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 American Journal of  
Food Science and Technology (AJFST)

Effect of  Pre-treatments on the Osmotic Dehydration and Mass Transfer Behaviour of  
Sweet Potatoes (Ipomoea batatas LamIpomoea batatas Lam.)

MFH Shikder1, Md Nahid Hossain Jany1*, Juwel Rana2, M. Burhan Uddin1

Volume 4 Issue 1, Year 2025
ISSN: 2834-0086 (Online)

DOI: https://doi.org/10.54536/ajfst.v4i1.4479
https://journals.e-palli.com/home/index.php/ajfst

Article Information ABSTRACT

Received: February 05,, 2025

Accepted: March 03, 2025

Published: May 08, 2025

Food security is increasingly threatened by rapid population growth, climate change, and 
resource constraints, necessitating efficient preservation techniques to minimize post-harvest 
losses. This study investigates the osmotic dehydration process of  two sweet potato (Ipomoea 
batatas Lam.) varieties, Local Sada and Kamala Sundari, under varying sugar concentrations 
(40%, 50%, 60%), temperatures (30°C, 40°C, 50°C, and 60°C), slice thickness (3 mm or 
5 mm), and pre-treatment conditions (blanched or unblanched). The research problem 
addresses the high perishability of  sweet potatoes post-harvest, leading to significant food 
losses, and the lack of  optimized osmotic dehydration parameters tailored to specific sweet 
potato varieties. The novelty of  this study lies in its comprehensive examination of  multiple 
processing parameters simultaneously within a single experimental framework, allowing for 
an in-depth understanding of  mass transfer mechanisms and varietal differences. Results 
indicate that increased sugar concentrations and temperatures enhance dehydration rates, 
with blanching further accelerating mass transfer by increasing cell permeability. However, 
varietal differences were significant: Kamala Sundari exhibited slower yet more controlled 
dehydration, maintaining better structural integrity, while Local Sada dehydrated faster but 
showed higher susceptibility to structural collapse. Slice thickness also played a crucial role, 
as thinner slices (3 mm) dehydrated more quickly but were prone to texture loss compared to 
thicker slices (5 mm). Unblanched samples, despite slower dehydration rates, retained better 
textural attributes. These findings have strong industrial relevance, providing a framework 
for optimizing osmotic dehydration conditions tailored to different sweet potato varieties, 
ensuring improved product quality and reduced post-harvest losses in food processing 
industries.

Keywords

Food Preservation, Mass Transfer, 
Osmotic Dehydration, Pretreatment, 
Structural Integrity, Sweet Potato

1 Department of  Food Technology & Rural Industries, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh 
2 Department of  Nutrition & Food Engineering (NFE), Daffodil International University (DIU), Bangladesh
* Corresponding author’s e-mail: nahidhj.research@gmail.com

INTRODUCTION 
Food security worldwide is increasingly threatened 
by rapid population growth, climate change and an 
overburdened set of  resources (Sarker et al., 2023). 
Protecting nutrient-rich crops through processing is vital. 
Sweet potatoes (Ipomoea batatas L) have become an 
important crop in developing nations due to their high 
calorific yield, nutritional profile, and ability to adapt to 
marginal growing conditions (Otálora et al., 2024). Food 
production is vital in providing essential nutrients and 
increasing food security, and it is critical to economic 
and public health stability (Peng & Berry, 2018). Tropical 
and sub-tropical regions rely heavily on tuber crops such 
as sweet potatoes for caloric intake (Rinaldo, 2020). 
However, the high amount of  moisture makes it highly 
perishable following harvest and usually results in food 
loss (Nath & Sil, 2008). Osmotic dehydration is a widely 
used method in the food industry to preserve fruit and 
vegetables by reducing the amount of  water they contain 
while conserving their nutritional and sensory quality. 
To do this, food items are submerged into an osmotic 
solution composed of  salt or sugar, which creates an 
osmotic pressure gradient to remove water from food 
structures while permitting solvent diffusion (Silva et al., 
2014; Cheng et al., 2023; Osae et al., 2024). Sweet potatoes 
(Ipomoea batatas L.) are particularly well known for their 

