Formulation of Stable Oil-in-Water Emulsions Using Locally-Available Gum and Oils.

Oyedele, Ayobami Olutayo (1985)

Thesis

The physicochemical properties of locally prepared coconut oil, and locally obtained palm oil, are reported. The surface and interfacial properties of Zanthoxylum tessmanii gum mucilages with oils are reported and compared with those of acacia gum mucilages. The surface tension values of the mucilages, and their interfacial tension values against the oils studied, namely, arachis oil, liquid paraffin, and coconut oil, are found to be markedly affected by both the concentration of the gum mucilages and the period of time of storage of the prepared surfaces and interfaces, at 20°C. The dynamic surface and interfacial tension values are interpreted to suggest changes in the film strength at the gum mucilageair and gum mucilageoil interfaces. The emulsifying properties of the zanthoxylum and acacia gums are also studied and compared. All the gum concentrations studied, ranging from 1.56% w/v to 6.25% w/v, produced stable emulsions. The stability of the emulsions was studied by droplet size, percentage creaming, and viscometric determinations. The zanthoxylum gum produced more viscous emulsions than acacia gum, and acacia gum produced emulsions more stable to creaming and, in a few cases, more stable also to coalescence, than the zanthoxylum emulsions. The 8:8:1 oil:water:gum ratio was found to be most suitable in the preparation of primary emulsions with the zanthoxylum gum, while the 4:2:1 ratio was reaffirmed to be most suitable for the preparation of acacia primary emulsions. Stable emulsions of arachis oil, liquid paraffin, coconut oil, and palm oil, were prepared using these ratios of the gums, while the effects of emulgent concentration, oil volume fraction, and temperature, on the stability of the emulsions were examined. Emulsion stability was improved with increases in emulgent concentrations and oil volume fraction, but was decreased with increases in temperature. However, palm oil emulsions showed maximum stability between 40°C and 50°C.

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