Emulsifying Properties of Afzelia Gum in Liquid Paraffin Emulsion

Abstract

Objective: Afzelia africana gum has been shown to possess surface activity. It is a good alternative to sodium carboxy methylcellulose in terms of suspending properties. This work was aimed at evaluating the emulsifying properties of the gum in liquid paraffin emulsion.Methods: Liquid paraffin emulsions (200 ml each) were prepared with different concentrations (1, 2, 3, 5 and 10 % w/v) of afzelia gum as an emulsifying agent. Similar preparations containing standard acacia gum at corresponding concentrations were also made. Liquid paraffin emulsions (200 ml each) were equally prepared using 60 ml liquid paraffin as the oily phase and 6 g of various combinations of afzelia gum and tween 80 as emulsifier blends. The emulsifier blends were of ratio 1:5, 1:2, 1:1, 2:1 and 5:1. The preparations were assessed for density and viscosity; and then for stability after 5 d of storage. Results:The viscosity of emulsion containing 10 % w/v afzelia gum was 668.90 mPa.s while that of an emulsion containing the same concentration of acacia gum was 23.56 mPa. s. Emulsion containing 3 % w/v afzelia gum (having a creaming index of 16 %) was found to be more stable compared to the emulsion containing 10 % w/v acacia gum (having creaming index of 28 %). The viscosity and stability of emulsions containing emulsifier blends of afzelia gum and tween 80 increased with increase in the proportion of afzelia gum. Conclusion:The gum is suitable for use at a concentration of 3 % w/v as an emulsifier in 30 % v/v liquid paraffin emulsion, and it is about three times better than acacia gum as an emulsifier. It is a good alternative to standard acacia gum for emulsification.

Emulsifying Properties of Hemicelluloses

“…Xylans are heteropolymers having a β- (1,4) linked backbone made of D-xylose. They are the major hemicelluloses in hardwood.…”

“…Hemicelluloses act by modifying the viscosity of dispersions [1]. They increase the consistency of dispersion media thereby inhibiting creaming and coalescence.…”

“…The variation may be related to the plant species, time of collection or method of extraction. This often results in variation of the emulsifying properties [1].…”

“…In terms of complexity, they are intermediate between gums and celluloses, and they have properties similar to these polymers. They are gummy in nature and can be investigated for their emulsifying properties just like gums and celluloses [1].…”

“…Emulsions are thermodynamically unstable formulations and tend to separate into the oil and aqueous phases [1]. Hence, there is a need for the incorporation of the third substance called emulsifier or emulsifying agent.…”