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2016 - 201912020 - 20211
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Subject: Processing and Food Engineering × Author: Sidhu, Jashandeep Singh ×
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    Mathematical modeling of osmo assisted freeze drying process for strawberries (Fragaria vesca)
    (Punjab Agricultural University, Ludhiana, 2021) Sidhu, Jashandeep Singh; Gupta, . S.K.
    The study entitled “Mathematical modeling of osmo assisted freeze drying process for strawberries (Fragaria vesca)” was undertaken to characterize the effect of process parameters; osmotic solution concentration (40-80 °Brix), solution to fruit ratio (4-8 STFR) and freeze drying temperature (-20 to -40°C) on drying kinetics and quality attributes. The treatments with -20°C freeze drying temperature required more time for drying as compared to -30 & -40°C (2to 4 hours) to reduce the moisture content from 87.2% wb to 4.2±0.1 % wb. The input parameters for osmo-freeze drying process for strawberry halves were optimized by „Multiple Response Optimization‟ technique with optimum operating conditions recorded as freeze drying time temperature: -40°C, osmotic solution concentration: 79.43° Brix and solution to fruit ratio (STFR): 6.61. Corresponding to these values, the value of responses was rehydration ratio: 7.150, shrinkage ratio: 0.627, colour change: 6.661, bulk density: 502.19 kg/m3, % vitamin-c retained: 71.846%, texture (hardness): 8.1871Kg-f, and overall acceptability: 83.431%. The best fit of experimental data for osmotic dehydration was observed in Penetration model followed by GEM model. The overall performance of the mathematical model developed in VISUAL BASIC-6.0 for prediction of freeze drying time for osmo-freeze drying was satisfactory (0.122-7.285 % error) and can be used for predicting the freeze drying time for osmo-freeze drying of strawberries. The osmo-freeze and freeze dried products packed in three types of packaging materials viz. high density polyethylene, laminate aluminium pouches & glass jars were kept under refrigerated and ambient storage conditions. Overall, it was concluded that osmo-freeze drying of strawberry halves at optimized conditions of 79.43°B osmotic solution, 6.61 solution to fruit ratio (STFR) and 40°C freeze drying temperature gave better quality product as compared to freeze drying and can be stored for 5 and 3 months in refrigerated and ambient conditions respectively.
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    Optimization of greenhouse drying process for white button mushroom (Agaricus bisporus)
    (Punjab Agricultural University, Ludhiana, 2016) Sidhu, Jashandeep Singh; Amarjit Singh
    The present study entitled “Studies on optimization of greenhouse drying process for white button mushroom (Agaricus bisporous)” was carried out in the Department of Processing and Food Engineering, Punjab Agricultural University. Mushrooms were pretreated with citric acid and samples without treatment were kept as control. The treated and untreated mushroom samples were dried in greenhouse and open sun during the month of October, 2015.On the basis of microclimate parameters, a mathematical thermal model “BITGREEN” for greenhouse was developed to optimize the drying conditions. The developed model was working satisfactorily to predict the microclimate inside the greenhouse. The drying parameters studied were moisture content, moisture ratio, drying rate, drying air temperatures, solar intensity and relative humidity. The quality parameters included rehydration ratio, shrinkage ratio, colour, texture (hardness), bulk density, protein content and overall acceptability. Moisture content of dehydrated mushrooms reduced from 88-90 (% wb) to 6.5 (% wb) for greenhouse drying (28-46°C) in 48 hours and 8.2 (% wb) for open sun drying (25-32°C) in 72 hours. The Lewis model showed best adequacy of fit for drying of mushrooms. The dried mushrooms were packed in two packaging materials viz. LDPE and PP and stored under refrigerated and ambient conditions for three months. The quality attributes of stored product like colour, texture, rehydration ratio, shrinkage ratio, water gain and overall acceptability were evaluated at 15 days interval. The greenhouse dried mushrooms packed in polypropylene (PP) and stored under refrigerated conditions were found to be highly acceptable upto 75 days of storage. Benefit-Cost ratio of 1.36:1 for subsidized greenhouse revealed that it is profitable to dry mushrooms in greenhouse.