study, state diagram of broccoli was developed considering freezing curve, glass line, maximal-freeze-concentration
conditions, solids-melting and BET-monolayer line. The freezing point, glass transition and solidsmelting
were measured and modeled by Chen’s model, Gordon-Taylor model, and Flory-Huggins model, respectively.
The ultimate maximal-freeze-concentration conditions (Tm′)u (i.e. end temperature of freezing) and
(Tg′′′)u [i.e. end glass transition at (Tm′)u] were found as −30.0 °C and −32.2 °C, respectively, and solids content
(i.e. Xs′) at this point was 0.70 g/g sample. The solids-water interaction (χ) during melting was estimated as 0.69
(dimensionless) from Flory-Huggins model, and BET-monolayer was observed as 0.089 g/g dry-solids at 20 °C.
Establishing Optimal Dehydration Process Parameters for Papaya By EmployingA ...IJERA Editor
This study employs a Firefly Algorithm (FA) to determine the optimal osmotic dehydration parameters for papaya. The functional form of the osmotic dehydration model is established via a standard response surface technique. The format of the resulting optimization model to be solved is a non-linear goal programming problem. While various alternate solution approaches are possible, an FA-driven procedure is employed. For optimization purposes, it has been demonstrated that the FA is more computationally efficient than other such commonly-used metaheuristics as genetic algorithms, simulated annealing, and enhanced particle swarm optimization. Hence, the FA approach is a very computationally efficient procedure. It can be shown that the resulting solution determined for the osmotic process parameters is superior to those from all previous approaches.
2012_Designed optimization of a single-step extraction of fucose-containing s...Marcel Tutor Ale, PhD
This document describes an experiment to optimize the extraction of fucose-containing sulfated polysaccharides (FCSPs) from the brown seaweed Sargassum sp. using a single-step extraction process. The researchers systematically examined how acid concentration, temperature, and time affected FCSP yield. They found that temperature and time had positive effects on yield, while acid concentration had a negative effect. An optimal single-step extraction procedure was defined as 0.03 M HCl at 90°C for 4 hours, which achieved a maximal FCSP yield of approximately 7% of the dry matter of Sargassum sp. Analysis confirmed the major constituents of the extracted polysaccharides were fucose, galactose, and glucur
Effect of specific growth rate on fermentative capacityHazem Hussein
This study investigated the effect of specific growth rate on the physiology and fermentative capacity of an industrial baker's yeast strain in aerobic, glucose-limited chemostat cultures. The researchers found that below a specific growth rate of 0.28 h-1, glucose metabolism was fully respiratory, while above this rate respirofermentative metabolism occurred with ethanol production. Fermentative capacity, measured offline as ethanol production under anaerobic conditions, increased with increasing specific growth rate from 10.0 mmol/g/h at 0.025 h-1 to 22.0 mmol/g/h at 0.40 h-1. Only the activities of enzymes pyruvate decarboxylase and phosphof
This document describes a study that used a Plackett-Burman experimental design to examine the effects of seven hydrocolloids on the textural properties and glucose dialysis retardation index (GDRI) of meat-based baby foods. Key findings include: 1) locust bean gum and kappa carrageenan increased food matrix force while iota-carrageenan increased pH and decreased acidity; 2) hydrocolloids did not clearly affect GDRI; and 3) locust bean gum showed potential for texture modification with minimal added glucose. The conclusions recommend further study using higher hydrocolloid concentrations and excluding those introducing significant free glucose.
Water plays a key role in many aspects of food. It acts as a medium for chemical reactions, supports microbial growth, and contributes to texture. Removing or binding water through processes like drying, freezing, or adding salts/sugars can improve a food's shelf life by slowing reactions and microbial growth. The storage quality of food depends more on its water activity than its total water content. Decreasing water activity through drying, freezing, or adding humectants retards spoilage processes and microbial growth, improving shelf life. The physical state and phase transitions of foods containing water depend on temperature, composition, and water content.
Protein Quantity at the Air-Solid Interface PublicationKorben Knudson
This research article examines how different lyophilization processes affect the stability of recombinant human growth hormone (rhGH) formulations. Five lyophilization methods that produce glasses with varying specific surface areas and protein distributions are compared. Methods that generate larger ice crystals through annealing or slower freezing, resulting in lower protein levels at the solid-air interface, better retain the secondary structure of rhGH and result in less degradation over storage. The findings suggest that differences in protein degradation between formulations and processes can be largely attributed to the amount of protein present at the solid-air interface after lyophilization, with more surface-located protein being more susceptible to degradation.
This document investigates the effects of drying temperature on the degradation kinetics of ascorbic acid (vitamin C) in tomatoes during the drying process. It studies ascorbic acid degradation in whole tomatoes that underwent caustic peeling (with or without prior osmotic pretreatment) as well as halved tomatoes at drying temperatures of 50, 60, and 70°C. The degradation rates were found to depend on both the sample pretreatment and drying temperature, with lower degradation observed in osmotically pretreated whole tomatoes and higher degradation in halved tomatoes. Increasing the drying temperature also increased the degradation rates.
This document discusses various methods for determining the moisture content of foods, including oven drying, vacuum oven drying, distillation, Karl Fischer titration, and physical methods. Oven drying is described in detail, including factors that influence moisture determination such as temperature, time, and type of oven used. The importance of moisture determination for food quality, stability, processing and legal requirements is also outlined.
Establishing Optimal Dehydration Process Parameters for Papaya By EmployingA ...IJERA Editor
This study employs a Firefly Algorithm (FA) to determine the optimal osmotic dehydration parameters for papaya. The functional form of the osmotic dehydration model is established via a standard response surface technique. The format of the resulting optimization model to be solved is a non-linear goal programming problem. While various alternate solution approaches are possible, an FA-driven procedure is employed. For optimization purposes, it has been demonstrated that the FA is more computationally efficient than other such commonly-used metaheuristics as genetic algorithms, simulated annealing, and enhanced particle swarm optimization. Hence, the FA approach is a very computationally efficient procedure. It can be shown that the resulting solution determined for the osmotic process parameters is superior to those from all previous approaches.
2012_Designed optimization of a single-step extraction of fucose-containing s...Marcel Tutor Ale, PhD
This document describes an experiment to optimize the extraction of fucose-containing sulfated polysaccharides (FCSPs) from the brown seaweed Sargassum sp. using a single-step extraction process. The researchers systematically examined how acid concentration, temperature, and time affected FCSP yield. They found that temperature and time had positive effects on yield, while acid concentration had a negative effect. An optimal single-step extraction procedure was defined as 0.03 M HCl at 90°C for 4 hours, which achieved a maximal FCSP yield of approximately 7% of the dry matter of Sargassum sp. Analysis confirmed the major constituents of the extracted polysaccharides were fucose, galactose, and glucur
Effect of specific growth rate on fermentative capacityHazem Hussein
This study investigated the effect of specific growth rate on the physiology and fermentative capacity of an industrial baker's yeast strain in aerobic, glucose-limited chemostat cultures. The researchers found that below a specific growth rate of 0.28 h-1, glucose metabolism was fully respiratory, while above this rate respirofermentative metabolism occurred with ethanol production. Fermentative capacity, measured offline as ethanol production under anaerobic conditions, increased with increasing specific growth rate from 10.0 mmol/g/h at 0.025 h-1 to 22.0 mmol/g/h at 0.40 h-1. Only the activities of enzymes pyruvate decarboxylase and phosphof
This document describes a study that used a Plackett-Burman experimental design to examine the effects of seven hydrocolloids on the textural properties and glucose dialysis retardation index (GDRI) of meat-based baby foods. Key findings include: 1) locust bean gum and kappa carrageenan increased food matrix force while iota-carrageenan increased pH and decreased acidity; 2) hydrocolloids did not clearly affect GDRI; and 3) locust bean gum showed potential for texture modification with minimal added glucose. The conclusions recommend further study using higher hydrocolloid concentrations and excluding those introducing significant free glucose.
Water plays a key role in many aspects of food. It acts as a medium for chemical reactions, supports microbial growth, and contributes to texture. Removing or binding water through processes like drying, freezing, or adding salts/sugars can improve a food's shelf life by slowing reactions and microbial growth. The storage quality of food depends more on its water activity than its total water content. Decreasing water activity through drying, freezing, or adding humectants retards spoilage processes and microbial growth, improving shelf life. The physical state and phase transitions of foods containing water depend on temperature, composition, and water content.
