Wednesday, November 7, 2007

Temperature Effects on Lipase-Catalyzed Esterification on Micro and Bench Scale

Jan W. Swarts, Petra Vossenberg, Anja E.M. Janssen, and Remko M. Boom. Food and Bioprocess Engineering group, Wageningen University and Research Centre, Bomenweg 2, Wageningen, Netherlands

Due to the small volumes of fluid in microchips, microfluidic chips have been accredited with complete temperature control. Fluids flowing through a micro channel can be heated to the chip's temperature within a second and cooled down to room temperature equally fast upon leaving the chip. This enables the researcher to have accurate control over the temperature profile fluids undergo. This research was focused on the possible thermal differences between micro scale and on bench scale esterification. Lipase type B from Candida antarctica was used to catalyze the esterification of propionic acid and 1-butanol in a water n-decane two phase system.

In this research the increase of enzyme activity and the temperature dependent inactivation of the enzyme were tested on micro scale (microliter reactor volume) and bench scale (milliliter reactor volume). On bench scale the enzyme was incubated at different time-temperature combinations and the residual esterification activity was determined. The inactivation of the enzyme was described by first-order inactivation. The effect of temperature could be described by the Arrhenius equation. Results of bench scale experiments were compared with results on micro scale.

Thermal effects on CalB can be determined on a micro scale, with very low consumption of reagents and catalyst, and then be applied to bench scale. This can reduce the cost of optimizing enzyme processes by downscaling. Furthermore, experiments requiring relatively short (< 1 minute) block-shaped heat up or cool down curves can better be performed on micro scale compared to bench scale.