rich nutrient content; therefore, sweet potato dehydration 
produces intermediate moisture products, which improve 
shelf  life and flavor profiles (Malakar et al., 2021).
Dehydration by osmotic is highly dependent on various 
variables, including the amount of  osmotic solution 
applied, processing temperature, sample thickness, 
pretreatment methods (blanching) used as well as sweet 
potato variety differences that influence cell structure, 
moisture content and chemical composition that 
ultimately impact dehydration rates as well as final product 
characteristics (de Souza Silva et al., 2011). Osmotic 
dehydration depends on many variables, including the 
quantity and temperature of  osmotic solutions used, 
sample thickness, method of  pretreatment (blanching) 
utilized and sweet potato varieties whose cells alter cell 
structures, moisture content and chemical composition to 
influence rate of  dehydration as well as final characteristics 
(Lagnika et al., 2021). Sweet potatoes degrade rapidly due 
to their high moisture levels, leading to significant post-
harvest losses (Sarker et al., 2023; Araújo & Pena, 2023). 
However, the effect of  key processing parameters such 
as sugar concentration, temperature, slice thickness, and 
pretreatment (blanching, etc.) on sweet potato degradation 
remains uncertain (Kadir et al., 2024; Dermesonlouoglou 
et al., 2025). Unblended on the kinetics of  osmotic 
dehydration has not been sufficiently researched, nor 



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has the significance of  varietal differences such as Sada vs 
Kamala Sundari in dehydration behavior been recognized 
fully. This study addresses these gaps by investigating how 
processing variables affect water loss and solids gains 
during osmotic dehydration, in combination with varietal 
characteristics to optimize dehydration processes for 
product quality and effectiveness.
This study aims to investigate the effects of  sugar 
concentration in the solution (40%, 50% and 60%) as 
well as the temperature, the thickness of  slices (3 and 
3 millimeters), and the pre-treatment method (blanched 
or. non-blanched) on the dehydration behavior of  two 
varieties of  sweet potato such as Local Sada as well as 
Kamala Sundari. The research focuses on studying the 
mechanisms of  water loss and gain of  solids during the 
process of  osmotic dehydration in order to improve 
processes to ensure efficient removal of  moisture 
while preserving the desirable structural and sensory 
characteristics (Lagnika et al., 2021; Pandiselvam et al., 
2022). The uniqueness of  this research is the holistic 
method of  analysis. In contrast to previous studies that 
looked at individual parameters on their own the research 
we are conducting simultaneously examines various critical 
variables, including slice geometry, pretreatment and 
differences between varietals within a single experimental 
framework (Antonio et al., 2008; Corrêa et al., 2017; Wu et 
al., 2020; Wang et al., 2025). This integrated analysis will 
provide extensive insight into the mechanisms of  mass 
transfer in osmotic dehydration. The report will also 
offer practical recommendations for the development 
of  specialized methods to preserve sweet potatoes. The 
findings will aid in the reduction of  postharvest losses as 
well as increasing the shelf-life of  this vital crop, with a 
substantial impact on industry and food security.

MATERIALS AND METHODS
Raw Materials and Identification
Two kinds of  sweet potatoes, Local Sada and Kamala 
Sundari, were purchased from a local market in 
Mymensingh, Bangladesh. A plant pathologist at 
Bangladesh Agricultural University verified the variety’s 
identity using morphological traits. Only fresh tubers 
with no defects were used in the tests.

Preparation of  Raw Materials
Tubers were cleaned under running tap water to eliminate 
soil, cleansed with a food-grade product, rinsed with 
distilled water, and dried by air. They were then peeled 
with a stainless-steel peeler to reduce the loss of  flesh and 
cut into 5 and 3 mm pieces using an automated slicer to 
ensure uniformity across the samples (Kwaw et al., 2023; 
Šovljanski et al., 2024).

Pre-Treatment (Blanching vs. Unblanching)
Slices were split in two parts. To blanch slices, they were 
soaked in water at a temperature of  90°C for 3 minutes 
before being chilled in ice water for 2 minutes in order to 
stop the cooking. The samples that were not blanched were 

processed with no heating treatment (Osae et al., 2024).

Osmotic Dehydration Process
Analytical-grade sucrose solutions were made at 40, 
40%, 50%, and 60% (w/v) after dissolving the necessary 
amount of  sucrose in the distilled water. Slices of  sweet 
potato (both blanched and unblanched with a thickness 
of  3 mm and 5 mm) were immersed in a solution of  
sugar at a fruit-to-solution ratio of  1:10. Dehydration 
was conducted in a temperature-controlled water bath at 
30°C, 40°C, 50°C, or 60°C for 6 hours, with a peristaltic 
pump circulating the solution at 500 ml/min (tube bore 
size: 8.0 mm). The samples were taken at predetermined 
intervals (30, 60, 120, 180, 240, 300, and 360 minutes) to 
determine the amount of  mass transferred (Antonio et al., 
2008; Pang et al., 2021; Rastogi, 2023).

