Acids and Cholesterol Experiments have determined that cellulose can aid in binding to secondary bile acids, allowing them to be excreted as well as accelerating intestinal transit (due to higher faecal weight). This minimises the time available for primary bile acids to be converted to secondary bile acids, thus decreasing the risk of developing colon cancer (29). Previous research has also suggested that added cellulose in the diet increases bile acid production and excretion and therefore decreased cholesterol levels in the blood as well as reducing lipid and TG levels (30) (31) (29) (32). For these reasons we have decided to analyse the relationship between cellulose and cholesterol in conjunction with the glucose and starch experiments (33). 3.11. Overview of the Human Gastrointestinal System In this research project we will primarily focus on 3 major sections of the gastrointestinal system; the stomach, the small intestine and the large intestine. However a larger focus will be on the stomach and small intestine as the absorption of a majority of compounds occurs in the small intestine (34).
  • 15. 3.11.1. Stomach The stomach receives and can temporarily store food, its function is to partially digest food and pump it through to the duodenum region of the small intestine. While food is contained in the stomach, parietal juice (an acidic solution) and an alkaline solution are released from the mucous cells of the stomach (16) (13). Hydrochloric acid is released as part of the acidic secretions. Although hydrochloric acid can aid in breaking down muscle fibres and connective tissue, the main purpose of its secretion is to lower the pH of the stomach. This allows for the enzymatic activation of pepsin and more importantly kills harmful organisms, protecting the body from infection (16). The pH of the stomach changes depending on what stage of the digestion cycle it is in. Typically when there is food present within the stomach, the secretion of hydrochloric acid will lower the pH down to around 1-2. However, after the food has been digested the stomach pH may increase to 3-5. As the stomach is very flexible, the volume usually depends on the amount of material present. The stomach can have a volume anywhere between 0.5-5 litres (16) (13). The retention time of material within the stomach is highly dependent on many factors including the type and amount of food. Food can remain in the stomach anywhere between 1-2 hours after which it is pumped via muscular contractions into the duodenum. The rate of gastric emptying is dependent on the volume of materials within the stomach, with a higher stomach volume corresponding to a higher rate of gastric emptying (16). It should be noted that very few substances are absorbed in the stomach and it is virtually impermeable to water. Some of the few substances that are absorbed from the stomach are aspirin and ethyl alcohol (13). 3.11.2. Small Intestine The small intestine is approximately 3.5 cm in diameter and about 6 metres long, of which the duodenum occupies the first 25 cm (13). The duodenum is where the mixing of digestive juices from the liver and the pancreas occurs and is also where bile acids are excreted. However, intestinal juices are secreted along the entire length of the small intestine. Approximately 95% of the water which enters the gastrointestinal tract is absorbed in the small intestine, as are glucose and cholesterol (16) (13). The retention time of the small intestine is slightly longer than that of the stomach, with typical times ranging between 105-135 minutes (16). Unlike the stomach, the typical pH range of the small intestine is more neutral to alkaline, rather than acidic. This is because the action of pancreatic enzymes and lipid absorption require alkaline pH (13). After the food mass has passed through the small intestine where water and nutrients are absorbed it continues on and enters the large intestine or colon.
  • 16. 3.11.3. Large Intestine Compared to the small intestine the large intestine is relatively short, being only 1.5 metres in length. However, it has a larger diameter of around 6 cm and spans from the end of the small intestine (ileum) to the rectum where the material that remains is expelled from the body (16) (13). The main function of the large intestine is to store faecal matter and regulate its release from the body. The large intestine also acts to absorb water and electrolytes from the chyme, as well as lubricating the passage for waste material to move through with ease (13). The retention time of the large intestine is long when compared to that of the stomach and small intestine. Although food can pass through the stomach and small intestine in less than 12 hours, remnants of the food can remain in the large intestine for up to a week. However, the majority of it is expelled by the 4th day after ingestion (13). Although the large intestine is still of interest in this project, it will not be a major focus as the compounds we are placing emphasis on are not absorbed in this region of the gastrointestinal tract. 3.12. Glucometry Various methods exist for the quantification of glucose concentration, with common techniques including High Performance Liquid Chromatography (HPLC), the Fehling test and enzymatic assays (35). These methods, though effective in quantifying glucose concentration, are hindered by disadvantages in that they can be expensive, time-consuming and technically difficult. Ideally glucose concentration determination in a laboratory setting (as well as in a clinical setting) should be inexpensive, fast, convenient and reliable. Blood glucose monitors were developed in order to provide a method of glucometry for diabetics that achieves an inexpensive, fast and convenient means of determining blood glucose concentration. In recent studies these glucometers have been used in a laboratory setting in order to measure glucose concentration in solutions other than blood. The Accu-Chek Performa Blood Glucose Monitor was used by Sopade and Gidley (36) during their research into the kinetics of starch digestion, and was also used by Blazek and Gilbert (14) when investigating the enzymatic digestion of starch by α-amylase. Two enzymes are commonly used for blood glucose monitors, namely glucose oxidase and glucose dehydrogenase (35). These enzymes oxidise glucose molecules to gluconic acid and gluconolactone respectively. The Accu-Chek Performa Blood Glucose Monitor is an example of a glucometer that uses glucose dehydrogenase enzymes in order to determine the glucose concentration of a sample. This glucometer uses test strips upon which glucose dehydrogenase is
  • 17. immobilised. In the presence of the coenzyme pyrroloquinoline quinine, glucose dehydrogenase oxidises glucose to gluconolactone which creates a DC signal that is converted to a digital display of the glucose concentration in the solution on the glucometer screen. The Accu-Chek Performa test strips require approximately 0.6 µL of solution and produce a response in approximately 5 seconds. The glucometer has a glucose concentration range of 0.6-33.3 mM, a temperature range of 6-44oC and can be used at relative humidity ranging from 10-90% (36). A comparison of blood glucose monitors in Australia (37) found that the glucometers available in Australia all show acceptable precision when determining the glucose concentration in blood. The accuracy and precision of some monitors was found to at times be compromised for glucose standard solutions, suggesting that researchers need to be careful when using glucometry as a method of determining glucose concentration in solutions which are not blood-based. A study which examined the utility of blood glucose monitors in biotechnological applications (35) determined that when using glucometers it is important to consider the pH, expected concentration range and presence of other sugars when selecting a glucometer for the determination of glucose concentration for biotechnological studies. The research of Sopade and Gidley suggests that the use of glucometry can be extended to analysing the kinetics of starch digestion (36). 3.13. Starch Quantification Techniques The quantification of the amount of starch in solution has been conducted by various researchers in the past (38) (39). Determination of the amount of starch that can adsorb to various materials, such as glass and pulp fibres for example, has been investigated by determining the amount of free starch in solution before and after introduction of the material to which the starch adsorbs. The difference in the free starch levels quantifies the amount of starch that is bound to the material. Simple sugars, oligosaccharides and polysaccharides (such as starch) produce an orange-yellow colour when they are exposed to phenol and concentrated sulphuric acid (40). By measuring the absorbance of starch samples that have been exposed to the phenol-sulphuric acid technique at 490 nm, the concentration of the total starch in the sample can be determined using the Beer- Lambert Law. This method for determining starch concentration is simple, rapid and sensitive, using reagents which are stable and relatively cheap. The method requires only one standard curve and the colours that are produced by the reaction of starch with phenol and sulphuric acid are stable and permanent (40).
