Study on Combined Drying Process of Black Currant by Vacuum Freeze and Vacuum Microwave

Vacuum freeze-drying combined with vacuum microwave for black currant as raw meterial was investigated.Results showed that the drying process of vacuum freeze-drying followed by vacuum microwave drying is feasible.The optimum parameters of combined drying were obtained as follows: microwave power of 1.34kW,absolute pressure of 11kPa,and the moisture content of conversion point of 20%(w b).Validation experiment verified that products qualities from the combination drying is similar to that from vacuum freeze-drying,but the combined vacuum freeze-drying and vacuum microwave drying method is effective on drying time saving and energy conservation for dehydrated black currant.