Studies on the Emulsifying Properties of Soybean Proteins

Part I. Factors affecting the emulsifying properties

Abstract

Some factors affecting the emulsifying properties of water extract, acid-precipitated protein and whey from defatted soybean meal were studied, and the following results were obtained: 1) Emulsifying capacity and interfacial tension decreased, and emulsion stability increased respectively with the increase of protein concentration. 2) Emulsifying properties of water extract and acid precipitated protein were remarkably affected by pH and minimum values were obtained at isoelectric range; on the contrary, whey was hardly affected by pH, and gave high values throughout the pH range. 3) Emulsifying properties of water extract and whey decreased slightly by heat treatment, but those of acid-precipitated protein were hardly affected by heating the protein solution. Jelly strength of emulsions from water extract and acid-precipitated protein increased by heating above 70°C. 4) Emulsion stability and jelly strength of emulsions clearly increased by the addition of sodium chloride, but emulsifying capacity increased only slightly.