Study On Postharvest Quality Deterioration And Hypobaric Storage Technology Of Cuiguan Pears

Cuiguan pear is the most important pear cultivar grown in Zhejiang province of China. Because of its unique eating quality that is superior to the most other available pear cultivars, Cuiguan pear is highly welcomed by consumers. However, Cuiguan pear is harvested at hot raining season and is susceptible to deterioration after harvest. The fruit will rapidly lost their market value, limiting the storage life about 2～3 weeks under common cold storage conditions. Hypobaric storage has been shown to significantly inhibit postharvest ripening and senescence, thus extending shelf life in various fruits and vegetables. However, there is no published data about the effect of hypobaric storage on Cuiguan pear. In order to overcome the defects of common cold storage, the authors came up with the idea of applying hypobaric storage technique in maintaining postharvest quality of Cuiguan pear.The physiological and quality changes of Cuiguan pear stored both at room and low temperature were investigated. The results showed that soluble sugar, titratable acid and vitamine C contents decreased rapidly after harvest, which indicated that quality deterioration in Cuiguan pear was a senescence process and closely related to nutrients loss. During postharvest senescence, the consumption of nutrients caused by respiration made the fruit lose their unique flavor. Meanwhile, the accumulation of active oxygen species due to inefficient scavenging capacity of SOD, CAT, POD resulted in damage of cell construction, which in turn promoted the senescence process mainly manifested as fruit softening and the formation of off-flavor. The deconstruction of cell membrane also provided the contact of PPO and polyphenolic compounds leading to flesh browning. The production of ethylene stimulated fruit respiration. Low temperature significantly inhibited fruit senescence process, therefore refrigeration is a key to postharvest storage of Cuiguan pear.The effect of hypobaric storage under different pressures on the physiological and quality characteristics of Cuiguan pear were studied as compared with the cold storage group. The pressures were controlled at 10±5kPa(A), 50±5kPa(B), 90±5kPa(C), respectively with air storage as control. Changes in fruit antioxidant enzyme activities, quality parameters, respiration and ethylene production rates were monitored during storage. The results indicated that hypobaric storage not only significantly (p≤0.05) slowed down respiratory and ethylene production rates, but also inhibited the decreases of fruit firmness, soluble sugar, titratable acids and Vitamin C contents. Hypobaric storage could maintain higher SOD, CAT and POD activities, reduced the accumulation of active oxygen species, maintained the stability of membrane system, and retarded occurrence of senescence and decay. Hypobaric storage under 10±5kPa pressure could extend the storage life up to 60 days. It is concluded that the hypobaric storage is an effective method of prolonging the postharvest life of Cuiguan pear.