THE EFFECT OF ETHANOL SOLVENT AND COLD PRESS EXTRACTION ON THE YIELD, PHYSICOCHEMICAL PROPERTIES, AND FATTY ACID PROFILE OF OKRA (ABELMOSCHUS ESCULENTUS L. 'AKROFU') SEED OIL

Abstract

The search for novel and sustainable sources of edible oils has intensified due to global food security concerns. Okra (Abelmoschus esculentus L.) seeds, often a post-harvest waste product, contain a significant amount of oil rich in unsaturated fatty acids, yet they remain underutilized. The extraction method critically influences the oil's yield, quality, and applicability. The study aimed to comprehensively evaluate the effects of two extraction methods ethanol solvent extraction (a green alternative) and cold press extraction (a non-thermal method) on the oil yield, physicochemical properties, proximate composition, and fatty acid profile of seeds from the Ghanaian 'Akrofu' okra variety. Okra seeds were subjected to oil extraction using both ethanol solvent (Soxhlet apparatus) and mechanical cold pressing. The extracted oils were analyzed using standard methods for yield, free fatty acids (FFA), peroxide value (PV), saponification value (SV), iodine value (IV), acid value, refractive index, moisture, ash, crude fibre, protein, carbohydrate, and key fatty acids (oleic and linoleic). Ethanol solvent extraction yielded a significantly higher quantity of oil (5.5 mL from 504.97g seeds) compared to cold press extraction (4.3 mL). However, cold-pressed oil demonstrated superior quality markers, including significantly lower FFA (0.775% vs. 0.825%) and a more desirable refractive index. Both methods produced oils with high saponification values (133.62 - 134.89 mg KOH/g) and iodine values (101.0 - 101.5 g I₂/100g), consistent with global standards for edible oils. The oil was predominantly unsaturated, with linoleic acid (an omega-6 fatty acid) being the most abundant (48.81 - 49.54%), followed by oleic acid (an omega-9 fatty acid) at 16.59 - 16.81%. The study confirms a clear trade-off: ethanol extraction maximizes yield, while cold pressing optimizes oil quality. The exceptionally high content of nutritionally valuable unsaturated fatty acids, particularly linoleic acid, positions 'Akrofu' okra seed oil as a promising and viable source of high-quality edible oil with significant potential for commercialization and improving nutritional outcomes in sub-Saharan Africa.