Study On Post-harvest Physiology And Storage Character Of Pears

This research takes the Heilongjiang province cold region pear ('520','Wanxiang', 'Dongmi') as experiment materials. It respectively studied on:(1)postharvest physiology and storage character of pears under different cold and MA storage conditions.(2)effect of frozen-thawing processing in postharvest storage quality of pear. The main research content and results were as follow:1. The study on the respiration of pears in normal temperature show that it had the obvious respiration peak, and pears were typical climacteric fruit. Different cold and MA storage conditions could restrain the respiration incoordinately, and delay the maturity and senescence.2.During the storage, the content of soluble solids, sugar, MDA, total phenols and PPO activity appeared up-trend first and down-trend late; the firmness and the content of pigments, titratable acid, Vc appeared gradually descend trend; the relative electric conductivity rate appeared gradually up-trend.3.To determine the appearance quality (firmness, pigments) of pear indicated: it was obviously effect on delaying softening and the fruits remaining green in cold temperature, and cold temperature with PE freshness protection package showed positive promotion effects. To determine the nutritional quality (sugar, titratable acid, Vc) of pear indicates:to compare with normal temperature, there was a abviously effect on keeping the content of sugar, acid,et al with the combination processing of 0℃and PE freshness protection package.4. The MDA content is negatively correlated with the hardness; and positively correlated with the relative electric conductivity rate, the relations of above three indexs respond the intact degree of fruit cell structure. The PPO activity is positively correlated with total phenols content, all above are the essential conditions that the enzymatic browning of fruit will occur, and conclusion that in certain temperature extent, the lower temperature is combined with PE film packing which puts up excellent effects on inhibiting softening of fruits.5.The most proper storage temperature of pear is 0℃, the sensory and nutritional quality of the pear can maintain successfully at this temperature, and it's obviously suppressed the maturity and senescence of the peat. In the meantime, the processing of suitable low temperature combined with 0.02 mmPE film packing make the effect of storage more excellent.6.The frozen storage of pear is belonged to one of the postharveat storage methods, it is 'Dongli', it's also a special features fresh fruit in the northern of China. The result of frozen-thawing processing experiment showed: to store 'Dongmi' at room temperature for 7 days ripening, and then put them around -24℃, nextly, put the frozen pear in microwave to defrost the center temperature to -2℃.There is a less loss of nutrition quality in this method, in the mean time, both the edible and the appearance quality are keeping good...