Abstract: Plum (Chuanhong cultivar) fruits were treated with varying concentrations of calcium chloride before storage at 0 ℃ to explore the effect and related mechanisms of calcium chloride treatment on chilling injury and enzymatic browning in plum fruits with the objective of discovering a new method to reduce chilling injury. The contents of polyphenols and malondialdehyde (MDA), the activity of PPO and chilling injury index in plum fruits from the control group were increased after storage at 0 ℃ for 12d, which suggests the start of chilling injury. Calcium chloride treatment delayed the increase of polyphenol content, activated PPO, POD and CAT, and dramatically decreased external chilling injury index. However, only the 2% calcium chloride treated group had significantly lower internal chilling injury index and MDA content than the control group, and the activity of superoxide dismutase (SOD) had no obvious difference between both groups, but the SOD level in  the 2% calcium chloride treated group was significantly higher than those in other groups. It showed that calcium chloride treatment inhibited chilling injury in plum fruits obviously in appearance. Based on a comprehensive comparison between the internal and external chilling injury indices, calcium chloride treatment at 2% concentration could inhibit chilling injury most effectively. At the end of storage, the content of polyphenol and POD activity in the 2% calcium chloride group was 1.16 and 3.7 times higher than those in the control group, and the internal chilling injury index was only 42% and that in the control group was as high as 57% after 72 d storage. In conclusion, 2% calcium chloride treatment could prevent chilling injury in plum fruits.

Key words: calcium chloride, plum, chilling injury, enzymatic browning