Deep Eutectic Solvents (DES) and Natural Deep Eutectic Solvents (NADES)-Mediated Extraction of Bioactives from Brewing By-Products: A Scoping Review for Functional Food and Sports Supplementation

The brewing industry generates substantial organic waste, prompting interest in sustainable valorization because these by-products retain significant residual nutritional and nutraceutical value. Based on these premises, this scoping review aims to evaluate whether DESand NADES-mediated extractions can represent a green alternative to conventional organic solvents, assessing their capacity to yield stable, biocompatible extracts with potential nutritional relevance for athletic supplementation. Following PRISMA-ScR guidelines and prospectively registered on OSF, we screened PubMed, Scopus, and Web of Science databases in June 2026, including 22 primary studies. Results show that DES and NADES can effectively dismantle brewing by-products, recovering antioxidants—specifically ferulic acid, p-coumaric acid, and xanthohumol (up to 285.92 mg GAE/100 g dw)—protein concentrates (up to 54.7 wt% total protein) rich in essential amino acids and branched-chain amino acids (BCAAs), as well as immunomodulatory prebiotic fibers (β-glucans, arabinoxylans) and liquid phases that bio-ferment into polyunsaturated fatty acids (PUFAs). Non-conventional technologies such as ultrasound and microwave-assisted extraction accelerate extraction kinetics by reducing solvent viscosity. It should be emphasized that the included studies are exclusively in vitro and characterize extracted compounds without evaluating effects on human subjects or athletic performance. However, several safety and regulatory gaps remain, including the presence of gluten in barley-derived extracts, the potential co-ingestion of antinutritional factors (e.g., oxalic acid), and the lack of toxicological data on intact eutectic phases. While DES- and NADES-derived extracts show promising in vitro bioactivities, further research is needed to validate their safety, bioavailability, and efficacy before they can be considered for human consumption or sports nutrition applications.