表没食子儿茶素没食子酸酯对米糠蛋白体外胃蛋白酶消化性质的影响

研究表没食子儿茶素没食子酸酯（Epigallocatechin gallate，EGCG）对米糠蛋白（Rice bran protein，RBP）体外胃蛋白酶消化性质的影响。结果表明，随着EGCG添加量的增加，RBP的初始消化速率和消化率逐渐下降。电泳结果显示，EGCG通过诱导RBP形成共价交联聚集体影响RBP消化性，并且会抑制胃蛋白酶对清蛋白亚基、球蛋白亚基和谷蛋白酸性亚基的降解作用。RBP消化产物中绝大部分蛋白肽分子量都分布在0~800 u。随着EGCG添加量的增加，消化产物中0~800 u的组分所占比例逐渐下降，800～3000 u组分所占比例显著（P<0.05）增加。随着EGCG添加量的增加，RBP体外胃蛋白酶消化产物清除ABTS+?、DPPH?、O2-?、?OH的能力以及金属螯合能力均显著（P<0.05）上升，这可能是EGCG酚羟基和RBP抗氧化肽共同作用的结果。

Effects of Epigallocatechin Gallate on in vitro Pepsin Digestibility of Rice Bran Protein

The effects of epigallocatechin gallate (EGCG) on in vitro pepsin digestibility of rice bran protein were investigated. The results showed that with the increase of EGCG, the initial digestion rate and digestibility of RBP gradually decreased. The electrophoresis results implied that EGCG induced RBP to form covalently cross-linked aggregates which could affect the digestibility of RBP, and degradation of albumin subunit, globulin subunit and acid subunit of glutelin by pepsin was inhibited. The molecular weight of majority peptides in RBP digestion products were distributed between 0-800 u. With the increase of EGCG, the proportion of components from 0 to 800 u in the digestion products gradually decreased, and the proportion of components from 800 to 3000 u increased significantly (P<0.05). With the increase of EGCG, the abilities of the digestion products to scavenge ABTS ⁺ ?, DPPH ?, O2- ?, ? OH, and metal chelating abilities significantly increased (P<0.05). The improvement of antioxidant activities may be the result of the combined action of EGCG phenolic hydroxyl groups and RBP antioxidant peptides.