Protein Quantity at the Air-Solid Interface PublicationKorben Knudson
This research article examines how different lyophilization processes affect the stability of recombinant human growth hormone (rhGH) formulations. Five lyophilization methods that produce glasses with varying specific surface areas and protein distributions are compared. Methods that generate larger ice crystals through annealing or slower freezing, resulting in lower protein levels at the solid-air interface, better retain the secondary structure of rhGH and result in less degradation over storage. The findings suggest that differences in protein degradation between formulations and processes can be largely attributed to the amount of protein present at the solid-air interface after lyophilization, with more surface-located protein being more susceptible to degradation.
This document investigates the effects of drying temperature on the degradation kinetics of ascorbic acid (vitamin C) in tomatoes during the drying process. It studies ascorbic acid degradation in whole tomatoes that underwent caustic peeling (with or without prior osmotic pretreatment) as well as halved tomatoes at drying temperatures of 50, 60, and 70°C. The degradation rates were found to depend on both the sample pretreatment and drying temperature, with lower degradation observed in osmotically pretreated whole tomatoes and higher degradation in halved tomatoes. Increasing the drying temperature also increased the degradation rates.
This document discusses various methods for determining the moisture content of foods, including oven drying, vacuum oven drying, distillation, Karl Fischer titration, and physical methods. Oven drying is described in detail, including factors that influence moisture determination such as temperature, time, and type of oven used. The importance of moisture determination for food quality, stability, processing and legal requirements is also outlined.
This document summarizes a study on the hydrothermal dissolution of willow biomass in hot compressed water. The key findings are:
1) A 95% dissolution of willow was achieved at temperatures as low as 200°C and pressures of 10 MPa, with lignin and hemicellulose dissolving first, followed by cellulose between 280-320°C.
2) A proposed dissolution mechanism involves the rapid fragmentation and hydrolysis of lignin, hemicellulose, and cellulose into oligomers and other water-soluble products like glucose.
3) A continuous flow process was found to be more effective for dissolution than a batch process, due to reduced recondensation of dissolved oligomers.
Experimental and simulated thermal properties and process time for canned esc...anda96
This article analyzes the sterilization process for canned escamoles (Liometopum apiculatum), an edible ant larvae in Mexico. Thermal properties and process times were experimentally determined and simulated for canned pickled and brined escamoles under sterilization conditions. Temperature changes in the cans were monitored and used to calculate thermal conductivity, specific heat, and density, which were affected by temperature and heating medium. Pickled escamoles showed uniform heating, highest quality retention, and shortest process times.
This study developed a process for producing L-lactic acid from potato starch waste using Lactococcus lactis in a novel dialysis sac bioreactor. Fermentation in the bioreactor was compared to shake flask fermentation. The bioreactor allowed for complete starch consumption within 24 hours compared to 48 hours in shake flasks. Maximum lactic acid concentration and productivity in the bioreactor were 1.2-fold and 2.4-fold higher than shake flasks, respectively. L. lactis cells remained viable for 4 cycles in the bioreactor compared to 1 cycle in shake flasks, demonstrating improved recycling of cells.
JBEI Research Highlights - November 2021SaraHarmon4
- Poplar sapling were grown in high or low growth temperatures with and without additions of methanol to the soil. Leaf gas exchange, metabolomic profiles and photochemistry were assessed throughout an 8 week incubation period. High growth temperature plants showed suppression of leaf water use, photosynthesis and transpiration, but an upregulation of isoprene emissions and an increased optimum temperature of electron transport rate. Metabolomics analysis revealed a substantial number of metabolites with altered abundance in heat stress, and distinct subsets altered by methanol treatment at both temperatures.
- Overexpression of the rice BAHD acyltransferase AT10 in sorghum increased xylan-bound p-coumarate and reduced lignin in transgenic lines. Biom
Effect of heat treatment, water activity and storage temperature on the oxida...Omar Zeballos
This document summarizes a study investigating the effects of heat treatment, water activity, storage temperature, and time on the oxidative stability of whole milk powder. Three types of milk powder (low-heat, medium-heat, and high-heat) were stored at two temperatures (25°C and 45°C) and three water activities for up to 63 days. Oxidative stability was assessed using electron spin resonance spectrometry to measure free radicals, TBARS to measure secondary lipid oxidation, fluorescent spectroscopy and size-exclusion HPLC to measure protein damage, and sensory evaluation. Results showed that lipid oxidation increased greatly at 45°C, especially for low-heat powder. Sensory quality declined fastest for low-heat powder stored at
Cut orientation and drying temperature effect on drying and rehydration kinet...Jesús A. Sánchez-González
Yacon (Smallanthus sonchifolius) is commonly consumed fresh and is known for its nutritional and functional properties, however, this raw material still needs an added value that allows greater stability and availability. Against this, drying is a good processing alternative. This study aimed to evaluate for the first time the influence of temperature and the orientation of cut on drying and rehydration behavior of Yacon cylinders with longitudinal (L) and transversal (T) cut. Drying was performed at 50 and 60 °C and rehydration was performed with water at 30 °C. Drying and rehydration kinetics were described by the Page and Peleg models, respectively. As results, the effects of drying temperature are greater than the effects of the type of cut. The Page’s model parameters indicated that the treatment with T cut dried at 60 °C was the treatment that dehydrated fast, while the water transfer during the process followed a super-diffusive mechanism. Regarding rehydration, the kinetics of water gain indicate that there was no difference between the rate of water gain among the treatments. However, the T cut samples dried at 50 °C presented a lower amount of water gained at the end of rehydration. In conclusion, the present work demonstrates the influence of temperature on accelerating water transfer as well as the non-isotropicity of food matrices. In addition, drying is presented as a good alternative for the processing of yacon, either in snacks or for subsequent processes such as making flour.
Synthesis of hydroxyapatite from eggshell and its electrochemical.pdfjporcayoc
This work reports the surface modification of titanium through the deposition of a hydroxyapatite coating
synthesized from natural sources. Hydroxyapatite was synthesized from eggshell using a wet precipitation
method. It was deposited as a coating on a Ti surface using electrophoretic deposition (EPD) at different electrophoretic
deposition times and voltages. The electrochemical evaluation of the obtained coatings was performed
through potentiodynamic polarization curves in a simulated physiological solution. The results showed
that the eggshell is an excellent alternative for the synthesis of hydroxyapatite, and that its heat treatment at
700 °C shows the best crystallinity conditions. The optimum conditions for deposition of the hydroxyapatite
coatings were 30 V and 18 min. Potentiodynamic polarization tests showed that hydroxyapatite coatings improve
the chemical stability of the Ti surface when subjected to the corrosive action of simulated physiological
solutions at 37 °C.
Multiple response optimization analysis for pretreatments of Tequila’s stilla...Roberto Bolaños
The objective of this work was study the effect of three pretreatments (alkalinization, thermical treatment, and sonication) on Tequila’s
stillages hydrolysis process in acidogenesis stage, through the following response variables: soluble chemical oxygen demand (CODs),
total sugar and volatile fatty acids profile and the hydrogen production at the time. The stillages were subject to these pretreatments
(according to a 23 factorial design); afterward they were transferred to a batch reactor at 35 C and inoculated with an anaerobic digestor
sludge. Multiple response optimization (MRO) analysis was done to find the global optimum for the response variables described above.
This optimum is able to maximize simultaneously all these variables. It was found adequate to be useful hydrolyzing the organic matter
present in Tequila’s stillages. Mathematical models were fitted to observe the estimated effects of pretreatments on each response variable,
then the MRO was applied.
2007 Elsevier Ltd. All rights reserved.
This study evaluated the effects of ultrasound pretreatment on osmotic dehydration of mango cubes. Mangoes were cut into cubes and some samples received ultrasound pretreatment before being subjected to osmotic dehydration in a 45° Brix sucrose solution at 65°C. Samples were analyzed for water loss, solid gain, and effective diffusion coefficients over time. Results showed that ultrasound pretreatment increased water loss, solid gain, and the effective diffusivity of water and solids compared to samples without pretreatment. Modulated temperature differential scanning calorimetry was also used to characterize changes in the food matrix, such as increases in glass transition temperature, with decreasing moisture content.
