SUPERCRITICAL CARBON-DIOXIDE EXTRACTION OF ONION OLEORESIN

Supercritical carbon dioxide (SC-CO,) extraction on a laboratory-scale , was applied to produce oleoresin from dried onion (Allium cepa L). T he goal of this work was to determine the optimal conditions of extrac tion for producing oleoresin with the highest yield and the best quali ty. A polynomial model was developed on the data. The square of correl ation coefficient was R-2 = 0.9022 (at P less than or equal to 0.05). The statistical analysis showed that the extraction pressure, temperat ure, and time have significant influence on the yield of the oleoresin . Increasing these parameters resulted in an increase in the yield. Ma ximum yield was obtained when the extraction pressure and temperature were above 350 bar and 57 degrees C, respectively. At the lowest press ure (150 bar) applied the highest concentration of sulphur was produce d in the oleoresin. The concentration of sulphur increased as a functi on of temperature when the pressure was maintained at 300 and 400 bar. The composition of volatile compounds of oleoresin differed from that of distilled onion oil. (C) 1998 SCI.