Study Of Immobilized β-galactosidase Prepared By Porous Ceramic As Sorbent And Glutaraldehyde As Crosslinking Agent

This purpose of this study was to hydrolysis the lactose in milk by immobilizedβ-galactosidase,with a view to solve the problem that the freeβ-galactosidase generate low lactose milk with large quantity of enzyme and high cost besides getting rid of exogenous protein.Aftter Ceramic adsorption,we used glutaraldehyde to cross link immobilized enzyme.The parameter of immobilizedβ-galactosidase was determined, results are as follow:l.Lactase ceramic fixed tests carried out find that the best carrier is aluminum oxide plating porous ceramic microspheres.Absorbing lactase with this carrier,the results were as follow:When the flow velocity was 0.5mg/ml;pH=6.5;temperature was 25℃and the concentration of enzyme solution was 1.5mg/ml,the activity of immobilizedβ-galactosidase is highest.2.Using ceramic as carrier;glutaraldehyde as cross linking agent with concentration 1.2%;temperature 39℃,after time 4h the activity of immobilized enzyme was 115.4u/g(the activity of free enzyme was 262.2u/g).The recovery rate of immobilized enzyme was 44%.3.prepared immobilizedβ-galactosidase with ceramic as carrier, glutaraldehyde as cross linking agent.The optimum reaction temperature is 50℃,the optimum pH=7.Dynamics parameter of immobilized enzyme:Km = 0.78mol / L,Vm = 593.43μmol /(min g) compared with the free enzyme:Km=0.3 lmol/L,Vm=634.58μmol/(min g).The binding capacity of immobilized enzyme and substrate decline. After 9 weeks,the activity of immobilized enzyme could keep above 95% at low temperature.4.After detecting the condition of Immobilized enzyme successive catalyzed milk and the stability,we find that:In the packed bed reactor, retention time 270min,reaction temperature 50℃,35.5g immobilization enzyme,substrate flow velocity F=40ml/h,the hydrolysis rate of lactose was 73.2%,witch meet the requirement that low lactose milk contain 75% lactose.The half time period of Immobilized enzyme successive catalyzed milk is 11 days.Results of this study have a certain guiding function for the low-lactose milk generateion in industrial production.