超声预处理对驴乳酪蛋白酶解物抗氧化性及结构的影响

Effects of ultrasonic pretreatment on antioxidant activity and structure of donkey milk casein hydrolysate

中文关键词:  超声  酶解  酪蛋白  抗氧化性  结构

英文关键词:ultrasonic  hydrolysis  casein  antioxidant activity  structure

中文摘要:

      目的 探究超声协同酶解对驴乳酪蛋白抗氧化性及结构的影响, 优化复合处理工艺参数, 解析超声预处理对酶解过程的促进机制。方法 以驴乳酪蛋白为原料, 单因素试验优化超声参数(200 W、20 min、6 s/6 s间歇比), 筛选中性蛋白酶与胰蛋白酶(质量比2:1)复配, 结合响应面法优化酶解条件(酶添加量4.86%、55.28 ℃、pH 7.76)。通过十二烷基硫酸钠-聚丙烯酰胺凝胶电泳(sodium dodecyl sulfate polyacrylamide gel electrophoresis, SDS-PAGE)、红外光谱法等分析蛋白分子质量、二级结构及官能团变化, 测定1,1-二苯基-2-三硝基苯肼(1,1-diphenyl-2-picrylhydrazyl, DPPH)自由基清除率等抗氧化指标。结果 超声协同酶解使抗氧化能力达69.77%, Fe3+还原能力提升65.3%, 显著优于单一处理。结构显示α-螺旋减少至26.70%, 无规卷曲增至28.35%, 芳香族氨基酸暴露, 巯基氧化为二硫键, 分子质量降低。响应面模型预测值与实测值吻合度高(R2=0.9937)。结论 超声预处理通过破坏蛋白胶束结构, 协同酶解释放抗氧化短肽, 显著提升抗氧化性, 研究结果为高附加值驴乳抗氧化产品的生产提供可参考的工艺参数, 有助于推动驴乳产业的发展, 提高驴乳的经济价值。

英文摘要:

      Objective To explore the effects of ultrasonic synergistic enzymatic hydrolysis on the antioxidant activity and structure of donkey milk casein, optimize the process parameters of composite treatment, and analyze the promotion mechanism of ultrasonic pretreatment on the enzymatic hydrolysis process. Methods Using donkey milk casein as raw material, the ultrasonic parameters (200 W, 20 min, 6 s/6 s intermittency ratio) were optimized by single factor experiment, the neutral protease and trypsin (the mass ratio was 2:1) were screened, and the enzymatic hydrolysis conditions were optimized by response surface method (enzyme addition amount 4.86%, 55.28 °C, pH 7.76). The changes of protein molecular weight, secondary structure and functional groups were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and infrared spectroscopy. The antioxidant indexes such as 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging rate were determined. Results Ultrasonic synergistic enzymatic hydrolysis resulted in antioxidant ability of 69.77% and a 65.3% increase in Fe3? reducing capacity, which was significantly better than that of the single treatment. The structure showed that the α-helix decreased to 26.70%, the random coil increased to 28.35%, the aromatic amino acids were exposed, the sulfhydryl groups were oxidized to disulfide bonds, and the molecular weight was reduced. The predicted value of the response surface model was in good agreement with the measured value (R2=0.9937). Conclusion The results of ultrasonic pretreatment significantly improves the antioxidant activity by destroying the structure of protein micelles and releasing antioxidant short peptides in synergy with enzymes, which provides a reference process parameter for the production of high value-added donkey milk antioxidant products, which is helpful to promote the development of donkey milk industry and improve the economic value of donkey milk.