IMMOBILIZATION OF Aspergillus oryzae β-GALACTOSIDASE TO PRODUCE LACTOSE-FREE MILK

Abstract

Aspergillus oryzae β-galactosidase enzyme, in this thesis study, was immobilized onto Eupergit CM, using covalent binding method with 100 % immobilization yield and 129.82 % activity yield by optimizing the immobilization conditions. Characterization of free and immobilized Aspergillus oryzae β-Galactosidase was also studied. After immobilization, optimum pH shifted from 4.5 to 5.5, while the optimum temperature (55 ° C) did not change. For free and immobilized enzymes, kinetic constants were also determined by using the Lineweaver-Burk graph. The Km values of the free and immobilized enzymes were determined to be 307.7 and 234.2 g / L, respectively, while the Vmax values were determined to be 0.366 and 0.415 g D-Glucose / L.min respectively. There was no decrease in the initial activity of the immobilized enzyme after repeated 20 batch experiments and after storage for 15 days under optimum conditions. In addition, using the immobilized enzyme, the lactose in the semi-skimmed UHT cow's milk was completely hydrolyzed within four hours. In conclusion, it can be concluded that the immobilized Aspergillus oryzae β-Galactosidase obtained in this thesis can be used in the industrial production of lactose-free milk.