  • 18. As previously discussed, starch contains two different branched molecules, namely amylose and amylopectin. The phenol-sulphuric acid technique only quantifies the total starch concentration of a solution and does not determine the amount of amylose or amylopectin in a sample. The amount of amylose in solution can be determined by quantifying the iodine binding capacity of the starch. When amylose in aqueous solution is exposed to iodine it forms a blue coloured helical complex. By measuring the absorbance of this blue solution the Beer-Lambert Law can be used in order to determine the concentration of amylose in the solution. By combining the iodine technique and the phenol-sulphuric acid technique, the amylopectin concentration in solution can also be determined as this is equal to the difference in concentration of starch and amylose (41). 3.14. Kinetics The kinetics of adsorption and desorption of materials onto pulp fibres have been investigated by other researchers. During their research into the adsorption and desorption kinetics of calcium carbonate onto pulp fibres, Kamiti and Van De Ven modelled these kinetics with a modified Langmuir equation (42). The same model equation was used by Saint-Cyr, Van De Ven and Garnier when investigating the kinetics of paper yellowing inhibitors onto pulp fibres (43). The model equation is shown below: 𝑑𝜃 𝑑𝑡 = 𝑘1(𝑛0 − 𝜃) − 𝑘2 𝜃 𝐸𝑞𝑢𝑎𝑡𝑖𝑜𝑛 1 In the equation above, θ represents the fractional coverage of fibres by the adsorbed particles, k1 represents the rate of adsorption, k2 represents the rate of desorption and n0 represents the initial concentration of adsorbing particles, divided by the maximum amount that can deposit in a unit volume of suspension (42) (43). The kinetics relating to the binding of starch by α-amylase have also previously been researched. Warren, Butterworth and Ellis found in their study into the surface structure of starch that the kinetics of pancreatic α-amylase binding to granular starch molecules could be modelled by Freundlich enzyme kinetics (10).
  • 19. 4. Methodology In order to achieve the objectives of this research project, the methodology detailed in the following sections was carried out over a twelve week period. 4.1. Glucose to Nanocellulose Binding Experiments In order to investigate the potential of glucose to adsorb to nanocellulose, we initially conducted a literature search in order to determine if previous published works had found evidence of glucose binding to nanocellulose. After conducting this literature review we carried out a series of experiments using glucometry in order to measure glucose concentration and determine if glucose adsorbs to nanocellulose. These experiments are briefly described below. The glucometer used during these experiments was the Accu-Chek Performa Blood Glucose Meter. As discussed previously in the Section 3.12, this glucometer uses test strips upon which glucose dehydrogenase is immobilised. In the presence of the coenzyme pyrroloquinoline quinine, glucose dehydrogenase oxidises glucose to gluconolactone which creates a DC signal which is then converted to a digital display of the glucose concentration in the solution on the glucometer screen. The Accu-Chek Performa test strips require approximately 0.6 µL of solution and produce a response in approximately 5 seconds. The glucometer has a glucose concentration range of 0.6- 33.3 mM, a temperature range of 6-44oC and can be used at relative humidity ranging from 10- 90%. Prior to conducting experiments investigating the adsorption capability of glucose onto nanocellulose we first conducted a calibration experiment in order to find a correlation between the glucose concentration reported by the glucometer and the known glucose concentration. In order to conduct this experiment we first created a 15.07 mM glucose solution in 100 mL of deionised water. We then measured the concentration of this solution with the Accu-Chek Performa, taking repeated measurements approximately every 5 minutes for a duration of approximately 30 minutes. The measurements were conducted by dipping the test strip of the glucometer into the beaker containing the glucose solution. We repeated this experiment using a 2.02 mM glucose solution. The results of these experiments are discussed in Section 5.1. Due to unexpected results produced from our calibration experiment, we repeated the calibration experiment changing the methodology slightly each time. In all instances we made a 15 mM glucose solution in 100 mL of deionised water. The first variation we made to the methodology was to extract the glucose sample from the beaker using a clean syringe and then transferring the sample by syringe to the glucometer test strip. This was conducted with the aim of collecting a
  • 20. sample likely to be more indicative of the entire glucose solution, rather than only testing the glucose solution at the surface. Unfortunately this did not eliminate the unexpected results produced by the glucometer, which as explained in more detail in Section 5.1, was reporting a continuous increase in glucose concentration with time, exceeding the known glucose concentration. Another modification to the method involved collecting the glucose solution from different locations within the beaker of solution. This aimed to eliminate concentration spacial variation. We also measured the concentration of the glucose solution in the presence and absence of the magnetic stirrer, immediately after stirring, after waiting for the solution to settle after stirring and when mixed with Bovine Serum Albumin (BSA). None of these methods were successful in eliminating the increase in measured glucose concentration with time. We also attempted mixing the 15 mM glucose solution with blood samples provided by APPI in an attempt to eliminate the time variation. Having attempted all of the above variations to the calibration experiment method, a 15 mM glucose solution was created in 100 mL of deionised water and allowed to mix overnight. The Accu-Chek Performa was then used to measure the glucose concentration and the increase in glucose concentration was found to have been eliminated, allowing for a calibration curve to be created as shown in Section 5.1. Having successfully conducted the calibration experiment, the capability of glucose to bind to nanocellulose was tested by again creating a 15 mM glucose solution and allowing it to mix overnight. Once this mixing was complete, 3.726 g of VTT nanocellulose was added to the 15 mM glucose solution and mixed overnight. 4 mL of the glucose and nanocellulose solution was then transferred by syringe to a microtube, allowing for a titre experiment to be carried out. This experiment involved taking 2 mL out of the “neat” microtube (i.e. the tube containing 4 mL of the master solution) and adding it to a microtube containing 2 mL of deionised water. Once this 2 mL of the glucose and nanocellulose solution mixed with the water (making a diluted 4 mL solution) 2 mL of this new solution was extracted and added to another microtube containing 2 mL of deionised water. This procedure of dilutions was continued until a dilution which was one part nanocellulose/15 mM glucose solution and 63 parts deionised water was created. The diluted solutions in the microtubes were then analysed by the glucometer for glucose concentration. These concentrations were then compared to the measured concentration of the 15 mM glucose
