Vol. 11, Special Issue 2 (2022)

Author(s):
Deep P Patel, Kusum Meghwal, Maya Sharma and RG Burbade

Abstract:
Osmotic dehydration is a process in which partial water is removed by immersion of water containing cellular solid in a concentrated aqueous solution of high osmotic media for a specific time and temperature. Preliminary trials were planned for finalizing the concentration of osmo-lyte (sugar solution: 40, 50 and 60ºBrix) and temperature of syrup 35, 45 and 55°C. On the basis of sensory analysis, samples dried at 45°C with 60ºBrix sugar concentration was considered best. The osmotically dehydrated banana slices were further dried using convective dryer at four different drying temperatures of 50, 55, 60 and 65°C at constant air velocity of 2.0 (± 0.1) m/s. In order to select the appropriate drying model, five mathematical drying models were fitted to the experimental data. Results indicated that moisture content of the product was reduced exponentially with drying time and no constant rate period was observed. Mathematical models were fitted to the experimental data and the best model was chosen as one with the highest coefficient of correlation (R²) and the least reduced chi-square (γ²), root mean square error (RMSE) and mean bias error (E_MB). The Page model gave the best results for describing the drying behaviour of osmotically dehydrated banana slices. The minimum and maximum values of water activity and rehydration ratio for osmo-convectively dried banana slices were found in the range of 0.268 to 0.322 and 1.4516 to 1.5461 for 50 and 65 ºC drying air temperatures, respectively.