采后“乌叶”和“兰竹”荔枝果实果皮褐变的差异性研究

The Difference in Pericarp Browning between Harvested ‘Wuye’ and ‘Lanzhu’ Litchis

摘要:

果皮褐变是影响采后荔枝果实品质和货架期最重要的因素。本文比较研究了在（8±1） ℃贮藏条件下“乌叶”和“兰竹”荔枝果实果皮褐变的差异性及其与酚类物质代谢的关系。结果表明：与“兰竹”荔枝果实相比，采后“乌叶”荔枝果实较不容易发生果皮褐变，贮藏期间，“乌叶”荔枝果实的果皮褐变指数显著低于“兰竹”；“乌叶”荔枝果实的果皮花色素苷、类黄酮和总酚含量高于“兰竹”，而多酚氧化酶（PPO）和过氧化物酶（POD）活性则低于“兰竹”。贮藏期间，荔枝果皮的花色素苷、总酚、类黄酮含量和PPO活性不断下降，而POD活性则不断上升，但在同一贮藏期间，“乌叶”荔枝果皮的花色素苷、总酚、类黄酮含量都高于“兰竹”，而PPO和POD活性则低于“兰竹”。据此认为，采后“乌叶”荔枝果实较不容易发生果皮褐变与其保持较低的果皮PPO和POD活性而减少果皮花色素苷、总酚和类黄酮含量的下降有关。

Abstract:

Harvested litchi (Litchi chinensis Sonn.) fruit is susceptible to pericarp browning, which is the most important factor affecting the quality and shelf-life of this fruit. The difference in the pericarp browning between harvested ‘Wuye’ and ‘Lanzhu’ litchis was investigated during storage at 8 ± 1℃ in relation to phenolics metabolism . The results showed that as compared with ‘Lanzhu’ litchis, ‘Wuye’ litchis tended to be less susceptible to pericarp browning, and the browning index in the pericarp of ‘Wuye’ litchis during storage was remarkably lower than that of ‘Lanzhu’ litchis. There were higher contents of anthocyanin, total phenolics, and flavonoid in the pericarp of harvested ‘Wuye’ litchis than those of ‘Lanzhu’ litchis, whereas the activities of polyphenol oxidase (PPO) and peroxidase (POD) were lower as compared with ‘Lanzhu’ litchis. During storage, the contents of anthocyanin, total phenolics, and flavonoid as well as PPO activity in the pericarp of harvested ‘Wuye’ litchis and ‘Lanzhu’ litchis decreased continuously, while POD activity showed a continuous increase. However, during the same storage time, there were higher contents of anthocyanin, total phenolics, and flavonoid as well as lower activities of PPO and POD in the pericarp of ‘Wuye’ litchis than those in ‘Lanzhu’ litchis. From the results, it can be concluded that, ‘Wuye’ litchis tend to be less susceptible to pericarp browning, which is related to low PPO activity and decrease in anthocyanin, total phenolics, and flavonoid contents.