Abstract:

In this study, the processing parameters of vacuum freeze-drying for instant rice were explored. The slow frozen and the rapid frozen rates were analyzed and compared. Results indicated that the optimal processing parameters for vacuum freeze-drying of instant rice were primary stage freezing temperature of －50 ℃, freezing time of 1.5 h; drying temperature of －20 ℃, frozen time of 8 h; second stage drying temperature of 50 ℃, frozen time of 5.5 h; final stage frozen temperature of －50 ℃, frozen time of 1.5 h; the vacuum pressure of 10 Pa. Results indicated that rapid frozen could provide higher product quality based on the analysis of comprehensive quality and nutritional components.

Key words: instant rice, vacuum freeze-drying, freeze-drying curve, frozen rate