Green extraction ofãrabica coffee cherry husk usingã deep eutectic solvent

Coffee cherry husk—millions of tons of waste—hides a treasure trove of health-boosting compounds. Now, a green solvent unlocks them without harming the planet.

Every year, coffee processing discards mountains of cherry husks. But this waste isn't useless—it's packed with polyphenols and other phytochemicals that can be turned into valuable products. The challenge? Traditional extraction relies on organic solvents that pollute the environment and pose health risks. Enter natural deep eutectic solvents (DESs): a greener, safer alternative that's gaining ground in green chemistry.

Researchers crafted a DES from choline chloride and citric acid in a 1:2 ratio. They mixed it with varying amounts of water (20–50% w/w) and used ultrasound-assisted extraction at 25°C for 60 minutes. The team then measured total phenolic content (TPC), flavonoid content (TFC), and antioxidant activity (AA) in the extracts. The winning formula? 40% water in the DES, which yielded the highest levels: 27.00 mg GAE/g for phenolics, 17.19 mg CE/g for flavonoids, and 11.24 mg AAE/g for antioxidants.

To identify the compounds, they used high-resolution LC-QTOF mass spectrometry. A remarkable 718 distinct compounds were detected—far more than in other sample groups. This shows the DES extraction is not just effective but also highly selective.

The implications are clear: by using a green solvent, we can turn coffee waste into a goldmine of phytochemicals, reducing environmental harm while boosting value. It's a win-win for science and sustainability.

Key Points

• 40% water/ChCA gave highest phenolics, flavonoids, antioxidants
• 718 compounds detected by LC-QTOF in coffee husk extract
• Green DES extraction turns waste into high-value phytochemicals