Abstract: The purpose of this study was to investigate the main factors affecting of the vacuum freeze-drying of green sweet peppers such as blanching, soaking solution and freeze-drying parameters. The results indicated that blanching at 95 ℃ for 70 s could inactivate enzymes completely to prevent green sweet peppers from browning and improve the recovery rate. In addition, soaking treatment with 20 ℃ solution containing 5% NaCl, 4% glucose and 0.4% CaCl2 for 20 min could effectively improve the retention rate of chlorophyll and recovery rate of green sweet peppers after blanching. Moreover, the optimal freeze-drying parameters were fast freezing at －20 ℃ and 30 Pa, sublimation at 5 ℃ for 3 h and resolution at 40 ℃ for 1.5 h. Under these treatment conditions, the quality of freeze-dried sweet peppers was significantly improved.

Key words: sweet pepper pieces, blanching, vacuum freeze-drying, color protection