Study On Postharvest Quality Deterioration And Hypobaric Storage Technology Of Loquat Fruit

Loquat is one of the most important fruit grown in Zhejiang province of China. Because of its unique eating quality such as softness, juicy taste and nutritional value, loquat is highly welcomed by consumers. However, loquat is harvested at hot raining season and susceptible to deterioration, mechanical damage, moisture and nutritional losses after harvested, leading to the short storage life and market limit at ambient temperature. Low temperature storage is effective in inhibiting loquat fruit decay and reducing moisture and nutritional losses. However, loquat fruit easily developed some physiological disorders including stuck peel, firm and juiceless flesh, and internal browning, which were collectively referred to flesh leatheriness and thought as chilling disorders. Hypobaric storage has been shown to significantly inhibit postharvest ripening and senescence, thus extending shelf life in various fruits and vegetables. However, there is very few published data about the effect of hypobaric storage on loquat fruit. Thus, in this study, effects of hypobaric storage technique on physiology and quality of loquat fruit were investigated.Loquat fruit were stored both at 10℃and 0℃temperatures and the changes in physiology and biochemistry were measured. The results showed that soluble sugar, titratable acid and vitamine C contents decreased rapidly after harvest. During postharvest senescence, the consumption of nutrients caused by respiration made the fruit lose their unique flavor. Meanwhile, flesh browning happened due to the damage of cell membrane and subsequently the contact of PPO and polyphenolic compounds. During cold storage at 0℃, the fruit firmness increased gradually, activities of PE and PG and water-soluble pectin content declined while contents of protopectin and lignin, and PAL activity increased. When fruits were stored at 10℃, little decrease in fruit firmness was detected, PE and PG activites and water-soluble pectin content were higher than those of the fruits stored at 0℃, PAL activity decreased steadily, and flesh woodiness did not appear.The effect of hypobaric storage under different pressures on the physiological and quality characteristics of loquat fruit were studied at low temperature storage. The pressures were controlled at 20±5kPa,90±5kPa, respectively, and air storage was used as control. Changes in browning index, rates of respiration and ethylene production, fruit firmness, extractable juice rate, and enzyme activities that related to flesh quality were measured during storage. The results indicated that hypobaric storage not only significantly slowed down respiratory and ethylene production rates, but also inhibited the decrease of contents of soluble sugar, titratable acids and Vitamin C. Furthermore, hypobaric storage inhibited the increase of PAL activity, delayed the increases of flesh firmness and lignin content, inhibited the decrease of extractable juice rate, thereby maintaining good eating quality and extending the storage life of cold-stored loquat fruit. Hypobaric storage under 20±5kPa pressure could extend the storage life up to 35 days. It is concluded that the hypobaric storage is an effective method of extending the postharvest life of loquat fruit.