Kinetic model for lactose hidrolysis in a recirculation hollow-%bre bioreactor

Enzymatic hydrolysis of lactose by -galactosidase (Lactozym) has been studied in a jacketed stirred-tank reactor (JSTR) and in a recirculation hollow-%bre bioreactor (RHFB). The hollow-%bre module was manufactured with modi%ed cellulose-acetate membrane (Cuprophan). The variables tested were: temperature (25–40◦C), lactose concentration (0.0278–0:208 M) and enzyme concentration (0.100–4:51 g l−1). Within the experimental range analysed, the conversions in the RHFB, were lower than in the JSTR. A kinetic model is proposed for enzymatic hydrolysis of lactose in the RHFB, which considers competitive inhibition by the product (galactose) and reversible adsorption of the enzyme–galactose complex on the hollow-%bre membrane. The adsorption enthalpy of the enzyme–galactose complex onto the membrane was determined as being 77 5 kJ mol−1. ? 2003 Elsevier Ltd. All rights reserved.