γ-氨基丁酸/L-瓜氨酸增强白果分离蛋白凝胶性

γ-Aminobutyric acid and L-citrulline enhancing the gelation performance of Ginkgo biloba seed protein isolate

以白果分离蛋白(GSPI)为成胶基质材料,将γ-氨基丁酸(GABA)和L-瓜氨酸(L-Cit)分别加入到GSPI水溶液中,均质后再将溶液pH分别调至5.0、6.0和7.0,制备了热诱导凝胶。采用物化分析法、机械力学、蛋白凝胶电泳、SEM及FTIR表征了溶胶的物性、凝胶性和微观结构,并探讨GABA、L-Cit对GSPI凝胶性能的影响及其机制。结果表明,GABA、L-Cit对GSPI溶解度无提升作用,但能显著降低蛋白疏水性;GABA促进溶胶聚集并降低其ζ-电位,而L-Cit在pH 7.0时则促进解聚和提高ζ-电位;两者均能促进蛋白分子疏水基团向内折叠。在pH5.0和pH7.0时,以上两种氨基酸特别是L-Cit显著提高蛋白凝胶性能,而在pH6.0时则弱化凝胶性能。其影响机制可能是氨基酸与GSPI之间的静电作用,而这种效应依赖于所在体系的pH。

Thermally-induced gels were prepared from adjusting pH of the homogenized solution formed byγ-aminobutyric acid(GABA),L-citrulline(L-Cit)and Ginkgo biloba seed protein isolate(GSPI)aqueous solution to 5.0,6.0 and 7.0,respectively.The physiochemical characteristics,gelation performance,and microstructure of the gels obtained were characterized by physiochemical analysis,mechanical mechanics,protein electrophoresis,SEM,and FTIR,followed by analysis on the influence of GABA and L-Cit on the gelation performance and potential mechanism of GSPI gel.The results showed that GABA and L-Cit had no effect on the solubility of GSPI,but could significantly reduce the hydrophobicity of GSPI.GABA promoted sol aggregation and decreased itsζ-potential,while L-Cit promoted sol depolymerization and increasedζ-potential at pH 7.0.Moreover,the two amino acids facilitated the folding of hydrophobic groups inside the protein molecule.Additionally,the two amino acids,especially L-Cit,significantly enhanced protein gelation at pH 5.0 and 7.0,while decreased protein gelation at pH 6.0.The mechanism might be the electrostatic interaction between amino acids and GSPI,which depended on the pH of system.