Physicochemical characteristics and fatty acid composition of ginger (Zingiber Officinale) and garlic (Allium Sativum) oils cultivated in the north-central region of Nigeria

Garlic (Allium sativum) and ginger (Zingiber officinale), as cooking spices, are popular medicinal plants for treating various ailments and physiological disorders. These plants contain a lot of polyunsaturated fatty acids and other bioactive metabolites. This study aims to evaluate physicochemical properties, fatty acid profile, and quality parameters of the oil extracted from Allium sativum and Zingiber officinale.

Fresh Allium sativum and Zingiber officinale were purchased from a local market in Lafia local government, Nasarawa state, Nigeria. The samples were cleaned to remove foreign particles, sun-dried, and the oil was extracted by steam distillation. Physicochemical parameters of the extracted oil including peroxide value (PV), iodine value (IV), acid value (AV), saponification value (SV), unsaponifiable matter (USM), specific gravity (SG), and refractive index (RI) were determined using standard analytical methods, and fatty acid profile was determined by using gas chromatograph.

Physical properties of the extracted oil from Allium sativum and Zingiber officinale were in the range of 0.90-0.97 at 15 oC for SG, and 1.49-1.50 at 40 oC for RI. The chemical parameters ranged from 2.42 to 2.61 meq/kg for PV, 105.64 to 116.20 mg I2/g for IV, 2.60 to 4.52 mg KOH/g for AV, 182.15 to 191.22 mg KOH/g for SV, and 1.02 to 1.11 mg KOH/g for USM. In gas chromatography, 13 and 16 fatty acids were identified in Allium sativum oil and Zingiber officinale oil, respectively. Linoleic acid (25.81-52.20%), oleic acid (20.77-24.06%), and palmitic acid (19.75-20.52%) were the main fatty acids in both samples. The quality parameters including ratio of polyunsaturated/saturated fatty acids (0.64-2.43), ratio of hypocholesterolemic/hypercholesterolemic fatty acids (2.03-3.87), atherogenicity index (0.27-0.91), and thrombogenicity index (0.50-0.80) were within the acceptable range. The fatty acid profile and the quality parameters of the oil samples imply their medicinal and flavoring strength, and candidate them for extended use in food, drug, and cosmetics industries.