Green extraction of caffeine from coffee pulp using a deep eutectic solvent (DES).

The objective of this work was the development of a green extraction method based on the use of a deep eutectic solvent (DES) to extract caffeine from coffee pulp (CP). Choline chloride and glycerol were used as hydrogen bond acceptor and hydrogen bond donor, respectively. ATR-FTIR and viscosity measurements were conducted for the characterization of DES mixtures. The effects of DES mixtures concentration (C_DES), liquid-to-solid ratio (L/S), extraction temperature (T) on caffeine extraction yield (C_Caf) and extract antiradical activity (A_AR) were studied, and the extraction process was optimized. The optimum of extraction was achieved at a temperature of 55 °C, a solvent/pulp ratio of 47 mL/g, and a DES concentration of 70% w/v in aqueous solution. In addition, a mathematical model to describe the kinetic mechanisms of the extraction was developed, whereas the dependence of the best descriptive model constants on extraction variables was...