Gas Chromatography Mass Spectroscopy (GC-MS) Characterization and Physicochemical Evaluation of DialiumGuineense (African Black Velvet Tamarind) Seed Oil

Abstract

Vegetable oils obtained from different oil plants are mainly used as a source of food and in the production of cosmetics, lubricants, paints, pharmaceuticals, biodiesel, among others.  Nowadays, plant –based oils contain a variety of phytochemicals and are largely preferred to animal fat because of its low or complete absence of cholesterol, presence of unsaturated free fatty acids, complex carbohydrates and fat-soluble vitamins like as A, D, E, and K. This study aimed to determine the physicochemical properties of Dialiumguineense (African black velvet tamarind) seed oil as well as to determine the bioactive compounds present in order to ascertain its suitability for consumption and industrial uses. This study assessed the moisture content, acid value, iodine value, peroxide value, free fatty acid, saponification value, specific gravity, colour and unsaponifiable matter of the seed oil obtained from Dialiumguineense dried fruit purchased from Itam market, Uyo, Akwa Ibom State, Nigeria. The seed oil was also characterized to determine the bioactive compounds present. The physicochemical properties and bioactive compounds of Dialiumguineense seed oil were evaluated using standard methods and Gas Chromatography-Mass Spectrometry (GC-MS) respectively. Results of the physicochemical properties indicated that some key properties such as acid value (14.52 mg KOH/g), iodine value (17.8g/100g), and peroxide value (4.075 meq O2/kg), were within acceptable industrial limits, except for moisture content (3.06%), which exceeded the permissible range. GC-MS analysis identified 65 compounds, with major bioactive components such as undecane, azulene, dodacane, naphthalene, 9,12-Octadecadienoic acid, n-hexadecanoic acid, cis-vaccenic acid, octadecanoic acid, squalene and vitamin E. The biological activities of each of the identified phyto-components ranged from antimicrobial, anti-inflammatory, anticancer, antioxidant and antitumor activities. This study further revealed that the seed oil of Dialiumguineense has many bioactive compounds of biological importance; hence it is fit for consumption and industrial uses.