A Comparative Study of the Physicochemical Characteristics of Certain Fatty Bases in Topical Formulation

Purpose: To investigate the physicochemical characteristics of shea butter and theobroma fats using wool fat as a standard base in the formulation of topical applications. Methods: Aqueous emulsions of shea butter and theobroma fats were made using wool fat as a standard base. Physical parameters such as absorption capacity in aqueous and organic media, slip-up point, density, water uptake capacity, acid value and peroxide values were evaluated. The globule structural stability of the formulations was evaluated in terms of sizes, coalescence and changes in the viscosity on storage for six weeks. Results: Melting of the shea butter, theobroma and wool fat commenced at 33±0.6 °C, 31±0.2 °C and 38±0.4 °C, respectively. The respective densities were 0.84±0.01g.cm-3, 0.89±0.01g.cm-3 and 0.87 ±0.04 g.cm-3. Water uptake capacity of shea butter was 19.16±1.6 and this compared favourably with that of theobroma fat (26.6±0.4) which was about half the capacity of wool fat (54±1.1). Acid value of shea butter fat was relatively higher than those of wool fat (2.9±1.1) and theobroma fat (1.5±0.1). Emulsions formed from the fats were found to be stable within the first two weeks of storage after which creaming occurred and they finally coalesced to form a heterogenous system. Generally, all the emulsions manifested decreases in viscosities which were more marked in the shea butter and theobroma than the wool fat. Conclusion: In the formulation of topical preparations, both shea butter and theobroma demonstrated closely related physicochemical and emulsion properties with the standard wool fat and therefore can be substituted for wool fat. Keywords: Shea butter, Theobroma, Fatty bases, Topical formulation, Viscosity