不同荔枝品种采后果皮褐变与多酚氧化酶关系的研究

Relation between Polyphenol Oxidase and Postharvest Pericarp Browning in Different Litchi Cultivars

以无核荔枝、妃子笑、紫娘喜3个荔枝品种为试材,研究了不同耐贮性荔枝品种果实采后果皮多酚氧化酶活性与果皮褐变之间的关系,结果表明,在相同贮藏阶段,3个荔枝品种中无核荔枝褐变指数最高,妃子笑次之,紫娘喜最低。不同处理条件下妃子笑、紫娘喜果皮PPO酶活性均呈先上升后下降的趋势,常温贮藏时无核荔枝果皮PPO活性逐渐下降,低温贮藏则先下降后上升再下降。果实贮藏前期,PPO结合酶、游离酶与总酶活性以无核荔枝最高,妃子笑次之,紫娘喜最低。新采收果实中,紫娘喜果皮PPO同工酶仅2条带,妃子笑3条,而无核荔枝有4条。不同处理对同工酶带数无影响,但低温减少了无核荔枝某些阶段果皮PPO同工酶带数。不同品种荔枝果皮褐变进程差异与果实贮藏前期果皮PPO酶活性差异及同工酶带数有关。

The relationship between pericarp browning and polyphenol oxidase （PPO） activity among postharvest fruits of ‘Feizixiao＇, ‘Ziniangxi＇ and ‘Wuhe＇, with different storability, were investigated in this paper. The results indicated that ‘Ziniangxi＇ was the strongest storability cuhivar and ＇Feizixiao＇ followed. During postharvest storage, PPO activity increased firstly and then decreased in pericarp of ‘Feizixiao＇ and ‘Ziniangxi＇ no matter which treatment conducted, while adverse trend at low temperature in pericarp of ‘Wuhe＇, of which PPO activity showed a decreasing trend at room temperature. During the early stage of postharvest storage, ‘Wuhe＇ and‘Ziniangxi＇ showed the highest and lowest PPO activity of free form, bound form and total enzyme, respectively. On the first day of postharvest fruits, there were four, three and two PPO bands of isoenzymes in pericarp of ‘Wuhe＇,‘Feizixiao＇ and ‘Ziniangxi＇, respectively. No effect was found on different treatments and numbers of isoenzymes in pericarp of ‘Feizixiao＇ and ‘Ziniangxi＇, however, the numbers of PPO isoenzyme declined in pericarp of ‘Wuhe＇ at low temperature. The results suggested that PPO and numbers of isoenzyme may contribute to the difference of postharvest browning process at early storage stage in pericarp.