Recovery of Bioactive Compounds from the Biomass of Aromatic Plants After Distillation Using NADES: A Sustainable Alternative Extraction Method

After the fragrant steam of distillation fades, what's left is often thrown away—but that leftover plant fiber might just hold a treasure trove of health-boosting compounds, if we know how to unlock it.

Distilling aromatic plants for their essential oils is an energy-hungry process that leaves behind mountains of fibrous biomass and hydrosols. These by-products are a disposal headache and a waste of potential. But a new study suggests we can turn this waste into wealth by using natural deep eutectic solvents, or NADES, to pull out valuable polyphenols from the leftover plant material.

The researchers tested nine plant species from two families—Asteraceae and Lamiaceae—including tarragon, purple coneflower, lavender, sage, and rosemary. After steam distillation, they extracted the residual biomass with either ethanol, a conventional solvent, or various NADES made from choline chloride combined with citric or lactic acid at different ratios. One solvent, a 1:1 mix of choline chloride and lactic acid (CLA11), stood out: it recovered the highest amounts of chicoric and rosmarinic acids, two key phenolic compounds.

CLA11 outperformed ethanol across all biomasses from both plant families. Not only did it extract a greater number of compounds, as seen in UHPLC-HRMS analysis, but it also yielded higher concentrations of chicoric and rosmarinic acids, measured by HPLC-DAD. This means NADES could be a game-changer for the food, pharmaceutical, and cosmetic industries, offering a greener way to create new products.

By replacing toxic solvents with eco-friendly NADES, we can make the entire essential oil production chain more sustainable. It's a win-win: less waste, more value, and a healthier planet.

Key Points

• NADES (CLA11) beats ethanol for polyphenol recovery.
• Nine aromatic plant biomasses tested after steam distillation.
• Green extraction boosts sustainability of essential oil production.