Evaluation of lavender essential oils and by-products using microwave hydrodistillation and conventional hydrodistillation

This study investigated the impact of two extraction methods, traditional hydrodistillation (TDH) and microwave-assisted hydrodistillation (MAH), on the essential oil yield and chemical profile of Lavandula angustifolia L., as well as the bioactive potential of the resulting wastewater. Essential oil composition was analyzed via GC–MS, revealing similar qualitative and quantitative profiles for both methods, with α-terpinolene and (–)borneol as major constituents. Wastewater analysis via LC–MS/MS and spectrophotometric assays demonstrated the presence of significant total phenolic content (3.29–1.78 mg GAE/g) and 32 individual phenolics (463.1 µg/kg for TDH; 479.33 µg/kg for MAH). These findings suggest that both essential oil and wastewater obtained by either method possess considerable bioactive potential, with the MAH method potentially offering advantages over TDH for essential oil extraction. Further exploration of wastewater applications in various industrial sectors is warranted.