Effect Of MAP, IW And Harpin On Chilling Injury Of Plum Fruit And Its Partial Mechanism

Chilling injury (CI) often be caused in plum fruit storaged below 6℃. The surface of the fruit appears spots, and the pulp becomes browning, the quality of fruit is breakdown. Therefore, it is necessary to develop new strategy to delay or reduce chilling injury of plum fruit during cool storage. In this paper, some postharvest treatments were assayed for reducing CI in plum fruit (cv. Ruby) storaged at 0℃, including MAP with 0.01mm PE, IW with 15 days and Harpin dipping at 100 mmol/L. It was studied that effect of the treatments on CI of plum fruit and its partial mechanism. The results indicated as below:1. Both MAP and IW significantly decreased CI index, browning index, amount of CI spots and browning of pulp, and maintained the sensory quality of fruit. MAP and IW also significantly reduced water loses, kept aroma and colors. However, Harpin treatment increased CI index and browning index, but lowered water loss, and maintained aroma and colors.2. MAP didn't affect total sugar content, however increased titratable acidity (TA) content and decreased ascorbic acid (ASA) content, soluble solids content (SSC) and SSC/TA. IW didn't influence SSC and SSC/TA, however increased the content of TA and ASA, and decreased total sugar content. Harpin didn't influence the content of SSC, TA, ASA and SSC/TA, however, increased total sugar content.3. MAP and Harpin increased activity of peroxidase (POD) and polyphenoloxidase (PPO) and enhanced the content of water soluble pectin (WSP) and HCl dissolve pectin (HDP). IW increased WSP content, decreased activity of POD, PPO, PE, PG and HDP content. MAP significantly increased activity of PE and decreased activity of PG. No significant effects were found in membrane permeability rate with the treatments of MAP and IW; however, Harpin decreased the rate.4. Both POD activity and browning index had positive correlationship in treatment of MAP, IW and Harpin; however, PPO activity and browning index had subtractive correlationship in treatment of MAP and IW. MDA content and browning index had significantly positive correlationship in treatment of MAP and Harpin.