Green synthesis of chitosan magnetic nanoparticles and their application with poly-aldehyde kefiran cross-linker to immobilize pectinase enzyme

Abstract

Abstract Today, the pectinase enzyme has become a valuable compound in the beverage industry. Among the different types of carriers, magnetic nanoparticles have been welcomed for their unique properties. The immobilization steps of the pectinase enzyme, including partial oxidation of kefiran polysaccharide and its application as a cross-linker, produced Fe3O4 magnetic nanoparticles, coating Fe3O4 magnetic nanoparticles by chitosan and enzyme immobilization on the substrate. Fourier transform infrared (FTIR), dynamic light scattering (DLS), x-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM) tests were used to identify groups and structures. Efficacy, biochemical properties, the reusability of the enzyme and kinetics of free and immobilized pectinase activity were also evaluated. Investigating the structure of chitosan magnetic nanoparticles showed the maximum recovery of the immobilized pectinase enzyme activity in 2% of the poly-aldehyde kefiran and the particle/enzyme ratio of 4: 1. Optimum pH and temperature were found for free (pH 4.0 at 50 °C) and immobilized (pH 4.0 at 60 °C) enzymes, and after one month, the remaining activity of the immobilized pectinase was 60.23%. The immobilized pectinase maintained its activity to 70.02% after 10 cycles. Km value of the immobilized enzyme (2/680 mg/ml) less than free enzyme (3/201 mg/ml) and Vmax of the free enzyme (0.595 μmol of galacturonic acid/min) less than the immobilized enzyme (0.801 μmol of galacturonic acid/min) were reported. Our results showed that the application of magnetic chitosan nanoparticles with poly-aldehyde kefiran cross-linker is an efficient, practical and green method for improving the properties of pectinase enzyme.