Potential use of trona (kaun) and goat fat in the in-situ emulsification of coconut oil to form creams

Abstract

The study was carried out to investigate the in situ emulsifying property of trona (an alkaline mineral) and the influence of goat fat on the consistency and stability of the resulting emulsions formed by mixing an aqueous solution consisting of cetomacrogol (20%w/v), trona (in varying concentrations, 0.5 to 3%w/v) with an oil mixture consisting of coconut oil and goat fat in varying proportions. The emulsions were evaluated for creaming rate (liquid emulsions only), consistency, and globule structure. Emulsions were also formed with well-known surfactants- (cetrimide and sodium lauryl sulphate) as standards. Stable emulsions (without creaming) were formed when the trona or surfactant concentrations were not less than 2.5%w/v. Lower concentrations produced emulsions with varying degrees of creaming (10-50%) within 2 weeks. Inclusion of goat fat (up to 20%w/v in the oil phase) increased the consistency of the emulsions from liquid to a semisolid state. The consistency further increased during storage at 30°C for 2 weeks. The depth of penetration of a plunger into the cream samples (measure of consistency) was 10mm (fresh samples) and 2mm (aged samples). Trona produced creams with the finest globule size compared with cetrimide or sodium lauryl sulphate. The mean globule sizes of the freshly prepared cream samples were 2.3 ± 1.1μm (trona), 7.5±1.4μm (cetrimide) and 16.2±1.2 (sodium lauryl sulphate). There was no significant increase (p>0.05) in globule size in the aged cream samples, indicating that the creams were generally stable. The liquid emulsion without goat fat showed a significant change in the globule structure for the aged samples, indicating instability. Thus, trona has a potential in the in situ emulsification of the vegetable oil, and goat fat imparted a cream consistency and stability to resulting emulsions.