pH值对罗非鱼蛋白-大豆蛋白混合热凝胶特性及体外消化性的影响

以罗非鱼和大豆为原料分别提取鱼分离蛋白(fish protein isolate,FPI)和大豆分离蛋白(soy protein isolate,SPI),制备罗非鱼蛋白-大豆蛋白(FPI∶SPI=1∶1,质量比)热诱导凝胶,探讨pH值(6.0、6.5、7.0、7.5)对混合蛋白热凝胶特性和体外消化性的影响。结果表明:pH 6.5时罗非鱼蛋白-大豆蛋白混合蛋白热凝胶储能模量G′值大于单一蛋白,凝胶特性最好,硬度和胶黏性相比FPI都得到提升。pH值会影响蛋白质与水分子的结合能力,混合蛋白热凝胶的持水性在pH 6.5时比其它pH值条件下强(P<0.05),达到最大值84.02%,与扫描电镜结果一致,网络结构致密且光滑平整。pH 6.5时,混合蛋白热凝胶的消化率达91.57%,高于其它pH值下的消化率(P<0.05)。因此,通过调节pH值可以改善FPI和SPI混合蛋白热凝胶的凝胶特性和消化性。

Effect of pH Value on Gelling Properties and in vitro Digestibility of Heat-induced Gel from Tilapia Protein-Soy Protein Mixtures

Tilapia and soy were used to extract fish protein isolate(FPI)and soy protein isolate(SPI),and the heat-induced tilapia protein-soy protein(FPI∶SPI=1∶1,mass ratio)gel was prepared.Thermally induced gels were used to investigate effect of pH(6.0,6.5,7.0,7.5)on the gelling properties and in vitro digestibility of the mixed proteins gel was determined.The results showed that at pH 6.5,the elasticity modulus G′value of the tilapia protein-soy protein mixed protein gel was greater than the elasticity modulus G′value of the single protein.The pH value affected the binding capacity of the protein and water molecules,making the water retention capacity of the mixed protein gel at pH 6.5 stronger than other pH values(P<0.05),reaching a maximum value of 84.02%,which was consistent with the scanning electron microscope results.The network structure was dense and smooth.At pH 6.5,the digestibility of tilapia-soybean protein thermogel was 91.57%higher than other pH values(P<0.05).Therefore,by adjusting the pH value,the gel properties and digestibility of the mixed protein thermogel of FPI and SPI could be improved.