不同浓度卡拉胶对汉麻分离蛋白凝胶性质及结构的影响

Effects of Different Concentrations of Carrageenan on the Gel Properties and Structure of Hemp Protein Isolate

为阐明不同浓度的卡拉胶(0.4%、0.8%、1.2%、1.6%、2.0%,w/w)对汉麻分离蛋白凝胶特性和结构的影响,以未添加卡拉胶的汉麻分离蛋白凝胶为对照,测定复合凝胶的持水能力、质构、流变特性,同时检测了卡拉胶的加入对复合凝胶水分分布、蛋白结构及分子间作用力的影响。结果表明:添加卡拉胶显著(P<0.05)提高了汉麻分离蛋白凝胶持水能力和凝胶强度,改变了蛋白结构。与对照组相比,0.8%卡拉胶的添加显著(P<0.05)提高凝胶的硬度、弹性模量并降低了凝胶的频率依赖性,并与水分子结合最为紧密,α-螺旋向β-折叠和无规卷曲转变,增加凝胶刚性结构;此时维持凝胶结构的主要作用力由疏水相互作用力向二硫键转变,凝胶网络更加致密,电镜结果证明了这一结论。因此,添加0.8%的卡拉胶可显著(P<0.05)提高汉麻分离蛋白的凝胶性质并改善其结构,为提高汉麻分离蛋白在食品领域的应用提供了理论和实验基础。

To elucidate the influence of different concentrations of carrageenan(CA,0.4%,0.8%,1.2%,1.6%,2.0%,w/w)on the gelation properties and structure of hemp protein isolate(HPI),with the hemp protein isolate without adding CA as the control,the water-holding capacity,texture,rheological properties of the composite gels were determined.Meanwhile,the effect of CA addition on the water distribution,protein structure and intermolecular forces in the composite gels was also investigated.The results showed that the addition of CA significantly(P<0.05)improved the water-holding capacity and gel strength,and changed the protein structure.Compared to the control group,adding 0.8%CA significantly increased the hardness,elastic modulus and reduced the frequency dependence of the gel compared to the control group(P<0.05).And most tightly bound to water molecules,with a shift fromα-helix toβ-sheet and random curling,increasing the rigid structure of the gel.At this time,the primary force maintaining the gel structure shifted from hydrophobic interaction force to disulfide bonding and the gel network became denser,which was proved by scanning electron microscopy results.Therefore,the addition of 0.8%carrageenan could significantly(P<0.05)improve the gel properties and structure of hemp isolate protein,which would provide a theoretical and experimental foundation for the application of hemp protein isolate in the food industry(P<0.05).