酶解大豆蛋白对酸奶发酵酸度及流变特性的影响研究

Study on Acidity and Rheological Behaviour of Yogurt Mixed with Enzymatic Soy-protein Hydrolysate

本文采用不同水解度的大豆蛋白中性蛋白酶As1.398酶解液取代不同量的牛奶,研究发酵液在酸奶发酵过程中的酸度变化和表观粘度变化,探讨发酵酸奶在不同剪切速率下的切应力、流变指数和粘度系数。研究结果表明:在牛奶中添加大豆蛋白的酶解产物,有助于酸奶中酸的形成。当DH5.61%的大豆蛋白酶解产物替代7.5%～10%的牛奶时,其达到发酵终点所需时间最短。在牛奶中添加7.5%的DH3.76%大豆分离蛋白的水解产物能显著增加发酵酸奶的表观粘度。采用大豆蛋白酶解液替代部分牛奶生产酸奶能有效降低酸奶的柔性,其质构特性属于非牛顿流体。用DH8.89%大豆蛋白酶解液代替部分牛奶生产的酸奶在高剪切速率下其切应力远大于对照组。

Acidity change and apparent viscidity change of yogurt mixed with different amount and different hydrolytic degreepea-protein hydrolysate by neutral protease As1.398 were studied in this paper. Rheological shear stress, parameter andviscosity index in different shear rate were studied in yogurt.The result showed that to mix enzymatic soy-protein hydrolysatewith milk would contributed to acidic forming in yogurt. It took shortest time to be the fermentive end for yogurt when milkwas mixed with 7.5%～10% enzymatic soy-protein hydrolysate which hydrolytic degree was 5.61%. The apparent viscidityof fermented yogurt was increased when milk was mixed with 7.5% DH3.76% enzymatic soy-protein hydrolysate. Flexibilityof yogurt was reduced when milk mixed with soybean hydrolysate and the yogurt was non-newtonian fluid. Shear stress ofyogurt in high shear rate was far higher than CK when milk was mixed with DH8.89% enzymatic soy-protein hydrolysate.