Abstract: 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 7S and 11S 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.

Key words: soy protein isolate, soybean soluble polysaccharide, conjugate, physicochemical properties, aggregation