Supercritical CO2 extraction of essential oil and oleoresin from chamomile (Chamomilla recutita [L.] Rauschert)

Flowers of chamomile (Chamomilla recutita [L.] Rauschert) were extracted with supercritical carbon dioxide using a fixed bed extractor. The experimental work was conducted to identify the best process conditions to maximize the yield of extract and its content of α-bisabolol and chamazulene. The experimental setup used a fixed bed extractor (diameter of 3.96×10−2 m and length 16.55×10−2 m). The fixed bed was formed with triturated chamomile (−28 to +200 mesh) with an apparent density of 370 kg/m3. Assays were conducted at temperatures of 30 and 40 °C, pressures of 100, 120, 160 and 200 bar. The solvent flow rates were 1.67×10−5, 3.33×10−5 and 6.67×10−5 kg/s. A typical run took 10 h. The chemical composition of the extracts was determined using GC/MS and GC. The pressure and solvent flow rate significantly affected the mass transfer rate and the yield while the temperature did not. The maximum yield (mass of extract/mass of dried feed) was 4.33% (40 °C, 200 bar, 6.67×10−5 kg/s). The overall extraction curves were well described by both a spline fitting and the pseudo steady state model of Sovová. The major compounds of the essential oil and of the oleoresin were β-farnesene, α-farnesene, γ-cadinene, α-bisabolol oxide B, α-bisabolol, chamazulene, α-bisabolol oxide A, cis and trans-dicycloether (MW 200).