EFFECTS OF POLYSACCHARIDES UPON THE FUNCTIONAL-PROPERTIES OF 11-S GLOBULIN OF BROAD BEANS

The effect of polysaccharides upon the conformational stability, emulsifying properties and thermal gelation ability of the 11 S globulin (legumin) from broad beans under conditions of both protein-polysaccharide incompatibility and complex formation has been investigated. Under conditions of incompatibility (pH 7.6 for carboxyl-containing and neutral polysaccharides) the conformational stability of the legumin is not changed by the presence of the polysaccharides. At the same time a significant decrease in the emulsifying threshold and an increase in the stability of oil-in-water emulsions, stabilized by the protein, as well as some decrease in the gelation threshold in the presence of polysaccharides have been observed. Under conditions of legumin-polysaccharide complex formation (pH 4.2-6.0, low ionic strength for carboxyl- and sulphate-containing polysaccharides) a significant decrease in the temperature and enthalpy of legumin denaturation as well as a decrease in the minimum biopolymer concentration required for emulsions formation and an increase in emulsion stability have been observed. As a rule, legumin-polysaccharide complexes were poorly soluble even at a substantial excess of polysaccharide. Their solubility which was independent of the method of mixing was a limiting factor for preparing gels and stable foams on using these complexes.