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 3600psi (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 CO2flow 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.     

PHYSICOCHEMICAL AND SENSORY CHARACTERISTICS OF SELECTED MICHIGAN SWEET CHERRY (Prunus avium L.) CULTIVARS

Sweet cherry cultivars grown in Northern Michigan in 1992 were analyzed for sensory and physicochemical characteristics. ‘Emperor Francis’, a yellow/red blushed, light color cultivar had the highest Brix/acid ratio at the 4th harvest, and it scored higher in sensory tests for sweetness flavor and overall acceptability than the dark cultivars, ‘Sam’ and ‘Hedelfingen’. Harvest dates showed significant effect on titrable acidity, Brix, Brix/acid ratio, sugars, weight and diameter of fruits. Brix/acid ratio showed significant correlation with sweetness. Correlation coefficients between overall consumer acceptability and measured parameters for three sweet cherry cultivars indicate that firmness has potential as an objective overall index for acceptability.