Valorization of domestic spent coffee grounds: modeling and optimizing the extraction of bioactive compounds with supramolecular solvents

Spent coffee grounds (SCG) represent the most significant and abundant by-product produced by the coffee industry and provide an economical source of several bioactive metabolites with potential applications across multiple sectors. Previous research demonstrated the feasibility of using supramolecular solvents (SUPRAS) for the extraction of chlorogenic acids, caffeine, and caffeic acid from SCG. Based on previous findings, this work focuses on modeling and optimizing the SUPRAS composition through a statistical approach using Extreme Vertices Mixture Design (EVMD). The methodology involves the assessment of two amphiphiles (decanoic acid and 1-hexanol) and two solvents (ethanol and tetrahydrofuran). All replicas was aligned with the special cubic model, demonstrating significant estimate proficiency. The optimal extraction conditions were 47.60% water, 27.30% 1-hexanol, and 25% ethanol allowing to obtain 3.50 mg/g, 3.90 mg/g, and 0.40 mg/g of caffeine, 5-CQA, and caffeic acid respectively. In general, it is concluded that the SUPRAS extraction process allows one to obtain extracts from the SCG biomasses, which may serve as sustainable food ingredients and nutraceutical products.