Green extraction and separation of Dendranthema indicum essential oil by supercritical carbon dioxide extraction combined with molecular distillation

The optimal extraction parameters of Dendranthema indicum extract using supercritical carbon dioxide extraction were organized by response surface methodology (RSM) with Box - Behnken design (BBD). The peak extraction yield (9.37%) was obtained in the condition of 750 W of microwave power, 40 °C of extraction temperature, 26 MPa of extraction pressure, and 105 min of extraction time. Subsequently, molecular distillation was applied to separate essential oil from D. indicum extract. The separation yield of D. indicum essential oil obtained at 80 (DIEO80) and 90 °C (DIEO90) were 0.21 g/100 g and 0.44 g/100 g, respectively, which was lower than those of 100, 110 and 120 °C, while they presented transparent with no precipitate. DIEO90 possessed the strongest antioxidant activities (16.08 μmol TE/g for 1,1-diphenyl-2-picrylhydrazyl scavenging activity, 46.05 μmol TE/g for ferric reducing antioxidant power, respectively). Furthermore, alkenes , alcohols and esters were identified the main volatile flavor components for D. indicum extract and essential oils. The proportions of major contributing components such as 1,8-cineol (6.45%–15.04%), isopinocarveol (6.02%–11.78%), (E)-α-bergamotene (3.02%–5.62%), (E)-β-famesene (2.80%–12.92%), germacrene D (2.83%–8.23%), 6-ethenyl-2,2,6-trimethyloxan-3-ol (5.86%–6.88%), (6-Ethenyl-2,2,6-trimethyl-oxa- n-3-yl) acetate (9.11%–10.51%) and β-elemene (4.16%–6.44%). Though molecular distillation, compounds with low boiling points were enriched in DIEO80 and DIEO90, and compounds with high boiling points were in other oils. Overall, the sequential green process based on supercritical carbon dioxide extraction with molecular distillation is an efficient method for extraction and separation of essential oil. • Supercritical CO 2 extraction combined with molecular distillation is developed to extract and separate essential oil. • Supercritical carbon dioxide extraction is optimized by response surface methodology (RSM) with Box- Behnken design (BBD). • Molecular distillation at lower temperature obtained lower yield but superior properties. • Dendranthema indicum essential oil obtained at 90 °C presented the strongest antioxidant activities.