Total Solids Determination 
The quantity of  total solids in those sweet potato pieces 
was measured using gravimetric analysis by drying in 
a vacuum oven at 70°C for 24 hours according to the 
procedure explained in the work of  AOAC (Association 
of  the Official Analytical Chemistry). Sweet potato slices 
were then transferred to aluminum dishes pre-weighed 
to ensure that all dishes’ weights were precisely recorded 
(Tayyab Rashid et al., 2020; Osae et al., 2024; Rindang 
et al., 2024). The dishes and the slices were then put 
in a vacuum oven set at 70°C for a drying time lasting 
24 hours (Balladin & Headley, 1999). After drying, the 
samples were allowed to cool down to room temperature 
with a desiccator to avoid moisture absorption from 
the surroundings. The aluminum dishes that held dried 
samples were weighed to determine the weight (Pang et 
al., 2021). The content of  total solids (TS) was calculated 
by using the following equation (Equation 1):
Total Solid (TS),% =(W3-W1)/(W2-W1)             (1)
Where, W1 = Weight of  aluminum dish, W2 = Weight of  
dish and sample, W3 = Weight of  dish and the vacuum 
dried samples

Determination of  Mass Transfer
The mass transfer during the osmotic dehydration process 
of  sweet potato slices was assessed by measuring two key 
parameters: Water Loss (WL) and Solid Gain (SG).

Water Loss (WL)
To determine the loss of  water during dehydration 
osmotically of  slices of  sweet potatoes, we estimated 
their decrease in weight after dehydration by capturing 
their mass at the beginning (Mi) prior to observing how 
dehydrated each slice was at various intervals of  sampling 
(30, 60, 120, 180, 240, and 360 mins) by using Genina-
Soto et al.’s (2001) equation that is described below 
(Equation 2):
Water loss (WL),% =(Mi-Mo)/Mi              (2)
Where, Mi is the initial mass of  the sweet potato slice, 
and Mo is the mass of  the osmotically dehydrated slice at 
a specific time interval.



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Solid Gain (SG)
Solid gain was assessed by measuring the growth in the 
solids content of  the sweet potato slices because of  the 
absorption of  sugar in the Osmotic solution. The total 
solids of  both the original slices (TSi) and the dehydrated 
osmotically soaked cut (TSo) were determined by 
gravimetric analysis by using a vacuum oven to dry at 
70°C for a period of  24 hours (Pang et al., 2021). The gain 
in solids was calculated by using the following equation 
(Equation 3):
Solid Gain (SG),% =(TSo-TSi)/Mi               (3)
Where, TSo = Total solids of  the sample after osmotic 
dehydration, TSi = Initial total solids of  the sample 
before dehydration, and Mi = Initial mass of  the sweet 
potato sample.
This part should contain adequate detail to reproduce 
reported data. It can be divided into subsections to 
demonstrate data type and collection, and also if  several 
methods are described. Methods already published should 
be indicated by a reference; only relevant modifications 
should be described. The methodology should be written 
concisely in detail by maintaining the continuity of  the texts. 

RESULTS AND DISCUSSION
This research set out to assess the effects of  sugar solution 
concentration on the dehydration of  osmotic fluids by 
analyzing various parameters, including concentration (40%, 
50% or 60%), temperature (30°C, 40°C, 50°C, 60°C), sample 
preparation method (blanched versus non-blanched), and 
sample size (3mm thick samples for uniformity during the 
experiment). Key findings and conclusions can all be drawn 
based on the experiment’s results.

Osmotic Dehydration Behavior
Effect of  Pretreatment on the Dehydration Behavior 
of  3mm Thick Sweet Potato (var. Local Sada)
Results indicate that increasing sugar solution 
concentration between 40% and 60% increases the 
efficiency of  osmotic dehydration significantly due to 
an increase in pressure gradient caused by an increase in 
concentration (Antonio et al., 2008). Dehydration rates 

