摘要：Research background. Pectinase enzyme has become a valuable compound in beverage industry. One of the most significant concepts to overcome the drawbacks of using industrial enzymes is the immobilization of enzymes. In the present study, magnetic chitosan microparticles were utilized as a substrate for pectinase enzyme immobilization. New methods of enzyme immobilization involve the use of non-chemical cross-linkers between the enzyme and the substrate. The aim of this study was to immobilize the pectinase enzyme using polyaldehyde kefiran as a macromolecular crosslinker on magnetic particles. Experimental approach. Pectinase enzyme was immobilized in four steps: relative oxidation of kefiran and its application as a crosslinker; production of magnetic iron (II, III) oxide (Fe3O4) microparticles; coating of magnetic Fe3O4 microparticles with chitosan; and immobilization of enzyme on the substrate, prepared by the use of oxidized kefiran crosslinker. Parameters, such as crosslinking concentration, time, and ratio of chitosan magnetic microparticles to enzyme, were optimized. Fourier-transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), transmission electron microscopy (TEM), and vibrating sample magnetometer (VSM) were used to identify the groups and investigate the structures. The biochemical properties (stability of enzyme activity at different pH, temperature and time), enzyme reusability, kinetics parameters (Km and Vmax) and apple juice turbidity, using free and immobilized pectinase enzymes, were also measured. Results and conclusions. Cross-linker concentration, crosslinking time and ratio of CMMP to enzyme were important factors in activity recovery of pectinase enzyme. FTIR analysis correctly identified functional groups in the structures. The results showed that after enzyme stabilization, the particle size and molecular mass increased and decreased the magnetic saturation strength, respectively. According to the thermal kinetic study, the immobilized pectinase was higher than its free form. In the present study, findings indicate the excellent stability and durability of the immobilized pectinase. Findings indicate the excellent stability and durability of the immobilized pectinase in present study. Finally, a magnetic pectinase micro-biocatalyst was used to clarify apple juice, which reduced turbidity of processing. Novelty and scientific contribution. This study investigates the usage of kefiran oxidized as a new cross linker for the immobilization of pectinase enzyme. Magnetic pectinase micro-biocatalyst has a good potential for industrial applications in the food industry, with high thermal stability.
关键词：magnetic microparticles;pectinase;chitosan;kefiran;apple juice
