This work is based on osmotic drying of potato and yam for commercial and consumption purposes

1. OPTIMIZATION
OF THE OSMOTIC
DEHYDRATION
OF POTATO AND
YAM SLICES

2. OUTLINE
BACKGROUND
OF STUDY
STATEMENT OF
PROBLEM
AIM AND
OBJECTIVES
SIGNIFICANCE
OF STUDY
SCOPE OF STUDY LITERATURE
REVIEW
METHODOLOGY

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).
• 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.

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. • 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
Potato And
Yam Slices
• The osmotic solution will be obtained by dissolving
commercial NaCl in water. The concentration of the
solution will be from 10 – 30%.
Preparation
Of The
Osmotic
Solution

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.