不同贮藏期米糠制备的米糠蛋白酶解产物抗氧化性分析

为研究米糠酸败对米糠蛋白酶解产物抗氧化性的影响,以不同贮藏期米糠制备的米糠蛋白为原料,通过碱性蛋白酶水解制备米糠蛋白酶解物,研究不同贮藏期米糠制备米糠毛油和米糠蛋白氧化程度以及米糠蛋白酶解物抗氧化性。结果表明,米糠在贮藏过程中米糠脂质发生水解和氧化,米糠蛋白发生氧化,米糠蛋白二硫键和非二硫共价键参与氧化聚集体的形成。随着米糠贮藏时间的延长,米糠蛋白水解度先增加后下降,贮藏3 d后达到最大;米糠蛋白酶解液清除2,2’-联氮-二(3-乙基-苯并噻唑-6-磺酸)二铵盐自由基、1,1-二苯基-2-三硝基苯肼自由基、O2-·、·OH能力和金属螯合能力先增加后下降。结果显示,米糠短期贮藏会促进米糠蛋白水解,提高酶解产物的抗氧化性;米糠长期贮藏抑制米糠蛋白的水解,降低酶解产物的抗氧化性。

Antioxidant Activity of Enzymatic Hydrolysates of Rice Bran Proteins Prepared from Rice Bran with Different Storage Times

In order to explore the effect of rice bran rancidity on the antioxidant activity of enzymatic hydrolysates of rice bran proteins (RBP), the oxidation degrees of crude rice bran oil (RBO) and RBP prepared from rice bran samples with different storage times were investigated as well as the antioxidant activity of alcalase hydrolysates of RBP. The results indicated that storage of rice bran could lead to hydrolysis and oxidation of RBO as well as oxidation of RBP, and the disulfide and non-disulfide covalent bonds participated in the formation of oxidation aggregates of RBP. As storage time of rice bran increased, the degree of hydrolysis (DH) of RBP firstly increased until reaching the maximum value on the third day of storage and then decreased. The free radical scavenging capacity against 2,2’-azinobis (3-ethylbenzothiazoline-6-sulfonic acid) radicals (ABTS+·), 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals, superoxide (O2-·), radicals hydroxyl (·OH), as well as metal-chelating capacity of RBP hydrolysates showed the same trend. These results indicated that shortterm storage of rice bran resulted in increased DH of RBP and antioxidant activity of their hydrolysates, whereas long-term storage reduced the DH of RBP and the antioxidant activity of their hydrolysates.