LIPASE-CATALYZED ALCOHOLYSIS WITH SUPERCRITICAL CARBON-DIOXIDE EXTRACTION .1. INFLUENCE OF FLOW-RATE

A combined process of lipase (E.C. 3.1.1.3) catalysis and extraction o f product with supercritical carbon dioxide was studied. The effect of different flow rates of the extraction fluid on the selective removal of the ethyl esters (EE) synthesized in a lipase-catalyzed alcoholysi s of cod liver oil with ethanol was investigated. The faster the flow rate, the faster the extraction rate and the higher the recovery of EE . For example, after a 270-min extraction, the total recovery of EE wa s 1520 mg for a flow rate of 0.3 liter carbon dioxide at atmospheric p ressure and room temperature/min (NL/min) as compared to 250 mg when 0 .015 NL/min was used. The concentration of EE in the carbon dioxide wa s found to decrease with increasing flow rate, which indicates that th e rate of diffusion of EE limits their extraction at fast flow rates. A high flow rate was found to result in a more selective extraction of EE, i.e., less amounts of other lipid components present in the react ion mixture were coextracted with the EE. Further, by increasing the f low rate, the equilibrium of the reaction was shifted slightly toward ester synthesis. An increase in the flow rate from 0.015 to 0.075 NL/m in resulted in an approximately 10% increase in total conversion (from 73 to 82%), whereas only a negligible increase was obtained when the flow rate was increased further to 0.15 NL/min.