制备条件对大豆分离蛋白-淀粉复合膜机械性能的影响

Effect of Preparing Conditions on the Mechanical Properties of Soy Protein Isolate/Starch Composite Film

为了改善大豆分离蛋白膜的机械性能,将淀粉添加到大豆分离蛋白中制备复合膜,以复合膜的抗拉强度和断裂延伸率为评价指标,研究了淀粉添加比例、甘油添加比例、成膜液pH以及成膜温度对复合膜机械性能的影响。结果表明:复合膜的抗拉强度和断裂延伸率均随着淀粉添加比例的增加呈现先升高后降低的趋势,在淀粉添加比例为50%时最大;pH值和成膜温度对复合膜的抗拉强度和断裂延伸率的影响呈现相同的趋势,抗拉强度逐渐增强,断裂延伸率先升高后降低;随着甘油添加比例的增加,复合膜的抗拉强度逐渐降低而断裂延伸率逐渐增加。在单因素试验的基础上采用响应面方法对复合膜的制备工艺条件进行优化,得到优化工艺:淀粉添加比例50.3%、甘油添加比例46.4%、成膜液pH 9.6、成膜温度60.2℃,在此条件下制备的大豆分离蛋白-淀粉复合膜的断裂延伸率为104.2%,抗拉强度为6.3 MPa。

In order to improve the mechanical properties of the soy protein isolate film,soy protein isolate and starch were used as raw materials to prepare composite film. The tensile strength and elongation at break were used as evaluation indexes to study the effects of starch addition,glycerol addition,film-forming solution pH,and film-forming temperature on the mechanical properties of the composite film. The results showed that the tensile strength and the elongation at break of the composite film increased firstly and then decreased with increase of the starch content. The tensile strength and the elongation at break reached the maximum when the starch content was 50%. The effect of film-forming solution pH and film-forming temperature on the tensile strength and elongation at break of the composite film showed the same trend,the tensile strength gradually increased,and the elongation at break increased firstly and then decreased. With the increase of glycerol content,the tensile strength of the composite film also decreased gradually and the elongation at break gradually increased. Based on the single factor experiment analysis,the preparing process conditions of the composite film were optimized by response surface methodology. The optimized conditions were as follows: starch addition 50.3%,glycerol addition 46.4%,film-forming solution pH 9.6,film-forming temperature 60.2 ℃. The elongation at break of the composite film prepared under these conditions was 104.2%,and the tensile strength was 6.3 MPa.