Immobilization of β-galactosidase from Enterobacter cloacae : Characterization and its use in the continuous production of low lactose milk

Immobilization of �-galactosidase from Enterobacter cloacae was carried out using barium alginate gel (2%). Maximum activity (39.33 IU/mg) of the immobilized enzyme was observed at pH 9.0 and temperature 50 o C. The immobilized enzyme was found to be stable in pH range 8.5-9.5 and temperature range 4-50 o C. The enzyme activity was stimulated by only Ca 2+ , Mn 2+ and EDTA at 0.5 mM concentration. Immobilized enzyme was used for the preparation of low lactose milk in a jacketed packed bed column reactor (height 150 mm, internal diam 22 mm). At 89 mm bed height and dilution rate 4.30 h -1 , 61.25 and 46.67% conversion of lactose were observed using lactose (4%) solution and milk (lactose content 4.2%) as substrate, respectively.