EFFECT OF DYING METHODS ON MOLECULAR-PROPERTIES AND FUNCTIONALITIES OF DISULFIDE BOND-CLEAVED SOY PROTEINS

Effects of drying methods on hydrophobicity, solubility, water hydrati on capacity, viscosity, and adhesive strength of soy protein isolates treated with Na2SO3 (disulfide bond-cleaving agent) were investigated. Treatment with 0.1 M Na2SO3 resulted in 28% decrease in disulfide lin kages in soy proteins. While hydrophobicity and solubility increased, water-holding capacity of soy proteins decreased due to the treatment. Spray-dried product had higher hydrophobicity, solubility, water hydr ation capacity, and viscosity compared to freeze-dried product. Adhesi ve strength on wood increased due to modification; however, the drying process had no significant effect on this property. Viscosities of sp ray-dried product, freeze-dried product, and unmodified soy proteins w ere 2,200, 100, and 240 cP, respectively. Fluorescence spectra of spra y-dried and freeze-dried products indicated a partial folding of molec ules around tryptophan. High-performance liquid chromatographic elutio n profiles showed no significant differences in molecular sizes of unf olded molecules of spray-dried and freeze-dried proteins.