2026-07-26T03:25:05Zhttps://riubu.ubu.es/oai/request

oai:riubu.ubu.es:10259/119542026-07-25T00:05:30Zcom_10259_4244com_10259_5086com_10259_2604col_10259_4245

Barea Gómez, Pedro Illera Gigante, Alba Ester Candela Gil, Helena Melgosa Gómez, Rodrigo Benito Román, Oscar Sanz Díez, Mª Teresa 2026-07-24T07:12:06Z 2026-07-24T07:12:06Z 2026-05 1935-5130 https://hdl.handle.net/10259/11954 10.1007/s11947-026-04393-z 1935-5149 This study assesses subcritical water hydrolysis (SWH) as a sustainable approach for protein recovery from okara, following isoflavone valorization. The initial extract, obtained at 120 °C, contained over 1200 µg of isoflavones per gram of dry okara. The solid residue underwent a second protein extraction step in both batch and semi-continuous modes. The batch extraction was conducted at 180 °C for 3 h at 5 MPa in a 0.5 L reactor. Under these conditions, total amino acid recovery reached 81 ± 3% (12.6 g/L), with 20 ± 1% of free amino acids, mainly glutamic acid, and a favorable profile of essential amino acids. These results were comparable to protein extraction from untreated okara, indicating that the prior isoflavone extraction did not hinder protein hydrolysis, but rather contributed positively within the cascade framework. Hydrolysis was also performed in a semi-continuous mode in a 2.3 L reactor, with a residence time of 2.75 min, in a two-stage temperature process (180 °C and 270 °C). The second stage yielded a significantly higher extraction than the first one, achieving a total 70.4% protein recovery (1.22 g/L) with 10% of free amino acids, with glutamic acid as the dominant one. Carbohydrate analysis revealed high hydrolysis yields for galactans, arabinans, and xylans, but these exhibited lower thermal stability compared to proteins. Okara emerges as a promising by-product for a bio-cascade process, combining a mild first stage for isoflavone extraction with a more severe second stage for protein extraction/hydrolysis. Open access funding provided by FEDER European Funds and the Junta de Castilla y León under the Research and Innovation Strategy for Smart Specialization (RIS3) of Castilla y León 2021-2027. This work was supported by the Junta de Castilla y León (JCyL) and the European Regional Development Fund (ERDF) [grant number BU027P23]. P. Barea and H. Candela pre-doctoral contracts are funded by JCyL and the European Social Fund (ESF) [ORDEN EDU/1868/2022 and ORDEN EDU/1009/2024, respectively]. application/pdf eng Springer Food and Bioprocess Technology. 2026, V. 19, n. 7 https://doi.org/10.1007/s11947-026-04393-z Atribución 4.0 Internacional http://creativecommons.org/licenses/by/4.0/ info:eu-repo/semantics/openAccess Subcritical water Isoflavones Protein Amino acid profile Scaling-up process Okara Productos de la soja Proteínas Soybean products Proteins Cascade Valorization of Okara by Subcritical Water Hydrolysis: Assessment of Protein and Amino Acid Profile in Batch and Semi-Continuous Systems info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion Food and Bioprocess Technology 19 7