Extração e caracterização da biomassa e do óleo da microalga Desmodesmus sp. usando dióxido de carbono supercrítico

Abstract

The use of supercritical fluid extraction of natural products has been shown to be a viable and promising alternative to conventional methodologies. Due to the characteristics of supercritical extraction, which allow to obtain better quality products with no chemical waste, this extraction technique has been widely used in the obtaining of bioactive molecules from microalgae, as antioxidants, fibers, phytosterols, nutrients, among others. This work aimed to study the technical feasibility of supercritical extraction of oil from the microalgae Desmodesmus sp. using carbon dioxide as solvent. Conventional method, using hexane as solvent, was used in order to compare the extraction of oils from microalgal biomass study and the results show the efficiency and selectivity of supercritical fluid extraction in respect to the fatty acids concentration. The best yields of oil occurred at the operational conditions of 300 bar and 100 °C, 500 bar and 70 °C and 440 bar and 90 °C, reaching values of 3.342%, 3.103% and 2.586%, respectively. The residual biomass after supercritical fluid extraction was assessed in order to evaluate the residual potential and the results indicated that it is a promising one, due to its high concentration in carbohydrates and proteins. The analysis by gas chromatography indicated the myristic acid (C14:0), palmitic (C16:0), stearic (C18:0), oleic (C18:1) and γ-linolenic (C18:3) as the main fatty acids present in the Desmodesmus sp. oil. Simple models were used to model the extraction curves, Esquível et al. (1999), Sesti & Reverchon Osseo (1994) and Zeković (2003) and all of them were able to represent supercritical extraction of oil from microalgae Desmodesmus sp.