Stabilization of Multilayer Emulsion as Influenced by Sweet Potato Pectin Concentration, pH and Salt

Abstract

This study aimed to investigate the effect of sweet potato pectin concentration, pH and salt on the stability of whey protein isolate (WPI)-stabilized oil-in-water emulsion. Primary emulsion stabilized by WPI was produced by homogenization using Microfluidizer. Sweet potato pectin was added to the primary emulsion at different concentrations (0 – 1.2 wt %) to produce multilayer emulsion. Particle size, zeta-potential and creaming index of the multilayer emulsion was analysed at different pectin concentrations (0 – 1.2 wt %), pH (3 – 7) and salt concentrations (0 – 400 mM). Decreasing of zeta-potential (+2.38 to –14.8 mV) showed the adsorption of pectin layer around the emulsion droplets. Creaming index was the lowest (3.64%) at the highest pectin concentration (1.2 wt%) which showed great stability against creaming. Multilayer emulsion showed better stability at high pectin concentration and has better stability at a wider range of salt concentration compared to primary emulsion. Pectin addition largely improved the stability of emulsion especially at pH 4 and 5. Multilayer emulsion prepared using sweet potato pectin can be utilized to produce food emulsion with good stability against environmental stresses (pH and salt content).