Supercritical carbon dioxide extraction of volatile oil from Italian coriander seeds

Supercritical CO₂ fluid extraction of the volatile oil from Italian coriander seeds was carried out under different conditions of temperature (40 and 50 °C), pressure (90, 100 and 150 bar), mean particle size (0.4, 0.6 and 0.8 mm) and CO₂ flow rate (0.79, 1.10 and 1.56kg/h) in order to evaluate their influence on the yield and composition of the volatile oil. Hydrodistillation with the same mean particle sizes was performed and used as a comparative method. The best supercritical fluid extraction conditions were found to be 90 bar, 40 °C, 1.10 kg/h and 0.6 mm. The chemical composition of each supercritical fluid extraction sample was analysed by GC and GC–MS and the global composition was compared with that obtained by hydrodistillation. The dominant components were linalool (65–79%), γ-terpinene (4–7%), camphor (3%), geranyl acetate (2–4%), α-pinene (1–3%), geraniol (1–3%) and limonene (1–2%). Moreover, supercritical fluid extraction samples were collected at specific intervals of amount of CO₂ consumed, during each extraction, and the contribution of the main volatile components from each sample, for the global volatile compositions, was evaluated. In general, the first sample of each extraction contained up to 50% of the mass of each component.