Palm Kernel and coconut oils: Analytical characteristics, process technology and uses

Abstract

Palm kernel and coconut oils are the most used of the lauric acid group of oils. The characteristic of this group is their high content of saturated acids, lauric and myristic, and it is from this feature that their principal uses are derived. Due to their triglyceride composition, both oils have steep melting curves and melt below body temperature. Their low degree of unsaturation gives them high oxidative stability. As a result of these properties they are found widely used as hard butters and in vegetable fat ice-creams, coffee whiteners and similar products. Their use in margarine gives that product an attractive coolness in the mouth. Coconut oil is also used extensively as a raw material for soaps and detergents and as a body oil. The oils are susceptible to hydrolytic splitting and to trace metal catalyzed oxidation. They are particularly affected by contamination with other oils which produce either reduced oxidative stability or, when the contaminant is high melting, an unacceptable palate cling. Refining is normally done with caustic soda solutions and refining conditions are chosen to minimize neutral oil losses due to saponification. Physical refining is also practised and is particularly useful for treating palm kernel oils with high free fatty acid content. To improve their quality and applicability for several uses, both oils are hydrogenated, fractionated and interesterified in various combinations. Fractionation is done either by dry “pressing” or with the assistance of detergents or solvents, the highest quality products being obtained using solvents. The relatively high solubility of the fatty acids can result in effluent problems.