碱性氨基酸修饰乳清蛋白基质凝胶功能性

Basic amino acids modify the functional properties of whey protein-based gels

摘要:

将L-精氨酸（L-Arg）、L-赖氨酸（L-Lys）和L-组氨酸（L-His）分别加入到质量浓度为120 g/L的乳清蛋白溶液中，使每种氨基酸的最终质量浓度均分别为1 g/L、3 g/L和5 g/L，均质后再经90 ℃加热30 min制备热诱导凝胶，并探讨碱性氨基酸对凝胶功能的改造。通过物化、全质构、吸水性和凝胶电泳等分析手段，表征溶液的pH及其所成凝胶的形貌、质构、水化性质及凝胶内的蛋白浸出组分。结果表明，L-Arg、L-Lys及L-His均能明显提高蛋白成胶溶液的pH，蛋白都能形成颜色、形貌及“站立性”无明显差别的热诱导凝胶；L-Arg、L-Lys显著提高凝胶弹性、黏聚性、咀嚼性及回复性，降低凝胶硬度和胶黏性，而L-His除降低胶黏性外，对凝胶其它质构特性无显著影响。此外，它们对凝胶持水性提升幅度不大，但能够显著提高凝胶溶胀性，并有效抑制凝胶网络内蛋白浸出，促进蛋白凝胶网络结构的完整化。

Abstract:

Basic amino acids (BAA) like L-arginine (L-Arg), L-lysine (L-Lys) and L-histidine (L-His) with final mass concentrations of 1 g/L, 3 g/L or 5 g/L were added to 120 g/L whey protein solutions, respectively, and then these samples were thoroughly homogenized and then heated at 90 ℃ for 30 min to prepare heat-induced gels. The work was targeted to investigate the feasibility of BAA modify the functional properties of the gel. The physicochemical changes, texture profile analysis, water sorption and gel electrophoresis were employed to characterize the pH of the gel forming solution, the morphology, texture, hydration properties and leaching protein fractions of the gels. The result indicated that L-Arg, L-Lys or L-His both significantly increased the pH of gel-forming solutions, and whey proteins with treated with BAA can be formed a heat-induced gel with no visible difference in color, morphology and \"self-standing ability\". L-Arg and L-Lys also significantly increased the springiness, cohesiveness, chewiness and resilience of the gel but dramatically decreased its hardness and gumminess, whereas L-His has no dominant influence on the changes of textural properties of the gels (except decreased gumminess). In addition, BAA is incapable of favorably improving water holding capacity but substantially enhancing swelling ratio of the gel, also notably inhibiting protein fractions leaching from the gel, which promoting the integrity of the whey protein gel matrix.