The Study And Application On Technqiues Of Maintaining Freshness Of Grape And Melon In Xinjiang

In chapter one, the domestic and foreign development in maintaining fruit fresh was reviewed, the investigations in controlling postharvest decay of grape and melon were summed up and applications of ClO2 in sterilizing and inhibiting microorganism were introduced. The contents of the following researches were proposed based on the review.In chapter two, in order to protect grape from bleaching caused by SO2 generator on sale, a reagent to absorb excessive SO2 was selected. And then, a new grape preservative was prepared by packaging the reagent and original long-term SO2 generator in proportion. Some factors which influence SO2 generating, including temperature and dose of the new grape preservative, were investigated by comparing with original long-term SO2 generator. Besides, the accumulation of SO2 on grape was investigated. The results indicated that the new grape preservative could reduce excessive accumulation of SO2 on grape and avoid bleach of grape caused by excessive SO2 in the storage.In chapter three, two additives were selected to control the releasing velocity of ClO2 generator. Of which, the active reagent can make ClO2 generator produce ClO2 gas in low temperature, and the passivator can make ClO2 liberated slowly in high temperature. Therefore, improved ClO2 generators can produce ClO2 properly in ambient and low temperature, and provide the needed concentration of ClO2 for maintaining freshness of fruit in transportation and storage. The effect of relative humidity on ClO2 generating was also investigated.In chapter four, seven postharvest decay--causing fungi of grape and melon were isolated, purified and inhibited, respectively. The results indicated that ClO2 was more effective than 6-Hβacid or 4-Hαacid. The effect of temperature on ClO2 preservative against the seven fungi and the effect of ClO2 preservative on the growth of seven fungi seeded on the melon were evaluated. The results indicated that ClO2 preservative could prevent growth of the seven fungi in different temperature, as well as those seeded on the melon effectively.In chapter five, the new grape preservative was applied to store Hongti grape. The results indicated that the treated grapes were good in quality and kept normal general appearance and their original organoleptic after three months storage at 0-2℃. And the new ClO2 preservative was applied to keep grape and melon fresh in storage at 1-2℃. After three months, both Jiashi and New Queen melons kept good quality, normal general appearance and original organoleptic too.