Lipase Activity in SCCO 2 181 Applied Biochemistry and Biotechnology Vol. 113–116, 2004 Copyright © 2004 by Humana Press Inc. All rights of any nature whatsoever reserved. 0273-2289/04/113/0181–0187/$25.00 181 *Author to whom all correspondence and reprint requests should be addressed. The Effect of Temperature, Pressure, Exposure Time, and Depressurization Rat on Lipase Activity in SCCO 2 M ARCELO L ANZA , W AGNERL UÍS P RIAMO , J OSÉ V LADIMIR O LIVEIRA , C LÁUDIO D ARIVA , AND D ÉBORA DE O LIVEIRA * Department of Food Engineering, URI–Campus de Erechim, Av. Sete de Setembro, 1621-Erechim-RS, 99700-000, Brazil, E-mail: odebora@uricer.edu.br Abstract We investigated the influence of temperature, pressure, exposure time, and decompression rate on lipase activity in high-pressure CO 2 medium. A high-pressure, variable-volume view cell was employed in the experiments, varying the temperature from 30 to 70 ° C in the pressure range of 70–250 bar at various high-pressure exposure times (60–360 min) and adopting several decompression rates (10–200 kg/[m 3 ·min]). The results obtained show that an increase in temperature and density led to an enhancement of enzyme activity losses while the decompression rates had a weak influence on enzyme inactivation. Index Entries: Lipase activity; high pressure; decompression rate; CO 2 ; SCCO 2 ; exposure time. Introduction Bioconversion of vegetable oils through the use of enzymes as cata- lysts in supercritical medium is undoubtedly a matter of great scientific and technological interest. The possibility of using a much less pollutant fuel (biodiesel) compared to diesel from petroleum and producing many chemi- cal raw materials for food, pharmaceutical and cosmetic industries has motivated research efforts in the biotransformation of vegetable oils with the desired end result of high-value-added products or drastic reduction in environmental investments (1).