Influence of selected physicochemical factors on the stability of emulsions stabilized by Bambara groundnut flour and starch

Abstract

There is a continuous search for suitable emulsifiers of natural origin that can be used in food and pharmaceutical emulsions. Bambara groundnut is an important source of nutrient in many African communities with rich blend of high protein and carbohydrate composition which makes it a potential candidate as an emulsifier, and where it can serve additional nutritional role in such emulsions. The current study aimed at investigating the stability of Bambara groundnut-stabilized emulsions physicochemical changes. The stability of the emulsions increased significantly with the speed of homogenization (up to 15, 000 rpm beyond which the difference in stability was not significant). Compared to control (pH 7), emulsion stability decreased with acidity (about 80 % stability by Day-5 at pH 2) and alkalinity (90 % stability at pH 10 by Day 5) with corresponding increase in droplet size. Emulsion stability increased with increasing NaCl concentration (65 % stability at 2 % NaCl compared to 82 % stability at 10 % NaCl). Stability however decreased sharply with increasing concentration of vinegar (45 % stability at 10 % vinegar compared to 81 % stability at 2 % vinegar). The Bambara groundnut flour-stabilized emulsions were more stable (ordinarily and in the presence of the additives) than the Bambara groundnut starch-stabilized ones. Stability values in the Bambara groundnut flour emulsions, in most cases, double those for Bambara groundnut starch.