Effects of Osmotic Conditions on the Osmosis-Vacuum Microwave Drying of Tilapia Meat
LIU Bing1, DUAN Zhenhua1,2,*, YU Qun1, LIU Yan1, HU Bingyang1
1. College of Food Science and Technology, Hainan University, Haikou 570228, China;
2. Institue of Food Research, Hezhou University, Hezhou 542899, China
Abstract：In order to obtain the optimum conditions for osmotic pretreatment before microwave drying of tilapia fillets, the effects of osmotic solution composition, osmosis time, temperature and slice size on the water content, water activity and qualities (shrinkage rate, rehydration rate and chromatic aberration) of dried tilapia fillets were studied. The results showed that higher osmotic dehydration efficiency for fish fillets was obtained with higher concentrations of sugar solutions, but under this condition dried product quality was unsatisfactory. The water content of tilapia fillets decreased with increasing osmosis time up to 2 h; however, no significant improvement in osmosis efficiency was observed when osmosis was prolonged beyond 2 h. Moreover, osmosis at elevated temperature led to improved dehydration efficiency but was hampered due to the destruction of the texture and microstructure of fillets at excessively high temperatures. Larger fillets had higher water content but poorer quality after being dried. The optimum conditions for osmotic dehydration before vacuum microwave drying of tilapia fillets were determined as osmosis of 500 mm² slices at 30 ℃ for 2 h in aqueous solution of 20% salt and 10% white granulated sugar.
