Abstract: In order to improve recovery rate, texture, color and taste of freeze-dried yam slices, crucial steps in the preparation process of yam slices such as blanching, soaking treatment and freeze-drying were investigated. The results indicated that the optimal blanching of yam slices at 95 ℃ for 60 s could prevent browning and consequently was beneficial to soaking and freeze-drying. The optimal soaking process at 30 ℃ for 30 min using soaking solution composed of 5% NaCl, 10% glucose and 10% maltodextrin could improve recovery rate. The optimal freeze-dried process was quick-freezing at －30 ℃, and then sequential freeze-drying at 5 ℃ for 7 h and 35 ℃ for 2 h. Freeze-dried yam slices obtained using the optimized process displayed better recovery and sensory quality.

Key words: yam slices, blanching, maltodextrin, freeze-drying