Influence of the degree of esterification of soluble soybean polysaccharide on the stability of acidified milk drinks

Abstract Soluble soybean polysaccharide (SSPS), an anionic polysaccharide extracted from the by-product of soybean protein, has been widely used as a stabilizer for the stabilization of casein dispersions. The methyl esterified carboxylic group of galacturonic acid (GalA) in SSPS has a vital influence on its physicochemical and functional properties. In particular, the degree of esterification (DE) of SSPS plays an important role in the stability of acidified milk drinks (AMDs). Thus, in this work, the DE of SSPS was determined by 1H NMR spectroscopy and titration method. The influence of DE of SSPS on the stability of AMDs was comprehensively investigated and evaluated by using LUMiSizer. It was found that the SSPS with a low DE showed better stabilization in AMDs compared to SSPS with a high DE. Zeta potential measurements can aid in elucidating the mechanisms responsible for the improved stability of AMDs, which showed that the decrease in DE resulted in the more negative zeta potential of SPSS coated casein particles. These results demonstrated that SSPS with a low DE has a high ability to stabilize AMDs, mostly due to the large electrostatic repulsive force of SSPS and the steric repulsive force of adsorption layer that is formed on the surface of casein particles.