Computer-aided control of water activity for lipase-catalyzed esterification in solvent-free systems

Biotechnology Progress
K Won, S B Lee

Abstract

A computer system for on-line monitoring and control of the water activity (a(w)) in solvent-free media has been developed. The performance of this system was investigated by carrying out the lipase-catalyzed esterification of n-capric acid with n-decyl alcohol. A humidity sensor measured the relative humidity in the reactor headspace, which was then transmitted electrically to a digital computer that was used as a feedback controller. The water activity control was achieved by sparging either humidified air or dried air through the reaction medium at a flow rate determined by the digital feedback controller. The use of humid air and dry air for a(w) control made it possible to induce a larger a(w) gradient and thereby higher water transfer rate. As a result, the water activity quickly reached the desired a(w) values. We tested whether water activity in the reaction medium can be monitored by measuring relative humidity in the headspace. When the water activity in the liquid phase was determined from measurements of water content in the medium and compared to that measured directly with the humidity sensor, the a(w) in the reaction medium did not differ significantly from that in the headspace. This indicates that there is a ne...Continue Reading

References

Jul 31, 1992·Biochimica Et Biophysica Acta·R H ValivetyA R Macrae
Dec 2, 1988·Biochimica Et Biophysica Acta·M GoldbergM D Legoy
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Citations

Jun 1, 2002·Current Opinion in Chemical Biology·Manfred T Reetz
Aug 8, 2007·Biotechnology Advances·Pierre Villeneuve
Nov 11, 2006·Biotechnology and Bioengineering·Anna E V PeterssonBo Mattiasson

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