Avaliação do óleo de partes distintas do tambaqui (Colossoma macropomun) e aproveitamento de seus resíduos na produção de biodiesel

Abstract

Due to the need to expand the energy supply, there is an increasing search for renewable energy. Vegetable oils, animal fats, recovered cooking oils and wastes from fish production are being appraised. The present work aimed evaluate, by different extraction methods, the yield of oil from different parts from the Tambaqui (Colossoma macropomum), including its wastes, determine the fatty acid composition of oils obtained and produce biodiesel taking advantage of this fish wastes. In this work we evaluate methods of oils in cold extraction, with fresh material using the Folch method and extraction with hexane; Cold extraction, using dehydrated material utilizing the Duarte modified methodology and finally the conventional Soxhlet extraction. The oils obtained were initially analyzed by thin layer chromatography (TLC) and immediately converted to the respective methyl esters of fatty acid. It was also extract oils from the Tambaqui offal, by heating in a stove at 60º C. The oil used in biodiesel production was submitted to physicochemical analysis, immediately esterified by the Fischer method using methanol, to reduce its acidity, and immediately submitted to alkaline transesterification. The fatty acid composition, from de oils obtained and from biodiesel, was determined by gas chromatography utilizing flame ionization detector (GC-FID). The biodiesel properties were determined according to instructions from the Brazilian National Agency of Petroleum, Natural Gas and Biofuels (ANP) by the resolution Nº 7, 2008. According to the results obtained, the oil extraction method that presented the best yield was the Duarte modified methodology (12.31%) while the Folch method and the extraction with hexane presented yield of less than 2%. By Sokhlet extraction, using diverse samples from Tambaqui (fillet, head and wastes mixture), it was obtained a yield of 42.48%, 42.87%, 41.87%, respectively. From the Tambaqui offal, by the heating in a stove, it was obtained a yield of 46.78% of oil. The physicochemical results indicated hight acidity for the wastes mixture oils (1.62%) in relation to offal oil (0.49%). The saponification value for offal oil was 163.86 mg of KOH/g lower than that found in the literature for fish oil (189-193). The chromatography results present differences both in biodiesel oils chemical composition, as in this constituents’ proportion. The major fatty acid determined in the samples were oleic (C18:1 ω-9) and palmitic (C16:0). The biodiesel presented aspect, bulk density, kinematic viscosity within the limits set by the ANP, being that the determined flash point was well above the recommend minimum, an indication that biofuel produced presents a low risk of flammability, however the acid value and the oxidative stability found themselves out of the pre-established parameters. Therefore, the Tambaqui offal oil shows promise for biodiesel production, although there is a need to expand the study.