Green extraction of glycoproteins and polysaccharides from wine lees using natural deep eutectic solvents

Natural deep eutectic solvents (NADES) (citric acid/betaine-CA/BET; tartaric acid/betaine-TA/BET; urea/choline chloride-UR/ChCl) coupled with autoclaving (121 °C, 20 min) were tested for extracting glycoproteins from wine lees, a yeast-based by-product. NADES exhibited physicochemical stability during autoclaving, except for UR/ChCl which showed humidity loss. Their extraction capacity was compared to McIlvaine buffer (MC), previously used as solvent. MC and UR/ChCl yielded glycoproteins with high molecular weight (>250 kDa) while CA/BET provided a higher yield (73.58 %) and smaller glycoproteins (20-250 kDa). Extracts' foaming (1.0 g/L) and emulsifying (10.0 g/L) properties were tested at different pHs (3.4, 5.4, 7.0). MC extract was the best in producing stable foams, while UR/ChCl was the most effective in promoting emulsions' stability and viscosity. Intermediate performances were reported by CA/BET while TA/BET was poorly effective. These findings suggest that NADES can enhance the efficiency of high-temperature wine lees extraction, improving the recovery of yeast compounds for food applications.