Soy soluble polysaccharide stabilization at oil–water interfaces

Soybean soluble polysaccharide (SSPS) is obtained from the by-product of the production of soy protein. SSPS has been employed as a functional ingredient in numerous food applications. When used to prepare oil-in-water emulsions, SSPS forms thick, stable interfaces in a wide pH range, in both acidic and neutral conditions. SSPS forms stable interfacial layers at relatively low biopolymer concentrations (about 4% (w/w) in 20% (w/w) oil-in-water emulsions), and although rich in galacturonic acid, its functionality does not seem to be affected by varying concentration of cations. This work describes the emulsifying properties of SSPS and its stability under various environmental conditions and the principles that regulate the stabilization behavior of this polysaccharide. SSPS contains a high molecular weight polysaccharide fraction with interfacial properties and a small molecular weight fraction. A polypeptide fraction, with an estimated molecular mass of 50 kDa, is covalently linked to the SSPS backbone chains and acts as an anchor to the oil–water interface. The carbohydrate moieties of the SSPS stabilize the emulsion droplets via steric interactions, forming a thick (ranging between 15 and 30 nm, depending on the SSPS type), hydrated layer on the surface of the oil droplet.