Physico – Chemical and Bacteriological Analysis of Well Water at Crescent Roa...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
This document summarizes research on the hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor system. Key points:
- Algae can be converted to an upgradeable biocrude through hydrothermal liquefaction at 350°C and 20 MPa in a continuous-flow reactor, without the need for solvents. High carbon conversions were achieved even at high algae concentrations.
- Catalytic hydrotreating was effectively used to upgrade the biocrude through hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization, producing hydrocarbon fuels.
- Catalytic hydrothermal gasification of the aqueous byproduct stream effectively produced fuel gas and allowed for
Abstract— Biofuel production from microalgae biomass appears as a promising long term alternative. Dunaliella tertiolecta is a microalgae with high tolerance to salinity, temperature, and light, making it relatively easy to grow. The aim of this study was to establish a pilot-scale culture to evaluate the biomass yield and bioethanol production. The cell culture of D. tertiolecta was started in 20 ml tubes and escalated to 20 L containers. The biomass yield was 0.153 g L-1 of dry basis (db) and its characterization showed protein (37% db) as major component followed by carbohydrates (35.6), lipids (13% db) and ash (6.5%). The carbohydrate fraction was composed of starch (27.1% db) and fiber (8.5 %) and its neutral sugar characterization yield glucose (91% molar). The main components of the lipid fraction were linolenic and palmitic acids. The biomass was subjected to an acid pre-treatment for the saccharification of complex carbohydrates, and the hydrolyzed biomass was fermented by Saccharomyces cerevisiae. It was possible to produce 0.615 ml g-1 of ethanol. In conclusion, D. tertiolecta has the potential for bioethanol production, making it a promising option for the biofuels future.
Comparative study between film and coating packaging based onJesus Almaraz Muñoz
This study compared the effectiveness of a shrimp concentrate film and coating at preserving fish sausages during chilled storage. The coating increased the lag phase of total microorganisms and enterobacteria to 15 and 10 days, respectively, while the film drastically inhibited the growth of these microbes. Both helped maintain quality by decreasing pH and volatile bases during storage, with greater effects seen from the film. The coating kept sausage properties similar to controls for 25 days while the film resulted in a lower moisture and pH product resembling pickled sausage that remained stable for at least 42 days.
The Calculation of Optimal Osmotic Dehydration Process Parameters for Mushroo...Agriculture Journal IJOEAR
Abstract— The Firefly Algorithm (FA) is employed to determine the optimal parameter settings in a case study of the osmotic dehydration process of mushrooms. In the case, the functional form of the dehydration model is established through a response surface technique and the resulting mathematical programming is formulated as a non-linear goal programming model. For optimization purposes, a computationally efficient, FA-driven method is used and the resulting optimal process parameters are shown to be superior to those from previous approaches.
Moisture Adsorption Isotherms Characteristics of a New Moisture AdsorbersIJMREMJournal
The purpose of the study was to analyze the effect of the replacement rate of the most hygroscopic moisture adsorber on the adsorption properties of a new moisture adsorbers formulated. Moisture adsorption isotherms of this new moisture adsorbers formulated were determined at 4 ± 1 °C, using the standard static gravimetric method. All moisture adsorption isotherms of new moisture adsorbers were type II following Brunauer’s classification. The moisture isotherms were sigmoid shaped and showed a clear dependence on the substitution rates of the most hygroscopic moisture adsorber (ads 3). Of the eighteen new moisture adsorbers formulated, only AB (40:60) and AL (60:40) adsorbers had the characteristic appearance of better moisture adsorbeers in modified atmosphere packaging of fruits and vegetables (tomato and mushroom). Thus, their incorporation into the packaging could avoid the condensation of water vapor by maintaining an optimal relative humidity. Based on statistical parameters, additive isotherm approach of Labuza (1968) could not correctly describe the adsorption characteristics of all this new moisture adsorbers formulated. However, this model gave better prediction with the new AB moisture adsorbers than with the new AL moisture adsorbers with sums of relative mean errors of 165.89% and 293.71%, respectively.
Moisture Adsorption Isotherms Characteristics of a New Moisture AdsorbersIJMREMJournal
The purpose of the study was to analyze the effect of the replacement rate of the most hygroscopic moisture
adsorber on the adsorption properties of a new moisture adsorbers formulated. Moisture adsorption isotherms
of this new moisture adsorbers formulated were determined at 4 ± 1 °C, using the standard static gravimetric
method. All moisture adsorption isotherms of new moisture adsorbers were type II following Brunauer’s
classification. The moisture isotherms were sigmoid shaped and showed a clear dependence on the substitution
rates of the most hygroscopic moisture adsorber (ads 3). Of the eighteen new moisture adsorbers formulated,
only AB (40:60) and AL (60:40) adsorbers had the characteristic appearance of better moisture adsorbeers in
modified atmosphere packaging of fruits and vegetables (tomato and mushroom). Thus, their incorporation into
the packaging could avoid the condensation of water vapor by maintaining an optimal relative humidity. Based
on statistical parameters, additive isotherm approach of Labuza (1968) could not correctly describe the
adsorption characteristics of all this new moisture adsorbers formulated. However, this model gave better
prediction with the new AB moisture adsorbers than
The objective was to compare cooling of peaches via free and forced convection. Peaches were submerged in ice baths with one peach stirred (forced convection) and the other stationary (free convection). Temperature was measured every minute until reaching 7.5°C. Forced convection cooled the peach faster, in 25.14 minutes with a convection coefficient of 3,105 W/(m2K), while free convection took 43.17 minutes with a coefficient of 41.38 W/(m2K). COMSOL models showed faster cooling under forced convection due to higher heat transfer rates.
The objective was to compare cooling of peaches via free and forced convection. Peaches were submerged in ice baths with one stirred (forced convection) and one stagnant (free convection). Temperature was measured every minute until reaching 7.5°C. Forced convection cooled the peach faster, in 25.14 minutes with a convection coefficient of 3,105 W/(m2K), while free convection took 43.17 minutes with a coefficient of 41.38 W/(m2K). COMSOL models showed faster cooling under forced convection. Differences from theory were likely due to approximations in the experimental setup and peach properties.
This document evaluates models for predicting thermophysical properties of foods. It summarizes the performance of different models for predicting ice fraction, apparent specific heat capacity, specific enthalpy, and thermal conductivity based on a comparison to experimental data. The best performing models were: Chen (1985b) for ice fraction prediction, Schwartzberg (1976) for apparent specific heat capacity, Chen (1985a) for specific enthalpy prediction, and Levy (1981) for thermal conductivity prediction.
More Related Content
Similar to Thermal characteristics and state diagram of freeze dried broccoli 2017
This document summarizes a study on the hydrothermal dissolution of willow biomass in hot compressed water. The key findings are:
1) A 95% dissolution of willow was achieved at temperatures as low as 200°C and pressures of 10 MPa, with lignin and hemicellulose dissolving first, followed by cellulose between 280-320°C.
2) A proposed dissolution mechanism involves the rapid fragmentation and hydrolysis of lignin, hemicellulose, and cellulose into oligomers and other water-soluble products like glucose.
3) A continuous flow process was found to be more effective for dissolution than a batch process, due to reduced recondensation of dissolved oligomers.
Experimental and simulated thermal properties and process time for canned esc...anda96
This article analyzes the sterilization process for canned escamoles (Liometopum apiculatum), an edible ant larvae in Mexico. Thermal properties and process times were experimentally determined and simulated for canned pickled and brined escamoles under sterilization conditions. Temperature changes in the cans were monitored and used to calculate thermal conductivity, specific heat, and density, which were affected by temperature and heating medium. Pickled escamoles showed uniform heating, highest quality retention, and shortest process times.
This study developed a process for producing L-lactic acid from potato starch waste using Lactococcus lactis in a novel dialysis sac bioreactor. Fermentation in the bioreactor was compared to shake flask fermentation. The bioreactor allowed for complete starch consumption within 24 hours compared to 48 hours in shake flasks. Maximum lactic acid concentration and productivity in the bioreactor were 1.2-fold and 2.4-fold higher than shake flasks, respectively. L. lactis cells remained viable for 4 cycles in the bioreactor compared to 1 cycle in shake flasks, demonstrating improved recycling of cells.
