Antifungal chitosan-based lipoic acid/berberine sulfate composite film for suppressing Penicillium italicum and preserving mandarin fruit

Postharvest losses, specifically due to Penicillium italicum disease, pose a significant challenge to the mandarin industry. To enhance mandarin preservation efficacy, this study developed a chitosan (CS)-based berberine sulfate/alpha-lipoic acid composite film (CS@BS/ALA) and evaluated its effects on mandarin preservation. Among the various concentrations, 4 % CS demonstrated optimal wettability and adhesion. Incorporating BS/ALA into CS formed a dense double-network structure that reduced oxygen permeability. CS@BS/ALA treatment effectively inhibited weight loss, delayed fruit softening, maintained gloss, and preserved the brix acid ratio. It also enhanced antioxidant capacity by reducing malondialdehyde (MDA) content and sustaining superoxide dismutase (SOD) and phenylalanine ammonia-lyase (PAL) activities. Furthermore, antimicrobial tests revealed pronounced inhibitory effects of CS@BS/ALA against Penicillium italicum . These findings indicate that CS@BS/ALA extends mandarin shelf life by regulating respiratory metabolism, enhancing antioxidant defenses, and suppressing microbial infection, thereby providing an innovative solution for reducing postharvest losses.