Naringinase (EC 184.108.40.206) was immobilized onto glutaraldehyde cross-linked chitosan beads by an adsorption
method. Using one-factor-at-a-time and orthogonal array designs, the optimal immobilization conditions were determined as
follows: gel microspheres prepared with 3.5 g/100 mL chitosan as the carrier, 1.0 g/100 mL NaOH as the coagulant, 7.0%
glutaraldehyde solution, 2.0 h of cross-linking, 2.0 mg/mL of naringinase concentration and 3.0 h of adsorption at 25 ℃.
The maximum specific activity of the immobilized naringinase under these conditions was 7.37 U/g (based on dry chitosan)
without showing obvious differences in the optimum pH and temperature compared to the free enzyme. After 7 cycles of
repeated use at 40, 50 ℃ and 60 ℃, the immobilized enzyme maintained above 70%, 60% and 50% of its original activity.