Physicochemical evaluation of the oil obtained from the coffee bean (Coffea arabica) using different extraction methods for its potential use in the production of biodiesel

Abstract

Biodiesel is a renewable, biodegradable, and non-toxic fuel, comprised of monoalkyl esters of long-chain fatty acids derived from vegetable oils or animal fats. Worldwide, the need has arisen to search for new production alternatives from agro-industrial residues such as coffee grounds.  The purpose of this research was to find a method for oil extraction from spent coffee grounds for its subsequent use in the production of biodiesel. The oil extraction process was carried out through steam stripping, Soxhlet, and mechanical agitation methods; using different solvents such as water, hexane, ether, and methanol, the best result was observed with the Soxhlet method using hexane as a solvent. Physicochemical characterization of the oil obtained was made. It was concluded that the oil obtained from spent coffee grounds presents adequate physicochemical properties to be used in the biodiesel production according to Colombian technical standards, because its low humidity, acidity, iodine, and saponification index give it stability against undesired reactions such as the formation of soaps or gums as well as reducing oxidation, polymerization or hydrolysis processes..