  • 21. standard solution in order to determine if the addition of 3.726 g of VTT resulted in a reduction in glucose concentration. Having conducted the titre experiment with the solution containing 15 mM of glucose and 3.726 g of VTT nanocellulose, another 15 mM glucose solution was created and 9.117 g of VTT added to it. Having mixed this solution sufficiently the titre experiment outlined above was repeated for this solution containing 9.117 g of VTT. The experiments involving the addition of VTT to 15 mM glucose solutions were repeated, this time using a 5 mM glucose master solution. To the 5 mM master solutions two different amounts of VTT (namely 11.425 g and 22.94 g) were added in order to determine if at this lower glucose concentration, the glucose would bind to the high volume of VTT. At this point in time it was determined that the moisture content of the nanocellulose could be impacting on the results, producing false positive readings in relation to the reduction of glucose concentration. As a result the moisture content of VTT and Daicel nanocellulose, as well as the moisture content of Tapioca Starch were determined. This was achieved by measuring a known mass of each substance into a small aluminium plate and then placing the plate in an oven for approximately two hours. During this time the materials became dried and were reweighed at the end of the two hours. This allowed the determination of how much moisture the “un-dried” state of each material contained. The results of this moisture content determination are reported in Table 5-1-3 in Section 5.1. Having determined the moisture content of various substances as described above, the titre experiment previously conducted using the 15 mM and 5 mM master solutions was repeated for a 2 mM glucose master solution. In this instance 7.995 g of Daicel nanocellulose was added to the glucose solution rather than VTT nanocellulose, due to the lower moisture content of Daicel. As a control, 7.995 g of Daicel was also added to deionised water. The results of this experiment are discussed in Section 5.1.
  • 22. 4.2. Starch to Nanocellulose Binding Experiments From the literature review it is apparent that starch has the capacity to adsorb onto the surface of cellulose. It was desired to design an experimental methodology to test these findings with nanocellulose, having a much higher surface area. As starch is insoluble in water at room temperature, to make a starch solution the starch must be “cooked” or heated to weaken hydrogen bonds, allowing the starch molecules to swell and take on water, allowing them to be dissolved. To prepare a stock starch solution for the following experiments, 9 g of tapioca starch was added to 191 mL of deionised water in a heated vessel. The temperature of the heated vessel was set at 80°C and a mixer was applied to the water-starch solution to facilitate dissolution. The solution was left to mix and be heated until the viscosity visually increased, and then decreased. Following this the solution was mixed for an additional 10 minutes before the heat and mixer were turned off. Following preparation of the stock starch solution, the exact concentration of this solution needed to be calculated. This was achieved following the procedure for moisture content determination outlined in Section 4.1. The method employed in order to determine the starch concentration was the sulphuric acid- phenol method. When sulphuric acid and phenol are added to a starch solution, a brown colour is created when starch is present. The higher the concentration of starch in solution the darker the colour. Therefore spectrophotometry can be used to determine the concentration of starch in a solution, however a calibration curve must first be constructed. To construct the calibration curve for starch concentration using the sulphuric acid – phenol method, the stock starch solution was used to make 10 different concentrations of starch by dilution across the range 0-10 g/L. This range was chosen as it was found to have been used in similar previous experiments. However, when these solutions were tested for absorbance at 490 nm in the spectrophotometer, it was observed that the maximum absorbance was reached at a starch concentration of approximately 0.5 g/L. Therefore the method for constructing the calibration curve was repeated for a concentration range of 0-0.5 g/L. To make up the solutions required for use in the spectrophotometer, the following were added to a 15 mL centrifuge tube:  2mL starch solution  125μL 80% Phenol solution
  • 23.  5mL 98% Sulphuric acid These solutions were allowed to sit for 10 minutes before being shaken vigorously and placed in a water bath at 30°C for 10 minutes. An eppendorf tube was used to transfer approximately 3 mL of the sulphuric acid – phenol assays into cuvettes to be analysed in the spectrophotometer at 490 nm. From the data gained from the spectrophotometer and the known concentration of starch solutions a calibration curve was constructed. To verify starch adsorption onto nanocellulose, four beakers were prepared with each containing different starch concentrations according to Table 4-2-1 below: Table 4-2-1: Various Starch Concentrations for Sulphuric Acid - Phenol Method Beaker Starch Deionised water Daicel nanocellulose Starch concentration 1 0 mL 300 mL 1.207 g 0 g/L 2 0.7 mL 300 mL 1.207 g 0.1 g/L 3 1.4 mL 300 mL 1.207 g 0.2 g/L 4 2.09 mL 300 mL 1.207 g 0.3 g/L The nanocellulose and water were added first and allowed to mix with a magnetic stirrer for approximately 45 minutes. Following this the designated amount of stock starch solution was added to the beakers and mixed for 45 minutes, allowing interaction between the starch and nanocellulose. To measure the concentration of the free starch (not adsorbed onto nanocellulose), 10 mL was taken from each beaker and placed into a centrifuge tube. These tubes were centrifuged for 10 minutes at 5000 rpm, with the nanocellulose bound starch complexes settling at the bottom of the tubes allowing the supernatant, or free starch, to be separated. 