Study of Osmo-Dehydration of Mahua Flowers (Madhuca Indica)
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Date
2022
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Publisher
DRPCAU, PUSA
Abstract
Mahua flowers are underutilized forest produce which has a very high potential for
nutritional and economic benefit for the people. There is a wide scope of its utilization in
effective way using engineering interventions. Hence, the present research was executed to
study an important processing aspect of Mahua flowers i.e. osmotic dehydration. The process
of osmosis was carried out by employing BBD experimental design with four independent
variables having three levels each which included sugar concentration (SG) – 45, 55 and
65%; solution temperature (ST) – 40, 45, 50°C; immersion time (IT) - 60, 120 and 180 min
and solution to product ratio (SPR) - 3:1, 4:1 and 5:1. The impact of these independent
variables on three dependent variables - weight reduction (WR%), solute gain (SG%) and
water loss (WL%) of osmo-dehydrated commodities was studied with 29 experimental design
variations. The results were analysed using ANOVA and a second order polynomial model
was fitted to the data. The optimization was done using RSM, which gave an optimal solution
as sugar concentration (SC)-59.31%, solution temperature (ST)- 49.39°C, immersion time
(IT)-153.85 min and solution to product ratio (SPR)-3.32 :1 in order to obtain optimized yield
of water loss (WL)-18.32%, solute gain (SG)-2.99%, and weight reduction (WR)- 15.97%
with desirability value 1.0. Furthermore, three distinct drying air temperatures (50, 60 and
70°C) were employed in a laboratory model tray dryer to conduct drying investigations on
raw fresh, blanched and osmosed Mahua flowers. On the basis of recorded data of weight
loss with elapsed drying time, drying rate and moisture content reduction were evaluated.
Drying of Osmosed Mahua flowers samples at 70°C drying air temperature resulted in shorter
drying time as compared to raw fresh and blanched samples. The minimum time for drying
was achieved by osmosed Mahua flowers at 70°C and it attained a final moisture content of
8.30%. The overall variation in bulk density was 0.414 – 0.467(g/cm3), in true density was
1.060 -1.435(g/cm3) and porosity was 0.582 -0.689 for different Mahua samples after drying.
Osmo-dehydrated mahua flowers at 60°C showed the greatest hardness/peak force of 12.60 N
with 0.580 second fracture time. the osmosed Mahua flowers dehydrated at 60°C resulted as
the best acceptable product with overall acceptability of 6.93 with best rehydration
characteristics. Good quality raisin like product could be obtained from drying of Mahua
flowers by using osmotic dehydration technique followed by hot air tray drying at 60oC.