小麦籽粒多酚氧化酶提取方法的比较研究

Comparing activity of polyphenol oxidase by three extraction methods in wheat kernel

采用3种不同方法提取21个小麦品种籽粒的多酚氧化酶(PPO),以综合研究不同的提取方法与其活性的关系,结果显示:在3种提取方法中,用十二烷基硫酸钠(SDS)提取全麦粉PPO的活性平均值和变异系数最高,分别为57.2 U/(g.min)和77.7%;而用磷酸盐提取全麦粉PPO活性平均值为19.6 U/(g.min),变异系数为59.6%,低于前者。用磷酸盐提取完整籽粒的PPO活性平均值及变异系数最低,分别为5.1 U/(g.min)和16.7%。简单相关分析结果表明,分别用磷酸盐和SDS提取全麦粉PPO活性的相关性最好,相关系数达0.954;其次是磷酸盐提取的完整籽粒和SDS提取全麦粉的PPO活性的相关性,其相关系数为0.925;最小的是用磷酸盐分别提取完整籽粒和全麦粉PPO活性的相关性,相关系数为0.877。相关性均达极显著水平。同时研究了磷酸盐和SDS分别提取PPO活性的时间特性,结果表明:对于PPO活性差异较大的品种,其活性曲线的差别也较大;对于同一品种,这2种方法提取的PPO活性面积(活性曲线下包含的面积)也差异明显。上述说明磷酸盐缓冲液中加入SDS可有效地改善PPO的提取效果;不同品种、不同的提取方法,PPO的活性曲线也有明显差异。

Polyphenol oxidase （PPO） is one of the major factors which influence the quality of wheat flour and related products. It＇s very essential to understand PPO characters in improving appearance of noodle and steam bread, In this study, three methods were used to extract PPO from 21 wheat varieties and their activity were measured, The results indicated that PPO extracted from whole kernel meal by SDS （method 3） had highest activity, being up to 1.4- 3.9 folds of that extracted by phosphate （method 2）. The PPOextracted from intact grain by phosphate （method 1） had lowest activity 5.3- 42.1 times lower than that extracted by method 3, The values of PPO activity measured by the three methods were significantly related with each other. The results of time course showed that activity curve of high PPO varietywas different from that of low PPO variety. Even for a variety, method 2 and 3 gave different PPO activity areas. It is suggested that SDS could improve PPO extraction and its activity measurement.