Evaluation and application of extracts of rosemary leaves, araçá pulp and peel of bacuri in the inhibition of the oxidation reaction of biodiesel

Abstract This research evaluated the efficiency of the extracts of aromatic plants and native fruits with antioxidant properties, such as bacuri (Platonia insignis), araca (Psidium cattleianum) and rosemary (Rosmarinus officinalis), in biodiesel, through the study of the induction period and the oxidation reaction rate constant at the temperature of 110 °C using the simplex-centroid mixtures. The araca pulp, rosemary leaves and bacuri peels extracts showed total phenol content of 3.67, 19.29 and 19.60 mgGAE/gdrymatter, respectively. The experimental design used was a simplex centroid with 7 assays and a duplicate of the central point. Biodiesel and extracts were mixed in the proportion established by the simplex-centroid experimental design, and ethyl alcohol was removed previously. All the samples with extracts showed an induction period higher than the control, indicating the antioxidant efficiency of all the extracts. All models obtained were significant at the 5% level. The most relevant results were obtained in the tests containing the highest proportions of the bacuri and rosemary leaves extracts. It was possible to obtain the optimization, in which an optimal mixture was achieved with 50% of bacuri and 50% of rosemary leaves extract, and with induction period of 8.14 h, a value above the minimum of 6 h provided in the legislation EN 14214 [ 1 ].