JBEI Research Highlights - November 2021SaraHarmon4
- Poplar sapling were grown in high or low growth temperatures with and without additions of methanol to the soil. Leaf gas exchange, metabolomic profiles and photochemistry were assessed throughout an 8 week incubation period. High growth temperature plants showed suppression of leaf water use, photosynthesis and transpiration, but an upregulation of isoprene emissions and an increased optimum temperature of electron transport rate. Metabolomics analysis revealed a substantial number of metabolites with altered abundance in heat stress, and distinct subsets altered by methanol treatment at both temperatures.
- Overexpression of the rice BAHD acyltransferase AT10 in sorghum increased xylan-bound p-coumarate and reduced lignin in transgenic lines. Biom
Effect of heat treatment, water activity and storage temperature on the oxida...Omar Zeballos
This document summarizes a study investigating the effects of heat treatment, water activity, storage temperature, and time on the oxidative stability of whole milk powder. Three types of milk powder (low-heat, medium-heat, and high-heat) were stored at two temperatures (25°C and 45°C) and three water activities for up to 63 days. Oxidative stability was assessed using electron spin resonance spectrometry to measure free radicals, TBARS to measure secondary lipid oxidation, fluorescent spectroscopy and size-exclusion HPLC to measure protein damage, and sensory evaluation. Results showed that lipid oxidation increased greatly at 45°C, especially for low-heat powder. Sensory quality declined fastest for low-heat powder stored at
Cut orientation and drying temperature effect on drying and rehydration kinet...Jesús A. Sánchez-González
Yacon (Smallanthus sonchifolius) is commonly consumed fresh and is known for its nutritional and functional properties, however, this raw material still needs an added value that allows greater stability and availability. Against this, drying is a good processing alternative. This study aimed to evaluate for the first time the influence of temperature and the orientation of cut on drying and rehydration behavior of Yacon cylinders with longitudinal (L) and transversal (T) cut. Drying was performed at 50 and 60 °C and rehydration was performed with water at 30 °C. Drying and rehydration kinetics were described by the Page and Peleg models, respectively. As results, the effects of drying temperature are greater than the effects of the type of cut. The Page’s model parameters indicated that the treatment with T cut dried at 60 °C was the treatment that dehydrated fast, while the water transfer during the process followed a super-diffusive mechanism. Regarding rehydration, the kinetics of water gain indicate that there was no difference between the rate of water gain among the treatments. However, the T cut samples dried at 50 °C presented a lower amount of water gained at the end of rehydration. In conclusion, the present work demonstrates the influence of temperature on accelerating water transfer as well as the non-isotropicity of food matrices. In addition, drying is presented as a good alternative for the processing of yacon, either in snacks or for subsequent processes such as making flour.
Synthesis of hydroxyapatite from eggshell and its electrochemical.pdfjporcayoc
This work reports the surface modification of titanium through the deposition of a hydroxyapatite coating
synthesized from natural sources. Hydroxyapatite was synthesized from eggshell using a wet precipitation
method. It was deposited as a coating on a Ti surface using electrophoretic deposition (EPD) at different electrophoretic
deposition times and voltages. The electrochemical evaluation of the obtained coatings was performed
through potentiodynamic polarization curves in a simulated physiological solution. The results showed
that the eggshell is an excellent alternative for the synthesis of hydroxyapatite, and that its heat treatment at
700 °C shows the best crystallinity conditions. The optimum conditions for deposition of the hydroxyapatite
coatings were 30 V and 18 min. Potentiodynamic polarization tests showed that hydroxyapatite coatings improve
the chemical stability of the Ti surface when subjected to the corrosive action of simulated physiological
solutions at 37 °C.
Multiple response optimization analysis for pretreatments of Tequila’s stilla...Roberto Bolaños
The objective of this work was study the effect of three pretreatments (alkalinization, thermical treatment, and sonication) on Tequila’s
stillages hydrolysis process in acidogenesis stage, through the following response variables: soluble chemical oxygen demand (CODs),
total sugar and volatile fatty acids profile and the hydrogen production at the time. The stillages were subject to these pretreatments
(according to a 23 factorial design); afterward they were transferred to a batch reactor at 35 C and inoculated with an anaerobic digestor
sludge. Multiple response optimization (MRO) analysis was done to find the global optimum for the response variables described above.
This optimum is able to maximize simultaneously all these variables. It was found adequate to be useful hydrolyzing the organic matter
present in Tequila’s stillages. Mathematical models were fitted to observe the estimated effects of pretreatments on each response variable,
then the MRO was applied.
2007 Elsevier Ltd. All rights reserved.
This study evaluated the effects of ultrasound pretreatment on osmotic dehydration of mango cubes. Mangoes were cut into cubes and some samples received ultrasound pretreatment before being subjected to osmotic dehydration in a 45° Brix sucrose solution at 65°C. Samples were analyzed for water loss, solid gain, and effective diffusion coefficients over time. Results showed that ultrasound pretreatment increased water loss, solid gain, and the effective diffusivity of water and solids compared to samples without pretreatment. Modulated temperature differential scanning calorimetry was also used to characterize changes in the food matrix, such as increases in glass transition temperature, with decreasing moisture content.
Physico – Chemical and Bacteriological Analysis of Well Water at Crescent Roa...theijes
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
This document summarizes research on the hydrothermal liquefaction of algae feedstocks in a continuous-flow reactor system. Key points:
- Algae can be converted to an upgradeable biocrude through hydrothermal liquefaction at 350°C and 20 MPa in a continuous-flow reactor, without the need for solvents. High carbon conversions were achieved even at high algae concentrations.
- Catalytic hydrotreating was effectively used to upgrade the biocrude through hydrodeoxygenation, hydrodenitrogenation, and hydrodesulfurization, producing hydrocarbon fuels.
- Catalytic hydrothermal gasification of the aqueous byproduct stream effectively produced fuel gas and allowed for
Abstract— Biofuel production from microalgae biomass appears as a promising long term alternative. Dunaliella tertiolecta is a microalgae with high tolerance to salinity, temperature, and light, making it relatively easy to grow. The aim of this study was to establish a pilot-scale culture to evaluate the biomass yield and bioethanol production. The cell culture of D. tertiolecta was started in 20 ml tubes and escalated to 20 L containers. The biomass yield was 0.153 g L-1 of dry basis (db) and its characterization showed protein (37% db) as major component followed by carbohydrates (35.6), lipids (13% db) and ash (6.5%). The carbohydrate fraction was composed of starch (27.1% db) and fiber (8.5 %) and its neutral sugar characterization yield glucose (91% molar). The main components of the lipid fraction were linolenic and palmitic acids. The biomass was subjected to an acid pre-treatment for the saccharification of complex carbohydrates, and the hydrolyzed biomass was fermented by Saccharomyces cerevisiae. It was possible to produce 0.615 ml g-1 of ethanol. In conclusion, D. tertiolecta has the potential for bioethanol production, making it a promising option for the biofuels future.
Comparative study between film and coating packaging based onJesus Almaraz Muñoz
This study compared the effectiveness of a shrimp concentrate film and coating at preserving fish sausages during chilled storage. The coating increased the lag phase of total microorganisms and enterobacteria to 15 and 10 days, respectively, while the film drastically inhibited the growth of these microbes. Both helped maintain quality by decreasing pH and volatile bases during storage, with greater effects seen from the film. The coating kept sausage properties similar to controls for 25 days while the film resulted in a lower moisture and pH product resembling pickled sausage that remained stable for at least 42 days.
The Calculation of Optimal Osmotic Dehydration Process Parameters for Mushroo...Agriculture Journal IJOEAR
Abstract— The Firefly Algorithm (FA) is employed to determine the optimal parameter settings in a case study of the osmotic dehydration process of mushrooms. In the case, the functional form of the dehydration model is established through a response surface technique and the resulting mathematical programming is formulated as a non-linear goal programming model. For optimization purposes, a computationally efficient, FA-driven method is used and the resulting optimal process parameters are shown to be superior to those from previous approaches.
