Milk lactose removal by β-galactosidase immobilized on eggshell membrane

Eggshell membrane (ESM) is used in immobilization studies due to its large surface area, non-toxicity and biodegradability. In this study, β-galactosidase was immobilized on ESM using the adsorption and cross-linking method. The interactions between enzyme and ESM after immobilization were determined by ATR-FTIR (attenuated total reflection fourier transform infrared spectroscopy) and SEM (scanning electron microscope). The optimum temperature of the free enzyme was found to be 35 °C, and this value was 45 °C for the immobilized enzyme. Immobilized enzyme managed to retain more than 50% of its activity after 8 reuses. In the lactose removal experiment from milk, the highest reaction efficiency was found as 55.8% under specified optimization conditions for β-galactosidase immobilized ESM after 3 h. Due to the microfiber protein structure of the ESM, it has improved enzyme stability properties, as a result of the multi protein–protein interactions formed after the immobilization between the proteins in the ESM and the enzyme molecules.