at 40% concentration were lower than at 50% and 60% 
concentration, suggesting a minimum concentration is 
necessary for effective moisture removal (these results 
align with established principles of  osmosis (Table 1); 
an increase in concentration accelerates water molecules 
through a semipermeable membrane that surrounds food 
ingredients) (Jain & Chauhan, 2022).
Temperature was an integral component of  osmotic 
hydration (Wang et al., 2025). Rising from 30°C to 
60°C would decrease viscosity in this sugar mixture 
and thus accelerate mass transfer (Lagnika et al., 2021). 
Additionally, rising temperatures boost energy kinetics 
for water molecules, allowing easier escape from samples. 
However, extreme temperatures such as 60°C may cause 
changes to color, texture, nutritional quality, and other 
aspects. These extreme changes were especially prevalent 
with blanched samples due to increased thermal changes 
(Wang et al., 2025).
Blanching, which involves brief  exposure to hot water 
or steam, enhances permeability within a sample’s cell 
structure, facilitating faster water removal during osmotic 
dehydration. This was particularly evident at higher 
sugar concentrations (50% and 60%) and temperatures 
between 50°C and 60°C. Unblanched samples exhibited 
slower dehydration rates due to their intact cell walls, 
which presented resistance against diffusion; blanching 
improved dehydration efficiency but may have led to some 
loss of  soluble solids, as seen previously. Interactions 
among sugar concentration, temperature, and sample 
type (blanched vs. unblanched) revealed complex 
dynamics (Osae et al., 2024). For instance, while a 60% 
sugar solution mixed with 60°C resulted in the highest 
dehydration rates, it might not be optimal in terms of  
sensory or nutritional attributes of  samples; thus, a 
balance must be found between dehydration efficiency 
and product quality preservation. Furthermore, blanched 
samples benefitted more from increased temperatures 
than unblanched ones, emphasizing the necessity of  
tailoring processing conditions according to specific 
characteristics of  the raw material used (Wu et al., 2020; 
Pang et al., 2021).

Table 1: Water loss over time at various temperatures and sugar solution concentrations for 3mm thick sweet potato 
slices (var. local sada)



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Effect of  Pretreatment on the Dehydration Behavior 
of  3mm Thick Sweet Potato (var. Kamala Sundari)
This research studies the dehydration characteristics of  
sweet potato slices from two varieties, Local Sada and 
Kamala Sundari, under varying conditions of  sugar 
solution concentration (40%, 50%, and 60%), temperature, 
and pretreatment methods (blanched or unblanched). Local 
Sada was tested with 3mm and 5mm slices, while Kamala 

Sundari only required 3mm slices for experiments (Table 
2). Our findings indicate that higher sugar concentrations 
and elevated temperatures significantly accelerate both 
varieties’ water loss and solid gain. However, varietal 
differences were evident; Kamala Sundari showed slower 
dehydration rates but superior structural integrity than 
Local Sada. Blanching enhanced dehydration efficiency in 
both cases, leading to greater softening with local Sada.

Table 2: Water loss over time at various temperatures and sugar solution concentrations for 3mm thick sweet potato 
slices (var. kamala sundari)



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A comparison between these varieties underscores the role 
that thickness and cellular structure have on dehydration 
kinetics. Thinner slices (3 mm) dehydrated faster for 
local Sada than thicker (5 mm), emphasizing geometry’s 
role in mass transfer. On the contrary, Kamala Sundari 
displayed more controlled dehydration conditions that 
preserved quality attributes more effectively than Local 
Sada; these insights highlight the necessity of  customizing 
dehydration parameters to specific sweet potato varieties 
to optimize both efficiency and product quality; such 
tailored approaches can help achieve desired outcomes 
while mitigating adverse side effects like excessive 
shrinkage or nutrient loss (Rastogi, 2023).

Effect of  Sugar Solution Concentration, Temperature, 
Blanching on Dehydration Behavior of  5mm Thick 
Sweet Potato (var. Local Sada)
Results indicate that increasing sugar solution 
concentration dramatically accelerates osmotic 
dehydration. At 40% sugar concentration, dehydration 
rates were relatively lower than 50% and 60% sugar 
concentrations (Table 3). This can be explained by 
the higher osmotic pressure gradient created by more 
concentrated solutions, which drives water out more 
effectively (de Souza Silva et al., 2011; Silva et al., 2014). 
At every temperature condition, 60% sugar solutions 
demonstrated superior dehydration efficiency. These 
findings confirm the principles of  osmosis, where an 
increased concentration gradient causes water molecules 
to migrate out from food materials into hypertonic 
solutions more quickly (Omar et al., 2020). Reducing 

