Simultaneous Recovery of Mannooligosaccharides and Chlorogenic Acids from Spent Coffee Grounds: Integration of Enzymatic Hydrolysis with Natural Deep Eutectic Solvent Extraction

Although mannooligosaccharides (MOSs) and chlorogenic acids (CGAs) from spent coffee grounds (SCGs) possess complementary bioactivities, their simultaneous recovery is hindered by entrapment within fibrous matrices and distinct polarities. This study developed a two-step strategy combining enzymatic hydrolysis and extraction using natural deep eutectic solvents (NADESs). Optimal enzymatic conditions were 6.51 U/g of Viscozyme L and 15.84 U/g of mannanase at 45 °C for 14 h. The conductor-like screening model for real solvents (COSMO-RS) predicted that choline chloride-organic acid NADESs had the highest solubilities for five MOSs and nine CGAs among 27 candidates. Extraction with choline chloride-citric acid NADES achieved the highest MOS and CGA yields at 114.81 and 2.11 mg/g of SCG, respectively, with an antioxidant capacity of 0.14 mmol of Trolox equivalent/g of SCG. This work demonstrates that integrating biocatalysis with solvent informatics can overcome matrix and polarity limitations, offering a sustainable strategy for upcycling food waste into functional ingredients without generating harmful residues.