The Potential of Natural Deep Eutectic Solvents for the Extraction of Phenolic Compounds and Caffeine from Green Coffee (Coffea arabica) Beans

Chandimala, U. R. and Sik, Beatrix and Ajtony, Zsolt (2026) The Potential of Natural Deep Eutectic Solvents for the Extraction of Phenolic Compounds and Caffeine from Green Coffee (Coffea arabica) Beans. ACTA AGRONOMICA ÓVÁRIENSIS, 67 (1). pp. 90-104. ISSN 1416-647X

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Abstract

A natural deep eutectic solvent (NDES) mixture was studied for extracting phenolic compounds from green coffee beans (GCB) (Coffea arabica). Dehydrated, finely ground GCBs were extracted with water, 50 % aqueous ethanol, and NDES (glucose and glycerin, 1:1 M) at 30 ˚C for 30, 60, and 90 min using a shaking incubation method. The process was repeated at 50 °C for 30 min. Total phenolic content (TPC) was measured via the Folin-Ciocalteu test. Chlorogenic acids (3-, 4-, and 5-caffeoylquinic acid) and caffeine were quantified by HPLC-PDA. At 30 °C, the highest TPC (48.7 ± 0.6 mg GAE/g) was found in the NDES 30-min extract, comparable (P > 0.05) to NDES 60-min (47.4 ± 0.1 mg GAE/g) and 90-min (48.6 ± 1.1 mg GAE/g) extracts. The highest chlorogenic acid content (52.4 ± 0.6 mg/g) was in 50 % ethanol, 30-min extraction, similar (P > 0.05) to other ethanolic extracts and NDES 60- and 90-min extracts. Caffeine content (12.1 ± 0.2 mg/g) peaked in 50 % ethanol, 30-min extract, similar (P > 0.05) to most other extracts except NDES 30-min (11.3 ± 0.3 mg/g). NDES at 50 °C gave 46.9 ± 0.5 mg/g TPC, 48.6 ± 0.7 mg/g chlorogenic acid, and 11.1 ± 0.2 mg/g caffeine, not significantly different from 30 °C. These results indicate glucose–glycerin NDES is a promising, eco-friendly solvent for extracting phenolic compounds from GCBs, providing an alternative to 50 % ethanol.

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