Comparative Assessment of Extraction Techniques on the Physicochemical Properties and Fatty Acid Composition of Arachis hypogaea and Melothria sphaerocarpa Seed Oils

Abstract

Aim: This study investigated the influence of different extraction methods on the physicochemical properties and fatty acid profiles of Arachis hypogaea (groundnut) and Melothria sphaerocarpa (melon) seed oils sourced from Elele Market, Rivers State, Nigeria. Methodology: Groundnut and melon seeds were cleaned, blended, and divided into four portions. Oils were extracted using four methods: solvent (n-hexane), cold, hot, and Soxhlet extraction. The extracted oils were evaluated for yield, relative density, refractive index, viscosity, pH, moisture content, acid value, free fatty acid content, and saponification value using standard procedures. Fatty acid composition was determined via gas chromatography–mass spectrometry (GC-MS). Results: Solvent extraction yielded the highest oil content, while cold extraction produced oils with the highest density. Moisture content, pH, and saponification values remained relatively unaffected by the extraction methods. GC-MS analysis identified 12–19 fatty acid constituents in A. hypogaea oils and 5–9 in M. sphaerocarpa oils, depending on the extraction technique. Common fatty acids detected included palmitic acid, oleic acid, linoleic acid, stearic acid, and methyl stearate. Squalene and mesitylene were also identified in selected samples. Conclusion: The extraction methods significantly influenced the oil yield, some physicochemical properties, and the fatty acid composition of A. hypogaea and M. sphaerocarpa seed oils. These findings offer valuable insights for optimizing oil processing techniques for nutritional, industrial, and cosmetic applications.