Evaluation of Chemical Properties of Crude and Processed Palm Kernel Oil from South South Nigeria

Palm kernel oil, derived from the kernel of the oil palm fruit, is an important edible oil and raw material for soap and oleochemical industries in South South Nigeria, but its chemical quality across different processing levels and sources has not been systematically evaluated for professional guidance. This study evaluated the chemical properties of crude palm kernel oil and processed palm kernel oil collected from smallholder processors, medium-scale refineries, and large industrial processors in Rivers and Edo States. Twenty-five samples at each processing level were collected and analysed for free fatty acid content, iodine value, saponification value, peroxide value, moisture and volatile matter content, unsaponifiable matter, and fatty acid composition by gas chromatography with flame ionisation detection. Free fatty acid content showed a wide range from 1.2 percent in industrial refined oil to 18.4 percent in crude smallholder product, reflecting the significant degradation occurring without post-harvest quality control. Peroxide values were elevated in crude samples stored beyond two weeks. The fatty acid profile was dominated by lauric acid at 47 to 52 percent and myristic acid at 15 to 18 percent across all processing levels. Iodine values ranged from 14 to 22 g I2/100g. Saponification values were 240 to 258 mg KOH/g, consistent with the high proportion of medium-chain fatty acids. Industrial refined oil met all Codex Alimentarius standards. The findings recommend adoption of improved post-harvest handling and rapid processing to control free fatty acid development in smallholder palm kernel oil.

Keywords: palm kernel oil, free fatty acid, fatty acid composition, processing levels, South South Nigeria