Enhanced stability, reusability, and lactose hydrolysis of β-galactosidase immobilized in ZIF-L frameworks

BACKGROUND: The immobilization of β-galactosidase (lactase) on solid supports is widely pursued to enhance enzyme stability, reusability, and catalytic efficiency for industrial applications. In this study, Zeolitic Imidazolate Framework-L (ZIF-L), a zinc-based metal–organic framework, was employed as a support for lactase immobilization to improve its performance in lactose hydrolysis processes. RESULTS: The immobilization process yielded 5.6 mg of enzyme per gram of support, with the immobilized lactase retaining 67.3% of its initial activity. Scanning electron microscopy (SEM) confirmed the morphological integration of the enzyme with ZIF-L, while Fourier-transform infrared (FTIR) spectroscopy indicated chemical interactions associated with successful immobilization. The immobilized enzyme demonstrated good operational stability, retaining 86% of its initial activity after four consecutive cycles. In terms of storage stability, 77% of the enzyme's activity was maintained after 2 weeks at 4 °C. Catalytic efficiency was significantly improved post-immobilization, with lactose hydrolysis reaching 68% within 1 h and 93% after 3 h at 37 °C, outperforming the free enzyme under the same conditions. CONCLUSION: ZIF-L proved to be an effective support material for lactase immobilization, offering enhanced stability, reusability, and catalytic efficiency. These results underscore its potential for application in dairy processing and other industrial sectors requiring efficient lactose hydrolysis.