Effect Of Soy Soluble Polysaccharide On The Properties Of Soy Protein Gels And A Brief Study On Its Mechanism

Soy soluble polysaccharide(SSPS) is a globular polysaccharide with various functional properties, it’s applied to a variety of foods as both dietary fiber and texture modifier. Adding soy soluble polysaccharide in soy protein gels or tofu, can not only increase the dietary fiber in gels but may also improve its texture. No reports on the effect of soy soluble polysaccharide addition on the gel behavior of soy protein gels is available until now. This thesis is aimed to study the impact of soy soluble polysaccharide on the gel performance of soy protein gels, the mechanisms underlying this phenomena is also studied. This research can provide some theory basis for the application of soy soluble polysaccharide on soy protein gels and tofu.When Ca SO4,GDL or TGase were applied as coagulant respectively, the gel performance after SSPS addition were studied. When Ca SO4 or GDL served as coagulant, as SSPS addition increase, the gel strength and water holding capacity of soy protein gels decreased, core size of the gels increased. When TGase was performed as coagulant, the situation was much different from those of the other two coagulants. The gel strength increased as SSPS addition increased from 0% to 0.75% and decreased as it increased from 0.75% to 1.25%. As the SSPS addition increased from 0% to 1.25%, the core size of the gel microstructure increased and the WHC value decreased.Study was conducted using zeta potential method to learn the way SSPS affect soy protein gels when GDL was applied as coagulant. For each SSPS addition, as the p H value decreased, the zeta potential value increased; for each p H value, as the SSPS addition increased, zeta potential value decreased. Solvents whose p H value were 7, 6, or 2.5, 2 were transparent or near transparent. As for other treatments, the system was either opaque or formed big aggregates. As SSPS addition increased, the p H for forming big aggregates decreased, when SSPS addition were 1% and 1.25%, no big aggregates were detected for all p H. Which suggested that as SSPS addition improved, the amount of soy protein taking part in gel formation decreased.SDS-PAGE profile and enzyme digested SSPS were used to study how SSPS change the gel behavior of soy protein gels coagulated by TGase. For SDS-PAGE profile, soy protein gels with 0.75% SSPS addition coagulated by TGase can be stained by glycoprotein method. And the pectinase treated SSPS has a positive impact on the formation of soy protein gels, while the trypsin treated SSPS has a negative impact on the gel strength of soy protein gels. Which indicated that the protein moiety linked to SSPS may participate in the gelation of soy protein and improve its gel strength in this way.