CaCl_(2)调节银杏果分离蛋白/果胶复合凝胶质构特性

Calcium chloride regulating the texture of Ginkgo biloba seed protein isolate/pectin composite gels

将CaCl_(2)加入质量浓度为120 g/L银杏果分离蛋白(GSPI)水溶液及质量浓度为5 g/L果胶(酯化度分别为38%和76%)水溶液中,使Ca^(2+)最终质量浓度分别为0.05、0.11和0.22 g/L,基于此溶胶制备热诱导GSPI/果胶复合凝胶。采用粒径和ζ-电位法、流变学及质构学、SDS-PAGE、FTIR和SEM测试了溶胶的物化性质、成胶过程及复合凝胶的功能性和微观结构,探讨了Ca^(2+)对蛋白/果胶复合凝胶性能的影响及其潜在的机制。结果表明,添加Ca^(2+)降低溶胶粒径,但不改变其带电量;降低溶胶流变学特性,破坏复合凝胶形成;进而弱化凝胶质构特性,但对其持水性无显著影响。Ca^(2+)破坏蛋白与果胶间的作用,竞争性地与果胶结合。随着Ca^(2+)质量浓度的增加,以上效应表现更显著。相比之下,高酯化度果胶比低酯化度果胶对Ca^(2+)更为敏感。

CaCl_(2)was added into the composite solutions of Ginkgo biloba seed protein isolate(GSPI)with a mass concentration of 120 g/L and pectin(esterification degree of 38%and 76%,respectively)with a mass concentration of 5 g/L to make solutions with the final Ca^(2+)mass concentration of 0.05,0.11 and 0.22 g/L.The solutions obtained were then heated to develop GSPI/pectin composite gels.Physiochemical properties of gel-forming solutions,gelling process of the solutions,functionality and microstructures of the composite gels were analyzed by particle size andζ-potential method,rheology,texture profile analysis,SDS-PAGE,FTIR and SEM.The effect of Ca^(2+)on the properties of protein/pectin composite gels and the underlying mechanisms were further investigated.The results indicated that the addition of Ca^(2+)reduced the particle size of GSPI/pectin but showed no influence on their electric charge,degraded the rheological properties of the heat-induced gels,and impaired the formation of fine structure of the gels.As a result,the gels'textural properties were compromised,but their water holding capacity was not affected significantly.Ca^(2+)disrupted the balance of GSPI/pectin assembly because they bound competitively to pectin and obstructed the interaction between GSPI with pectin.The increase of Ca^(2+)mass concentrations resulted in a more pronounced effect.In contrast,pectins with high esterification degree were more sensitive to Ca^(2+)than pectins with low esterification degree.