Abstract:

In this study, after 30 minutes of thermal treatment at 50 ℃, freshly harvested Jiefangzhong loquats from Putian, Fujian province were divided into cold storage (2－5 ℃) and normal temperature storage (18 －25 ℃). The changes in lignin content, fruit hardness and the activities of polyphenol oxidase (PPO), phenylalanine ammonia-lyase (PAL), cinnamyl alcohol dehydrogenase (CAD) and peroxidase (POD) were tracked at 7-day storage intervals for providing experimental evidence for dealing with the effect of prestorage treatment on lignification and the activities of these enzymes related to lignification in refrigerated loquats. During cold storage, the firmness and PAL activity in loquats were both obviously elevated and a positive correlation between the two parameters was observed, with a correlation coefficient of 0.914. Prestorage thermal treatment could delay increases in lignin content and hardness and reduce the activities of PPO, PAL, CAD and POD. Combination of Prestorage thermal treatment with low temperature storage appears to provide an effective approach for delaying lignification of loquat fruits and prolonging their storage life.

Key words: loquat, lignification, polyphenol oxidase, phenylalanine ammonia-lyase, cinnamyl alcohol dehydrogenase, peroxidase