Determination of Hydrophile - Lipophile Balance Value of Raphia hookeri Mann (Family: Palmae) Gum by Emulsification Method

Abstract

Background: The hydrophile-lipophile balance (HLB) value is the major determinant of the applications of surfactants and any material that has potential for surface activity.
Objective: To determine the HLB value of Raphia hookeri Mann (Family: Palmae) gum by emulsification method.
Methods: Exudates of Raphia hookeri were collected and the gum was extracted and purified via dissolution in water, precipitation using ethanol, defatting using diethyl ether, oven-drying and pulverization. The pH and viscosity of 3 %w/v dispersion of the gum were determined in comparison with those of Tween 80 and Span 60. Series of emulsions were formed with the gum and Tween 80 as well as the gum and Span 60, in varying ratios of 1:5, 1:2, 1:1, 2:1 and 5:1. The emulsions were kept for 5 days at room temperature after which they were assessed for stability by checking the extent of creaming. The most stable emulsion was selected and the fractions of gum and standard surfactant incorporated were used for calculating the HLB value of the gum.
Results: The pH of 3 %w/v dispersions was in the order: Raphia hookeri gum < Span 60 < Tween 80 while the viscosity of the dispersion of Raphia hookeri gum was found to be more than four folds higher than those of Span 60 and Tween 80. The most stable emulsion was found to be the one containing Raphia gum and Tween 80 in ratio of 5:1 and the HLB value of the gum was found to be 11.44.
Conclusion: Raphia hookeri gum is more acidic and produces more viscous dispersion compared to Tween 80 and Span 60. The HLB value of the gum falls within the range of 8 - 16 which is characteristic of oil-in-water emulsifiers.

Keywords: Raphia hookeri Mann, Gum, Hydrophile-lipophile balance, Emulsification.