Moisture Adsorption Isotherms Characteristics of a New Moisture AdsorbersIJMREMJournal
The purpose of the study was to analyze the effect of the replacement rate of the most hygroscopic moisture adsorber on the adsorption properties of a new moisture adsorbers formulated. Moisture adsorption isotherms of this new moisture adsorbers formulated were determined at 4 ± 1 °C, using the standard static gravimetric method. All moisture adsorption isotherms of new moisture adsorbers were type II following Brunauer’s classification. The moisture isotherms were sigmoid shaped and showed a clear dependence on the substitution rates of the most hygroscopic moisture adsorber (ads 3). Of the eighteen new moisture adsorbers formulated, only AB (40:60) and AL (60:40) adsorbers had the characteristic appearance of better moisture adsorbeers in modified atmosphere packaging of fruits and vegetables (tomato and mushroom). Thus, their incorporation into the packaging could avoid the condensation of water vapor by maintaining an optimal relative humidity. Based on statistical parameters, additive isotherm approach of Labuza (1968) could not correctly describe the adsorption characteristics of all this new moisture adsorbers formulated. However, this model gave better prediction with the new AB moisture adsorbers than with the new AL moisture adsorbers with sums of relative mean errors of 165.89% and 293.71%, respectively.
Moisture Adsorption Isotherms Characteristics of a New Moisture AdsorbersIJMREMJournal
The purpose of the study was to analyze the effect of the replacement rate of the most hygroscopic moisture
adsorber on the adsorption properties of a new moisture adsorbers formulated. Moisture adsorption isotherms
of this new moisture adsorbers formulated were determined at 4 ± 1 °C, using the standard static gravimetric
method. All moisture adsorption isotherms of new moisture adsorbers were type II following Brunauer’s
classification. The moisture isotherms were sigmoid shaped and showed a clear dependence on the substitution
rates of the most hygroscopic moisture adsorber (ads 3). Of the eighteen new moisture adsorbers formulated,
only AB (40:60) and AL (60:40) adsorbers had the characteristic appearance of better moisture adsorbeers in
modified atmosphere packaging of fruits and vegetables (tomato and mushroom). Thus, their incorporation into
the packaging could avoid the condensation of water vapor by maintaining an optimal relative humidity. Based
on statistical parameters, additive isotherm approach of Labuza (1968) could not correctly describe the
adsorption characteristics of all this new moisture adsorbers formulated. However, this model gave better
prediction with the new AB moisture adsorbers than
The objective was to compare cooling of peaches via free and forced convection. Peaches were submerged in ice baths with one peach stirred (forced convection) and the other stationary (free convection). Temperature was measured every minute until reaching 7.5°C. Forced convection cooled the peach faster, in 25.14 minutes with a convection coefficient of 3,105 W/(m2K), while free convection took 43.17 minutes with a coefficient of 41.38 W/(m2K). COMSOL models showed faster cooling under forced convection due to higher heat transfer rates.
The objective was to compare cooling of peaches via free and forced convection. Peaches were submerged in ice baths with one stirred (forced convection) and one stagnant (free convection). Temperature was measured every minute until reaching 7.5°C. Forced convection cooled the peach faster, in 25.14 minutes with a convection coefficient of 3,105 W/(m2K), while free convection took 43.17 minutes with a coefficient of 41.38 W/(m2K). COMSOL models showed faster cooling under forced convection. Differences from theory were likely due to approximations in the experimental setup and peach properties.
This document evaluates models for predicting thermophysical properties of foods. It summarizes the performance of different models for predicting ice fraction, apparent specific heat capacity, specific enthalpy, and thermal conductivity based on a comparison to experimental data. The best performing models were: Chen (1985b) for ice fraction prediction, Schwartzberg (1976) for apparent specific heat capacity, Chen (1985a) for specific enthalpy prediction, and Levy (1981) for thermal conductivity prediction.
Similar to Thermal characteristics and state diagram of freeze dried broccoli 2017 (20)
2. 2. Materials and methods
2.1. Materials
Five kg fresh broccoli (Brassica oleracea, variety: Calabrese) grown
in Oman were purchased from local super market and stored at re-
frigerated condition (4 °C). Only florets were cut from the bunch and
were placed into 50 ml plastic containers. These florets were then
frozen at −40 °C for at least 18 h. The frozen florets in the plastic
containers were freeze dried at 20 °C (i.e. process started from −40 °C
at the surface and ended at the 20 °C starting from surface to the center)
under a vacuum of 200 Pa for 4 days using an Edwards K4 Freeze Dryer
(Corawky, Crawley, England). Freeze-dried florets were then ground
into powder using a KMF grinder (KIKA Werke, Wilmington, USA). The
pH value was recorded using pH meter (EUTECH Cyberscan pH 11,
Singapore) from broccoli-water mixture (i.e., 10 g broccoli in 100 ml
distilled water). Moisture, protein, fat, ash, and crude fiber were ana-
lyzed using the standard methods of the International Official Methods
of Analysis [29]. Carbohydrate was calculated by subtracting total of
moisture, protein, fat, and ash contents from 100.
2.2. Moisture adsorption isotherm
Moisture adsorption isotherm of freeze-dried broccoli was measured
by static isopiestic method [30,31]. Freeze dried broccoli samples of
2–3 g were stored in 8 different air-tight aluminum cells maintained at
different relative humidity values. These cells were stored in chilled
room set at 5, 20, and oven set at 45, 60 and 80 °C. The desired relative
humidity in each cell was created using saturated salt solution in a
beaker placed inside the cells. The saturated salt solutions used to
maintain relative humidity were: lithium chloride, potassium acetate,
magnesium chloride, potassium carbonate, magnesium nitrate, sodium
bromide, strontium chloride and potassium chloride. The water activity
values of the saturated solutions were taken from Rahman [30]. The
saturated condition was ensured by maintaining a layer of salt crystals
at the bottom of the beaker. All samples in the cells were equilibrated
until a constant mass was achieved (i.e. 3–6 weeks). Thymol in a 5 ml
beaker was also placed inside the cells to prevent the mold growth.
Isotherm data within water activity of 0.05 and 0.45 were fitted to the
theoretical BET model to determine BET-monolayer moisture content
[31–33] using the following equation:
=
− + −
M
M B a
a B a[(1 )(1 ( 1) ]
w
b w
w w (1)
where Mw and Mb are the moisture content at any water activity (aw)
and BET-monolayer moisture content (g/g dry-solid), respectively and
B is a constant related to the net heat of sorption. The BET-monolayer
water was estimated by linearized regression of Equation (1). The va-
lues of Mb was calculated from the slope (S) and intercept (I) of the
linearized regression of aw/(1-aw)Mw against aw. The value of mono-
layer can be calculated from Mb = 1/(S + I) and B = (S + I)/I [34].
2.3. Differential scanning calorimetry (DSC)
Differential Scanning Calorimetry (DSC Q20, TA Instruments, New
Castle, DE, USA) was used to measure the thermal characteristics of
broccoli florets. Mechanical refrigerated cooling system capable to cool
the sample up to −90 °C and heat up to 500 °C was used. The instru-
ment was calibrated for heat flow and temperature using distilled water
(melting point 0 °C; enthalpy, ΔHm 334 kJ/kg), and indium (melting
point 156.5 °C; enthalpy, ΔHm 28.5 kJ/kg). Aluminum Tzero pan of
40 μl (model: T140818, TA Instruments, New Castle, DE, USA), which
could be sealed with lid (model: T130823, TA Instruments, New Castle,
DE, USA) was used in all experiments. This new pan showed more
sensitivity and provided linear base line as compared to the conven-
tional hermitical sealed pan. An empty sealed pan was used as reference
and nitrogen gas at a flow rate of 50 ml/min was used as a carrier gas.
Samples of 10 mg with moisture 85.0, 80.0, 75.0, 70.0 and 60.0 g/
100 g sample were initially scanned from −90 to 250 °C (according to
the protocol as discussed later) to determine the level of moisture loss
from the sealed aluminum pans. Broccoli samples with different
moisture were prepared by adding predetermined water to 5 g freeze
dried broccoli and equilibrated at 4 °C for 24 h after mixing these
thoroughly (Xw: from 0.10 to 0.95 g/g sample) or drying in infrared
moisture analyzer (Xw: from 0.05 to 0.01 g/g sample).
