Influence of Grewia polysaccharides on the stability of oil-in-water emulsions

Abstract

The aqueous dispersion of the polysaccharide isolatedfrom the inner bark of the stem of Grewiamollis exhibits a relatively high viscosity at low concentrations.Two extraction methods were adopted to isolate twodifferent polysaccharide fractions from the plant – the native grewiapolysaccharide gum (GPG) and the starch-free grewia polysaccharide (SFGP). Theinfluence of these polysaccharides on the stability of oil – in – wateremulsions was investigated at three concentrations – 0.5%, 1.0% and 1.5% w/v.Theformulated emulsions were evaluated using parameters such as emulsionstability, storage stability, creaming index, heat stability, globule size andsize distribution, and emulsion rheology. The results show that the GPGformulated emulsions were more stable than the SFGP emulsions at each paritylevel of concentration, exhibiting better emulsion/storage stability, lowercreaming index and finer microstructure which were concentration dependent. Thehigher degree of esterification of SFGP did not result in correspondingimprovement in emulsion stability over GPG-containing emulsions. GPG may bepreferable to SFGP when stabilization of oil-in-water emulsions is indicated.