| dc.description.abstract | Enzymatic hydrolysis of lactose is an important biotechnological process because the hydrolyzed products can be consumed by people with lactose intolerance. The aim of this study was purification, immobilization, and characterization of β-galactosidase from E. cloacae. This research also studied the hydrolysis of lactose in UHT milk. The stages of this research were production and purification β-galactosidase from E. cloacae; characterization of enzyme; optimization of immobilization formula; and hydrolisis of UHT milk. The β- galactosidase from E. cloacae was purified and showed a purification of 30.26- fold, a yield of about 6.18%, and a specific activity of 101.781 U/mg. Free and immobilized enzyme exhibited maximum activity at an optimal pH of 7.0 and an optimum temperature of 40°C. This enzyme was activated by Co2+, Mn2+, and Mg2+; however, was inhibited by Ca2+, Zn2+, Cu2+, and Hg2+. KM for free and immobilized β-galactosidase were 0.434 and 2.068 mM, respectively. Optimal formulation of cell and enzyme immobilization were consist of 10% (w/v) cell with 5% (w/v) sodium alginate and 10% (v/v) purified enzyme with 5% (w/v) sodium alginate, respectively. This researh found that entrapped β-galactosidase was higher in the hydrolysis of lactose present in milk (28.09%) after 6 hours in batch process as compared to entrapped E. cloacae (22.01%) after 18 hours. Free β-galactosidase was higher in the hydrolysis of lactose present in milk (78.20%) after 6 hours as compared to free E. cloacae (55.14%) after 18 hours. | en |
