RT info:eu-repo/semantics/article T1 Recovery of the protein fraction with high antioxidant activity from red seaweed industrial solid residue after agar extraction by subcritical water treatment A1 Trigueros Andrés, Ester A1 Sanz Díez, Mª Teresa A1 Alonso Riaño, Patricia A1 Beltrán Calvo, Sagrario A1 Ramos Rodríguez, Cipriano A1 Melgosa Gómez, Rodrigo K1 Subcritical water extraction K1 Biorefinery K1 Macroalgae residue K1 Protein K1 Amino acids K1 Antioxidant activity K1 Ingeniería química K1 Chemical engineering AB In this work valorization of the underexploited industrial solid residue generated after agar extraction from Gelidium sesquipedalewas studied by using subcritical water in a semicontinuous fix-bed reactor. First, a complete characterization of this by-productwas carried out, determining up to 21%(w/w) of protein content (for a nitrogen factor of 4.9) with high content of essential aminoacids, 37% (w/w) of carbohydrate fraction and high amount of ash, 22% (w/w). The effect of temperature, in the range from 129to 200 °C, and flow rate, in the range from 2 to 6 mL min−1, on protein and carbon fraction extraction/hydrolysiswas studied.Atconstant flow rate of 2 mL min−1, a maximum in the protein extraction was achieved at 185 °C. Higher temperatures led todegradation of protein or its hydrolysis products. Free amino acids release followed the same trend as the protein fraction. Themost temperature sensitive amino acids, as determined by gas chromatography (EZ:faast Phenomenex), were serine and asparticand glutamic acids. As a consequence, the selectivity towards non-polar amino acids increased by working at high severityfactors. A Pearson correlation between antioxidant capacity of the collected extracts with the bioactive compounds determined inthe extracts (total polyphenolic compounds –TPC-, peptides and free amino acids) was established, being stronger for TPC. Theash content in the solid residue after treatment steadily increased with temperature due to non-solubilization being possible itsapplication in agriculture as fertilizers. PB Springer SN 0921-8971 YR 2021 FD 2021 LK http://hdl.handle.net/10259/6027 UL http://hdl.handle.net/10259/6027 LA eng NO Agencia Estatal de Investigación [grant number PID2019-104950RB-I00 / AEI / https://doi.org/10.13039/501100011033] and the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) [grant number BU301P18 and BU050P20] DS Repositorio Institucional de la Universidad de Burgos RD 23-nov-2024