采后红富士苹果色泽变化与氧化酶的关系

供试红富士苹果在贮藏初期(1-4周)果皮的花青苷含量有一个再合成过程,且这种合成过程无需光照条 件。不同的贮藏温度条件下花青苷合成发生时期不一样。20℃条件下,果皮花青苷含量第2周增加了31.2％。从第3 周开始,果皮的花青苷含量急剧下降;0℃条件下,果皮的花青苷含量第4周有增加达到最高峰。不同贮藏温度条件 下果实的花青苷的降解速度也存在较大差异,在高温(20℃)条件下贮藏,SOD活性变化与苹果果皮内花青苷含量的 变化相吻合,表明SOD可减缓苹果果皮内花青苷的降解。POD存在2种调控机制:在贮藏前期,果实具有较高的 POD活性,能够清除H2O2,起保护反应。贮藏后期POD活性高促进了果实的衰老。而低温(0℃)条件下贮藏,除SOD 酶在贮藏初期增加外,其他相关酶活性在贮藏后期均保持较低水平,变幅较小,果实的花青苷含量在整个贮藏期间 变化不显著。

Relationship between activity of some oxidases and coloration change in Red Fuji apples during postharvest storage

Results of storage of Red Fuji apples showed that there existed the re-synthesis of anthocyanin in the skin under no light condition at the initial stage of storage (from 1 to 4 weeks after postharvest) and the storage temperature also affected the process. The content of anthocyanian in apple skin increased about 31.2% in the second week and degraded significantly from the third week when storied at higher temperature (20℃), however, the anthocyanian content reached its highest level in the fourth weeks of storage at lower temperature (0℃). The results also indicated that the storage temperature affected the degradation of anthocyanian. At higher temperature, the activity of SOD might have relationship with the changes of anthocyanian content, so it is inferred that SOD may reduce the degradation of anthocyanian. On the other hand, POD might have two regulating mechanisms: At the initial period of storage, the higher activity of POD in apple fruit could annihilate H2O2 and had protective reaction, but promoted the process of fruit senescence at the later period of storage. The other related enzymes except SOD remained the lower activity and the anthocyanin content changed slightly during the later storage period when fruit storied at lower temperature.