A Bibliometric Analysis of the Supercritical CO2 Extraction of Essential Oils from Aromatic and Medicinal Plants: Trends and Perspectives

Every year, lavender distillation produces mountains of solid waste—but what if that 'trash' hides a treasure trove of bioactive compounds? This study turns waste into a valuable powder.

Lavender distillation generates massive amounts of solid waste annually, typically discarded and causing environmental headaches. Yet this waste still holds residual essential oil and other bioactive compounds. Researchers set out to recover these valuables using green extraction methods—microwave-assisted (MAE) and ultrasound-assisted extraction (UAE)—and then dry the extracts into stable powders.

The team optimized pretreatment conditions like moisture content and particle size, then compared MAE and UAE. They found that most phenolic compounds (61%) end up in the leachate after distillation, while 43% remain in the solid waste. Drying the waste before extraction changed efficiency, and UAE outperformed MAE, yielding higher phenolic content and stronger antioxidant activity.

Drying the extracts—whether spray or freeze—didn't significantly alter phenolic content. However, adding maltodextrin as a drying agent boosted process yield, especially with freeze-drying. The result? An integrated process that transforms lavender waste into a stable, bioactive powder, offering a sustainable solution to an environmental problem.

Key Points

• Lavender waste holds 43% of original phenolics.
• UAE beats MAE for phenolic yield and antioxidants.
• Maltodextrin boosts freeze-drying yield, not phenolic content.