Balsam Pear Storage At Low Temperature And Research On Technology Of Cold Shock Treatment

Bitter melon (Momordica charantia), also known as Kam lychee, bitter gourd,which is native to tropical areas are now widely planted in South Asia, southeast Asia,China, and the Caribbean islands. Because the Bitter melon are mostly harvested inJuly and August, the hottest period of time during the whole year, the intensiverespiration metabolism of fruit under room temperature easily caused the fruit turnedbrown and rotten, losing the dietary value and commercial value in short time.Therefore, storing at lower temperature is important for keeping good quality ofBalsam pear. However, chilling injury occured when fruit were stored undertemperature below10℃. So in this experiment, we mainly studied the optimalstoring condition including temperature for Balsam pear and mechanism of coldshock treatment reducing chilling injury occuring. The results were as followed:1.Chunxiao Balsam pear were stored at temperature6℃,8℃,10℃and12℃.The variation tendency of physiological-biochemical characteristic and nutrientcontentsshowed that low temperature storage significantly inhibited respirationintensity of Balsam pear, reduction of both soluble solids and soluble proteincontent during the decomposition and consumption, and also significantly inhibitedthe degradation of chlorophyll in fruit. However, too low temperature caused chillinginjury of Balsam pear, and the low temperature of6℃and8℃abnormally elevatedfruit respiration intensity, increasing cell membrane permeability, leading tosymptoms of chilling injury such as depression, with particular spot on surface,resulting inlost of dietary value.2.The treatment group of0℃cold air processing1h,2h and3h、the treatmentgroup of5℃cold air processing6h,7h and8h and the controlled group were storedat6℃. Experimental results showed that the effects of the two treatment groups by0℃cold air processing for2h and5℃cold air processing for8h were the best, whichreduced the incidence of chilling injury, meanwhile and the rise in the cell membranepermeability,increasingfree amino acid accumulation in the organization, delaying therespiratory peak appearing, to some extent alleviated the Balsam pear chilling injury. 3.Chunxiao Bitter melon were treated with0℃cold air for1h,2h,3h,4h,5h,and5℃cold air for2h,4h,6h,8h,10h,12h respectively. Then we studied activeoxygen metabolism of the two treatment groups. Results showed that the cold shocktreatment rapidly increased the contents of superoxide anion (O2-．) and hydrogenperoxide (H2O2), at the same time the activity of oxygen removal enzyme, for instant,superoxide dismutase (SOD), peroxidase (POD) and catalase (CATwere increased,and relieved the decline of ascorbic acid peroxidase (APX) activity,which may be to astress reaction of low temperature.4.The treatment group of0℃cold air processing for2h、5℃cold airprocessing for8h and the control group were stored at6℃. Then we studied therelationship between active oxygen metabolism, cold resistance and chilling injury ofBalsam pear. Results showed that cold shock treatment at0℃for2h and5℃for8hsignificantly inhibited the production of superoxide anion (O2-．) and hydrogenperoxide (H2O2) in Balsam pear fruit during storage period at6℃, improving theactivity of the active oxygen removal enzyme_superoxide dismutase (SOD), catalase(CAT) and ascorbic acid peroxidase (APX), and increasing contents of endogenousantioxidants, total phenol and ascorbic acid during low temperature storage. Coldshock treatment at the same time also improved the activity of plant defence systemrelated to enzyme phenylalanine ammonia solution (PAL) and polyphenol oxidase(PPO).5.In conclusion, the mechanism of cold shock to reduce the occurring of Balsampear fruit chilling injury stored at low temperature were as followed:The brief rise ofthe active oxygen content of cold shock treated Balsam pear fruit would activateoxidation system of the Balsam pear fruits, which also increased the activity ofsuperoxide dismutase (SOD), catalase (CAT) and ascorbic acid peroxidase (APX),andcontents of endogenous antioxidants, total phenol and ascorbic acid during lowtemperature storage period; Cold shock treatment at the same time also improved theactivity of plant defence system related to enzyme phenylalanine ammonia solution(PAL) and polyphenol oxidase (PPO).To sum up, the goal of reducing Balsam pear fruits chilling injury during storage under low temperature could be achieved througha variety of ways.