Physicochemical Stability of Maize Germ Oil Body Emulsions As Influenced by Oil Body Surface−Xanthan Gum Interactions

Abstract

Two types of oil body cream, differing in protein content and composition, were prepared from maize germ. The cream rich in extraneous germ proteins (OB-A) constituted of oil bodies with a significantly lower size compared to the cream (OB-W) which was practically free from the extraneous germ proteins. In addition, the stability of the former cream against oil body coalescence was much higher upon long-term aging. Dilution of both creams to a 5% oil body level produced emulsions that were very unstable against creaming. The creaming stability was greatly improved following addition of 0.1% xanthan, the result being more spectacular in the case of the cream rich in extraneous maize germ proteins. The enhancement of the physical stability of oil droplets upon long-term storage is attributed to electrostatic xanthan gum-oil body surface protein interactions, verified by zeta-potential measurements, that lead to the diminution of depletion flocculation effects and to enhancement of steric stabilization due to the adsorption of the polysaccharide molecules to the oil body surface.