Controlling Chilling Injury Of Plum With Two Kinds Of Intermittent Warming In Postharvest And Its Partial Mechanism

Chilling injury (CI) often be caused in plum fruit storage at 0-4℃. The symptom expressed as skin pitting, staining and flesh browning. CI influences seriously the quality of fruit during storage. In this paper, we investigated effect of two kinds of intermittent warming (IW-1 and IW-2) combined with modified atmosphere packaging (MAP) on chilling injury of two plum cultivars (cvs. Ruby and Friar), and explore its partial machnism. The results indicated as below:1. IWs significantly inhibited symptom of CI, and delayed symptom of flesh browing. Afetr 49 and 61 days of storage, CI index and flesh browning index of Ruby and Friar were 52%, 47% and 43.66% and 48.66% of the control, respectively.2. IWs significantly reduced malondialdehyde (MDA) content. MDA contents of Ruby and Friar treated by IW-1 and IW-2 were only 71.3%, 47.5% and 89.1%, 80% of the control. IWs also maintained the integrity of cell membrane in some extent, IW-2 showed better than IW-1.3. IWs inhibited the decline of activity of SOD, CAT and POD in plums, increased PPO activity of Ruby; however, little effect on PPO of Friar. No significant differences were found in PAL activity between the treatments and control, and two cultivars.4. IWs maintained a higher fruit firmness, and content of ASA and SSC, effectively inhibited the decline of TA content. The treatment also kept colour and taste quality of fruit. IW-2 showed better than IW-1 in maintaining quality of plums.In summary, IW would be an effective mothed for reducing CI of plums during storage by enhancing resistance enzyme activity, maintaining membrane permeability and reducing MDA content. At the same time, the quality of the plum was maintained by IW treatment during storage.