Supercritical CO2 Extraction of Lavandula angustifolia Mill. Flowers: Optimisation of Oxygenated Monoterpenes, Coumarin and Herniarin Content

INTRODUCTION: Lavandula angustifolia is good source of oxygenated monoterpenes containing coumarins as well, which are all soluble in supercritical CO₂ (SC‐CO₂). OBJECTIVE: The study objective is to investigate SC‐CO₂ extraction parameters on: the total yield; GC–MS profile of the extracts; relative content of oxygenated monoterpenes; the amount of coumarin and herniarin; and to determine optimal SC‐CO₂ extraction conditions by response surface methodology (RSM). Methodology. SC‐CO₂ extraction was performed under different pressure, temperature and CO₂ flow rate determined by Box–Behnken design (BBD). The sample mass and the extraction time were kept constant. The chemical profiles and relative content of oxygenated monoterpenes (as coumarin equivalents, CE) were determined by GC–MS. Coumarin and herniarin concentrations were dosed by HPLC. RESULTS: SC‐CO₂ extracts contained linalool (57.4–217.9 mg CE/100 g), camphor (10.6–154.4 mg CE/100 g), borneol (6.2–99.9 mg CE/100 g), 1,8‐cineole (5.0–70.4 mg CE/100 g), linalyl acetate (86.1–267.9 mg CE/100 g), coumarin (0.95–18.16 mg/100 g), and herniarin (0.95–13.63 mg/100 g). The interaction between the pressure and CO₂ flow rate as well as between the temperature and CO₂ flow rate showed statistically significant influence on the extraction yield. Applying BBD, the optimum extraction conditions for higher monoterpenes and lower coumarin content were at 10 MPa, 41°C and CO₂ flow rate 2.3 kg/h, and at 30 MPa, 50°C and CO₂ flow rate 3 kg/h for higher monoterpenes and coumarin content. CONCLUSION: SC‐CO₂ extraction is a viable technique for obtaining lavender extracts with desirable flavour components. The second‐order model based on BBD predicts the results for SC‐CO₂ extraction quite satisfactorily. Copyright © 2017 John Wiley & Sons, Ltd.