The comparison of storage ability of ‘Yali' pear in different soluble solids contents grades

Abstract:【Objective】‘Yali'pear (Pyrus bretschneideri Rehd.) is one of the traditional pear cultivar in China, quality of‘Yali'pear could be maintained for almost 6-8 months under optimal storage conditions, but the fruit were very sensitive to carbon dioxide and low temperature, which caused core and flesh browning during long period storage, and caused a huge economic loss to commercial companies.And the susceptibility of pear to browning depends a lot on fruit internal quality, the fruits harvested in different area and orchards had a totally different susceptibility on browning, and the browning incidence was different in different year based on climatic conditions. Besides that, the individual fruit internal quality was different from one to another, and led to a different browning sensitivity. Due to the complicated preharvest factors, it is difficult to make the direct relationship between preharvest quality and post-harvest disorder. Sugar is one important major nutrition compounds in fruits, which afford the necessary energy to fruits during storage. In this study, in order to better understanding the effects offruit sugar and some other preharvest quality characters on the fruit post-harvest storage ability and the disorder, illuminating the direct relationship of internal quality and browning disorder of‘Yali'pear, and providing scientific basis for controlling and predicting browning disorder technique, the fruits were classified to different groups based on soluble solids contents using non-destructive detection technique, and the relationships of browning disorder and internal quality during long period storage were investigated.【Methods】According the non-destructive detect results, the fruits were divided into SSC＜ 10.0%, SSC 10.0%-10.9%, SSC 11.0%-11.9% and SSC≥ 12.0% four different groups according to the soluble solids contents, which were taken as a key factor of internal quality, by non- destructive sugar tester (SACMI, Italy) based on the NIR reflectance spectroscopy, and then the fruits were placed into a storage room kept at 8 ℃, and the temperature was decreased by 1 ℃ for every 3 days until the temperature was reduced to -0.5 ℃, and the relative humidity was maintained at 85.0%-90.0%. The fruits were sampled after storage for 4, 6 and 8 months and under shelf (20 ℃) for 10 days, the core browning and superficial scald incidence were studied, and changes of fruit color, firmness, soluble solids contents, titration acid, ascorbic acid, respiration intensity and ethylene production of different SSC groups were determined, and the correlations between them were analyzed.【Results】The different SSC groups showed significantly differences in browning disorders incidence during the long periods storage (> 6 months), the higher SSC content, the lower core browning incidence, and showed a significantly negative correlation (p ＜ 0.05); SSC＜9.0% groups showed a higher superficial scalds incidence than SSC 10.0%-10.9%, SSC 11.0%-11.9% and SSC≥ 12.0% groups, but the superficial scald incidence did not have a obvious correlation with SSC grades; at the meanwhile, there were positive correlation among titratable acid and ascorbic acid with SSC grades, and with the increase of storage time and shelf life, the core browning index increased rapidly, and the content of titration acid (TA) and ascorbic acid (AA) in fruit decreased significantly, compared with the harvest date, the average content of TA and AA declined by 45.32% and 49.96%, 51.46% and 54.43%, 53.80% and 68.34% after storage for 4, 6 and 8 months respectively, and showed a further decline during shelf-life period; in addition, the respiration intensity and ethylene production in different SSC groups showed significantly difference during long-periods storage, especially after storage for 8 months, SSC≥ 12.0% groups showed a significantly higher respiration intensity than other groups, and maintain relative stabilization during the whole shelf periods, the average respiration rate and ethylene release rate were followed by the order of (SSC≥ 12.0%)> (SSC 11.0%-11.9%)>(SSC 10.0%-10.9%)>(SSC＜10.0%).【Conclusion】The higher soluble solids contents in‘Yali’pear could significantly reduce the core browning incidence in long-periods storage, they have a significantly negative correlation; besides that, the fruits weight, TA, AA and respiration and ethylene rate were all significantly correlated with core browning, which may be made as important prediction and controlling characters of core browning incidence in‘Yali’pear.