酶解大豆蛋白工艺及其对面团流变特性的影响

Study on enzymatic hydrolysis of soybean protein and its influence on dough rheological property

采用响应面优化中性蛋白酶酶解大豆分离蛋白工艺条件,确定了最佳水解条件为加酶量6%、水解时间6 h、底物浓度3.7%、温度42℃、pH 7.0,得到水解度为7.74%。酶解得到水解度为3.1%、4.4%、5.2%、6.2%、7.4%的五种样品,并采用SDS-聚丙烯酰胺凝胶电泳来分析其分子量的变化规律。在小麦粉中分别添加2%的大豆分离蛋白和酶解样品,通过粉质仪和拉伸仪研究其对面团流变学特性的影响。结果表明,大豆分离蛋白酶解后产生两条新的肽段,其分子量约为30.5ku和26.4 ku;添加大豆分离蛋白的面团吸水率、稳定时间、面团拉伸能量、拉伸阻力、拉伸比例均有所增大;而添加酶解样品则均有所降低,并随着水解度的增加其对面团流变特性的破坏越严重。

The processing conditions of soy protein isolate with neutral protease were optimized by response surface, which were ： enzyme dosage 6% , hydrolysis time 6 h, substrate concentration 3.7% , temperature 42 ℃ and pH 7.0. The degree of hydrolysis was 7.74%. Five samples with different degree of hydrolysis, 3.1% , 4.4% , 5.2%, 6.2% and 7.4% , were prepared. Their variations of molecular weights were analyzed by SDS - PAGE. 2% of soy protein isolate or the hydrolysate samples were added into wheat flour, and the influences of the additions on dough rheological properties were investigated by Brabender farinograph and extensograph. Results showed that two new peptide fragments emerged after enzymatic hydrolysis of soy protein isolate with molecular weight about 30.5 ku and 26.4 ku ; the water absorption of dough, stability, tensile energy, resistance to extension and stretching ratio were all increased when adding soybean protein isolate; when adding the hydrolysates, they were all decreased, and the dough rheology property got worse and worse with the increase of hydrolysis degree.