Preservation of food materials is a sure way of ensuring that man and animals alike have enough food to eat and avoid shortages

1. DRYING KINETICS OF OSMOTICALLY PRETREATED
YAM SLICES

2. OUTLINE
• Background of study
• Statement of problem
• Aim and objectives of the study.
• Significance of the study
• Scope of the study
• Summary of previous studies on osmotic dehydration
• Proposed research methodology

3. BACKGROUND
OF STUDY
Yam is an important source of carbohydrate in the world.
Fresh yam has high moisture content which makes it
susceptible to deterioration, hence there is need to dry.
Drying is a universal method for preserving food materials
by reducing their moisture contents to low levels that
prevent microbial spoilage. The removal of water in yam
can be done either by directly drying the yam by pretreating
it in an osmotic medium before it is being subjected to
drying.
The application of osmosis in food processing and as a
dehydration process have been primarily motivated by
economical factors and the quality improvement of the final
product.
Drying kinetics is the ratio of the mass of absorbed water
during rehydration to the mass of water removed during
drying.

4. STATEMENT
OF
PROBLEM
The convectional drying method which does
not involve osmotic treatment involve long
drying duration which reduces the nutritional
value of the food item. It also causes damage
to sensory characteristics and damage the color
and flavor of the food.
Long drying causes shrinkage, which affect
their structure and texture. Hence pretreatment
with an osmotic solution, which reduces the
moisture content of the food material before
drying in the oven, preserves the quality of the
food and conserves the energy required for
drying.

5. AIMS AND
OBJECTIVES
AIM
The aim of this study is to
investigate the drying kinetics of
osmotically treated yam slices.
OBJECTIVES
The objectives of this project are;
•To determine the model that best
describes the drying behavior of the
pretreated slices.
•To determine the kinetic parameter of
the drying process.
•To determine the effect of the osmotic
treatment on drying of pretreated slices.

6. SIGNIIFICANCE
OF STUDY
In the food processing industry, the drying
sector was faced with challenges in long
drying process of food materials for
preservation without loosing its nutritional
properties. The need to dry food materials in
order to increase its shell life keeps increasing
rapidly so as increase in the need to use
osmotic treatment in drying of food materials.
Osmosis dehydration is preferred over other
methods due to retention of color, aroma,
nutritional constituents and flavor of food
materials.

7. SCOPE AND
LIMITATION
This study is focused on yam slices (2cm
diameter, 1cm thickness) that will be soaked in
salt solution of varying concentrations for 30
minutes before drying in an oven at different
temperatures. The effect of pretreatment on the
drying kinetics of the slices would then be
investigated.

8. LITERATURE REVIEW
AUTHORS WORKS RESULTS
Piotrowski et al.2004 He studied the influence of osmotic
dehydration on the microwave convective
drying of frozen strawberries.
It was reported that osmotically dehydrated
strawberries took less time to dry than the ones
not osmotically dehydrated.
Chavan et al. (2010) He developed a process for preparation of
ripe banana using osmotic dehydration.
It was reported that there was marginal decrease
in moisture content and that products were found
microbiologically safe and sensorily acceptable
up to 6 months storage at ambient condition.
Sunjka and Raghavan (2004) They accessed different pretreatment
methods for osmotic dehydration of
cranberry at different concentration.
They reported that time and concentration of
osmotic agents significantly affected dehydration
and that different chemical treatment showed no
chemical change in product quality.

9. MATERIALS AND METHODS
The yam would be divided into the pretreated sample and the untreated sample. The treated sample will be weighed first before treatment using an osmotic solution of NaCl. The yam slices to be
treated will then be soaked in the osmotic solution of different concentration of 10%, 15%, 20%, 25% and 30% (Clifford et al 2014). After soaking in the osmotic solution the yam slices will then be
removed and put in a desiccator to prevent further absorption of water before it is being weighed.
Step 1:Pretreatment
The drying will follow a 2 step process;
The yam slices will be peeled, washed an sliced into a 2cm diameter and a thickness of 1cm using an adjustable hand slicer. The NaCl solution will then be prepared by dissolving NaCl in water.
The material to be used in this work includes yam that will be bought from a local market in uyo Akwa ibom state, sodium chloride (NaCl) and water etc. Some apparatus to be used includes; , Conical
flask (250,500ml),Measuring cylinders (10, 20ml),Plastic funnels, Timer and a desiccator.

10. MATERIALS AND METHOD CONTD.
Step 2; Oven drying The treated and untreated sample
will be subjected to moisture
analysis as the sample will be
weighed and placed in single layers
on pre weighed drying trays, and
there after loaded into the oven.
The sample will be taken out of the
for weighing every 30 mins to
determine the moisture loss until a
constant weight is obtained.
Drying kinetics Drying kinetics is the representation
of the drying rates versus the drying
time or the moisture content.
Different drying models will be
tested on each data to determine
their fitness. The model with the
best fit will then be selected as the
model describing the drying
process.Drying rate and other
parameters will then be determined
from the selected models.The effect
of treatments in the osmotic
solution on the drying behavior will
then be examined.

11. THANK YOU.