Poster Presentation 1B-61

Assessment of the Effects of Process Variables on Enzymatic Activity of Two Lipases in SCCO₂

Débora de Oliveira,^1* Andresa Carla Feihrmann,¹ João Paulo Bender,¹ Cláudio Dariva,¹

José Vladimir de Oliveira,¹ Marco Di Luccio¹ and Denise Guimarães Freire²

¹Department of Food Engineering

URI - Campus de Erechim

Av. Sete de Setembro, 1621

Erechim, RS, 99700 - 000, Brazil

Phone: (+55) 54-5209000

Fax: (+55) 54-5209090

E-mail: odebora@uricer.edu.br

²Department of Biochemistry

Instituto de Química, UFRJ, CT, Bloco A

Rio de Janeiro, RJ, 21945 - 970, Brazil.

The possibility of using a much less pollutant fuel (biodiesel) when compared to diesel from petroleum has motivated the biotransformation of vegetable oils. Enzyme-catalyzed reactions of vegetable oils in high-pressure CO₂ seems to be a promising technique for obtaining high grade products with very satisfactory reaction rates. To conduct such reactions, the knowledge of enzyme behavior at high pressures is of primary importance as the loss of activity may lead to undesirable poor reaction rates and reduction of desired product production. To understand the potential of pressure application to enzyme processes as well as for a rational design of alcoholysis reactors, we have investigated in this work the influence of temperature, pressure, exposure time and decompression rate in high-pressure CO₂ medium on the enzymatic activity of a commercial immobilized lipase (Lipozyme IM) and a lipase from Penicillium restrictum immobilized in a hydrophobic resin. The experiments were performed in a high-pressure variable-volume view cell, varying the temperature (30-70^oC), pressure (70-250bar), using some high-pressure exposure times (60-360min) and adopting several decompression rates (10-200kgm^-3min^-1). Results show that temperature and reduced density had a positive effect on enzyme activity loss, while the exposure time and decompression rate had a significant negative effect.