Effects of hot water treatments on chilling tolerance of harvested bitter melon

It is important to enhance the chilling tolerance of harvested bitter melon for the extension of storage life. Harvested bitter melons were immersed in hot water of 38℃ for 10 min, 42℃ for 5 min or 50℃ for 1 min, respectively, then packaged with commercial polyethylene film bags, and stored at 4℃ for 16 days. The treatment of 42℃ for 5 min exhibited the best sensory quality without obvious chilling injury, with the lowest membrane leakage, and both the decline of catalase activity and the increase of peroxidase activity were suppressed markedly. However, the treatment of 50℃ for 1 min resulted in serious chilling injury, increased membrane leakage, rapid decrease of catalase activity and obvious increase of peroxidase activity. The changes in those indexes of the treatment of 38℃ for 10 min were between those of the treatment of 42℃ for 5 min and the treatment of 50℃ for 1 min. The results showed that appropriate heat treatment could effectively enhance the chilling tolerance, and prolong the storage life of bitter melon stored at lower temperature.