THE OPTIMIZATION AND CHEMICAL PROCESSING OF YAM AND POTATO IS REQUIRED SO AS TO ENSURE THE SAFE PRESERVATION OF THESE AGRICULTURAL PRODUCTS. THIS HELPS IN THE UNITED NATIONS AGENDA FOR FOOD SUSTAINABILITY
3. BACKGROUND OF STUDY
Potato is a starchy tuber of the plant
Solanum Tuberesome which are edible
and available worldwide. They are
relatively cheap to grow, rich in nutrient
and can make can a delicious treat.
Yams are multispecies and vegetative
propagated tuber crops cultivated widely
in the tropics (FAO 2002). Over 90% of the
world yam production occurs in the yam
belt of West and Central Africa, with
Nigeria alone accounting for about 68% of
the World’s total production (Sobukola
2007).
Osmotic dehydration is the removal of
water from the lower concentration of
solute to higher concentration through
semi permeable membrane which results
in the equilibrium condition in both sides
of the membrane (Tiwari 2005).
4. STATEMENT
OF
PROBLEM
About 20-40% of potato
and yam production goes to
waste due to lack of
adequate storage capacity
and moisture retention.
This brings the question of
‘how can potato and yam
be preserved to avoid
waste?’.
5. AIM AND OBJECTIVES
The aim of this study is to evaluate the effect of the osmotic
solution on the potato and yam slices. The following objectives
shall be pursued in the course of this study;
To optimize the dehydration of the food materials.
To investigate the effect of process variables such as thickness,
time and concentration on the effect percentage moisture
removal.
To derive a quadratic model of mixture removal for the
process.
6. SIGNIFICANCE
OF STUDY
This study will help to discover the best way
to which potato and yam slices will be
dehydrated using osmotic agents such as
salt. It is also important because weight
measurement will be taken before and after
soaking the food material in the osmotic
agent and the difference in weight taken.
This study will draw attention to amount of
moisture gained while soaking and also the
amount of moisture lost after dehydration.
7. SCOPE
OF
STUDY
The scope of this study
will be a laboratory scale
dehydration of potato
and yam slices using salt
solution as the osmotic
agent under controlled
conditions of time and
the size of food material.
8. LITERATURE
REVIEW
• Mehdia Mihoubi and Ali Ferradji(2015) did a study on
the optimization of osmotic dehydration of potato
slices in sugar solution using Response surface
methodology (RSM) to determine the optimum
processing conditions that yield maximum water loss
(WL), weight reduction (WR) and minimum solid gain
(SG). The optimum conditions of dehydration were
found to be: temperature, immersion time and sugar
concentration. They reported that at the optimum
point, water loss, solid gain and weight reduction
were found.
• Mokhtar et al.( 2019) did a study on the dehydration
of potato slices following brief dipping in osmotic
solutions in order to allow the osmotic medium to
occlude to the surface of the slices, holding the slice
under ambient conditions. They found out that water
loss can therefore, be achieved for as long as the
osmotic driving force prevails between the surface
and the interior of the slice. The absorption of sugar
and salt resulted in the movement of water towards
the surface of the slices under osmotic gradients,
which was subsequently lost from the slices by a
combination of evaporation and draining.
9. MATERIALS
AND
METHOD
Materials
The potato (sweet) and yam that will
be used for this study will be obtained
from Use Offot market, Uyo in Akwa
Ibom state. Also, salt(NaCl) will be
gotten from the market for the
preparation of the osmotic agent.
Methodology
The potato and yam slices will be
immersed into the osmotic solution
which ranges from 10 – 30% in
concentration to determine the water
loss and salt content gained.
Optimization of this process will be
carried out using RSM (Response
Surface Methodology).
10. Preparation Of The
Potato And Yam Slices
• The potato and yam
tuber will be washed
with clean water,
peeled manually and
cut into slices of
dimensions ( 2 – 10mm)
using a very sharp
stainless steel knife.
The slices will be rinsed
immediately in clean
water for about 1 min
to remove surface
starch and other
substances sticking to
the surface of the
slices. Finally, the
surface water will be
eliminated by using a
moistened towel.
Preparation Of The
Osmotic Solution
• The osmotic solution
will be obtained by
dissolving commercial
NaCl in water. The
concentration of the
solution will be from 10
– 30%.
11. Osmotic Dehydration Treatment
The potato and yam slices would be divided into the pretreated sample
and the untreated sample. The slices to be treated will be soaked in the
osmotic solution of different concentration of 10%, 15%, 20%, 25%,and
30%.The slices will be removed from the solution at 20, 40, 60, 80 and 100
minutes after immersion, drained, and the excess of solution on the
surface will be removed with absorbent paper.
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 sampled will be
taken out for weighing after every 30 mins to determine the moisture loss
until a constant weight is obtained. Then the treated and untreated
samples will be compared.
12. Mathematical models For Drying
Different authors have come
up with various mathematical
models used for drying. Some
of those models can be seen in
the table below.
Model Name Model References
Lewis MR=exp(-kt) Westerman et
al.(1973)
Henderson
and Pabis
MR=a exp(-kt) Yagcioglu et al.
(1999)
Logarithmic MR=a exp(-
kt)+c
Yaldiz and
Ertekein (2001)
Page MR=exp (-
kt^n)
Page (1949)
Simplified
Fick’s
Diffusion
MR=a exp(-
kt)+c
Celma et al.
(2007)
13. Drying Kinetics
Drying kinetics is the representation of the drying rates versus the drying
time or the moisture content. It is a graphical representation of the
evolution of the moisture content.
The above chosen models will be tested on each data to determine their
fitness. The model with the best fit will be selected as that 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.