2.4. Thermal analysis of samples containing un-freezable water
Sample (10 mg) (Xw: 0.25–0.01 g/g sample) was placed in an alu-
minum pan as mentioned earlier and then sealed with its lid. The
sample within the pan was cooled to −90 °C at 5 °C/min, and then kept
for 1 min. It was then scanned from −90 °C to 250 °C at a heating rate
of 10 °C/min to generate the heating DSC thermogram and thermal
characteristics of broccoli samples with un-freezable water were then
determined. A shift in the thermogram line was considered as glass
transition, an exothermic peak was considered as crystallization or
molecular ordering, and an endothermic peak was considered as solids-
melting. The glass transition shift was characterized by onset (Tgi), mid
(Tgp) and end (Tge) points; and specific heat change (ΔCp) at the tran-
sition (as clearly discussed later using experimental data). The exo-
thermic peak was characterized by onset (Tei), peak (Tep) and end (Tee)
points; and area of the peak was considered as enthalpy (ΔHe).
Similarly, solids-melting endotherm was characterized as onset (Tmi),
maximum-slope (Tmm), peak (Tmp) and end (Tme) points; and area of the
peak was considered as enthalpy (ΔHm).
The glass transition temperature needs to be modeled as a function
of solids content in order to develop glass line in the state diagram. The
on-set glass transition temperature was commonly modeled using the
Gordon-Taylor equation as [35]:
=
+
+
T
X T kX T
X kX
gi
s gs w gw
s w (2)
where Tgi, Tgs and Tgw are the onset glass temperatures of broccoli, dry-
solids broccoli, and water respectively; Xw and Xs are the mass fraction
of water and dry-solids (g/g sample) respectively, and k is the Gordon-
Taylor parameter. The solids-melting peak temperature was modeled by
Flory-Huggins equation as [36]:
⎜ ⎟ ⎜ ⎟− = ⎛
⎝
⎞
⎠
⎛
⎝
⎞
⎠
−
T T
R
ΔH
V
V
ε χε
1 1
( )
mp sp u
u
w
w w
2
(3)
where, Tmp and Tsp are the peaks of melting temperature for the
polymer (i.e. broccoli) with diluent (i.e. water), and of pure polymer
(i.e., only dry solids) (K) respectively, R is the gas constant (8.314 J/
g mol K), ΔHu is the heat of fusion for repeated polymer units in the
diluent (J/g), Vw is the molar volume of the diluent (m3
/g mol), Vu is
the molar volume of polymer unit (m3
/g mol), εw is the volume fraction
of the diluent, and χ is the Flory–Huggins polymer-diluent interaction
parameter. The volume fraction of water was calculated from the fol-
lowing equation considering the volume of water and volume of solids
estimated from mass fractions and density values of water and solids
[9]:
=
+
ε
X ρ
X ρ X ρ
( / )
( / ) ( / )
w
w w
w w s s (4)
where, Xw is the mass fraction of water (w.b., g/100 g sample), ρw is the
density of water (kg/m3
), Xs is the mass fraction of solids content (g/
100 g sample), and ρs is the density of dry-solids (kg/m3
). The density of
freeze-dried broccoli (i.e. dry-solids) was considered as 1622 kg/m3
,
which was estimated from the proximate compositions (i.e. protein,
carbohydrate, fat and ash) of broccoli [30].
S. Suresh et al. Thermochimica Acta 655 (2017) 129–136
130
3. 2.5. Thermal analysis of samples containing freezable water
The procedure of thermal analysis for samples containing freezable
water (Xw
oo
: 0.30-0.95 g/g sample) was similar to Rahman et al. [26]. A
10 mg broccoli sample sealed in aluminum pan was cooled to −90 °C at
5 °C/min and kept for 1 min. The sample was then scanned from
−90 °C to 250 °C at a heating rate 10 °C/min in order to determine
glass transition, freezing point, apparent maximal-freeze-concentration
condition [(Tm′)a and (Tg′′′)a] and solids-melting. The solids-melting
data was considered acceptable up to moisture 0.80 g/g sample (i.e.
moisture loss up to 1%) as identified in preliminary experiments. The
glass transition was determined from the shift in the DSC thermogram.
The freezing point and apparent maximal-freeze-concentration condi-
tion were determined from the ice melting endothermic peak and shift
just before the endothermic peak. The freezing process was character-
ized by onset and maximum slope temperatures, and freezing enthalpy
from the area of the endothermic peak. The initial or equilibrium
freezing point was considered as the maximum slope in the ice melting
endotherm as suggested by Rahman [23]. It was observed earlier that
this point was very close to the measured value of the established
cooling curve method. Al-Rawahi et al. [20] also found that the max-
imum slope was close to the freezing point measured by commonly
established cooling curve method.
Samples with moisture 0.4 and 0.5 g/g sample were scanned simi-
larly as mentioned earlier with 30 min annealing at (Tm′)a −1 [37,38].
The annealed maximal-freeze-concentration [(Tm′)n and (Tg′′′)n] was
determined similarly from the shift just before ice melting endotherm.
The use of annealing condition allowed to maximize the formation of
ice before second heating cycle and to avoid the appearance of exo-
thermic or endothermic peak before glass transition [20]. The average
value of 4 replicates of (Tm′)n and (Tg′′′)n at moisture 0.4 g/g sample was
considered as ultimate maximal-freeze-concentration condition [(Tm′)u
and (Tg′′′)u]. The sample containing moisture of 0.4 g/g sample was
considered to determine ultimate (Tm′)u since it gave the lowest possible
value. The value of maximal-freeze-concentration solids content (i.e.
Xs′) was determined from the intersection point of the extended freezing
curve (TF versus Xs) by maintaining similar curvature as Chen [39]
model and drawing a horizontal line passing through ultimate (Tm′)u
[9]. Finally Xs′ was read on the x-axis by drawing a vertical line passing
through the intersection point and the intersection point on the glass
Fig. 1. A. Water adsorption isotherm as a function temperature, B: Plot of solids content at BET-monolayer as a function of temperature.
Fig. 2. DSC thermogram for the sample with un-freezable water (moisture: 0.067 g/g sample), A: DSC thermogram, B: Expansion of glass transition region for clear visualization, C: On-
set glass transition as a function of solids content (o, experimental point; − Gordon-Taylor model), D: Plot of ΔCp at glass transition as a function solids content.
S. Suresh et al. Thermochimica Acta 655 (2017) 129–136
131
4. line as Tg′. The intersection point of the extended freezing curve by
maintaining similar curvature as Chen’s [39] model and glass line was
termed as Xs′′ and Tg′′.
The commonly used Chen [39] model based on Clausius-Clapeyron
equation was used to model the freezing point data using the following
equation:
= − ⎡
⎣⎢
− −
− − +
⎤
⎦⎥
δ
β
λ
X CX
X CX EX
ln
1
1w
s
o
s
o
s
o
s
o
s
o
(5)
where δ is the freezing point depression (Tw-TF), TF is the freezing point
of food (°C), Tw is the freezing point of water (°C), β is the molar
freezing point constant of water (1860 kg K/kg mole), λw is the mole-
cular weight of water, Xs
o
is the initial solids mass fraction before
freezing (g/g sample), C is the un-freezable water (g/g dry-solids) and E
is the molecular weight ratio of water and solids (λw/λs).
3. Results and discussion
3.1. Moisture adsorption isotherm
The moisture contents of the fresh and freeze-dried broccoli were
90.2 and 6.7 g/100 g sample, respectively and the pH of the fresh
broccoli was 6.8. Similarly Koh et al. [40] reported the range of
moisture content of fresh broccoli from 83.9 to 90.3 g/100 g sample.
The protein, fat, crude fiber, ash and carbohydrate of freeze-dried
broccoli were respectively 24.3, 3.8, 8.7, 8.6 and 56.6 g/100 g sample.
These results are similar to those reported by Liu et al. [41] and Madhu
and Kochhar [42]. Fig. 1A shows that the equilibrium water content
increased with the increase of water activity (in most of the cases the
error bars were within the symbol). The BET-monolayer was calculated
based on Eq. (1) and Fig. 1B presents the solids content at the BET-
monolayer as a function of storage temperature. The BET-monolayer
value of broccoli was determined as 0.089 g/g dry-solids at 20 °C, thus
broccoli would be most stable at or below this moisture considering
theoretical water activity concept of foods’ stability. A linear regression
equation was developed as:
= −T X1003.20 903.63b bs (6)
where Tb is the temperature (°C) at BET-monolayer, and Xbs is the solids
content (g/100 g sample) at BET-monolayer. The regression correlation
(R2
) is 0.947. The above equation was used to develop BET-monolayer
line in the state diagram [28] as emphasized by Zhao et al. [18].
