菜籽分离蛋白分子质量分布及酶解条件的研究

以脱脂"双低"油菜籽为原料,利用碱溶解酸沉淀法提取菜籽分离蛋白;用SDS-PAGE凝胶电泳研究菜籽蛋白的分子质量的组成;以水解度和氮回收率为考察指标,用响应面分析法拟合了Alcalase 2.4L酶解菜籽蛋白成菜籽肽的二次多项数学模型,优化了酶解菜籽分离蛋白的工艺参数。SDS-PAGE凝胶电泳研究表明利用碱溶解酸沉淀提取的菜籽分离蛋白主要是2S清蛋白。响应面分析法研究的试验结果表明,酶的使用量、pH、酶解温度、酶的使用量与pH的交互作用对Alcalase 2.4L酶解菜籽蛋白的水解度和氮回收率的影响均显著(P0.05)。通过求解菜籽肽的二次多项数学模型的逆矩阵方程,可得Alcalase 2.4L水解菜籽分离蛋白的最佳条件为:酶的使用量0.05 Au/g,pH 9.0,酶解温度54℃;在此酶解条件下,菜籽分离蛋白浓度为5%时,水解5 h,所得的水解度和氮回收率分别为35.12%及52.96%。

Molecular Weight Distribution of Rapeseed Protein Isolate and Optimization of Enzymatic Hydrolysis Process

Defatted meal of double-zero rapeseed was used as material in this study. The methods of alkaline extraction and acid precipitation were employed to extract rapeseed protein isolate, followed by SDS-PAGE gel electrophoresis to explore its molecular weight distribution. On the basis of single-factor experiments, response surface methodology (RSM) was used to built second-order polynomial equations and optimize conditions of enzymatic hydrolysis process with Alcalase 2.4L, and the selected response values were degree of hydrolysis (DH) and nitrogen recovery (NR). Analyses by electrophoresis showed that this ptotein isolate was mainly composed of more 2 S albumins than 12 S globulins. The experimental results showed that adding enzyme amount, pH, temperature and the interaction of enzyme amount and pH had significant effects on DH and NR (P < 0.05). Maximum yield was obtained according to the inverse matrix equation of the second-order polynomial model when adding enzyme amount, pH and temperature were 0.05 Au/g, pH9.0, 54oC, respectively. These conditions resulted in DH 35.12%, NR 52.96% after 5h hydrolysis with a protein substrate of 5% (w/v).