Enrichment of fruit juice clarification from xylanase immobilized onto polystyrene surface using cysteine-capped copper nanoparticles

This research introduces a straightforward and efficient technique for anchoring enzymes onto a polystyrene surface by employing cysteine-functionalized copper nanoparticles as a bridging agent. The process entails activating the polystyrene surface through nitration and silanization using (3-mercaptopropyl) trimethoxysilane, followed by the attachment of cysteine-capped copper nanoparticles via thiol groups. This nanoparticle layer serves as a platform for the covalent immobilization of xylanase, facilitated by glutaraldehyde treatment. The immobilization procedure resulted in an immobilization yield of 25.79 ± 0.82%, calculated based on protein depletion, while the immobilized xylanase retained approximately 77% of its initial catalytic activity after immobilization. The immobilized enzyme also exhibited enhanced thermal and pH stability compared to its soluble counterpart. Furthermore, the immobilized enzyme was applied in clarifying fruit juices, leading to a 29.9% improvement in clarity for orange juice and a 26.9% enhancement for grape juice. This study highlights the promising potential of the developed approach in the fruit juice clarification industry.