Effect of different harvest maturity and cooling methods on POD activity and browning of Yali pear

The indexes of browning index,peroxidase( POD) and isozymes activity were determined,which was after the rapid and slow cooling treatment of different maturity of pears.The results showed that the POD isozymes activity of slow cooling treatment pear core was higher than that of rapid cooling at the same period. The change trend was opposite to pear core browning index trend.It was shown that the POD isozymes was closely related to the browning of pear core and slow cooling storage of pear could effectively inhibit browning.Meanwhile,the POD isozymes activity of mid- harvest pear was highest,early picking follows by,and late picking was the lowest. So different maturities were also the factors affected the browning of pear. Slow cooling in combination with mid-harvest pears could effectively inhibit browning.