Glucose Reduction in NFC Apple Juice by Immobilized Glucose Oxidase/Catalase: Quality and Safety Assessment

Increasing consumer awareness of the adverse health effects of excessive sugar intake increase the interest in technologies for the reduction of sugar levels in fruit-based products. Apple juice, although perceived as a natural and healthy product, is characterised by a relatively high naturally occurring carbohydrates. The use of immobilised glucose oxidase and catalase represents a promising biotechnological strategy for selective glucose reduction, offering biocatalyst reuse and easy separation from the final product.

The aim of the study was to reduce the glucose concentration in NFC apple juice through the use of glucose oxidase and catalase immobilized in a gel matrix. The scope of the work included an assessment of the effectiveness of the immobilized enzymes in reducing the glucose concentration in apple juice and process assessment. Glucose oxidase (Aspergillus niger) and catalase (from bovine liver) were immobilized using 3% sodium alginate and 0.2 M CaCl₂. During the experiments, immobilized enzymes were added to juice samples, and were incubated for 6 hours in a water bath at 35°C, with additional oxygenation of the juice. In the next stage, selected samples were subjected to physicochemical analyses to determine the effect of the process on juice quality, including sugar profile and selected food safety-related parameters.

As a result of the process applied, a significant reduction in glucose concentration was observed. Enzymatic treatment led to an increase in parameters such as formol number or gluconic acid concentration.

Overall, this preliminary quality and safety assessment study demonstrates the potential of glucose oxidase/catalase immobilized in alginate beads for glucose reduction in NFC apple juice and provides a basis for further evaluation of its effects on physicochemical quality and safety-related indicators.