利用碱性蛋白酶水解大豆分离蛋白制备出水解度为14.1%的水解物,并在醇-水介质中对其进行类蛋白反应修饰。固定底物质量分数30%,反应时间4 h,利用响应面分析法对类蛋白反应条件进行优化,得到最优条件为:酶添加量5.26 kU/g蛋白质,乙醇体积分数56.8%,温度33.1℃。在乙醇-水或甲醇-水介质中制备反应程度不同的修饰产物,并评价其对亚铁和钙离子的螯合能力。结果表明,亚铁离子螯合能力由39.8%提升至59.3%,钙离子螯合能力由62.1%提升至76.6%。大豆分离蛋白的酶解以及类蛋白反应修饰,是一个提高金属离子鳌合能力大豆蛋白螯合肽的新技术。

Soybean protein hydrolysates with a degree of hydrolysis of 14.1% were prepared by hydrolysis of soybean protein isolate with alcalase,and then modified by a plastein reaction in alcohol-water medium.Response surface analysis was applied to optimize the conditions of plastein reaction,when substrate concentration and reaction time were pre-set at 30% and 4 h.The suitable conditions obtained were as following: enzyme addition level of 5.26 kU/g proteins,volume ratio of ethanol to water of 56.8% and reaction temperature of 33.1℃.Some modified products with different reaction extents were prepared in ethanol-water or methanol-water medium,and their chelating activities for iron(II) and calcium(II) were evaluated.It was found that iron(II) chelating activity was increased from the original 39.8% to 59.3% while calcium(II) chelating activity was enhanced from the original 62.1% to 76.6%.The present results suggested that enzymatic hydrolysis coupled with plastein reaction might be served as a new approach to prepare iron soybean protein hydrolysates with better metal chelating activity.