Engineering a Robust Glucose Oxidase for Juice Preservation: Enhanced Catalytic Performance Drives Browning Inhibition and Shelf Life Extension

compared to the wild type. M1 retained 81.9% of its activity after 60 min at 60 °C, a remarkable improvement over the wild type's 6.2%. It also demonstrated broad pH tolerance, maintaining over 66% activity under alkaline conditions. When applied to apple juice preservation, M1 effectively suppressed browning, with the polyphenol oxidase inhibition rate reaching 87.1%, increased vitamin C retention by 37.9%, and exhibited direct antifungal activity against common spoilage fungi. This study provides a highly efficient and robust biocatalyst for extending juice shelf life while preserving nutritional quality.