Hot air treatment inhibits chilling injury in peaches by regulating metabolism of sugar and organic acid

Hot air (HA) treatment has been demonstrated to control chilling injury (CI) in peaches effectively, however, little is known about the effects of HA on the changes of sugar and organic acid. In order to explore the relationship among CI susceptibility, soluble sugar and organic acid metabolism, peach fruit (Prunus persica) were treated with HA (40°C, 4 h) and then stored at 1°C for 35 days plus 3 days at 20°C. Results showed that HA avoided or decreased the development of CI symptoms and maintained a better quality of peaches. HA suppressed sucrose degradation by inhibiting expression of invertase as well as enhancing the relative expressions of sucrose synthase and sucrose phosphate synthase. The low degradation of sucrose contributed to low contents of glucose and fructose in the treated groups. Besides, HA significantly increased contents of citric and malic acids during the whole storage by enhancing the expressions of citrate synthase and malate dehydrogenase, but inhibiting malate synthase. These results suggest that HA suppressed chilling injury by regulating sucrose degradation and organic acid metabolism. The high contents of sucrose, citric and malic acids contributed to enhancement of CI tolerance in peaches.