Inhibition Mechanism of Water-Soluble Chitosan-Curdlan Composite Coating on the Postharvest Pathogens of Serratia marcescens and Pseudomonas syringae in Cherry Tomatoes.

Cherry tomatoes, a very popular fruit, are highly susceptible to microbial infestation, which cause significant economic losses. In order to preserve cherry tomatoes better, we treat them with a Chitosan (CTS) and Curdlan (CUR) composite coating. The lowest inhibitory concentration of CTS/CUR composite coating on Serratia marcescens and Pseudomonas syringae, the growth curves, and the changes of the cell lysis rate were determined to explore the inhibitory mechanism of CTS/CUR composite coating on Serratia marcescens and Pseudomonas syringae and the microscopic morphology of Serratia marcescens and Pseudomonas syringae was observed using scanning electron microscopy at the same time. The results showed that the CTS/CUR composite coating could effectively inhibit the growth of Serratia marcescens and Pseudomonas, and the inhibitory effect reflected the concentration-dependent characteristics. The electron microscopy results indicated that the inhibition of Serratia marcescens and Pseudomonas syringae by the CTS/CUR composite coating might originate from its disruptive effect on the cell wall and cell membrane of the bacterium.

Characterizations of Water-Soluble Chitosan/Curdlan Edible Coatings and the Inhibitory Effect on Postharvest Pathogenic Fungi.

This study focused on developing a composite coating comprising water-soluble chitosan (CTS) and curdlan (CUR). Cherry tomatoes served as the test material for assessing the preservative efficacy of these coatings. The incorporation of CUR markedly enhanced the coating's surface properties, refined its molecular structure, and improved its tensile strength and elongation at break. Additionally, the coating demonstrated enhanced permeability to water vapor, oxygen, and carbon dioxide and improved light transmission. The storage experiment, conducted at 25 ± 1 °C with a relative humidity of approximately 92% over 10 days, revealed that the CTS/CUR composite coating at a 1:1 ratio significantly outperformed the individual CTS or CUR coating and uncoated samples in maintaining the quality of postharvest cherry tomatoes. The 1:1 CTS/CUR composite coating demonstrated superior preservative effects. This study suggested that water-soluble chitosan/curdlan composite coatings have considerable potential for use in the preservation of postharvest fruits and vegetables.