大豆分离蛋白/海藻酸钠复合膜的制备及在运动蛋白粉中的应用

Preparation of soy protein isolate/sodium alginate composite films and their application in protein powder for exercise

为了提高大豆分离蛋白膜的性能并应用于包装运动蛋白粉,利用海藻酸钠改性大豆分离蛋白,成功构建大豆分离蛋白/海藻酸钠二元复合膜分散体系,根据傅立叶变换红外光谱、X-射线衍射、扫描电子显微镜等方法明确不同海藻酸钠对可食性大豆蛋白膜的结构影响规律,根据机械性能及阻水性能等方法深入解析可食性大豆蛋白膜的性能变化趋势。结果表明,当海藻酸钠添加量为10%时,其复合膜拉伸强度达到最大,为(7.02±0.25)MPa。当添加量为2%时,复合膜阻水性最好,但较6%和10%差异不显著。另外经结构及形貌特征分析发现,成膜过程中海藻酸钠与大豆分离蛋白的共价交联作用显著增强其聚合物的分子间作用力,进而形成致密的凝胶网络结构且复合膜表面更趋光滑、平整。最后,将改性大豆蛋白膜用于包装运动蛋白粉,在贮藏60天后水分含量和菌落总数均符合标准要求。

To improve the properties of soy protein isolate film and its application in packaging protein powder for exercise,soy protein isolate was modified by sodium alginate,and soy protein isolate/sodium alginate binary composite dispersion systems were successfully constructed.The effects of different amount of sodium alginate on the structures of edible soy protein films were determined by Fourier transform infrared spectroscopy,X-ray diffraction,and scanning electron microscopy.According to the mechanical properties and water resistance,the properties of edible soy protein films were analyzed to clarify the structures and effects of edible soy protein membranes modified by sodium alginate.The results showed that,when sodium alginate was 10%,the tensile strength of composite film reached the maximum of 7.02±0.25 MPa;water resistance was the best at 2%of sodium alginate,but the effect was not significant compared with 6%and 10%sodium alginate.The structures and morphologies analysis showed that the covalent crosslinking of sodium alginate and soy protein isolate enhanced significantly intermolecular interaction force of the polymer significantly.Therefore,forming the dense gel network structures was formed,and the surface of the composite films became smoother and flatter.Finally,the modified soy protein films were used to package the protein powder for exercise.After 60 days of storage,the moisture content and the total number of bacteria still met the standard requirements.