Study On The Browning Enzymes And Substrates Of Fresh-cut Potato

Fresh-cut fruits and vegetables, characterized by freshness, convenience, and health, have been more and more important in the fruit and vegetable market supply. Commercial value of fresh-cut fruits and vegetables will be reduced because of browning caused by mechanical processing. This topic will study the comparison of browning related enzymes activity and substrate which is different varieties potatoes, inhibition browning group and contol group of potatoes. Browning mechanisms of fresh-cut potatoes were discussed. The main results showed as follows:1. The browning speed, water loss and comprehensive sensory quality in two species fresh-cut potatoes were significantly different. Kexin No. 4 appeared slight browning after cutted one hour and the browning became obvious after 4 hour, while Kexin No. 13 kept a good colour retention when cutted 12 hour and turned slight browning after 2 days later. The juice colour in two species were close in initially and significantly different after 25 min, showing more serious browning in Kexin No. 4 compared to Kexin No. 13. Generally water loss was lower in the fresh-cut Kexin No. 13 than Kexin No. 4. Compared to the control group, the a* value and b* value was lower and browning was slighter in the callus treatment. The significantly different browning degree between two species and callus treatmen helped future research on the mechanism of browning.2. Browning of potatoes may be related with PPO activity after cutted. The test results showed that treatment group of serious browning, PPO activity was high. During storage after cutted, The PPO activity of Kexin No.4 was always higher than Kexin No.13. Freshly harvested Netherlands No.15 after curing, PPO activity was lower than control group generally. The tyrosinase activity of Kexin No.4 was higher than Kexin No.13. The POD activity of Kexin No.13 was higher than Kexin No.4, but the control and the curing treatment were not significantly different. The PAL activities of Kexin No.4 and No.13 were not significantly different, the PAL activities of the control and the curing treatment were not significantly different.3. Enzymatic browning substrates may be protocatechuic acid rather than chlorogenic acid, which related with antioxidant ability of tissue. Chlorogenic acid of Kexin No.4 which is easily browning is lower than Kexin No.13 during storage time, protocatechuic acid and total phenolic content is higher than Kexin No.13, antioxidative value is lower than Kexin No.13.