2 mL of the supernatant was taken from each tube and used as the starch solution in the previously described sulphuric acid – phenol assay. Absorbances from the spectrophotometer at 490 nm were recorded and compared with values gained from the calibration curve data in order to determine the starch concentration. 4.3. Effect of Starch Binding to Nanocellulose on α-Amylase Action Experiments As mentioned previously in Section 3.6, α-amylase is the enzyme within the human body that is responsible for the hydrolysis of starch molecules into glucose monomers. It is currently unknown whether α-amylase has the ability to hydrolyse starch while it is bound to nanocellulose. Also if this does indeed occur, whether the glucose monomers are released from the nanocellulose following hydrolysis, negating the positive effects that are the basis of this project. Therefore an
  • 24. experimental methodology was required to determine whether the action of α-amylase would be an issue. Three reactors were used to determine the effect of 𝛼-amylase on starch adsorption onto nanocellulose, they are described in Table 4-3-1 below: Table 4-3-1: Reactor Contents Used in α-amylase Experiments Reactor 43g/L Starch Solution Deionised water Daicel nanocellulose 1 1.4 mL 300 mL 0 g 2 1.4 mL 300 mL 1.207 g 3 1.4 mL 300 mL 2.414 g Starch, deionised water and nanocellulose were added to Reactors 2 & 3 according to Table 4-3-1 above and were allowed to mix overnight using a magnetic stirrer. When these were thoroughly mixed, starch and deionised water were added to Reactor 1 and allowed to mix with a magnetic stirrer for approximately 45 minutes. Less mixing time was required for Reactor 1 as there was no nanocellulose present, which takes a significant amount of time for the fibres to swell in the solution and become properly dispersed. After this, the reactors all had the same concentration of starch, which was calculated to be 0.2 g/L. Initial glucose measurements were taken from all three reactors using the Accu-Chek Performa Glucose Meter described in Section 4.1. Then the reactors were placed in a water bath at 37°C to simulate temperature within the human body. Following this, 100 μL of α-amylase was added to all three reactors, which was determined to be an appropriate amount from reviewing relevant literature. Glucose concentration was then measured at regular intervals to measure changes in glucose concentration arising from starch digestion by α-amylase. According to the hypothesis it was expected that: - The glucose concentration in Reactor 1 will increase, as the starch won’t be bound to any nanocellulose, leaving it free to be hydrolysed by 𝛼-amylase to release glucose monomers. - Reactor 2 will either show a slight increase in glucose concentration or no increase in glucose concentration, as the starch would be bound to the nanocellulose. - Reactor 3 having the highest concentration of nanocellulose will show the smallest increase in glucose concentration or no rise at all due to the amount of nanocellulose in the reactor.
  • 25. 4.4. Literature Review A main component of this report is a review of current literature to determine the current state of knowledge surrounding the binding of nanocellulose to carbohydrates and fats, as well as possible areas for further investigation and continuation of the project. A diverse range of sources was accessed whilst conducting the literature review with many of the Monash University Library Databases being used. All references used in this project can be found within Section 8 of this report.
  • 26. 5. Key Results and Findings Having conducted the literature review as shown in Section 3 and carried out the experimental work as described in Section 4, we were able to produce a large volume of results and made multiple findings. The key results and findings from our review of literature and our experimental work are discussed in the sections below. 5.1. Glucose Binding to Nanocellulose In order to determine the ability of glucose to bind to nanocellulose, initially an extensive search of literature was conducted. This research aimed to identify previous works investigating the binding of glucose monomers to nanocellulose or similar materials, allowing us to conduct similar experiments in order to test our hypothesis that glucose will bind to cellulose. The search of literature yielded no results, therefore as far as we could determine this is the first documented investigation into the adsorption of glucose monomers onto nanocellulose. Having conducted the search of literature, we designed laboratory scale experiments as described in Section 4.1 of this report in order to investigate the adsorption of glucose monomers to nanocellulose. These experiments involved the use of glucometry in order to measure glucose concentration. Specifically, the Accu-Chek Performa Blood Glucose Meter was used in order to determine the concentration of glucose in solution. In order to conduct our experiments with the glucometer we first attempted to create a standard curve. The first standard solution that we attempted to measure with the glucometer was a glucose solution with a known concentration of 15 mM. Table 5-1-1 below shows the measured glucose concentration using the Accu-Chek Performa Blood Glucose Monitor. Table 5-1-1: Measured Glucose Concentration with Time for 15.07mM Glucose Solution Measurement Time (Minutes) Measured Glucose Concentration (mM) 0 5.9 2 8.3 6 11 10 12.8 15 14.9 20 16.3 25 17.9 30 19.7 33 21.1
