The integrated enzymatic production and downstream processing of hexyl glucoside

A bioreactor was designed based on the optimal reaction conditions for the beta -glucosidase mediated glucosylation of hexanol. Due to fast deactivation of the enzyme in a CSTR, a spray column reactor was used, providing a low shear environment for the enzyme. This resulted in an enzyme half life of almost 30 days. The glucoside production in the reactor was 2.5 g. l(-1), the initial production rate was 2.24 mg . U-1 . h(-1). The, product containing, hexanol phase was separated from the, enzyme containing, water phase with a flat sheet polypropylene membrane, which was pretreated using block copolymers to prevent breakthrough of water. Indeed, no breakthrough of water was observed during 41 days of continuous operation. In-line adsorption was used to semi-continuously remove the produced glucoside. Ten different adsorbents were tested in equilibrium adsorption experiments. Based on these results, alumina was chosen for in-line adsorption. Five alumina columns were used in the same reactor batch resulting in an average glucoside adsorption of 11.15 mg . g(-1). The maximum glucoside adsorption in the full process appeared to be much lower than in the equilibrium experiments. This decrease could be attributed to the presence of water in the column influent. Furthermore, glucose displaces the glucoside after the maximum glucoside adsorption has been reached. Based on these results and the desorption characteristics, a regenaration regime for the column is proposed. Straightforward calculations with this reactor system were performed for the production of 1 kg of hexyl glucoside. (C) 2001 Elsevier Science Inc. All rights reserved.