The main reason of this difference was that red clover had a soluble polyphenol oxidase (PPO) and PPO oxidized native phenols into quinines which bond to protein and inhibited proteolysis.

• 造成这种差异的原因是红三叶中含有一种多酚氧化酶，它催化植物中的酚类物质生成苯醌，苯醌与蛋白质发生聚合反应从而起到保护蛋白的作用。