Kinetics of Autoxidation of an Oil Extract from Terminalia catappa

Soxhlet extractor was used in the extraction of oil from milled seeds of Terminalia catappa using petroleum ether (40-60°). The optimal oil yield was 56.71±1.66% with a viscosity of 40.79±1.05 centipoises. Other parameters of the oil were found as follows; specific gravity-0.9248, refractive index-1.4646, acid value-3.35, peroxide value-8.6, saponification value-166.2, and unsaponifiable matter-1.46. The crude oil extract was water-degummed, bleached and deodorized to generate what we called refined oil. Autoxidation of the crude and refined T. catappa oil extract was done at five different temperatures of 0±0.1°, 20±0.1°, 40±0.1°, 60±0.1° and 80±0.1° and also in the presence of pure α-tocopherol at a concentration of 1.0% (w/v) by measuring peroxide value variations over 96 h. In all evaluations, the refined oil exhibited lower tendency towards autoxidation but not at temperatures above 60±0.1°. The use of Arrhenius equation revealed generally very low activation energies of 0.0261 cal/deg×mol and 0.0122cal/deg×mol for crude oil and antioxidant-treated crude oil, respectively and 0.0690 cal/deg×mol and 0.0177 cal/deg×mol for the refined oil. This study indicates T. catappa seed oil to be potential pharmaceutical oil with excellent characteristics.