Research On The Preservation Effect Of Ozone Coupling Low Temperature On Kiwifruit

Kiwifruit has high nutritive and economic value,its planting area is wide,but the post-decay loss is high.The effect of ozone treatment coupling low temperature on kiwifruit preservation were investigated,the optimum ozone treatment conditions and ozone preservation mechanism of kiwifruit were studied.Qinmei and Hayward were selected as experimental material in this study,treated separately by 0(CK),90,170,250 mg/m~3 ozone(continuous processing one hour per day),then packed with single 0.03mm thick PE bag,and storaged respectively at(0±1)and(2±1)°C,relative humidity of 90%-95%.The research aimed to study the ozone treatment conditions and preservation mechanism of kiwifruit,and analyze the positive effects of ozone treatment coupling low temperature on the storage of kiwifruit,so as to provide a theoretical basis for the storage of kiwifruit.The main results are as follows:(1)After 250 mg/m~3 ozone treated and stored in(0±1)°C,when Qinmei were stored to 126d,fruit hardness remained at a high level,its value was 2.57 times higher than CK group,during the storage of Hayward,the decreasing of fruit firmness was smaller than that of CK group.The content of titratable acid in Qinmei and Hayward was kept in a high level.When Qinmei stored for 126 days,the level of VC was 1.86 times higher than that of CK group,and the occurrence time of SSC content peak of Hayward was later than that of CK group at 126 days,which indicated that the treatment could slow the increase of SSC content during storage.After170 and 250mg/m~3 ozone treated,when Hayward were stored for 182 days at(0±1)°C,their VC content were 19.2%and 26.9%higher than that of CK group,and the content of reducing sugar was 23.6%and 41.2%higher than CK group respectively,while the weight loss rate decreased by 20.1%and 45.6%respectively,and the decay rate decreased by 24.9%and 39.9%,chilling rate decreased by 36.7%and 40.0%respectively.The weight loss rate of the treated Qinmei kiwi fruit decreased by 50.0%and 92.1%,and the decay rate decreased by 25%and 29.3%,the chilling injury rate was reduced by 31.5%and 31.5%respectively.Qinmei and Hayward were suitable for ozone treatment at 170 and 250mg/m~3 ozone concentration,once a day for 1 hour each time,lasting for 7days.The optimum temperature was(0±1)°C,and the optimum humidity was 90%-95%.(2)250mg/m~3 ozone treatment could increase the peak activity of POD in Qinmei and Hayward,and keep SOD and PAL activity at a high level at the end of cold storage.When Qinmei were stored to 126d,the treatment was 1.62 times higher than that of CK in PAL,while MDA was significantly lower than CK.When Hayward were stored to 182 days,the content of MDA in fruit was 78.9%lower than CK group.This treatment could also delay the occurrence time of respiration peak of Qinmei and Hayward,and the ethylene production could also be maintained at a low level.In addition,the PG activity of Qinmei and Hayward could be maintained at the lowest level,thereby reducing the degradation of pectin and delaying the fruit hardness decrease,and could effectively maintain cell wall integrity,chloroplast ultrastructure,prolong the storage life of kiwifruit.Ozone coupling low temperature preservation mechanism are that the ozone and low temperature both could effectively inhibit the kiwi's respiratory metabolism,ethylene metabolism and transpiration and other physiological effects,delay the collapse of cell structure,ozone could also effectively reduce fruit rot rate,chilling injury rate,and extend storage period.