  • 27. Measurements were taken over time with the hope of determining the steady-state measured concentration. Unfortunately, as can be seen in Table 5-1-1 steady-state was not achieved in the first 33 minutes of this experiment. In fact it can be seen that the measured concentration continues to increase, even after having exceeded the expected steady-state value of 15.07 mM. The results shown in Table 5-1-1 are also illustrated in graphical form in Figure 5-1-1. Figure 5-1-1: Measured Glucose Concentration vs. Time for 15.07 mM Standard Solution Due to the unexpected results using the 15.07 mM standard solution, we repeated the measurements for a 2.02 mM standard glucose solution. In this instance five measurements with the glucometer were taken for each time point, allowing for an average measured glucose concentration to be determined. It was expected that the measured glucose concentration would reach a steady state at approximately 2.02 mM after a given period of time, however as can be seen in Table 5-1-2 and Figure 5-1-2 as time progressed the measured concentration continued to increase beyond the expected value. This result was also seen for the 15.07 mM standard solution as can be seen by referring to Figure 5-1-1. 0 5 10 15 20 25 0 5 10 15 20 25 30 35 MeasuredGlucoseConcentration(mM) Time (mins) Measured Glucose Concentration vs. Time - 15mM Standard Solution
  • 28. Table 5-1-2: Measured Glucose Concentration vs. Time (2.02mM Glucose Standard Solution) Time (min) Trial 1 Trial 2 Trial 3 Trial 4 Trial 5 Average Standard Deviation 2 Low Low Low Low Low N/A N/A 4 0.7 0.7 0.7 0.7 0.7 0.7 0 7 0.8 0.8 0.9 0.8 0.8 0.8 0.05 10 1.0 1.0 0.9 0.9 1.1 1.0 0.08 15 1.2 1.3 1.3 1.2 1.3 1.3 0.05 20 1.5 1.5 1.6 1.7 1.7 1.6 0.1 25 1.7 1.9 1.7 1.9 1.9 1.8 0.11 30 1.9 2.1 2.1 2.1 2.1 2.1 0.09 37 2.3 2.4 2.4 2.4 2.4 2.4 0.04 50 3.0 2.9 2.9 3.1 3.0 3.0 0.08 The average measured glucose concentration for each time point shown in Table 5-1-2 above is plotted against time in Figure 5-1-2 below. Figure 5-1-2: Average Measured Glucose Concentration vs. Time (2.02mM Glucose Standard Solution) The variation of glucose concentration with time was unexpected, with the trends showing measured concentration using the Accu-Chek Performa Glucose Monitor increasing well beyond the known glucose concentration. In an attempt to rectify this unexpected result the supplier of the glucometer was contacted and previous published works that had used glucometry for glucose concentration determination were consulted. As a result it was determined that the unexpected results may have arisen due to the fact that the glucometer was designed for measuring blood glucose and therefore glucose solutions lacking the other elements of blood (i.e. cells, proteins etc.) could yield inaccurate results. 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 0 10 20 30 40 50 60 MeasuredGlucoseConcentration(mM) Time (mins) Average Measured Glucose Concentration vs. Time - 2.02mM Standard Solution
  • 29. Further to these enquiries, we also trialled many different experiments in an attempt to stop the variation of measured glucose concentration with time. Such experiments included modifying the method of transferring the glucose solution to the glucometer, varying the location within the beaker of glucose solution from which the sample was tested, taking samples with the magnetic stirrer present and with the stirrer absent and trialling different glucose solution concentrations. The results of these experiments all consistently displayed a continuous increase in glucose concentration with time. In a further attempt to eliminate the increasing measured glucose concentration with time, we added blood to the glucose solution in order to determine if using the glucometer on a blood solution would yield results that were consistent with expectations. This addition of blood stabilised the variation of glucose concentration with time, suggesting that the blood glucose meter was working as the supplier reported it should. This therefore suggested that as the supplier stated, the unexpected results being reported by the glucometer may be due to the fact that the meter is designed for blood samples and not for glucose solutions. This does not however explain how previous works were successful in using blood glucose meters as a method for determining glucose concentrations in solution. It was hypothesised that adding Bovine Serum Albumin (BSA) to glucose solutions could eliminate the increasing measured concentration by making the solutions closer to the composition of blood due to the addition of proteins. BSA was therefore added to glucose solutions of varying concentration and the glucometer was used to measure the glucose concentration over a three hour period. The results of this experiment found that the addition of BSA did not stop the increase in measured glucose concentration with time, with a steady-state measured concentration not being achieved and the known concentration being well exceeded by the glucometer concentration reading. It was determined that if the glucose solution was left to mix overnight that a steady state measured glucose concentration was achieved, albeit well above the known concentration. This did however allow us to produce a standard curve for the concentration measured with the Accu- Chek Performa Blood Glucose Meter, as is shown in Figure 5-1-3 below. Figure 5-1-3 shows the standard curve produced having used the titre experiment outlined in Section 4.1 using a glucose master solution with a concentration of 15 mM. This figure shows the measured concentration to be consistently four times higher than the known glucose concentration.
  • 30. Figure 5-1-3: Glucose Measured Concentration Standard Curve - 15mM Glucose Master Solution Having determined the standard curve as shown above, we repeated the experiment as is outlined in Section 4.1, this time making master solutions of 15 mM glucose mixed with 3.726 g and 9.117 g of VTT nanocellulose. The measured glucose concentration in these nanocellulose/glucose solutions could then be compared to the standard curve results, which represent the result for the glucose solution in the absence of nanocellulose. It would therefore be hypothesised that if the glucose had bound to the nanocellulose that the measured glucose concentration should be lower in the solution that contains nanocellulose. Figure 5-1-4 on the following page shows the results of this experiment. The trends shown in Figure 5-1-4 show that when 3.726 g of VTT was added to the 15 mM glucose solution, the glucose concentration as measured by the glucometer was very similar to that of the standard solution (i.e. the solution containing no VTT). This was true for all known glucose concentrations, except for higher concentrations which recorded a slightly higher measured glucose concentration when 3.726 g of VTT was added. This result was not expected, as it was anticipated that the addition of VTT nanocellulose would reduce the measured glucose concentration. However, due to the lack of precision of the glucometer and the high experimental error associated with its measurements, the increase in measured glucose concentration noted for the solution containing 3.726 g of VTT was likely due to experimental error. Therefore it is more likely that the glucose concentration of this solution is roughly the same as that of the glucose standard solution. It can be concluded from this result that the addition of 3.726 g of VTT did not result in a reduction in glucose concentration, hence suggesting that glucose did not bind to the VTT nanocellulose. 0 5 10 15 20 25 30 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 MeasuredGlucoseConcentration(mM) Known Glucose Concentration (mM) Measured Glucose Concentration on Accu-Chek vs Known Glucose Concentration
