热变性程度对谷氨酰胺转氨酶诱导大豆分离蛋白凝胶性质的影响

Effect of heating denaturation degree on gel properties of soy protein induced by transglutaminase

大豆分离蛋白(soybean protein isolated,SPI)由于在实际生产过程中工艺不同导致其结构和性质不一,会影响最终谷氨酰胺转氨酶(glutamine transaminase,TG酶)诱导形成的凝胶类产品。为探索不同结构SPI对酶诱导蛋白凝胶的影响,制备了不同热变性程度的SPI,研究其蛋白组成、表面疏水性、溶解性、粒径分布以及凝胶强度、持水性和凝胶形态。结果表明,热处理加剧SPI亚基的解离与聚集,并导致SPI的表面疏水性增强、溶解性下降,同时,粒径随温度的升高而增大,但升至95℃后减小。SPI凝胶强度在85℃时最低,而在95℃时最高。对于95℃热处理SPI的凝胶,随着蛋白浓度的增大,凝胶强度增大,气孔增多;随着TG酶浓度的增加,凝胶强度增大,而持水性在TG酶浓度为1.80 U/g时达到最低,同时气孔较多;50℃培养的SPI凝胶强度高于4℃培养样品。结果表明,大豆蛋白一定程度的热变性(尤其95℃热处理)有利于经TG酶诱导形成蛋白凝胶,这为工业生产提供了一定的理论依据。

Due to different techniques used in the actual production process,the structure and properties of soy protein isolate(SPI)were quite different,which affect the gel-like products induced by transglutaminase(TG).In order to investigate the effect of SPIs with different structures on enzyme-induced protein gels,SPIs with different degrees of denaturation by heat treatment were prepared.The protein composition,surface hydrophobicity,solubility,particle size distribution,gel strength,water holding capacity and gel morphology were studied.The results showed that heat treatment exacerbate the dissociation and aggregation of SPI subunits,resulting in enhanced surface hydrophobicity and decreased solubility of SPI.The particle size increased with the increase of temperature,but decreased when it rose to 95℃.The protein gel strength was lowest at 85℃and highest at 95℃.For the gel of heat-treated protein at 95℃,with the increasing of protein concentration,the gel strength and the number of pores increased.The gel strength increased with the increase of TG concentration,while the water holding capacity was the lowest at TG concentration of 1.80 U/g,and the pores increased.SPI gels incubated at 50℃are stronger than samples incubated at 4℃.The results demonstrated that a certain degree of heating denaturation of SPI(especially heat treatment at 95℃)is conducive to the formation of protein gels induced by TG,which provides a certain theoretical basis for industrial production.