Composition of supercritical carbon dioxide derived extracts of Chamaemelum nobile
The feasibility of extracting botanical substances from samples of Cameamelum nobile (Roman chamomile) with supercritical carbon dioxide (sc-C02) was investigated. The advantages of clean technology and the relevance of chamomile extracts to the fragrance, flavour, food, cosmetic and pharmaceutical industries sewed as motivation for the investigation. Extractions were performed on selected dried plant material using a commercial laboratory-size supercritical fluid extractor. The extraction conditions (temperature, pressure, time) were optimised in terms of yield of extract using computer-assisted surface response analysis based on a statistical design. A maximum yield of 3 % (m/m) was obtained at optimum conditions (39 ºC, 171 atm), in good agreement with steam distillation derived yields of 0.5 - 2 % (m/m) reported in the literature. The dependence of yield of extract on the density of the fluid allowed conclusions to be drawn on the mechanism of extraction, and these could be supported by calculated values of a few activation parameters. It turned out that components are either desorbed from the plant matrix by sc-CO2 at gas-like densities or dissolved in sc-CO2 at liquid-like densities. The extracts were analysed by GC/FID, GC/MS and GC-GC/TOF-MS. The three chromatographic techniques were complementary in identifying the major compounds present in the extracts, but the total of 462 substances identified by two-dimensional GC by far exceeded the identification output of the two other techniques. The results confirmed the acquisition of component-rich extracts with sc-CO2 with many components also found in steam distillation extracts. The study proved that sc-CO2 extraction has advantages over steam distillation in terms of shorter extraction times, milder extraction temperatures and a wealth of components that may constitute different compositions by manipulating extraction conditions.