sugar intake could have unintended side effects such as 
excessive shrinkage or structural collapse of  sweet potato 
slices; dehydration effectiveness must be balanced against 
high-quality products for best results. Temperature 
was an integral component in controlling osmotic 
hydration; higher temperatures between 30°C and 60°C 
resulted in greater degrees and rates of  dehydration for 
all levels tested. As temperatures increased from 30°C 
to 60°C, dehydration efficiency improved across all 
sugar concentrations tested; at higher temperatures, the 
viscosity of  sugar solutions was reduced, which improved 
mass transfer rates, while water molecules gained energy 
through friction, which assisted their migration away 
from sweet potato slices at elevated temperatures. 60°C 
was found to have the highest dehydration rates when 
combined with 50 and 60% sugar solutions. While higher 
temperatures may increase dehydration efficiency, they 
must still be used carefully to avoid adverse consequences 
(Jany et al., 2016; Potatoes et al., 2023).
Blanching significantly improved the osmotic dehydration 
process. Blanched samples exhibited higher water loss 
and solid gain than unblanched ones across all sugar 
concentrations and temperatures. Blanching disrupts the 
cellular structure, increasing membrane permeability and 
facilitating faster water diffusion and solute absorption. 
Neutralizing enzymes responsible for browning 
dehydrated products were particularly successful at 
neutralizing enzymes responsible for browning at higher 
sugar concentrations and temperatures (50, 60, and 80%) 
with temperatures reaching 50°C and 60°C. Unblanched 
samples experienced slower dehydration rates due to 

Table 3: Water loss over time at various temperatures and sugar solution concentrations for 5mm thick sweet potato 
slices (var. local sada)



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wall-like cells offering resistance against water diffusion 
(Rastogi, 2023). However, cell membranes in samples 
that were not blanched acted as barriers, slowing the 
dehydration process. A mixture of  60% sugar solution 
at 60°C and blanched samples resulted in maximum 
water loss, demonstrating its effectiveness as an efficient 
dehydration method. Unblanched samples treated 
with 40 % sugar solution at 30°C experienced minimal 
water loss due to reduced osmotic pressure variation 
and temperature-driven diffusion. These findings 
highlight the importance of  an efficient strategy for 
optimizing osmotic dehydration processes that prioritize 
effectiveness and quality products (Rashid et al., 2020).

Effect of  Sugar Solution Concentration, Temperature, 
and Blanching on Dehydration Behavior of  5 mm 
Sweet Potato (var. Kamala Sundari)
Sada and Kamala Sundari varieties were investigated 
for dehydration behavior when subjected to various 
sugar concentrations (40 %, 50%, 60% and 60 %), 

temperatures, and pretreatment conditions (blanched and 
non-blanched). Both varieties displayed that higher sugar 
concentrations and temperatures increased water loss 
through dehydration by osmosis; however, each variety 
showed different rates and amounts of  dehydration. 
Kamala Sundari displayed slower dehydration rates than 
Local Sada because of  its larger cells, which could aid 
in resisting the diffusion of  moisture more efficiently. 
Blanching aided in dehydration for both kinds, but 
Kamala Sundari showed greater structural strength, while 
local Sada was more susceptible to collapse and shrinkage 
(Table 4).
Comparative analyses of  two varieties show how their 
distinct characteristics affect dehydration. Despite similar 
processing conditions, Kamala Sundari was better at 
preventing dehydration while maintaining its unique 
characteristics than Sada from the local farm. Kamala 
Sundari varieties with skins that were not blanched showed 
slower but more even dehydration that preserved the 
sensory and texture throughout dehydration, highlighting 

Table 4: Water loss over time at various temperatures and sugar solution concentrations for 5mm thick sweet potato 
slices (var. kamala sundari)



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the importance of  adjusting dehydration parameters 
to specific types of  sweet potatoes. By tailoring the 
conditions for the specific variety, it is possible to get 
optimal results for dehydration without suffering adverse 
side effects like excessive shrinkage and loss of  nutrients, 
which ultimately enhance sweet potato’s use in food 
services (Corrêa et al., 2017).

Mass Transfer Behavior 
Kinetics of  Solid Gain in 3mm Thick Sweet Potato 
Slices (var. Local Sada) During Osmotic Dehydration
The study aimed to determine the impact of  sugar 
concentration, temperature, and the pre-treatment of  the 
sample (blanched as opposed to. not blanched) on the 
behavior of  mass transfer in 3mm-thick slices of  sweet 
potato (var. Local Sada) in the course of  the dehydration 
process, which took place over a 4-hour duration (Table 5). 
The study was carried out with 40, 50%, and 60% sugar 
solutions and temperatures ranging between 40°C and 60°C. 
The process of  osmotic dehydration is intrinsically time-
dependent. Understanding the dynamics of  time in the loss 
of  water and gain of  solids is essential for determining the 
optimal treatment parameters (Mari et al., 2024).
The results show an increase in sugar solution 
concentration had a significant impact on the mass 
transfer rate, specifically in terms of  loss of  water and 
gain. The water removal rate was quite low with a sugar 
concentration of  40 in the sample compared to 50 and 
60 %. This could be due to the greater Osmotic pressure 
gradient produced from the concentrated solution, which 
draws water out of  sweet potato slices more efficiently. 
In particular, that solution with 60% sugar showed the 
highest water loss in all temperatures. However, it is 
important to remember that higher sugar concentrations 
led to a higher gain in solids (sugar uptake) through sweet 

