Abstract:

Pectinase was immobilized with magnetic microsphere of chitosan and cross-linked with glutaraldehyde. The partial properties of immobilized enzyme were investigated. The magnetic microspheres were prepared with Fe3O4 magnetic nucleus and chitosan. Pectinase was immobilized while microspheres were crosslinked with glutaraldehyde. The preparation conditions of immobilized enzyme were determined by orthogonal test design. The partial properties of immobilized enzyme and free enzyme were compared and studied. The results showed that Fe3O4 magnetic nucleus could be made out when Fe2+:Fe3+ was 1:1 (volume ratio). When the amount of Fe3O4 was 1.0 g, chitosan concentration of 3%, 3.0 mg/mL pectinase amount, treated with 3.0% glutaraldehyde for 4 h, and the process time was 1 h under pH 4.0, the recovery rate of magnetic immobilized pectinase activity could reach to 68.4%. The optimum pH and optimum temperature of immobilized pectinase for the hydrolysis of pectin were determined to be pH 4.0 and 50℃, respectively. The immobilized pectinase was stable in the pH ranges from 2.6 to 5.6, and had good thermal stability under 70℃, which the residual enzyme activity was also 82.8% after treated at 70℃ for one hour. The apparent Michaelis constant of immobilized pectinase Kmapp equaled to 1.38 mg/mL. The recovery activity of immobilized enzyme was more than 61.0% after repeated six times. The immobilized pectinase prepared with magnetic microsphere of chitosan were good enough for the strength, the flexibility and the recovery rate, and had good operation stability.