大豆可溶性多糖对大豆分离蛋白的物性修饰

Modification of Physicochemical Properties of Soy Protein Isolate by Soybean Soluble Polysaccharide

在60℃,相对湿度为79%的条件下,通过Maillard反应进行共价接枝,得到大豆分离蛋白(SPI)-大豆可溶性多糖(SSPS)共价接枝物(SSC).根据糖基化产物在SPI等电点附近(pH=4.5)和中性条件(pH=6.5)下的溶解性将其分成两个组分SC45和SC65,对其进行SDS-PAGE凝胶电泳,并分析了其浊度、粒径和Zeta电位等物化性质.结果显示:反应后生成大相对分子质量的接枝物,SPI的7S和11S中各亚基均参与了糖基化反应,SSC两个组分的接枝度分别高达41.79%和36.75%;SC45在酸性环境中的浊度显著低于SC65,说明SC45在蛋白的等电点附近溶解性能优越,能有效降低蛋白的自聚集;SSC的稳定性主要是由接入的SSPS分子亲水侧链空间位阻作用提供的.

Soy protein isolate( SPI)-soybean soluble polysaccharide( SSPS) conjugates( SSC) were prepared through a Maillard reaction at 60 ℃ for seven days with a relative humidity of 79% . Then,the product was separated into two components( namely,SC45 and SC65) on the basis of their solubility at pH4. 5( near the isoelectric point of the SPI) and pH6. 5( neutral condition) respectively. Finally,the two components were characterized through SDS-PAGE and were analyzed in terms of turbidity,particle size and Zeta potential. The results show that( 1) the graft of a higher relative molecular mass forms after the reaction,and each subunit in the 7 S and 11 S of the SPI is involved in the glycation reaction;( 2) the graft degrees of the two components are respectively up to 41. 79% and 36. 75% ;( 3) in acid conditions,the turbidity of SC45 is significantly lower than that of SC65,meaning that SC45 has a better solubility near the isoelectric point and can effectively reduce the self-aggregation of the protein; and( 4) the stability of the SSC depends on the steric hindrance caused by the hydrophilic side chains of the SSPS.