Contribution of Free Fatty Acids to Emulsion Building and Stability: Understanding the Mechanism From the Case Study of a Crude Red Palm Oil ( <i>Elaeis guineensis</i> )—Based Emulsion Consumed in Africa and Known as Achu Soup/Sauce Jaune/Ncha

Abstract

ABSTRACT In edible emulsions, residual free fatty acids from oils are the primary drivers of lipid oxidation which adversely affects appearance, sensory properties and nutritional quality. These free fatty acids can be significantly reduced if converted into emulsifiers during emulsion preparation. This study helps to understand the mechanism of what happens during Achu Soup / Sauce Jaune / Ncha preparation, a traditional African emulsion prepared from crude red palm oil ( Elaeis guineensis ) and an alkaline solution without added emulsifiers. The effect of oil type (canola oil, olive oil and crude red palm oil), the nature of solutions used (alkaline and non‐alkaline solutions) and the successive refining steps of crude red palm oil (deacidification, degumming and bleaching) were evaluated. Oils and solutions used were characterised (chemical composition and acid value for oils; pH, anions and cations content for constituents used to prepare solutions). Results demonstrate that emulsion formation with crude red palm oil in the presence of an alkaline solution occurs via mild saponification between solution alkalinity and oil free fatty acids. Free fatty acids are a major contributor to both emulsion formation and physical stability. For the same proportion of oil and water, the higher the alkalinity of a solution, the higher the macroscopic homogeneity of the resulting emulsion. For the same alkaline solution, the higher the free fatty acids content of the oil, the higher the macroscopic homogeneity of the resulting emulsion.