Characterization of immobilized catalases and their application in pasteurization of milk with H2O2

The catalase (fromAspergillus niger) has been immobilized by a chemical method on the pous SiO₂ modified with γ-aminopropyltrietoxysilane, followed with glutaraldehyde and by a physical method in alginate and γ-carrageenan gel. Optimum support:enzyme ratios and pH values were determined for modified SiO₂ in a series of immobilization reactions of catalase in the presence of the crosslinking agent glutaraldehyde, and for alginate and γ-carrageenan in the presence of hemoglobin and bovine serum albimine. pH and temperaturedependent activity variations and the stability properties of immobilized catalase preparations were investigated. Rate constants for H₂O₂ decomposition and catalase deactivation were determined. The decomposition rate of H₂O₂ used in the cold pasteurizatioan of milk were investigated in a discontinuous batch type reactor system. Activity half-lives of immobilized catalase were determined.