Interaction of soy isolate with polysaccharide and its effect on film properties

When soy isolate was mixed with sodium alginate, the two polymers interacted to form electrostatic complexes. They also formed varying degrees of covalent bonding, depending on reaction time and the presence or absence of the reducing agent sodium cyanoborohydride. On the other hand, soy isolate and propyleneglycol alginate (PGA) formed mostly covalent complexes at alkaline pH. The interaction of soy protein with polysaccharide maintained or improved its solubility and emulsifying activity, particularly when covalent bonds were involved. The alkylated complexes also showed better film-making properties. However, protein-PGA films were more readily formed and had greater stability in water than the protein-alginate films.