Green extraction of phenolic compounds from the by-product of purple araçá (Psidium myrtoides) with natural deep eutectic solvents assisted by ultrasound: Optimization, comparison, and bioactivity

Lavender distillation creates mountains of waste every year—but that 'garbage' might just be a treasure trove of bioactive compounds waiting to be unlocked.

Every year, lavender distillation produces massive amounts of solid waste, usually discarded and causing serious environmental headaches. But hidden within this waste are residual essential oils and other bioactive compounds—a potential goldmine for sustainable extraction.

Researchers optimized two green extraction methods: microwave-assisted (MAE) and ultrasound-assisted extraction (UAE) of phenolic compounds from lavender waste. They also fine-tuned pretreatment conditions like moisture content and particle size. Strikingly, the majority of phenolic compounds (61%) ended up in the leachate after distillation, while 43% remained in the solid waste—showing that waste still holds significant value.

UAE outperformed MAE, yielding higher phenolic content and stronger antioxidant activity. Drying the extracts—via spray or freeze—didn't significantly change their phenolic content, but adding maltodextrin as a drying agent boosted process yield, especially with freeze-drying.

This integrated approach—green extraction plus drying—turns lavender waste into a stable, bioactive powder, offering a win-win for both industry and the environment.

Key Points

• 61% phenolic compounds found in leachate, 43% in solid waste.
• Ultrasound-assisted extraction outperformed microwave for phenolics and antioxidants.
• Maltodextrin boosts drying yield, especially with freeze-drying.