Abstract: 【Objective】 The objective of this study is to optimize packaging bags and provide a scientific foundation for exploring a simple and efficient new preservation technology of ‘Korla Xiangli’ pears during storage by studying the effect of modified atmosphere packaging on postharvest physiology and quality. 【Method】 Storage experiments were performed with commercially mature ‘Korla Xiangli’ pears using four packaging bags, including 0.02 mm thickness PE film bags, 0.04 mm thickness PE film bags, 0.05 mm thickness PE film bags and 0.04 mm thickness PVC film bags. The bags were sealed after the fruits were put into the bags. Theses fruits were stored under the conditions of temperature at (0±0.3)℃ and relative humidity at (RH) 90%-95%. The fruits of unsealed treatment were used as the control. The concentrations of O₂, CO₂ and ethylene in different packaging bags were monitored regularly. In business sales peak of ‘Korla Xiangli’ pears (refrigerated 180 d and 240 d), the changes of L and h values and chlorophyll fluorescence parameters of peel, relative electrical conductivity, malondialdehyde, ethanol, aldehyde, fruit firmness, total soluble solids, titratable acid, ascorbic acid and other physical and chemical indicators were determined, and the weight loss ratio, stalk preservation index, core browning index and sensory scores in different periods of storage were calculated. 【Result】The concentrations of O₂ and CO₂ in sealed bags reached equilibrium on the 30th day. The ability level of gas adjustment was 0.05 mm thickness PE film bags, 0.04 mm thickness PE film bags, 0.04 mm thickness PVC film bags and 0.02 mm thickness PE film bags from high to low in turn. The 0.04 mm thickness PVC film bags and 0.04 mm thickness PE film bags were optimum modified atmosphere packaging bags for ‘Korla Xiangli’ pears by two years tests. The results of indicators showed that the adopted packaging bags reduced weight loss ratio, slowed down the rise of L value of peel, relative electrical conductivity, malondialdehyde, ethanol, aldehyde, and core browning index, restrained h value, Fm and Fv and Fv/Fm of peel, improved stalk preservation index, fruit firmness, total soluble solids, titratable acid and ascorbic acid had a good effect of maintaining quality. On the 180 d, the L value, h value were significantly different between treatment and control groups (P＜0.05), and the stalk preservation index, core browning index and weight loss ratio were not significantly different (P>0.05), but in the late storage (240 d), the above indexes were significantly different between treatment and control groups (P＜0.05). The 0.04 mm thickness PE film bags and 0.04 mm thickness PVC film bags maintained sensory score of ‘Korla Xiangli’ pears, but the sensory scores of 0.05 mm thickness PE film bags were lowered significantly, and core browning was increased. 【Conclusion】‘Korla Xiangli’ pears more embodied in the storage period by using 0.04 mm thickness PE film bags and 0.04 mm thickness PVC film bags for modified atmosphere packaging, and the O₂ and CO₂ concentrations in bags played a main role, and when maintained O₂ at 14.5% to 17.0% and CO₂ at 2.5% to 3.0% had a good preservation effect. Ethylene concentration showed less effect on the preservation of ‘Korla Xiangli’ pear.

Key words: ‘Korla Xiangli&rsquo, pear, modified atmosphere packaging, postharvest physiology, quality maintenance, green keeping