Integrated sonication-assisted deep eutectic solvent for extraction of antibacterial compounds from cacao shells

Abstract

The valorization of cacao shells offers high added value because of the rich content of bioactive compounds. This study investigated the application of cacao shell waste as an antibacterial agent through green extraction processes. The extraction was carried out by integrating SAE-DES (sonication-assisted and deep eutectic solvent) with a choline chloride-lactic acid-based solvent. The parameters of extraction, including temperature, solid-to-solvent ratio, and DES concentration, were optimized applying a Box–Behnken design in RSM (response surface methodology). The optimum conditions were found to be 80 °C, a solid-to-solvent ratio of 1 : 10, and a DES concentration of 62.65%, with TPC (total phenolic content) and TFC (total flavonoid content) of 4.94 ± 0.10 g GAE per g sample and 5.97 ± 0.09 g RE per g sample, respectively. Additionally, the mass transfer coefficient (k_ca) and equilibrium constant (H_s) range from 8.73 × 10⁻³ to 14.80 × 10⁻³ min⁻¹ and 0.56 × 10⁻³ to 41.91 × 10⁻³ g solid per cm³, respectively. FTIR analysis confirmed the presence of significant functional groups of phenolic compounds in the extract. Furthermore, the extract was effective against Escherichia coli and Staphylococcus aureus.