Determination Method for L-Ascorbic Acid in Foods with Immobilized Ascorbate Oxidase

Abstract

Pumpkin (Cucurbita moschata) ascorbate oxidase was entrapped within 6% (w/v) Ca-alginate gel beads, and then the beads were treated with 1% (w/v) glutaraldehyde for 20 hr at 4°. The immobilized ascorbate oxidase was much more stable than the free form. Under the optimum conditions, the immobilized enzyme remained fully active for 3 months and after 50 assays. A linear relationship was found between immobilized ascorbate oxidase activity and L-ascorbic acid concentration in the range of 2-20 μg/ml. The immobilized preparation could be employed for the simple and rapid determination of L-ascorbic acid in foods.