Bio-refinery of brewery spent grain utilizing natural deep eutectic solvent-induced subcritical water

This research aimed to valorize brewery spent grain (BSG) using subcritical water hydrolysis (SWH) modified by six different natural deep eutectic solvents (DES) and determining their bipotentialities. DES-induced SWH BSG hydrolysates showed the highest sugar content 46.63 +/- 2.10 mg glucose, protein 228.08 +/- 5.52 mg BSA, total flavonoids 22.87 +/- 0.23 mg RE, phenolic compounds 8.00 +/- 0.25 mg GAE from per gram dried BSG. A total of 9 different essential amino acids were identified from the BSG-hydrolysates; among them, leucine, isoleucine, phenylalanine, and histidine were the most prominent. The major phenolic compounds in the hydrolysates are gallic acid, protocatechuic acid, catechin, 4-hydroxybenzoic acid, naringin, and ferulic acid. BSG hydrolysates demonstrated antimicrobial activities and FT-IR analysis confirmed the presence of bioactive compounds. This comprehensive profiling of different bioactive compounds from BSG using DES-mediated SWH can be helpful for the efficient valorization of BSG for industrial purposes.