%0 Journal Article
%A Calvo Garrido, Lourdes
%A Tirado Armesto, Diego Felipe
%A Fuente, Esther de la
%A Calvo Garrido, María Lourdes
%T A selective extraction of hydroxytyrosol rich olive oil from alperujo
%D 2019
%@ 0260-8774
%U https://hdl.handle.net/20.500.14352/12895
%X Alperujo, the solid-liquid waste generated by the current two-phase method of olive oil extraction, was dried,milled and treated with supercritical carbon dioxide (sc-CO2) to obtain a hydroxytyrosol (HT)-rich oil. At first,extraction rates were analysed as a function of operating variables and the pre-condition of the raw material.Samples with particle size diameter<0.80mm and in equilibrium moisture (1%) with the atmosphere, improvedoil extraction yield almost 40% compared with samples with the whole range of particle sizes. Extractionyield improved with solvent flow rate, but a minimum residence time was required. The optimum was0.18 kg h−1 (7.5 kg CO2 h−1 kg biomass−1). Higher pressures and lower temperatures resulted in higher extractionyields; at 30 MPa and 323 K the extraction curve slope was close to the theoretical oil solubility and theyield was 13%, like that obtained with n-hexane by Soxhlet (14%). However, the HPLC-DAD analysis identifiedhigher HT concentration (1900 ppm) in the supercritical extracts at the highest temperature. Consequently, at373 K, the total phenol content and the antioxidant capacity of the extracts was uppermost. No HT was found inthe n-hexane extracts.
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