  • 31. Figure 5-1-4: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 15mM Glucose Master Solution Figure 5-1-4 also shows that the addition of 9.117 g of VTT to the 15 mM master solution results in a slight reduction in measured glucose concentration for most known concentrations measured. Upon first inspection this suggests that the addition of such a mass of VTT has resulted in a reduction in glucose concentration, hence suggesting that glucose has adsorbed onto the VTT. However as can be seen by referring to Table 5-1-3 below, VTT has a moisture content of 96.44% and therefore when adding 9.117 g of VTT we are in fact only adding 0.327 g of cellulose and 8.79 g of water. Given that the solution to which the VTT was added only had a volume of 100 mL (approximately 100 g of water), this addition of 8.79 g of water would be expected to result in a decrease in the concentration of glucose. Therefore the reduction in measured glucose concentration seen in Figure 5-1-4 is likely due to the addition of water and therefore cannot be conclusively linked to the binding of glucose to the added nanocellulose. Table 5-1-3: Moisture and Solids Content of Starch and Cellulose Materials Used Tapioca Starch VTT Cellulose Daicel Cellulose Solid Content 88.04% 3.56% 24.86% Moisture Content 11.96% 96.44% 75.14% Figure 5-1-3 and Figure 5-1-4 above represent the results of the experiments using a 15 mM glucose master solution, the methodologies of which are discussed in Section 4.1. These experiments were repeated using a lower glucose concentration master solution of 5 mM, in order to determine if lowering the known glucose concentration would result in measureable binding of 0 5 10 15 20 25 30 35 0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 MeasuredGlucoseConcentration(mM) Known Glucose Concentration (mM) Measured Glucose Concentration on Accu-Chek vs Known Glucose Concentration (15mM) - Effect of VTT Nanocellulose 15mM Glucose Standard Solution 3.726g VTT Added to 15mM Glucose Standard Solution 9.117g VTT Added to 15mM Glucose Standard Solution
  • 32. glucose to the VTT. The results of these experiments using a 5 mM master solution are shown in Figure 5-1-5 below. Figure 5-1-5: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 5mM Glucose Master Solution The results shown above suggest that adding VTT nanocellulose to the glucose solution resulted in a reduction in free glucose (the glucose measured by the glucometer). However, this reduction corresponds to the reduction in glucose concentration expected due to the amount of water added with the VTT nanocellulose. Adding 22.94 g of “wet” VTT actually translates to adding approximately 22.12 g of water and only 0.87 g of “dry” VTT. Therefore, as was the case for the 15 mM glucose solution experiments, these results suggest the addition of VTT to a glucose solution does not result in a decrease in glucose concentration, hence suggesting that glucose does not adsorb to VTT nanocellulose. The experiments outlined above for 15 mM and 5 mM glucose master solutions were repeated for a 2.02 mM glucose solution. For these experiments we added Daicel nanocellulose rather than VTT due to the lower moisture content of the Daicel, as is highlighted in Table 5-1-3. The resulting solution was very viscous and when repeating the titre experiment the glucometer was unable to read the higher concentrations and gave “LO” results for the lower concentrations. This is highlighted in the Table 5-1-4 on the following page. 0 2 4 6 8 10 12 14 0.0 1.0 2.0 3.0 4.0 5.0 6.0 MeasuredGlucoseConcentration(mM) Known Glucose Concentration (mM) Measured Glucose Concentration on Accu-Chek vs Known Glucose Concentration in Water (5mM) 5mM Glucose Standard Solution 11.425g VTT Added to 5mM Glucose Standard Solution 22.94g VTT Added to 5mM Glucose Standard Solution
  • 33. Table 5-1-4: The Effect of Nanocellulose Addition on Measured Glucose Concentration - 2mM Glucose Master Solution Known Glucose Concentration (mM) Measured Glucose Concentration (mM) - Standard Solution Measured Glucose Concentration (mM) - 7.995g Daicel Added 2.05 4.92 ERROR 1.03 2.38 ERROR 0.51 1.18 0.72 0.26 0.66 LO 0.13 LO LO 0.06 LO LO 0.03 LO LO The error reported in the table above was due to the high viscosity of the solution. The figure on the left below shows the solution of Daicel Nanocellulose and glucose. As can be seen this is a very viscous solution. It was suggested that the viscosity could be indicative of a binding of the nanocellulose with the Daicel, however we hypothesised that the high viscosity was merely due to the swelling of the Daicel. In order to test this we made a solution with the same concentration of Daicel in water, with no glucose. This solution is seen in the middle figure below. As can be seen it has the same viscosity as the Daicel and Glucose solution shown in the figure on the left. The figure on the right allows comparison of the two solutions. Our hypothesis was therefore validated and it was assumed that the high viscosity is due to the swelling of the Daicel, not due to the interaction between the Daicel and the glucose. Figure 5-1-6: A) (Left) Daicel and Glucose Solution. B) (Middle) Daicel Solution. C) (Right) Comparison of Daicel + Glucose Solution and Daicel Solution Overall, our investigation into the interaction of glucose and nanocellulose found no conclusive evidence that glucose can adsorb onto cellulose. This is however only true for cellulose and nanocellulose in unmodified states and further research into the interaction of glucose with modified cellulose materials needs to be conducted in order to determine if such modifications could enable glucose to bind to cellulose materials.