potato slices. This is to be expected because the force 
for the diffusion of  solutes into food items is increased 
with sugar concentration. While this can improve the 
sweetness and preservation potential of  the food item, 
the excessive gain in solids could negatively impact 
sensory qualities like texture and taste (Silva et al., 2014).
In the initial stages of  the osmotic dehydration process 
(approximately 60-90 minutes), the loss of  water and 
gain in solids occurred rapidly. This can be explained by 
the pronounced concentration gradient between slices 
of  sweet potato and the supertonic sugar solution that 
causes water dispersal from the samples and the influx of  
solutes. When sugar concentrations were higher (50 % and 
60 %) and higher temperature (50°C or 60°C) this initial 
phase was more evident as blanched samples showed 
greater mass transfer rates compared to the unblanched 
samples. The temperature played an important role 
in determining the speed and amount of  mass loss 
during Osmotic dehydration. As temperatures increased 
from 40°C up to 60°C, both water loss and solid gain 
accelerated in all sugar concentrations. This is explained 
by two primary reasons: higher temperatures reduce the 
viscosity of  sugar solution, increasing the mass transfer 
rate. The higher temperatures enhance the energy of  the 
kinetic energy of  solute and water molecules, making it 
easier for them to move through the cell membranes of  
slices of  sweet potato (Pang et al., 2021; Rastogi, 2023; 
Mari et al., 2024).
 Notably, the highest levels of  loss of  water and solid 
gain were seen at temperatures of  60°C, specifically when 
combined with 50% or 60% sugar solutions. However, 
exposure for a long time to extreme temperatures can 
cause undesirable consequences like over-shortening, 
collapse of  the structure, or degrading of  heat-sensitive 
nutrients. So, even though increased temperatures 



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improve the efficiency of  mass transfer, however, they 
should be monitored to avoid negative consequences on 
the quality of  the product (Mari et al., 2024; Aćimović, 
2024).
The study revealed distinct variations in mass transfer 
behavior between unblanched and blanched samples. 
Blanching, a pre-treatment involving short exposure to 
steam or hot water, appears to improve the permeability 
of  sweet potato’s cell structure, permitting faster water 
removal and more solid gain when dehydration occurs via 
osmosis. This effect was especially evident when sugar 
concentrations were higher (50 % and 60 %) and at higher 
temperatures (50°C or 60°C). The unblanched samples 
had a lower rate of  loss of  water and solid gain, possibly 
because their cell walls were intact, which were more 
resistant to mass transport. While blanching increased the 
efficiency of  dehydration, it could have caused some loss 
of  soluble solids during the pre-treatment process, as was 

observed in earlier studies. This is a trade-off  between 
dehydration speed and the retention of  nutrients, which 
should be considered when selecting the pretreatment 
methods (Peng & Berry, 2018).
The interaction between sugar content and temperature 
and sample types (blanched instead of  unblanched) 
showed complex dynamics. Combining 60% sugar 
solution and a temperature of  60°C produced the highest 
% ages of  water loss and solid gain. However, this is 
not ideal for preserving sweet potato slices’ nutritional 
and sensory qualities. The blanched samples benefited 
more at higher temperatures than non-blanched ones, 
highlighting the necessity of  tailoring the processing 
conditions to the unique nature of  raw materials. These 
findings indicate the necessity of  a comprehensive 
approach to maximizing osmotic dehydration processes, 
considering both the effectiveness and quality of  the 
product (Osae et al., 2024).

Table 5: Solid gain dynamics in 3mm thick sweet potato slices (var. local sada)

Kinetics of  Solid Gain in 3mm Sweet Potato Slices 
(var. Kamala Sundari) During Osmotic Dehydration
Dehydration characteristics of  sweet potato slices from 
two varieties, Sada and Kamala Sundari, were studied 

under different sugar concentrations (40%, 50%, 
and 60%), temperatures, and pre-treatment methods 
(blanched and unblanched). Higher sugar concentrations 
and temperatures significantly increased both types’ water 



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loss and solids gain. There were slight variations between 
their rates and intensities of  dehydration; Kamala Sundari 
showed significantly slower dehydration rates due to its 
cell structure and retention characteristics compared with 
Local Sada. Blanching increased dehydration efficiency 
for both types, yet Kamala Sundari had greater structural 
integrity, while Local Sada was more susceptible to 
swelling and collapse. Even though processing conditions 
were similar, Kamala Sundari displayed more precise 
dehydration methods that preserved texture and quality 

than local Sada. Kamala Sundari samples that had not 
been blanched showed slower yet more stable dehydration 
while maintaining taste quality, indicating the need to 
adjust osmotic dehydration parameters for specific 
varieties of  sweet potatoes (Table 6). Utilizing optimal 
conditions based on a variety of  characteristics can 
assist in reaching desired dehydration outcomes without 
unintended side effects such as excessive shrinkage or 
loss of  nutrients, expanding sweet potato’s food-related 
applications (Rastogi, 2023).

