Inhibitory Effects and Mechanisms of Water-Soluble Chitosan/Curdlan Edible Composite Coating on Polygalacturonase and β-Glucosidase

Postharvest fruits such as cherry tomato (Lycopersicon esculentum var. cerasiforme A. Gray) are prone to rot owing to the infection of pathogens, leading to great economic losses to farmers. To investigate the inhibitory effect and mechanism of polygalacturonase and β-glucosidase activity in cherry tomatoes and pathogenic fungi such as Alternaria (Nees: Fr) and Botrytis cinerea, various analyses including molecular simulation, ultraviolet spectrum, fluorescence spectrum, circular binary chromatography, inhibition rate, and enzymatic activity test were studied. The results showed that composite coating of water-soluble chitosan (CTS)/curdlan (CUR) significantly inhibited the activities of polygalacturonase and β-glucosidase in cherry tomatoes, Alternaria (Nees: Fr), and Botrytis cinerea. In addition, composite coating induced changes in enzyme conformation leading to a decrease in the rate of cell wall degradation in cherry tomatoes. The composite membrane inhibited 85% of polygalacturonase and 88% of the polygalacturonase and the ASP ASN ARG PRO GLU GLN and TRP residue of the β-glucosidase, thereby significantly inhibiting the decay of cherry tomatoes. In conclusion, the composite coating might inhibit the enzyme activity altering the enzyme structure, which showed promise as an effective method for fruit preservation.