Ya pear fruits were treated with slow cooling and rapid cooling. brown index, activities of SOD, POD and CAT, MDA level and endomembrane microviscosity of the core tissue were investigated. The results showed that rapid cooling induced the browning of the fruits and the brown index reached 100% after 60 days storage. Activities of SOD, POD, CAT were decreased notably and MDA level and endomembrane microviscosity increased sharply by the treatment. The fruits under slow cooling treatment did not show any inc...