Table 6: Solid gain dynamics in 3mm thick sweet potato slices (var. kamala sundari)

Kinetics of  Solid Gain in 5mm Thick Sweet Potato 
Slices (var. Local Sada) During Osmotic Dehydration
Results demonstrate that increasing sugar solution 
concentration significantly alters mass transfer behavior, 
particularly regarding water loss and solid gain. At 
40% sugar concentration there was less water removed 
compared to 50% and 60% concentrations due to higher 
osmotic pressure gradients created by more concentrated 
solutions creating an effective gradient to draw moisture 
away from sweet potato slices more effectively (Table 
7). Of  all temperature conditions studied, 60% sugar 
solution demonstrated the greatest water loss. However, 
it should be noted that higher sugar concentrations also 

led to an increase in solid gain (sugar uptake) by sweet 
potato slices, expected as solute diffusion increases with 
sugar concentration. Although increasing solid gain may 
enhance the sweetness and preservation potential of  the 
product, excessive solid accumulation may have adverse 
impacts on sensory qualities such as texture and flavor 
(Antonio et al., 2008;  Sarker et al., 2023).
Temperature was an essential component in determining 
the rate and extent of  mass transfer during osmotic 
dehydration, with both water loss and solid gain increasing 
exponentially between 40°C and 60°C for all sugar 
concentrations. Higher temperatures decrease viscosity 
of  sugar solution and improve mass transfer rates, while 



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increasing water and solute molecules’ kinetic energies 
to assist them in passing across sweet potato slices’ cell 
membranes more freely. At 60°C, the highest water loss and 
solid gain rates were observed, especially when combined 
with 50% and 60% sugar solutions. More prolonged 
exposure to higher temperatures can produce adverse side 
effects, including excessive shrinkage or structural collapse 
and degradation of  heat-sensitive nutrients. While higher 
temperatures improve mass transfer efficiency, they must 
also be managed carefully to avoid adverse consequences 
on product quality (Wu et al., 2020).
Experiments have revealed significant variations in mass 
transfer behavior between blanched and unblanched 
samples. Blanching, which involves short exposures 
to hot water or steam, appears to increase the cell 
structure permeability of  sweet potatoes, leading to 
faster water removal and higher solid gain during osmotic 
dehydration. This effect was particularly visible at higher 
sugar concentrations (50% and 60%) and temperatures 
between 50°C and 60°C, where unblanched samples 
showed slower rates of  water loss and solid gain due 

to their intact cell walls’ more excellent resistance to 
mass transference. Blanching may increase dehydration 
efficiency yet can result in the loss of  some soluble solids 
during pre-treatment, according to previous studies 
(Rashid et al., 2020; Wu et al., 2020; Kwaw et al., 2023; 
Rastogi, 2023; Ahmad & Zaidi, 2023). 
Interactions among sugar concentration, temperature, 
and sample type (blanched vs. unblanched) revealed 
intricate dynamics. At 60% sugar solution and 60°C, water 
loss was highest while solid gain was greatest; however, 
this combination may not be optimal in preserving 
sensory and nutritional attributes of  sweet potato slices. 
Blanched samples showed greater benefit from higher 
temperatures than unblanched samples, emphasizing the 
significance of  adapting processing conditions according 
to each material’s specific properties. These interactions 
underscore the necessity of  taking a holistic approach 
when optimizing osmotic dehydration processes, taking 
both efficiency and product quality into consideration 
(Lagnika et al., 2021). For applications requiring rapid 
dehydration and increased sweetness, such as fruit 

Table 7: Solid gain dynamics in 5mm thick sweet potato slices (var. kamala sundari)



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preservation or intermediate moisture food production, 
using a 60% sugar solution at 50°C-60°C with blanched 
samples would be most efficient. On the other hand, 
milder conditions (e.g., 40%-50% sugar solution at 
40°C-50°C with unblanched samples) may be preferable.

