Comparison of sugar beet pectin, soybean soluble polysaccharide, and gum arabic as food emulsifiers. 1. Effect of concentration, pH, and salts on the emulsifying properties

Abstract

The present study compares the emulsifying properties of sugar beet pectin (SBP), soybean soluble polysaccharide (SSPS), and gum arabic (GA) in oil-in-water (O/W) emulsions. Emulsifying properties of each hydrocolloid were evaluated in terms of the emulsion droplet-size distribution, adsorption behavior at the oil–water interface, and the zeta potential. The standard emulsion contained 15 w/w% medium-chain triglyceride as the oil source and was processed with two passes through a high-pressure homogenizer at 50 MPa. The surface-volume mean diameter d 3,2 of the emulsions (pH 3.0) was equilibrated at <1.0 μm when the concentration of each hydrocolloid was equal to or higher than 1.5%, 4.0%, and 10.0% for SBP, SSPS, and GA, respectively, where the apparent shear viscosities of the emulsions at 10 s −1 were almost equivalent (30–35 mPa s). At these critical concentrations, the interfacial concentration of each hydrocolloid was in the order: SBP<SSPS<GA. Thus, SBP required the smallest amount to cover the surface of the oil droplets and to activate the interface. The zeta potential of the emulsions was in the order: GA<SSPS<SBP, indicating that electrostatically SBP was the most effective in stabilizing the emulsions. This was not compatible with the change in the d 3,2 upon storage, however, indicating that steric factors have a more important effect on the emulsion stability. The effect of pH and salts on the emulsifying properties of each hydrocolloid was also compared.