Studies On The Relationship Between Senescence And Browning Of Kuerle Fragrant Pear

The physiological changes of Kuerle Fragrant pear (Pyrus bretcheideri Rehd.) had been studied as fruit stored at room and low temperature, explaining the relationship between physiological changes and browning and looking for the optimum stored condition, in order to provide the theoretical fundamentals for controlling pear post-harvest browning and elongating the post-harvest storage time.The activity of PPO increased during storage period and dropped in later period. The activity of PPO at room temperature increased quicker than at low temperature. The content of polyphenols decreased quicker at room temperature. The result suggested that low temperature could postpone the appearance of browning.The superoxielation and phase of the membrane of the cells of the fruits had increased during storage period, advancing the appearance of browning. The activities of superoride dismutase (SOD) and the catalase (CAT) decreased made the membrane-lipid peroxided and accumulated a large quantity of malonaldehyde (MDA) which enhance the membrane-lipid peroxidation. It damaged the membrane system and destroyed the compartment of polyphenols and PPO, and the browning of the fruits developed.The ethylene climax was later than the appearance of maximum lipoxgyenase (LOX) activity. LOX advanced the senescence of the fruits.With pear fruits being dipped in CaC^ solution and CA storage delayed fruit softening significantly and inhibited the surperoxidation and phase of the membrane of the cells of the fruits, to prevent the appearance of browning. The calcium solution was higher, and the effect of storage was better. The combination of 5-8%02, <6%CO2 was recommended CA storage conditions for Kuerle Fragrant pear.