Kinetics of  Solid Gain in 5mm Thick Sweet Potato 
Slices (var. Kamala Sundari) During Osmotic 
Dehydration
Dehydration behavior of  5mm Sweet Potato slices from 
Local Sada was evaluated using different sugar solution 
concentrations (40%, 50% and 60%), temperatures and 
pre-treatment conditions (blanched vs unblanched). 
Higher sugar concentrations and elevated temperatures 
significantly accelerated water loss through osmotic 
dehydration; thicker 5mm slices showed slower 

dehydration rates due to longer diffusion paths for 
moisture removal (Table 8). Blanching improved 
dehydration efficiency by increasing cell permeability 
but led to greater softening and structural collapse than 
unblanched samples which retained better texture even at 
slower dehydration rates (Mari et al., 2024).
Comparison between blanched and unblanched 5mm 
slices illustrates the trade-offs between dehydration speed 
and product quality. Blanching may speed mass transfer 
more rapidly, yet its use compromises the structural 
integrity of  slices that are more easily prone to breakage. 
Unblanched slices showed a more gradual and controlled 
dehydration process, which better protected their physical 
properties than that of  blanching did - as reported by 
Neri et al. (2011). These results highlight the significance 
of  optimizing processing conditions based on slice 

Table 8: Solid gain dynamics in 5mm thick sweet potato slices (var. kamala sundari)

thickness and pretreatment to strike an equilibrium 
between efficiency and quality, increasing sweet potato 
applications such as intermediate moisture foods or fruit 
preservation while maintaining their desirable sensory 
attributes (Rindang et al., 2024).

Practical Implications and Industrial Relevance
This study’s results have far-reaching ramifications 

for food processing industries worldwide. By studying 
the effects of  sugar concentration, temperature, slice 
thickness, and pre-treatment on osmotic dehydration 
kinetics, our findings provide a solid framework for 
process optimization in industrial settings. Specifically, 
designed dehydration systems could maximize efficiency 
while protecting quality sweet potato products.
Examples of  optimal conditions identified (using a 60% 



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sugar solution at 50-60°C for blanched 3 mm slices, for 
instance) can be scaled up using continuous processing 
systems equipped with temperature-controlled baths and 
high-efficiency peristaltic pumps; such systems will ensure 
consistent product quality, reduce energy consumption, 
and reduce postharvest losses while simultaneously 
minimizing postharvest losses. Additionally, this method 
could serve as a model for dehydrating other moisture crops 
while broadening industrial applications. Future efforts 
should focus on conducting small-scale experiments and 
economic feasibility analyses to test the scalability of  
optimized conditions; additionally, integrating modern 
control systems for process management can further 
increase efficiency while maintaining quality throughout 
commercial operations.

CONCLUSIONS
The study provides a thorough understanding of  the 
osmotic degradation behavior of  slices of  sweet potato 
focused on two kinds (local Sada as well as Kamala 
Sundari) and various parameters like sugar concentration 
in the solution (40, 50 60, 80%) as well as temperatures and 
slices’ thickness (3 mm or 5 mm) and the pre-treatment 
conditions (blanched as opposed to. non-blanched). The 
results highlight the crucial importance of  these variables 
in determining the effectiveness of  dehydration and solid 
gain as well as the quality of  the product. The higher sugar 
levels and the elevated temperatures generally increased 
water loss and solid gain in all tests. However, differences 
between the different species were apparent in Kamala 
Sundari, which showed slower but controlled dehydration 
than Local Sada, which demonstrated higher removal 
of  moisture but higher vulnerability to the collapse of  
the structure. Slice thickness had a significant impact 
as thin slices (3 mm) dehydrated faster than those with 
thicker slices (5mm); however, the latter exhibited better 
structural integrity throughout processing. Blanching has 
been found to accelerate dehydration through increasing 
cell permeability, but it also weakened texture, particularly 
in smaller slices and the Local Sada type. Although less 
prone to drying, the samples that were not blanched 
maintained more physical characteristics, making them 
suitable for use in applications where texture is essential. 
These findings highlight the importance of  adjusting 
the dehydration parameters, including the sugar content, 
temperatures, and pre-treatment, to the unique features 
of  sweet potato varieties and the desired characteristics 
of  the product.
The study provides valuable insights for the food 
processing industry by optimizing osmotic dehydration 
conditions for specific sweet potato varieties, reducing 
post-harvest losses, and enhancing product quality. 
These findings also apply to other high-moisture crops, 
broadening food preservation strategies. Future research 
should explore alternative osmotic agents, integrate 
advanced drying techniques, and assess the economic 
feasibility of  industrial-scale implementation. This study 
advances food dehydration science, offering practical 
guidance for both research and industry applications.

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