Covalent Immobilization of Pectinase on Functionalized Magnetic Nanoparticles for Improved Catalytic Stability and...

In this study, the commercial pectinase enzyme derived from Aspergillus niger which is of critical importance in the food industry was covalently immobilized onto surface-functionalized magnetic nanoparticles to maximize its operational stability and reusability. The magnetic nanoparticles (MNPs) used as the carrier material were synthesized via the co-precipitation method. To enhance their chemical and physical stability, they were coated with silica using tetraethyl orthosilicate (TEOS), and amino groups were subsequently incorporated into their surfaces using 3-aminopropyl triethoxysilane (APTES). Pectinase was covalently immobilized onto these modified nanoparticles via glutaraldehyde, a cross-linking agent, and the successful synthesis of the nanobiocatalyst was confirmed by FT-IR and SEM-EDX analyses. As a result of catalytic performance evaluations, it was determined that the immobilization process did not cause any shift in the enzyme's optimal temperature (50°C) or optimal pH (pH 5.0). In contrast, the developed magnetic nanobiocatalyst exhibited a significantly superior profile compared to the free enzyme in terms of thermal stability, pH tolerance, and long-term storage stability. Operational stability (reusability) tests revealed that the immobilized pectinase could be easily recovered using an external magnetic field due to strong covalent bonds and managed to retain 81% of its initial activity even after 20 consecutive reaction cycles. The industrial applicability of the synthesized nanobiocatalyst was tested in a grape juice clarification process, resulting in a dramatic 82% reduction in the turbidity of the fruit juice. In conclusion, given its high catalytic performance and exceptional operational stability, this developed magnetic enzyme system has been shown to offer a sustainable biocatalytic solution with high potential for the fruit juice and food processing industries.