pH值偏移对豌豆分离蛋白冷致凝胶特性的影响

Effect of pH-Shifting Treatment on Gelation Properties of Pea Protein Isolate

豌豆分离蛋白(pea protein isolate,PPI)较差的凝胶性限制了其在食品中的应用。该文探究不同pH值(10、11、12)对转谷氨酰胺酶(transglutaminase,TG)诱导和葡萄糖酸-δ-内酯(glucono-δ-lactone,GDL)酸诱导豌豆分离蛋白凝胶(TG凝胶和GDL凝胶)特性和结构的影响。结果表明,pH值偏移可显著改善TG凝胶的性质,特别是pH12偏移改性后TG凝胶的持水性可达到最大值(92.13±2.40)%,硬度可达到最大值(413.82±4.90)g;游离巯基和非网络蛋白含量分别显著降低至(2.60±0.04)μmol/g和(6.00±0.40)%。TG添加量大于50 U/g时对凝胶的持水性和非网络蛋白含量没有显著影响。相反,pH值偏移对GDL凝胶的持水性和硬度无明显的改善作用。二级结构中α-螺旋和β-折叠含量的增加以及微观结构中孔径小、表面均匀致密的凝胶网络均表明pH值偏移可以显著改善TG凝胶的性质。

The poor gelation property of pea protein isolate(PPI)limits its application in food.This study investigated the effect of different pH values(10,11,and 12)on the induction of transglutaminase(TG)and glucono-δ-lactone(GDL)acid-induced PPI gels(referred to as TG gels and GDL gels)in terms of their characteristics and structures.The results showed that pH-shifting significantly improved the properties of TG gels,especially the water-holding capacity of the gel increasing to(92.13±2.40)%,and the hardness increasing to(413.82±4.90)g after pH12 shift modification.The content of free sulfhydryl groups and non-network proteins significantly decreased to(2.60±0.04)μmol/g and(6.00±0.40)%.The addition of TG enzyme more than 50 U/g had no significant effect on the water holding capacity and non-network protein content of the gel.On the contrary,the pH-shifting did not significantly improve the water holding capacity and hardness of GDL gels.The increase in the content ofα-helix andβ-sheet in the secondary structure and the formation of a gel network with small pore size and uniform surface density in the microstructure all demonstrated that pH-shifting significantly improved the properties of TG gels.