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Subject: Processing and Food Engineering × Author: Bassi, Saurabh × Start date: 2005 × Type: Thesis × Thesis Type: M.Tech. ×
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    Osmo-solar drying of pineapple slices with honey as osmotic medium
    (Punjab Agricultural University, Ludhiana, 2021) Bassi, Saurabh; Iqbal Singh
    Pineapple fruit is high in minerals and vitamins. It has moisture content of about 90% due to which it has perishability and limited shelf life. Osmotic dehydration is a technique for partially dehydrating water-rich foods; uses less energy than any other drying method. During the present study, the pineapple slices were partially osmotically dehydrated using honey as osmotic medium with the aim to prepare a healthy and nutritive pineapple slices. The osmomechanical drying process was optimized using RSM technique. The process parameters taken for osmotic drying were KMS concentration (0.5,1.0,1.5%), immersion time (24, 36, 48 hours) and honey pineapple ratio (2:1, 3:1, 4:1) whereas the quality was measured by quantifying ascorbic content, change in colour, water activity and overall acceptability (9-point hedonic rating scale). The mechanical drying was carried out at temperature of 60°C ± 3°C in tray dryer with trays having skewed rods. The pineapple slices were dried upto 15.5 to 18% final moisture as further drying becomes difficult due to drying of honey layer on the surface that prevents water movement from inner layers of pineapple. The optimum conditions were found to be 1.5% KMS concentration, 24 hours immersion time and 2.66:1 honey pineapple ratio. The quality parameters at optimum conditions were found as ascorbic acid content- 48.03 mg/100g, aw -0.603, ∆E- 23.31 with overall acceptability 74.7%. The optimum conditions were verified and the experimental values were found within significant limits. The osmo-solar drying of pineapple slices was carried out at optimum conditions with cabinet temperature variation from 28°C-55°C. The drying kinetics was studied using four drying models and two term model was found to have best fit for both mechanical and solar drying. The storage study was undertaken for osmo-solar dried slices in which the slices were packed in vacuum pack, laminated aluminium pack and LDPE and kept under ambient conditions. Vacuum packaging was found to have lesser degradation of quality in comparison to LAP and LDPE packaging. Solar drying of dehydrated pineapple slices had a benefit-cost ratio of 1.37, whereas mechanical drying yielded a ratio of 1.13. Solar drying of dehydrated pineapple slices had a considerably higher benefit-cost ratio than mechanical drying which demonstrates its feasibility over mechanical drying that makes energy efficient process.