Evaluation of antioxidant activity of natural extracts on the oxidative stability of cottonseed biodiesel

Abstract

The objective of this study was to evaluate the antioxidant activity of the natural extracts catechin, curcumin and quercetin on the oxidative stability of methylic cottonseed oil biodiesel. The oxidative stability was evaluated using the Rancimat method (EN 14112) for biodiesel with 500, 1000, 1500, 2000 and 3000 ppm of additives, and compared with the commercial antioxidant butyl hydroxyanisole at the same concentrations. Kinematic viscosity was also evaluated at the same concentration. All additives had a positive effect on the oxidative stability; moreover, all extracts presented better results than BHA. Catechin was the most effective additive, achieving an induction period almost three times greater than BHA for 3000 ppm. In addition, all three extracts caused a reduction in kinematic viscosity, but it remained within the technical specification. These results prove catechin, curcumin and quercetin to be powerful natural antioxidants.