Combined treatment of heat shock and low temperature conditioning reduces chilling injury in zucchini squash

Abstract

The severity of chilling injury in zucchini squash stored at 5°C and then transferred to 20°C was reduced by a prestorage treatment with hot water of 42°C for 30 min. The chilling injury was further reduced when zucchini squash were preconditioned at 15°C for 2 days after hot water treatment but before the 5°C storage. Zucchini squash stored at 15°C did not develop any symptoms of chilling injury. However, weight loss was most severe in zucchini squash stored at 15°C. Squash kept at 5°C had the least weight loss during the 2-week storage. Weight losses were comparable in squash treated and not treated with hot water. Analysis of polyamines in zucchini squash showed that putrescine increased with time during storage at 5°C. The putrescine level in hot water treated samples was low initially but increased rapidly during storage at 50C. Temperature conditioned squash showed a similar rate of increase in putrescine as those treated with hot water. Spermidine and spermine levels decreased in all samples during storage at 5°C. However, temperature conditioning as well as hot water treatments maintained higher levels of spermidine and spermine in the skin of zucchini squash.