  • 34. 5.2. Sucrose Binding to Nanocellulose From literature it was found that sucrose does not adsorb onto cellulose fibres as it has been used as an inert tracer in a packed bed of cellulose fibres in previous experimental work (9). Therefore no experimental work was conducted in this area, saving time to focus on other points. It would be advantageous to investigate chemical modification of nanocellulose to facilitate adsorption of sucrose onto the surface. 5.3. Starch Binding to Nanocellulose By conducting the sulphuric acid – phenol method described in Section 4.2, a calibration curve relating absorbance and starch concentration was constructed and can be seen in Figure 5-3-1 below. Figure 5-3-1: Calibration Curve Constructed for the Sulphuric Acid - Phenol Starch Concentration Determination Method Using an Absorbance of 490nm The calibration curve achieved an R2 value of 0.9834, which comparing to literature was determined to be within the required error range. From this curve we were able to relate the absorbance values gained from the UV-Vis spectrophotometer to starch concentration using the equation y=13.463x+0.1066. Where y is the absorbance at 490 nm and x is the corresponding concentration of starch in solution. This information allowed the following results to be obtained to test starch adsorption on nanocellulose. y = 13.463x + 0.1066 R² = 0.9834 0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 Absorbance Starch Concentration (g/L) Phenol-Sulphuric Acid Determination of Starch Concentration - Standard Curve
  • 35. Figure 5-3-2: Comparison of Initial Starch Concentration and Starch Concentration after the Addition of Daicel Nanocellulose for Initial Starch Concentrations Ranging from 0-0.3g/L It can be seen from Figure 5-3-2 above that overall the addition of Daicel nanocellulose related to a reduction in starch concentration. As the same amount of nanocellulose was added to each beaker, the greatest effect was in the beaker with the highest initial starch concentration of 0.3 g/L. However a reduction was also realised in beakers 2 & 3, showing that the greatest relative effect is noticed at higher initial starch concentrations. This suggests that the nanocellulose still had more binding capacity and was not yet saturated with starch. However the starch was not reduced to a concentration of zero, which suggests that nanocellulose concentration is also a factor and a state of equilibrium between bound and free starch is achieved in the solution. From these results we were successful in confirming the hypothesis that starch could be adsorbed onto nanocellulose. Following on from this we wished to investigate the action of α-amylase and whether it would have the capacity to reverse the effects that were established by the results discussed above. 0 0.05 0.1 0.15 0.2 0.25 0.3 1 2 3 4 StarchConcentration(g/L) Beaker Starch Adsorption on Nanocellulose Starch + nanocellulose Initial Starch Solution
  • 36. 5.4. Effect of Starch Binding to Nanocellulose on α-Amylase Action As can be seen in Table 5-4-1 below, there were no conclusive results achieved from the regular glucose concentration readings taken by the Accu-Chek Performa. Before the α-amylase was added to the reactors they showed a glucose concentration of “LO” on the glucometer, denoting a reading below the minimum detectable concentration of 0.6 mM. Table 5-4-1: Measured Glucose Concentrations over Time for Alpha-Amylase Experiment Time (min) Glucose Concentration (mM) Reactor 1 Reactor 2 Reactor 3 0 LO LO LO 30 LO LO LO 60 LO LO LO 120 LO LO LO 180 LO LO LO 240 LO LO LO 24 hours LO LO LO After measuring the glucose concentration at regular intervals up to 24 hours after the α-amylase was added to the reactors, it was observed that there was no apparent rise in glucose concentration as all the readings were still “LO”. However, this does not mean that the glucose concentration didn’t increase, as it is possibly it could have risen from 0.2 mM to 0.5 mM, for example. However we cannot say with conviction that the glucose concentration increased due to it being undetected by the glucometer. It would be advantageous to conduct further investigation in this area as the interactions between starch, nanocellulose and α-amylase are important in the context of this project.
  • 37. 6. Conclusions and Recommendations Having conducted this research project we have come to multiple conclusions regarding the potential application of nanocellulose as a negative calorie food additive. Conducting an extensive review of literature it was determined that no literature exists on the topic of the adsorption of the monosaccharide glucose to cellulose. The experiments that we conducted produced results concluding that glucose does not adsorb to nanocellulose. An extensive review of literature was also conducted regarding the adsorption of sucrose onto cellulose. It was concluded from the previous works discovered in this investigation of published literature that the disaccharide sucrose does not bind to nanocellulose. A large amount of literature was found regarding the binding of starch to cellulose. Our experiments confirmed our hypothesis that starch adsorbs to the surface of nanocellulose. We also conducted experiments investigating the effect that α-amylase has on starch bound to nanocellulose. We were unable to determine if α-amylase was hydrolysing the nanocellulose bound starch from these experiments, hence these experiments were inconclusive. A literature review of the effect of nanocellulose on cholesterol levels was also conducted, with this review suggesting that nanocellulose can regulate blood cholesterol levels. This regulation is not achieved through the binding of cholesterol to nanocellulose, but rather due to the fact that increased nanocellulose levels in the diet increases faecal mass, in turn increasing bile acid production, ultimately resulting in the breakdown of cholesterol and reduction in blood cholesterol levels. Nanocellulose in the diet can also be linked to the prevention of colon cancer due to the fact that it binds to secondary bile acids as well as increasing faecal mass, thus reducing levels of secondary bile acids present in the colon, which has been linked to colon cancer. Literature relating to the effect of fructans on blood cholesterol levels was also researched as part of this project. From this review of literature it was concluded that fructans ferment in the colon producing propionic acid, a chemical that inhibits cholesterol synthesis and lipogenesis in the liver. Fructans were also found to be able to bind to triglycerides. Therefore it was concluded from this literature review that fructans have the ability to reduce both cholesterol and triglyceride levels in the blood. Based on the conclusions drawn from the experiments conducted and literature reviewed throughout this project, multiple recommendations for future works have been made.
  • 38. Firstly, regarding the adsorption of glucose and sucrose onto nanocellulose, it is important to note that the experiments that have found that glucose and sucrose do not bind to nanocellulose have only been conducted using nanocellulose in a native form. It is therefore recommended that nanocellulose be chemically modified in order to alter its functionality, and experiments be conducted to determine whether glucose and sucrose will bind to this modified nanocellulose. The experiments regarding the effect that α-amylase action has on starch binding to nanocellulose produced inconclusive results. These results were deemed to be inconclusive due to the lack of sensitivity of the glucometry technique used for analysis of samples. It is therefore recommended that these experiments be repeated, however rather than using glucometry a more sensitive analytical technique such as high performance liquid chromatography should be employed. As previously discussed, this project found literature suggesting that nanocellulose and fructans could, in theory, result in a reduction in cholesterol and triglyceride levels in the blood. Our project did not however, test this experimentally and it is therefore recommended that future works experimentally investigate the use of fructans and nanocellulose to reduce cholesterol and triglyceride levels. In conducting this research project we were able to achieve our objective of investigating the use of nanocellulose as a negative calorie and cholesterol controlling food additive. Although not all of our results supported our hypothesis, many did, and those that didn’t based on these preliminary experiments, may prove to align better with our hypothesis if further experiments are conducted. Therefore, overall our project was a success and the use of nanocellulose as a negative calorie and cholesterol controlling food additive still remains a valid proposal, however requires further investigation. 7. Acknowledgements We would like to express our gratitude to Professor Gil Garnier, for his guidance and feedback throughout this project. We would also like to thank Mr Scot Sharman and Dr Heather McLeish for their continued assistance and advice while in the APPI laboratories.
