Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, PR China.
J Sci Food Agric. 2012 May;92(7):1554-61. doi: 10.1002/jsfa.4742. Epub 2011 Dec 9.
Egg white protein powder was hydrolyzed by three proteases-alcalase, trypsin, and pepsin-to produce antioxidant peptides. Three kinds of hydrolysates were prepared under optimal enzymatic parameters that were obtained from the preliminary one-factor-at-a-time test and response surface methodology. Thereafter, three enzymatic hydrolysates were sequentially fractionated by ultrafiltration membranes in cut-off MW of 30, 10, and 1 kDa, and tested in terms of their reducing power (RP). Effects of high-intensity pulsed electric field (PEF) were further investigated on the antioxidant peptides to improve their activities.
Alcalase hydrolysates possessed stronger RP ability than the other two hydrolysates, particularly for the fraction within < 1 kDa. After PEF treatment, this fraction showed an improvement of RP ability within 4 h; however, the effects were reversible. High-performance liquid chromatographic analysis showed some MW changes of PEF-treated sample compared with control.
Among the three kinds of proteases, alcalase could be regarded as the most appropriate enzyme for preparation of bioactive peptide from egg white protein, with the best antioxidant activity. Also, PEF showed some effects on the peptide and could be further applied to improve its antioxidant activity.
蛋清蛋白粉分别用三种蛋白酶（碱性蛋白酶、胰蛋白酶和胃蛋白酶）水解生成抗氧化肽。在初步单因素试验和响应面法获得的最佳酶解参数下，制备了三种酶解产物。然后，三种酶解产物依次用 MWCO 为 30、10 和 1 kDa 的超滤膜进行分级，并测试其还原能力（RP）。进一步研究了高强度脉冲电场（PEF）对抗氧化肽的作用，以提高其活性。
与其他两种水解产物相比，碱性蛋白酶水解产物具有更强的 RP 能力，特别是 <1 kDa 的部分。经 PEF 处理后，该部分在 4 小时内 RP 能力得到提高；然而，这种效果是可逆的。高效液相色谱分析表明，与对照相比，PEF 处理后的样品有一些 MW 变化。
在这三种蛋白酶中，碱性蛋白酶可被视为从蛋清蛋白制备生物活性肽的最合适的酶，具有最佳的抗氧化活性。此外，PEF 对肽有一定的作用，可以进一步应用于提高其抗氧化活性。
