3D enzymatic preparations with graphene oxide flakes and hydrogel to obtain lactose-free products

Abstract

Graphene oxide (GO), due to its properties, such as large specific surface area and the presence of numerous active groups on its surface, can be used as a carrier in enzyme immobilization. The procedure of its chemical activation before enzyme molecules binding was elaborated. β-galactosidase, the enzyme used in obtaining lactose-free products, was immobilized after GO activation with divinyl sulfone. The preparation was active, stable, but troublesome for separation. Thus, the innovative solution – 3D preparations were proposed. GO with immobilized enzyme was encapsulated in alginate gel. The 3D preparations have been physically stable in milk by at least 30 days, and their separation by sedimentation or filtration was very easy. Substrate diffusion was fast thus the process ran in a kinetic regime, and the Michaelis–Menten equation was applied. A continuous process of lactose hydrolysis was performed in a column filled with the 3D preparations. By controlling the residence time, it was possible to obtain low lactose concentration in the effluent stream at very low temperature, 6 °C, which corresponds to refrigerated milk storage conditions.