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  • 42. 50. Critical Evaluation of in Vitro Methods for Estimating Digestibility in Simple-Stomach Animals. Boison, S. & Eggum, B. O. 1991, Nutrition Research Reviews, pp. 141-162. 51. Characterization of three different potato starches and kinetics of their enzymatic hydrolysis by an alpha-amylase. Heitmann, T., Wenzig, E. & Mersmann, A. 1997, Enzyme and Microbial Technology, pp. 259-267. 52. The relation of physical properties of native starch granules to the kinetics of amolysis catalysed by porcine pancreatic alpha-amylase. Tahir, R., Ellis, P. R. & Butterworth, P. J. 2010, Carbohydrate Polymers, pp. 57-62. 53. Study of optimum conditions and kinetics of starch hydrolysis by means of thermostable alpha- amylase. Yankov, D., Dobreva, E., Beschkov, V. & Emanuilova, E. 1986, Enzyme and Microbial Technology, pp. 665-667.
  • 44. Task / Process / Procedure Method 1: Risk Assessment Hazard Type Consequence & Likelihood Risk Score Controls Currently in Place Controls to be Implemented By Who By When In Place (Sign) Description of hazard Inhalation of Sodium Hydroxide Chemical (R37) Consequence: Minor Likelihood: Occasional Medium (D3) Lab entry restricted to those wearing appropriate PPE. Operate in fume cupboard & wear safety mask. Operator As required Skin Contact with Sodium Hydroxide Chemical (R35) Consequence: Moderate Likelihood: Unlikely Medium (C4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE (lab coat & gloves). Operator As required Eye Contact with Sodium Hydroxide Chemical (R41) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE, especially safety glasses. Handle carefully. Operator As required Inhalation of Hydrochloric Acid Chemical (R37) Consequence: Moderate Likelihood: Unlikely Medium (C4) Lab entry restricted to those wearing appropriate PPE. Operate in fume cupboard & wear safety mask. Operator As required Skin Contact with Hydrochloric Acid Chemical (R35) Consequence: Moderate Likelihood: Unlikely Medium (C4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE (lab coat & gloves). Operator As required
  • 45. Eye Contact with Hydrochloric Acid Chemical (R41) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE. Handle carefully. Operator As required Inhalation of Phenol Chemical (R37) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Operate in fume cupboard & wear safety mask. Operator As required Skin Contact with Phenol Chemical (R35) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE (lab coat & gloves). Operator As required Eye Contact with Phenol Chemical (R41) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE. Handle carefully. Operator As required Inhalation of Concentrated Sulfuric Acid Chemical (R37) Consequence: Moderate Likelihood: Unlikely Medium (C4) Lab entry restricted to those wearing appropriate PPE. Operate in fume cupboard & wear safety mask. Operator As required Skin Contact with Concentrated Sulfuric Acid Chemical (R35) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE (lab coat & gloves). Operator As required Eye Contact with Concentrated Sulfuric Acid Chemical (R41) Consequence: Severe Likelihood: Unlikely High (B4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE. Handle carefully. Operator As required
  • 46. Inhalation of Nanocellulose Chemical (R20) Consequence: Minor Likelihood: Unlikely Medium (D4) Fume cupboard available. Wear safety mask, handle carefully. Operator As required Eye Exposure to Nanocellulose Chemical (R21) Consequence: Minor Likelihood: Unlikely Medium (D4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE, especially safety glasses. Handle carefully. Operator As required Inhalation of D(+)-Glucose Powder Chemical (Irritating if Inhaled) Consequence: Negligible Likelihood: Unlikely Low (E4) Fume cupboard available. Wear safety mask, handle carefully. Operator As required Eye Exposure to D(+)-Glucose Powder Chemical (R36) Consequence: Negligible Likelihood: Unlikely Low (E4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE, especially safety glasses. Handle carefully. Operator As required Inhalation of Starch Powder Chemical (R20) Consequence: Minor Likelihood: Highly Unlikely Low (D5) Fume cupboard available. Wear safety mask, handle carefully. Operator As required Eye Exposure to Starch Powder Chemical (R36) Consequence: Negligible Likelihood: Unlikely Low (E4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE, especially safety glasses. Handle carefully. Operator As required Inhalation of α-Amylase Solution Chemical (R20) Consequence: Minor Likelihood: Highly Unlikely Low (D5) Fume cupboard available. Wear safety mask, handle carefully. Operator As required
  • 47. Eye Exposure to α-Amylase Solution Chemical (R36) Consequence: Negligible Likelihood: Unlikely Low (E4) Lab entry restricted to those wearing appropriate PPE. Ensure wearing appropriate PPE, especially safety glasses. Handle carefully. Operator As required pH Monitor Physical – Electrical (P8) Consequence: Moderate Likelihood: Highly Unlikely Medium (C5) Regular maintenance checks. Check equipment condition before use and avoid contact with liquids. Operate only as directed. Operator As required Magnetic Stirrer Physical – Electrical (P8) Consequence: Moderate Likelihood: Highly Unlikely Medium (C5) Regular maintenance checks. Check equipment condition before use and avoid contact with liquids. Operate only as directed. Operator As required Water Bath Physical – Electrical (P8) Consequence: Moderate Likelihood: Highly Unlikely Medium (C5) Regular maintenance checks. Check equipment condition before use and avoid contact with liquids. Operate only as directed. Operator As required Computer/Laptop Physical – Electrical (P8) Consequence: Moderate Likelihood: Highly Unlikely Medium (C5) Regular maintenance checks. Check equipment condition before use and avoid contact with liquids. Operator As required Slipping/Tripping Physical – Gravitational (P3) Consequence: Severe Likelihood: Highly Unlikely Medium (B5) Regulations on storage of equipment and cleanliness of lab. Ensure workspace and lab floor is clear of obstacles. Operator As required Broken Glass Physical – Machinery (P1) Consequence: Moderate Likelihood: Unlikely Medium (C4) Dust pan and glass- specific bin provided. Handle glassware with care, notify appropriate individuals and ensure glass is completely cleared. Operator As required
  • 48. Ergonomic Hazards Associated with Desk Work Manual Handling Consequence: Minor Likelihood: Likely Medium (D2) Adjustable chair and computer screen. Ensure working with correct posture and taking breaks when necessary, sit in an adjustable chair, ensure computer screen can be adjusted to optimum-eye level and that workspace is tidy and free of obstacles affecting posture. Operator As required Repetitive Strain Injury (RSI) Manual Handling Consequence: Negligible Likelihood: Occasional Medium (E3) Ergonomically designed pipettes. Take breaks when necessary, avoid prolonged periods of lab work, spread work load between operators. Operator As required