Effects Of Modified Atmosphere Packaging And 1-Methylcyclopropene Treatments On Chilling Injury Of ’Youhou’ Sweet Persimmon During Cold Storage

‘Youhou’ is one of the main cultivars of sweet persimmons in China,but the fruit easily softens after harvest.Fortunately,low temperature can slow down the softening speed,at which the fruit is also subjected to chilling injury(CI)and leads to loss of the commercial value.Modified atmosphere packaging(MAP)can effectively reduce the physiological metabolism of fruits and delay the ripening and senescence of fruits by by respiration of fruits to keep low oxygen and high carbon dioxide in the packaging.As an ethylene receptor inhibitor,1-methylcyclopropene(1-MCP)has been widely applied to postharvest fruit preservation.In this study,we investigated the effects of different thicknesses of polyethylene packages(PE)treatments on the CI of ‘Youhou’ sweet persimmon during cold storage at 1 ± 0.5 ℃,RH 90% ± 5% to select the suitable packaging of MAP.We also investigated the effects of MAP,1-MCP,and combined MAP and 1-MCP treatments on the CI of ‘Youhou’ fruit during cold storage.To provide references for technology of preserve freshness.The results are as follows:1.Both 0.03 mm and 0.05 mm PE bags treatments can significantly reduced CI incidence and CI index,retarded the decrease of firmness,and treated fruit had lower levels of electrolyte leakage and malondialdehyde(MDA)than control.Compared with control,treatments remained higher juice yield and slighter flesh gelling,which also reduced the activities of polyphenol oxidase(PPO)and peroxidase(POD),and lightened the fruit browning.Treatment with 0.05 mm PE bags showed better performance compared with 0.03 mm.2.0.08 mm PE bags treatment can also inhibited the decrease of fruit firmness,delayed the increase of electrolyte leakage and MDA content and remained higher juice yield and slighter flesh gelling.Some fruits with treatment browned in the late period of cold storage,which was not caused by chilling injury(fruit browning caused by chilling injury only occurs at room temperature for a period of time,with flesh gelling).3.MAP,1-MCP,and MAP+1-MCP treatments inhibited the development of CI symptoms,reduced CI incidences and CI indices,retarded the decrease of L* value,reduced weight loss rate when out of storage in ‘Youhou’ fruit.The effects of MAP and MAP+1-MCP treatments were better than 1-MCP treatment.4.MAP,1-MCP,and MAP+1-MCP treatments retarded the decrease of firmness,total phenol and ascorbic acid content,reduced the increase of ethylene production and rot rate when out of storage in ‘Youhou’ fruit.The fruits of three treatments showed lower electrolyte leakage,MDA content,lipoxygenase,polyphenol oxidase and peroxidase activity than the control.MAP+1-MCP treatment showed an optimal result.5.Compared with the control,MAP,1-MCP and MAP+1-MCP treatments inhibited the decrease of juice yield and reduced the flesh gelling caused by CI.The effects of MAP and MAP+1-MCP treatments were better than 1-MCP treatment.1-MCP treatment promoted pectin degradation and increased polygalacturonase(PG)activity,while MAP and MAP+1-MCP treatment inhibited pectin degradation,restrained the increase of PG activity in the early storage and the decrease of PG activity in the late storage.To sum up,MAP treatment had obvious effect on maintaining the postharvest quality and reducing the CI of ‘Youhou’ fruit.Treatment with 0.05 mm PE bags showed the best performance.Compared with treatments of MAP and 1-MCP,the MAP+1-MCP treatment had superposition effect on some physiological indexes related to CI.