Efficient clarification of apple juice using immobilized pectinase on glass surface in a novel support-free plate bioreactor

This study presents the development and evaluation of a novel support-free plate bioreactor (SFPB) for immobilization of pectinase and its application in apple juice clarification. The SFPB was developed as an alternative to the conventional packed-bed bioreactor to address operational limitations when comparing at an equal surface area. Pectinase was covalently immobilized on the inner glass surface using 3-aminopropyl triethoxysilane and glutaraldehyde. The immobilization efficiency in the SFPB was 2.38 times higher than in the PBB. The immobilized enzyme retained approximately 70% of its initial activity after 225 min, compared to 47% in the PBB. Kinetic analysis showed increased Km and decreased Vmax for the immobilized enzyme, indicating reduced substrate affinity and catalytic activity. Under optimal conditions (pH 5.5, 50 °C, 0.8 mL min−1, 45 min), the SFPB reduced turbidity from 325 to 4.3 NTU and increased clarity from 12.6 to 89.3%. These results demonstrate that the SFPB is a simple, reusable, cost-effective, and efficient system for industrial juice clarification.