Yield and quality of onion flavor oil obtained by supercritical fluid extraction and other methods

Methods of extraction of onion flavor oil were studied including supercritical fluid extraction using carbon dioxide (CO2) liquid CO2 extraction and steam distillation-solvent extraction. The effect of using entrainers with supercritical fluid extraction was also studied, The yield and the quality of onion extracts obtained from the different methods were compared. The maximum yield of 0.0324 % was obtained by supercritical CO2 extraction at 3600 psi (24.5 MPa), 37C at a CO2 flow rate of 0.5 L/min. Ethyl alcohol used as entrainer enhanced the yield of onion oil over that obtained by supercritical CO2 experiment without entrainer at the CO,flow rate of 1.0 L/min. Gas chromatography and combined gas chromatography-mass spectrometry of the extracts indicated that the flavor profiles were different for extracts obtained by different methods. Supercritical and liquid CO2 extracts had fresh onion-like flavor as opposed to a cooked flavor of the extract obtained by steam distillation-solvent extraction.