The Study Of Technology And Mechanism Of Hypobaric Storage On Peach And Pear Fruit After Harvest

Fresh fruits easily senesce and deteriorate after harvest, which reduces their commercial values and results in huge economic losses every year. Therefore, an effective preservation technology for fruits is urgently needed.Hypobaric storage is an innovative food preservation technology that stores fruits and vegetables bellow ambient air pressure. This technology has demonstrated to significantly inhibit postharvest senescence and quality deterioration, thus extends the shelf life of various fruits and vegetables. Hypobaric storage is regarded as an emerging food storage technology in the21st century because of its advanced theoretical and technological characteristics. However, the role of hypobaric storage in senescence and quality deterioration of postharvest fruits is still unclear. Particularly, there is little information of energy production and metabolism in relation to biochemical and physiological activities in fruits during hypobaric storage. This paper studied the influence of hypobaric storage on postharvest physiology and quality of peach and pear. The main studies and results are reported as following:1. Hypobaric storage combined with pre-1-MCP for’Cuiguan’pear was studied. The combination significantly slowed down respiratory and ethylene production rates, inhibited the decreases of fruit firmness, soluble sugar, titratable acids and Vitamin C contents, maintained higher SOD and CAT activities, reduced the accumulation of active oxygen, delayed the increase of membrane osmolarity, and retarded occurrence of senescence and decay. After storage of60d, fresh fruits remained89.1%firmness, had better mouth feel and taste, and no browning flesh was observed.2. The effects of programmable pressures in hypobaric storage on the physiological and biological characteristics of’Cuiguan’pears were compared to cold storage in air. The vacuum pressure was programmable-controlled from5KPa to100KPa. Changes in fruits decay rate, quality parameters, and respiration and ethylene production rates were monitored during storage. Programmed hypobaric storage significantly slowed the rates of respiration and ethylene production, inhibited softening, slowed the Vitamin C loss, and maintained soluble solid contents. Programmed hypobaric storage extended the shelf-life of pears up to60days.3. The effects of hypobaric storage under ultra-low pressure on the physiological and biological characteristics of’Cuiguan’ pear fruits were studied. Ultra-low pressure was controlled at500±100Pa. The results indicated that hypobaric storage under ultra-low pressure did not only significantly slow down respiratory and ethylene production rates, but also inhibited the decreases of fruit firmness, TSS, titratable acids and Vitamin C contents. The hypobaric storage under ultra-low pressure could maintain higher SOD activities, delay the increase of membrane osmolarity, and retard occurrence of senescence and decay. Therefore, the hypobaric storage under ultra-low pressure is expected to be the future of fruit and vegetable preservation technology.4. The changes of physiological and biochemical characteristics of juicy peach under various storage conditions were studied. Result showed that hypobaric storage, controlled atmosphere and1-MCP slowed down markedly respiratory rate and Vitamin C loss rate of peach, and inhibited the decrease of fruit firmness and soluble sugar. All three methods also significantly reduced the browning rate of juicy peach. However, hypobaric storage was better in preserving the quality of peaches than other two methods during long time storage.5. The changes of physiological and biochemical characteristics of juicy peach in different degree of ripening were studied. Hypobaric storage did not only significantly slow down respiratory and ethylene production rates, but also inhibited the decreases of fruit firmness, L*, titratable acids and Vitamin C contents of highly ripened peaches. Hypobaric storage maintained the stability of membrane system, and retarded occurrence of senescence and decay. For low maturity peach fruits, their gradually ripening and softening happened during hypobaric storage and their normal respiration was also observed.6. The effects of hypobaric storage under different pressures on the energy metabolism of juicy peach fruit were studied. The pressures were controlled at10±5KPa and80±5KPa, respectively. Samples stored at ambient air were used as controls. The results indicated that hypobaric storage did not only maintain significantly higher H+-ATPase, Ca2+-ATPase, SDH and CCO activities than controls, but also inhibited the decreases of contents of ATP and energy charge level. Hypobaric storage under10±5KPa pressure was more effective to maintain energy level and the activities of mitochondria respiratory metabolism-related enzyme than ambient air storage. These results suggest that the benefits of hypobaric storage are associated with energy metabolism.7. The effects of hypobaric storage under different pressures on the respiration pathway and active oxygen metabolism of juicy peach fruit were studied. The pressures were controlled at10±5KPa and80±5KPa, respectively. Samples stored at ambient air were used as controls. The results indicated that the contribution of alternate oxidation pathway to the total respiration increased during hypobaric storage. Hypobaric storage maintained higher APX activities, reduced the accumulation of active oxygen, maintained the stability of membrane system, and retarded occurrence of internal browning. It is concluded that the hypobaric storage is an effective method of prolonging the postharvest life of juicy peach fruit, and the benefits of hypobaric storage are associated with active oxygen metabolism.All data from these studies demonstrate that hypobaric storage significantly delayed decay rates and maintained overall quality thereby extended the shelf life of peach and pear fruits. The role of hypobaric treatment in delaying senescence may be due to its abilities to maintain normal energy metabolism of mitochondria, enhance the contribution of the alternate oxidation pathway to the total respiration, increase antioxidant activity, decrease ROS accumulation, and maintain membrane integrity. Application of hypobaric storage technology in fresh fruit and vegetable preservation offers unique advantages over other technologies. Further optimization to improve hypobaric storage may be needed for future commercial applications.