• immobilized enzyme reactor;
  • lactose hydrolysis;
  • skim milk;
  • multi-response regression


A novel chemical reactor, consisting of β-galactosidase from Bacillus circulans immobilized onto a ribbed membrane made from polyvinylchloride and silica, was used to hydrolyze the lactose constituent of skim milk. Multiresponse nonlinear regression methods were employed to determine the kinetic parameters of rate expressions based on a proposed enzymatic mechanism that includes the formation of oligosaccharides. High-performance liquid chromatography (HPLC) methods were employed to monitor the concentrations of all species present in the effluent stream. For the experimental conditions used in this research, rate expressions which include the formation of trisaccharides, the inhibition effects of both the α and β anomers of galactose, and the corresponding mutarotation reaction are sufficient to model the reaction network.