Abstract: In order to explore the effect of controlled atmosphere (CA) storage on alleviating chilling injury (CI) in peach fruit and the possible underlying mechanism, the effect of CA treatment (5% O2 + 10% CO2) on internal browning index (IB), firmness, ethylene release rate, reactive oxygen species (ROS) content, malondialdehyde (MDA) content, compounds and key enzyme activities related to the ascorbic acid-glutathione (AsA-GSH) cycle and volatile contents in yellow-fleshed peach fruit (cv. Jinxiu) during low temperature ((0 ± 2) ℃) storage and shelf (20 ℃, 3 d) was investigated. The results showed that CA alleviated CI significantly relative to the control group; on the third day of the shelf life after 30-day cold storage (30dS3), IB was lower than 10%, fruit firmness decreased to below 10 N, and ethylene release rate was 1.7-fold as high as in the control. During the late period of cold storage, the contents of total ROS, MDA, and hydrogen peroxide (H2O2) were significantly lower and scavenging capacities against 1,1-diphenyl-lpicrylhydrazyl (DPPH) and 2,2’-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation free radicals were significantly higher in the CA-treated fruit than the control group (P < 0.05 or P < 0.01). Meanwhile, in the CA-treated peach fruit, the activity of superoxide dismutase (SOD) was increased by 36% on 30dS3, while the activities of AsA-GSH cycle-related key enzymes such as ascorbate peroxidase (APX), dehydroascorbate reductase (DHAR), glutathione reductase (GR) and monodehydroascorbate reductase (MDHAR) were enhanced, and the conversion of reduced ascorbic acid to dehydroascorbic acid was significantly inhibited. Moreover, CA treatment accumulated higher amounts of C6 alcohols, esters, and lactones compared with the control group at the end of the shelf life; on 30dS3, the contents of γ-hexalactone, γ-decalactone, and δ-decalactone were increased by 3.0, 2.6 and 5.0 folds compared with the control group, respectively. In addition, higher contents of sucrose and sorbitol and lower contents of glucose and fructose were observed in the CA-treated fruit. Therefore, CA treatment (5% O2 + 10% CO2) can alleviate CI and maintain aroma quality by activating the AsA-GSH cycle and SOD, and enhancing ROS scavenging capacity in peach fruit.

Key words: peach fruit; controlled atmosphere storage; chilling injury; reactive oxygen species metabolism; aroma volatiles