2026-04-17T09:37:01Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/60882022-11-08T13:31:41Zcom_10259_4244com_10259_5086com_10259_2604col_10259_4245

2021-11-04T09:22:56Z urn:hdl:10259/6088 Subcritical water extraction of phenolic compounds from onion skin wastes (Allium cepa cv. horcal): effect of temperature and solvent properties Benito Román, Oscar Blanco Alcalde, Beatriz Sanz Díez, Mª Teresa Beltrán Calvo, Sagrario Onion Extraction Subcritical water Quercetin Polarity Valorization The valorization of onion skin wastes (OSW) through the extraction, identification, and quantification of phenolic compounds was studied in this work, using subcritical water in a semicontinuous extractor (2.5 mL/min; 105–180 C; 5 MPa). The extraction of flavonoids resulted to be fast (<30 min) and temperature sensitive (maximum at 145 C; total flavonoids, 27.4 0.9 mg/g dry OSW (DOSW)). The experimental results were fitted to theWeibull model. The influence of the solvent properties on the flavonoids quantification was found to be critical. A precipitate was formed once the extracts cooled down. If removed, a significant fraction of the high temperature extracted flavonoids (as much as 71%, at 180 C) was lost. Such a condition a ected especially those compounds that show extremely low solubility in water at room temperature, whereas quercetin glycosylated derivatives were less a ected by the polarity change of the medium induced by the temperature change. It was demonstrated that it is necessary to re-dissolve the subcritical water extracts by the addition of ethanol, which led to a medium with a polarity equivalent to that obtained with water at high temperature. At 145 C, quercetin (15.4 0.4 mg/g DOSW) and quercetin-40-glucoside (8.4 0.1 mg/g DOSW) accounted for the 90% of the total flavonoids identified. By recovering high added value bioactive compounds from OSW the principles of circular economy were fulfilled, providing a new use for this agricultural waste. 2021-11-04T09:22:56Z 2021-11-04T09:22:56Z 2020-12 info:eu-repo/semantics/article 2076-3921 http://hdl.handle.net/10259/6088 10.3390/antiox9121233 eng Antioxidants. 2020, V. 9, n. 12, 1233 https://doi.org/10.3390/antiox9121233 info:eu-repo/grantAgreement/AEI/Plan Estatal de Investigación Científica y Técnica y de Innovación 2017-2020/PID2019-104950RB-I00/ES/VALORIZACION DE SUBPRODUCTOS MARINOS MEDIANTE TECNOLOGIAS DE FLUIDOS SUB- Y SUPERCRITICOS PARA LA OBTENCION DE BIOCOMPUESTOS VALIOSOS info:eu-repo/grantAgreement/Junta de Castilla y León//BU301P18 info:eu-repo/grantAgreement/Junta de Castilla y León//BU050P20 http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Atribución 4.0 Internacional MDPI