Effect of some stabilizing agents on globule characteristics and rheological properties of oil in water emulsions

Abstract

This study investigated the effects of some stabilizing agents (cassava, maize and bentonite mucilages) on globule characteristics and rheological properties of oil in water emulsions. Emulsions were prepared by mixing varying proportions of the mucilages with Arachis oil in the ratio of 60:40 (oil: water) with the aid of a mixer. Parameters evaluated were globule sizes and numbers, and flow properties of fresh and aged emulsions. Generally, starch mucilages and their emulsified systems displayed higher viscosities compared with that of bentonite mucilage and its emulsified system. For instance, mean values of viscosities of the mucilages at 4%w/v expressed in centipoises (cP) were 1448 ± 1.2 (cassava mucilage), 1140 ± 0.4 (maize mucilage) and 36 ± 2.1 (bentonite mucilage), while the emulsified systems were 1730 ± 1.3 (cassava emulsion), 1206 ± 0.8 (maize emulsion) and 22 ± 0.9 (bentonite emulsion) respectively. Globules were uniformly distributed. There was a general increase in globule sizes with time ranging from 12.44 – 23.16 μm (cassava emulsion), 18.92 – 31.12 μm (maize emulsion) and 26.17 – μm (bentonite emulsion) respectively and this is an indication of globule coalescence. However, the globules ruptured and disappeared within two weeks of storage. Globule coalescence was inversely related to the viscosity of the dispersed medium. The study has shown that inclusion of viscosity impacting agents in the dispersion medium in emulsified systems play vital role in the stability of emulsions. This finding has useful application in the formulation of drugs in dispersed systems.

Keywords: Viscosity impacting agents; Mucilage, Globule stability, Dispersed medium; Flow