3.2. Moisture leak from the DSC pan
Preliminary experiments were conducted to check the evaporation
of water from the sample sealed in the pans during heating, especially
at temperatures above 100 °C. Heating above 100 °C can create high
pressure in the pans and may cause moisture leak from the pans. The
moisture losses were observed as 10.10, 0.77, 0.73, 0.68, and 0.58%
(i.e. as compared to the initial sample mass) for the samples containing
moisture 85.0, 80.0, 75.0, 70.0 and 60.0 g/100 g sample, respectively.
These results indicated that there was negligible leak or break of the
seal of the aluminum pan containing samples having moisture at or
below 80.0 g/100 g sample. The leakage at very high moisture sample
(i.e. above moisture 80.0 g/100 g sample) was due to the pressure build
up in the pan as compared to the low moisture samples. Therefore,
thermal characteristics above 100 °C were considered only for the
samples containing moisture at or below 80.0 g/100 sample.
3.3. Samples containing un-freezable water
A DSC thermogram of freeze dried sample with un-freezable water is
presented in Fig. 2. Fig. 2A shows a glass transition marked as G (i.e.
shift in the thermogrm line), an exothermic peak marked as E and an
Table1
ThermalCharacteristicsofbroccolicontainingun-freezablewater(HeatingRate:10°C/min).
XsTgi(°C)Tgp(°C)Tge(°C)ΔCp(J/kgK)Tei(°C)Tep(°C)Tee(°C)ΔHe(kJ/kg)Tmi(°C)Tmm(°C)Tmp(°C)Tme(°C)ΔHm(kJ/kg)
0.99043.6±4.372.6±6.385.7±2.7985±4123.9±0.5146.7±0.5159.4±0.845.6±1.2176.9±13.0177.1±12.8178.4±11.9207.8±14.391.0±4.0
0.97020.7±0.649.5±6.465.2±2.11009±31120.9±0.7143.1±0.7155.6±0.140.3±2.5170.0±12.2170.2±12.1171.3±11.0200.9±3.8121.3±9.3
0.950-2.6±0.710.4±1.840.5±4.11124±27120.9±1.7138.8±6.1150.8±13.523.3±20.7154.6±17.3159.0±16.4165.8±13.8218.2±25.0153.8±20.7
0.933-6.9±7.43.2±8.336.6±6.51211±315117.0±1.1137.3±0.6148.0±1.538.7±1.1158.9±0.5159.8±0.8174.2±3.1246.5±0.2254.6±26.1
0.900-4.9±1.56.8±2.132.3±1.81085±79113.9±0.5134.3±4.1145.0±8.923.3±17.4152.5±1.9153.8±1.8162.6±13.0193.8±15.0150.1±21.3
0.850-31.5±6.5-19.4±7.9-6.1±7.1836±215111.0±1.4134.8±1.3149.6±0.421.8±5.5164.8±10.0163.1±10.4168.8±5.4193.1±9.6191.5±37.8
0.800-49.4±0.8-43.0±1.3-32.6±1.1976±53110.4±0.6134.2±0.2148.2±1.717.8±2.4131.8±22.2131.2±18.2144.6±17.9182.9±13.3311.2±23.3
0.750-61.6±0.7-56.2±1.5-48.4±1.8879±20110.4±0.9133.4±0.6144.9±2.312.4±1.1149.1±5.3150.3±7.9157.2±7.0189.3±5.8390.9±13.5
S. Suresh et al. Thermochimica Acta 655 (2017) 129–136
132
5. endothermic peak marked as M for solids-melting. The exothermic peak
before melting indicated the crystallization or molecular ordering. The
glass transition region was expanded in Fig. 2B (i.e. onset, mid and end
points of glass transition, and ΔCp are marked). The ΔCp as shown in
Fig. 2B was calculated from the heat flow data (i.e. y-axis), sample mass
and heating rate. The onset glass transition temperature decreased
significantly with the decrease of solids mass fraction (Table 1) and it is
considered as the glass line. The decrease was due to the plasticization
of solids matrix with increasing water (i.e. decreasing solids) (Fig. 2C).
This type of plasticization was completely different in nature as com-
pared to that of gelatin [26], starch and instant rice [27]. In these cases,
the glass transitions decreased with decreasing solids and leveled off at
much higher temperature than Tm′, whereas broccoli’s glass transition
leveled off much below Tm′. Broccoli showed similar nature as sugars
and sugar based products [2,14–18]. The data were fitted to the
Gordon-Taylor model and the values of k and Tgs were observed as 4.31
and 42.8 °C, respectively (r2
: 0.961 and p < 0.001). The higher value
of k indicated the high plasticization of solids with water. This ob-
servation is supported by Rahman et al. [26] who reported that a k
value of 10 indicated very high plasticization of solutes. The k value for
broccoli was similar to the sugars or sugar based fruits, which varied
from 2.6 to 4.0 [24]. The glass transition temperatures of dry solids for
fructose, glucose and sucrose were with the range of 7–18, 20–31, and
52–70 °C, respectively [24]. The Tgs for broccoli solids was within the
range.
The ΔCp at the glass transition varied from 836 to 1211 J/kg K
(Table 1) and these variations were insignificant when fitted with linear
(r2
: 0.31, p > 0.15) and non-linear (r2
: 0.37, p > 0.31) correlations
(Fig. 2D), indicating that water did not affect the amount of amorphous
solids fraction of broccoli. The average value of ΔCp was
1013 ± 112 J/kg K. The high ΔCp indicated that solids contained
higher level of amorphous solids. In the case of gelatin, Rahman et al.
[26] observed relatively higher decrease of ΔCp with decreasing solids,
which were 2022 J/kg K at solids content 0.90 g/g sample and 490 J/
kg K at solids content 0.75 g/g sample. However, ΔCp of dry sucrose
(i.e. zero moisture) was observed as 700 J/kg K [14].
3.4. Samples containing freezable water
Fig. 3 shows DSC thermogram for sample containing freezable water
and the thermal characteristics of broccoli containing freezable water
are shown in Table 2. The apparent (Tm′)a and (Tg′′′)a decreased with
the increase of solids (i.e. increasing water) up to solids content of
0.6 g/g sample and then increased further with the increase of solids
(i.e. at solids 0.7 g/g sample) (Table 2). This indicated that the max-
imal-freeze-concentration condition was observed at water content
0.4 g/g sample, and sample at 0.3 g/g moisture content indicated re-
stricted ice melting in a very viscous medium. For the samples con-
taining moisture 0.5 and 0.4 g/g sample, the apparent (Tm′)a were ob-
served at −30.8 and −34.5 °C, while (Tg′′′)a were observed as −35.0
and −40.5 °C, respectively (Table 2). However annealing condition
gave a (Tm′)u value of −31.1 ± 0.3 and −30.0 ± 0.1 °C for samples
containing moisture 0.5 and 0.4 g/g sample, respectively. The close
values indicated that annealing for the samples containing moisture 0.5
or 0.4 g/g sample could provide maximal-freeze-concentration condi-
tion. The increased value of (Tm′)a at moisture 0.3 g/g sample indicated
the difficulty of forming ice and its growth during freezing cycle as
noticed in the melting cycle. In this work (Tm′)u was considered as
−30.0 °C from the sample containing moisture 0.4 g/g sample since it
gave lowest possible value. The (Tm′)u and (Tg′′′)u are most commonly
determined from moisture 0.4 g/g sample [26,20]. Additionally the
higher difference between values obtained from annealed and un-an-
nealed samples also supported the difficulty of ice formation in con-
centrated solid matrix. Similarly (Tg′′′)u were observed as −34.8 ± 0.3
and −32.2 ± 0.2 °C for samples containing moisture 0.5 and 0.4 g/g
sample, respectively.
The freezing point as a function of solids is plotted in Fig. 4A (i.e.
line ed) which shows that freezing point decreased with the increase of
solids content. The Chen’s model parameters E and C were estimated as
0.095 and 0.199 g/g dry solids, respectively (p < 0.0001). Freezing
point for sample containing moisture 0.3 g/g sample was not included
in the modelling due to their restricted freezing process in the con-
centrated solids matrix. The value of Xs′ was determined from the
Fig. 3. DSC thermogram for the sample with freezable water (moisture: 0.4 g/g sample), A: Complete thermogram (F: freezing exothermic peak for freezing of water during cooling, H:
endothermic peak for melting of ice during heating cycle, M: endothermic peak for solids melting), B: Expansion of ice melting endotherm (G1: glass transition at low temperature, G2:
glass transition before ice melting endotherm to determine apparent maximal-freeze concentration conditions, F: ice melting endotherm), C: Expansion of G1 for clear visualization, D:
Endothermic peak for solids melting.
