REMOVAL OF DISSOLVED-OXYGEN BY IMMOBILIZE D ASCORBATE OXIDASE ONTO A PACKAGING FILM

In order to remove dissolved oxygen from liquid food, ascorbate oxidas e (AO) was covalently immobilized onto ethylene-vinyl alcohol copolyme r (EVOH) film. Maximal activity was observed at pH 6.0, 30 degrees C ( 1.14 mU/cm(2)). The immobilized AO still retained a higher residual ac tivity than free AO under practical conditions; at pH 4.0 correspondin g to citrus juice, 10 degrees C and 60 degrees C, the residual activit ies were 47.8%, 91.3%, and 49.4% whereas those of free AO were 3.1%, 6 3.3% and 0%, respectively. When the AO immobilized EVOH film was direc tly in contact with 2.5 mM L-ascorbic acid in 10 mM citrate buffer sol ution (pH 4.0), more than 85% of dissolved oxygen was removed within 4 h. In addition, flavors (d-limonene, linalool, and citral) in the sol ution were successfully preserved from the oxidative deteriorations; f or d-limonene, the residual ratio (71.6%) with AO immobilized EVOH fil m was 2.5-fold that with non-immobilized one (29.0%) after 28 days' st orage.