Studies On Post-harvest Browning Physiology And Combating Browning Of Yali Pear Fruit And Whangkeumbae Fruit

The physiological changes of Yali pear (bagged fruit and unbagged fruit) and Whangkeumbae, especially browning index, polyphenol content, polyphenoloxidase (PPO) and membrane lipid's peroxidation, had been studied as fruit stored at room and low temperature, explaining the relationship between physiological changes and browning, and studying the control of browning cores of Yali pear by two treatments with bagging and salicylic acid (SA). Furthormore, the study on this respect could provide a theoretical basis for ripening control, quality improvement and extension of storage life. The main results were as follows:1 The result suggested that low temperature and bagging could inhabit and postpone the appearance of browning. The fruit core appear more sever browning than fruit flesh, and Yali pear appear more obvious browning than Whangkeumbae.2 The browning of Yali pear appear carpel at first, and then appear core and flesh. During storage period, the PPO activity and the content of polyphenols in Yali pear and Whangkeumbae in that core was higher than that in flesh.3 Low temperature and bagging could inhabited PPO activity and Polyphenols content decreased of Yali pear and Whangkeumbae significantly. PPO activity and polyphenols content of post-harvest fruit flesh were lower than fruit core obviousy. The result suggested bagging and low temperature could delay senescence of the fruit and browning had been prevented.4 During the post-harvest storage period of Yali pear and Whangkeumbae, the relative electric conductivity had increased, and accumulated a large quantity of malonaldehyde (MDA), especially fruit core. The contents of MDA were little at low temperature than at room, and so did relative electric conductivity. The result suggested the membrane system had been protected at low temperature and browning had been prevented.5 The activity of SOD and POD of fruit core and that at room temperature was lower than that of fruit flesh and that at low temperature in Yali pear and Whangkeumbae, and the activity of SOD and POD of fruit core decreased quicker than that of fruit flesh. The activity of SOD and POD of fruit core and flesh of Whangkeumbae was lower than that of Yali pear, and the activity of SOD and POD of bagging yali pear was higher than that of unbagging Yali pear. The result showed fruitcore was easier to appear browning than fruit flesh, and browning of Yali pear was more obvious than of Whangkeumbae, and low temperature and bagging were two methods to delay senescence of the fruit and prevent browning.6 Treating the Yali pear with different concentration (0.002mmolL"1~0.2 mmolL1) of SA solution showed that SA could inhibit rotten rate and browning of fruit. And could inhibit PPO activity and polyphenols to be composed apparently. PPO activity in fruits discs increased gradually. 0.2mmoM/'concentration was the best choice to prolong the storage period.7 Treating Yali pear with different concentration (0.002mrnolL"I~0.2mmolL"1) of SA solution showed that 0.2 mmol-L"1 concentration could increase the SODn POD activity and inhabit the content of O2: obviously. The treatment of 0.002mmol-L~' concentration could inhabit MDA activity and membrane permeability, and could delay senescence of the fruit. The result suggested that could delay senescence of the fruit and browning had been prevented.