Xu Shiwei, Shen Yanting, Li Yonghui
Department of Grain Science and Industry, Kansas State University, Manhattan, KS 66506, USA.
Antioxidants (Basel). 2019 May 15;8(5):131. doi: 10.3390/antiox8050131.
Sorghum has a significant amount of proteins, especially kafirin; however, limited information is available on evaluating its potential for peptide antioxidants. The objectives of this study were to: (1) investigate the effects of two key variables, enzyme-to-substrate ratio and reaction time on kafirin hydrolysis using Alcalase; (2) evaluate the antioxidant performances of the hydrolysates and fractions from membrane ultrafiltration and gel filtration; and (3) identify peptide sequences in the antioxidant fraction using MALDI-TOF/TOF MS. Kafirin hydrolysates prepared at enzyme-to-substrate ratio of 0.4 Au/g and 4 h had a good balance of antioxidant activity, yield, and economic efficiency. Medium-sized fraction of hydrolysates (5-10 kDa) from membrane filtration possessed the highest antioxidant activities among various fractions. The fraction also unveiled a good inhibition effect against lipid oxidation in emulsion and ground meat systems. Smaller-sized fraction (F3) collected through gel-filtration chromatography had significantly stronger antioxidant activities than other fractions, and 26 representative peptide sequences were identified in the fraction.
高粱含有大量蛋白质，尤其是醇溶蛋白；然而，关于评估其作为肽类抗氧化剂的潜力的信息有限。本研究的目的是：（1）研究两个关键变量，即酶与底物的比例和反应时间对使用碱性蛋白酶水解醇溶蛋白的影响；（2）评估膜超滤和凝胶过滤得到的水解产物和馏分的抗氧化性能；（3）使用基质辅助激光解吸电离飞行时间串联质谱（MALDI-TOF/TOF MS）鉴定抗氧化馏分中的肽序列。在酶与底物比例为0.4 Au/g且反应时间为4小时的条件下制备的醇溶蛋白水解产物在抗氧化活性、产率和经济效率方面具有良好的平衡。膜过滤得到的水解产物的中等大小馏分（5-10 kDa）在各个馏分中具有最高的抗氧化活性。该馏分在乳液和碎肉体系中对脂质氧化也表现出良好的抑制作用。通过凝胶过滤色谱收集的较小馏分（F3）的抗氧化活性明显强于其他馏分，并且在该馏分中鉴定出了26个代表性肽序列。
