Combined vacuum-microwave and hot-air drying of scallop

Combined drying processes for vacuum-microwave and hot-air drying of scallop were studied and compared with single-stage vacuum-microwave (MV) drying as well as single-stage hot-air drying(AD) on the basis of drying time, shrinkage rate, rehydration rate, durability and sensory qualities. The results show that the combinations of vacuum-microwave+hot air+vacuum-microwave can reduce by 50% of the drying time as compared with those by single-stage hot air drying, and the dried scallop has lower shrinkage rate and higher rehydration rate than single-stage vacuum-microwave drying, higher durability than single-stage hot air dried scallop. When the power of microwave, the vacuum pressure and the temperature of hot air were controlled at 3 W/g, 0.090 MPa and 70℃，the rehydration rates after10 minutes and 20 minutes of the scallop dried by the combinations of MV5(min)+AD120(min)+MV and MV5(min)+AD180(min)+MV were 42.19%, 89.85% and 83.20%, 106.50%, respectively. The shrinkage rates of the dried scallop under the two combined drying processes were 49.43% and 53.71%, respectively. Furthermore, the dried scallop under the two combined processes had better sensory qualities such as better color, better texture and lower distortion.