S. Suresh et al. Thermochimica Acta 655 (2017) 129–136
133
6. intersection point (i.e. a) in Fig. 4A by extending the freezing curve (i.e.
ed) and maintaining the similar curvature as Chen’s model (Eq. (5)) and
a horizontal line passing through (Tm′)u = −30.0 °C. The Xs′ value (i.e.
0.70 g/g sample) was determined from the x-axis by drawing a vertical
line passing through point “a”. The un-freezable water content was
estimated as 0.30 g/g sample (i.e. Xw′ = 1- Xs′). The water represented
to the right side of the point was un-freezable water (i.e. unable to form
ice even at very low temperature). The values of Tg′ (i.e. point b, ver-
tical line passing through point a and crossing the glass transition line)
and Tg′′ (i.e. point c, by extending freezing curve as Chen’s model and
crossing the glass transition line) were determined as −73.5 and
−68.5 °C, respectively and Xs′′ (i.e. point c) was determined as 0.74 g/g
sample from the x-axis.
Fig. 4B is a plot of ice melting enthalpy as a function of solids
content and it showed two linear portions with different slopes. The
change of slope could be due to the change of ice melting as a function
of temperature and the binding nature of the water in broccoli. The
extended line to zero enthalpy (solids content: 0.68 g/100 g sample)
gave the un-freezable water as 0.32 g/g sample, which was close to the
un-freezable water determined from state diagram as 0.30 g/g sample
(i.e. solids content: 0.70 g/g sample). Similar extrapolation method was
also used for date-pits [43], gelatin [26], date-fruit flesh [23] and
mango [18].
3.5. Exothermic peak
The exothermic peak temperature and enthalpy are plotted in
Fig. 5A and B as function of solids content. The peak temperature and
the enthalpy decreased with the decrease of solids content (i.e. increase
of water), however a sharp decrease was observed at solids content
from 1.0 to 0.9 g/g sample. The decrease in enthalpy indicated a lower
fraction of disordered or amorphous component with increasing water
content that could be ordered before the solids-melting.
3.6. Solids-Melting
Fig. 5C shows that the solids-melting peak decreased with the de-
crease of solids content (i.e. increase of water), thus higher water
caused the onset of melting process at lower temperature. This could be
due to the nascent formation of the solids-polymers caused by water as
compared to the compact mass of the solids-polymers at low moisture.
Similar trend was also observed for cereal protein [44], gelatin [26],
date-pits [45] and instant rice [27]. The solids-melting peak tempera-
ture was modeled by Flory-Huggins equation (Equation 3) up to solids
content of 0.6 g/g sample as shown in Fig. 5C. The values of RVu/ΔHuVw
and χ for broccoli were estimated as 5.07 × 10−4
and 0.69, respec-
tively. The value of χ indicates the water-solids interaction during the
melting process and could be compared with the literature values for
other foods or food components. The melting point of dry solids was
observed at 178.4 °C. The values of χ were reported as 2.2 for gelatin
[26], 0.48-0.5 for starch [46], 0.0088 for artificial rice [27], and 0.0068
for date-pits [45]. This indicated that stiff molecules (i.e. artificial rice
and date-pits) showed low interaction with the water molecule during
the melting process. As compared to high (i.e. 2.2) and low (i.e. 0.0068)
values for gelatin and date pits respectively, the value of 0.69 obtained
for broccoli indicated that water was moderately interacted with the
solids during its melting process.
Fig. 5D shows that solids-melting enthalpy decreased with the in-
crease of solids content, thus higher melting energy was required for
higher water content. Similar result was observed for date-pits solids-
melting [45]. This could be due to the increased structural building by
hydrogen bonding within the solids matrix at higher level of water
[26], thus more energy was needed to melt the solids with higher water
content. In addition, there was a change in slope at solids content of
0.72 g/g sample (i.e. water: 0.28 g/g sample), which was close to the
un-freezable water (i.e. 0.30 g/g sample) determined from state
Table2
ThermalCharacteristicsofbroccolicontainingfreezablewater(HeatingRate:10°C/min).
XsTgi(°C)Tgp(°C)Tge(°C)ΔCp(J/kgK)(Tm′)a(°C)(Tg′′′)a(°C)ΔCp(J/kgK)(TF)m(°C)(ΔHF)m(kJ/kg)Tmi(°C)Tmm(°C)Tmp(°C)Tme(°C)ΔHm(kJ/kg)
0.70-67.9±2.9-63.8±3.0-56.8±4.2561±41-22.6±0.8-31.2±2.264±23-23.0±0.50.3±0.3138±27146±22155±17185±8335±25
0.60-66.8±0.2-62.6±0.2-56.8±0.9557±14-34.5±0.7-40.5±1.3412±25-19.2±2.124.8±3.2122±24131±18145±17173±10555±17
0.55-65.1±0.7-58.9±2.8-54.8±1.8529±22-34.1±0.6-39.6±0.9585±117-14.7±0.234.8±2.6122±28133±15150±17174±9568±43
0.50-64.1±0.3-59.5±0.5-54.2±0.8509±14-30.8±1.1-35.0±1.3941±153-11.5±1.851.4±8.3123±14132±6141±6165±1667±46
0.45-64.0±0.5-59.7±0.1-53.8±0.2519±10-28.8±0.4-32.8±1.01374±89-9.4±0.269.8±3.5149±4145±1157±1176±1763±32
0.40-63.0±0.3-56.7±0.1-51.1±0.2410±19-26.5±0.6-32.0±0.21361±220-6.7±0.887.4±10.2137±23144±21151±17169±13836±63
0.35-64.1±0.4-58.5±0.9-52.1±0.7391±24-25.1±0.5-31.1±0.71514±185-6.1±0.1105.0±4.5154±16151±10161±10177±10925±73
0.30-62.6±0.1-55.1±0.6-48.9±0.2381±9-22.1±0.7-29.0±0.81469±34-4.5±0.1118.8±1.5138±5143±3149±4164±51013±39
0.25-62.5±0.4-55.0±0.6-50.2±0.9345±8-19.4±0.5-31.7±0.71018±56-3.6±0.1136.8±1.3139±6143±5150±4165±31087±40
0.20-62.4±0.5-54.2±0.7-49.5±0.6321±22-17.9±0.1-32.5±0.7790±160-2.8±0.1153.1±3.9133±18129±1151±7165±71183±10
0.15-62.1±1.4-56.1±2.1-49.8±1.0271±27-14.5±0.7-32.9±1.1580±61-1.7±0.2177.9±7.7
0.10NDNDNDND-11.6±0.1-33.6±0.6419±94-1.2±0.2202.1±8.6
0.05NDNDNDND-7.9±0.4-39.8±0.5230±30-0.3±0.4234.7±11.3
S. Suresh et al. Thermochimica Acta 655 (2017) 129–136
134
7. diagram. In the case of starch granules, the shape of the melting peak
depended on the moisture content in the sample due to the presence of
different levels or types of organized structure [47–49].
4. Conclusion
Glass transition and solids-melting temperature of broccoli de-
creased with the decrease of solids content, while freezing point de-
creased with the increase of solids content. The ultimate maximal-
freeze-concentration temperature was observed as −30.0 °C at a char-
acteristic solids content 0.70 g/100 g sample (i.e. un-freezable water:
0.30 g/100 g sample). The intersection point of the glass line and
freezing curve as Chen’s [39] model was determined as −68.5 °C.
These thermal characteristics of broccoli were used to develop state
diagram, which showed different phases and state boundaries of broc-
coli. The developed state diagram could be used to determine the sta-
bility of bioactive components of broccoli during processing and sto-
rage. However, further research needs to be conducted in determining
stability kinetics of the active components of broccoli in the different
regions of the state diagram.
Acknowledgements
Ms. Sithara Suresh has received a Ph. D. scholarship from the Sultan
Qaboos University. Authors would like to acknowledge the supports of
the Sultan Qaboos University towards this research in the area of food
biophysics and food stability.
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