Effects Of Hypobaric And Refrigerated Preservation On Postharvest Mango Fruit

The effects of different hypobaric conditions on the storage quality of postharvest mangos with Tainong No.1 were studied.The harvested mangos were stored under three different low pressures:10kPa,20kPa and 30 kPa for 12℃.The physicochemical properties of the mango were measured every 5 days.The effects of hypobaric storage on the storage quality and oxidation resistance of postharvest mangos were explored.The results showed that the hypobaric and refrigerated preservation technology can effectively slow down the reduction of titratable acid,Vc and soluble solids contents of the fruits;retain the hardness of mango,inhibit the yellowing of mango and increase membrane permeability.The comparison of the preservation effects of the three kinds of pressure showed that,the quality of mango stored under 10 kPa and 20 kPa were better than those stored under 30 kPa.The mango stored under 10 kPa showed better efficiency in keeping lower yellowing index and higher hardness while the mango stored under 20 kPa can efficiently sustain the Vc,organic acids and any other nutrients.In practical production,considering storage effect and costs,20 kPa pressure is relatively appropriate for the postharvest storage of mango.The hypobaric and refrigerated preservation technology increased the antioxidant activity of enzymes including peroxidase(POD),superoxide dismutase(SOD)and polyphenol oxidase(PPO).It also effectively prevented the oxidation reaction which is a causative agent of accelerated ripening and senescence of fruits.After the 20th day,the activity of superoxide dismutase(SOD)and peroxidase(POD)of group B were apparently higher than group A and group C.The PPO activity of mango peels in each group gradually increased,and starts diminishing after reaching its peak value.After the 15th day,the PPO activity of each group gradually diminishes,but the PPO activity of group B was apparently higher than group A and group C throughout.In addition,hypobaric and refrigerated preservation technology effectively decreased the content of LOX,CAT activity,MDA in the fruits.The significant delay in LOX activity and reduction in the membrane lipid peroxidation level of the experimental groups,contributed to the stability of cell membrane structure and extension of the storability of mango.Low pressure treatment delayed and reduced the growing peak of PG,alpha Gal,beta Gal and XYL enzyme activity.The trend showed rapid decline in the fruit hardness from the 15th day,and the increase in protopectin rapidly declined while soluble pectin rapidly increased from the 20th day.However,the pectin had no obvious change from the 25th day.The peak of the PG appeared on the 15th day from the changing tendency of the PG,alpha Gal,beta Gal and XYL enzyme activity,which may be a function of the PG resulting in the decomposition of pectin.It also showed that the softening of the fruit is related to the hydrolysis of the pectic substances caused by the rise of the PC activity.However,the peak of the alpha Gal,beta Gal and XYL enzyme activity appeared mainly on the 15th day,but the pectin had no obvious change,which depicts that the later softening of mango fruit was caused by the alpha Gal,beta Gal,XYL enzyme.