Study On The Postharvest Physiology And Storage Property Of Walnut Fruit

Fresh walnut is wellcomed by a number of consumers because of its rich nutritionalvalue, health care role and a unique flavor. However，the technology of fresh walnutstorage has not been settled.Maturities and varieties influence the storability of fruitgreatly. In this study, fruit of different walnut varieties of Zhonglin5(Early maturingvarieties), Liaoning4(Mid-maturing varieties) were harvested on three date，i.e.Ⅰ(August3), II (August15) and III (August26), and fruit of Xifu1late-maturing varieties) were also picked on date III. Fruit were then storage under0to1℃,RH70%to80%during storage to invesgate the effects of different MaturityDegree and varieties on qualitative and Physiological attributes of flesh walnut fruit. Inorder to provide a new simple effective technology for fresh walnut storage，the effect ofmodified atmosphere package on refrigerated storage of the fruit was researched. Theresult showed that:The results showed that the walnut as a climacteric fruit had two obviously peak ofrestiration rate. The peak of restiration rate of different varties appeared almost at thesame time in one harvest maturity. The respiratory peak of each mature degree wasappeared at the same time. The two breathing peak (6d,33d)of harvest stage II wasappeared earlier and higher than the other two harvest period (the sameas6d42d); and the breathing peak of Zhonglin5was higher than the Liaoning4significantly. SSC showed climacteric changes. They increased in the formal anddecreased in the latter. The peak of harvest stage II is lower than the other two harvestperiod significantly. The SSC of Zhonglin5and xifu1were higher than Liaoning4significantly in harvest stage III，The weight loss rate and decay rate of different maturedegree were investigated, the results show that: Each harvest of fresh fruit water lossrate and decay rate difference was very significant. The effect of preservation followedthe sequence: harvest stage Ⅰ best,harvest stage III, followed by harvest stage the worst.The water-retention capacity of Zhonglin5was the best， it had the lowest decay rate at the same time,Liaoning4was the worst.The dynamic analysis results Peel cell wall enzymes (cellulase,pectinase, pectinesterase) showed that: the activity of three enzymes howed climactericchanges. They increased in the formal and decreased in the latter, the peak of harvestperiod II earliest and significantly higher than the other two harvest time; The firsttwo harvest period, the three enzyme activities of zhonglin5were significantly lower than ofLiaoning4significantly.The Determination of Peel antioxidants and antioxidant capacity (total phenoliccontent, flavonoid content, total antioxidant capacity of SOD, CAT and POD) showed thatthe antioxidant capacity of the harvest time I was significantly higher than theother two harvest period. Harvest stage III antioxidant capacity was significantly higher thanthe harvest period II, the harvest stage II prone to browning, intolerance storage.The antioxidant capacity of Zhonglin5was significantly higher than the other two varties，Liaoning4is weakest.The first two harvest period showed that lipoxygenase and lipase activity wassignificantly higher than average harvest stage III of Lipoxygenase. The determinationof fruits’ iodine value, acid value and the soluble protein content showed that: the qualityof deterioration harvest stage II was significantly higher than the other two harvest period.The modified atmosphere package could induce the Respiratory instensity and ethyleneproduction. The modified atmosphere and water-retention capacity of is Thk-PE is superiorto other packaging, and it reduced decaying index index effectively. At the end of storage,the gas composition of packaging were10.1%to13.0%O2,4.3%to6.5%CO2. This can be regarded as the walnut fruit suitable for modified atmosphere storageconditions, and can be seen the walnut fruit could resistant to at least about5%CO2.In production, it can be recommended that the harvest stage III can be as standard, Xi1is the best available, thk-PE packagingcan be used, or can be controlled atmosphere storage,CO2concentration lies in the upper and lower5%;when the decay index is about70%, in atimely mannerpeeling continue to bare fruit fresh walnut storage method orsales.