School of Food and Biological Engineering,Jiangsu University
The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan)
为减少乳清蛋白用量，用马铃薯蛋白替代乳清蛋白质量的一半制备热诱导凝胶。通过色度、质构、水分分布、流变等考察了总蛋白浓度（40~80 g/L）对于复合凝胶物理性质的影响。结果表明，复合凝胶的最低成胶浓度为50 g/L，与乳清蛋白80 g/L的最低成胶浓度相比，乳清蛋白用量减少了2.2倍。总蛋白浓度从50 g/L提高到80 g/L时，复合凝胶偏黄，硬度和弹性分别增加了5.28倍和5.90%，但束缚水含量降低了3.63%。储能模量（G'）显示较弱的频率依赖性。CLSM和SEM观察表明，蛋白浓度80 g/L的复合凝胶孔隙尺寸小，具有由颗粒聚集体组成的均一致密网络结构，因而具有较高G'。红外光谱表征结果表明，复合凝胶中β-折叠和β-转角约占蛋白二级结构的70%。溶解度测试结果表明，维持复合凝胶结构的作用力中氢键和疏水相互作用的贡献高于二硫键。
To reduce the content of whey protein, heat-set mixed gels of potato protein and whey protein were prepared by partially replacing whey protein with potato protein at the ratio of 50/50 by weight. The physical properties of mixed protein gels at different total protein concentrations (40~80 g/L) were investigated by color, textural properties, moisture distribution and rheological properties. The results showed that the lowest gelation concentration of mixed protein gels was 50 g/L. Compared with whey protein gels formed at the lowest gelling concentration of 80 g/L, consumption of whey protein in those gels decreased by 2.20 times. When the protein concentration increased from 50 to 80 g/L, mixed protein gels exhibited yellow color in the appearance. Hardness and elasticity increased by 5.28 times and 5.90%, respectively, but the content of immobilized water decreased by 3.63%. The storage modulus G' showed weak relation with the frequency. Laser confocal microscopy and scanning electron microscopy showed that the mixed protein gels at the concentration of 80 g/L had uniform and compact gel network, small pore size, and clear spherical particle aggregation morphology, thus it had a higher G'. The results of FT-IR showed that the amount of β-folding and β-turn structures account for about 70% of the secondary structures in mixed protein gels. The results of solubility test showed that hydrogen bond and hydrophobic interaction made more contributions to maintaining the structure of mixed protein gels than disulfide bond.