Abstract: This study aimed to optimize the conditions for the immobilization of tannase with tannin microspheres. Besides, the structure of tannase before and after immobilization was characterized, and the application of immobilized tannase hydrolyze Lonicera edulis fruit juice was investigated. The results showed that the optimum processing conditions were determined using response surface methodology as follows: enzyme concentration 0.03 mg/mL, glutaraldehyde concentration 0.10%; pH 5.4 and immobilization time 40 min, under which, the recovery of enzyme activity and the specific activity were 71.78% and 724.72 U/mg, respectively. Tannase was well immobilized onto tannin microspheres through SEM and IR spectroscopy. The content of ellagic acid in fruit juice increased by 29.12% after adding immobilized tanninase. ΔE*ab was 3.49 when 4 mg of immobilized enzyme was added, indicating a significant decrease in the staining effect. The juice treated with immobilized enzyme showed significantly reduced staining of the mucous membrane of the tongue when consumed by microscopic observation.

Key words: tannase, immobilization, Lonicera edulis, staining