Inhibitory effect of vanillin on Pseudomonas syringae pv. actinidiae of kiwifruit surface and its effect on the quality of fruits

The bacterial pathogen Pseudomonas syringae pv. actinidiae (Psa) adheres to the surface of kiwifruit and can spread over long distances during fruit transport and sales. It is crucial to investigate efficient approaches to eliminate Psa from the surface of kiwifruit, ensuring the prevention of Psa dissemination and maintaining the overall quality of kiwifruit. Vanillin is used for the preservation of agricultural products due to its antiseptic and bactericidal effect. In this paper, Psa was used to infect Cuiyu kiwifruits, and inhibition of exogenous vanillin on Psa and effects on the quality of the treated kiwifruits were investigated. According to the results of the inhibition of Psa through exposure to vanillin, the effectiveness of inhibition on the surface of kiwifruit was as follows: 61.29, 92.33, 96.79, and 100% for the concentrations of vanillin at 5.0 mg.mL(-1), 6.0 mg.mL(-1), 7.0 mg.mL(-1), 8.0 mg.mL(-1), 9.0 mg.mL(-1), and 10.0 mg.mL(-1), respectively. According to the quality results, kiwifruits treated with 8.0 mg.mL(-1) vanillin exhibited a significant reduction in weight loss and rotting rate, with a decrease of 23.09 and 28.39% respectively, as compared to the control group. Additionally, thesetreated samples maintained a high level of total soluble solids, exhibited delayed degradation of total sugar content during a later period, inhibited an increase in respiratory intensity, and demonstrated increased firmness. Furthermore, vanillin treatment significantly increased the active values of superoxide, catalase, and peroxidase dismutase by 16.37, 28.75, and 23.92% respectively, compared to the control group. However, the levels of vitamin C and titratable acidity were not significantly affected by vanillin treatment. In conclusion, exogenous vanillin treatment exhibited potent inhibition capabilities against Psa, and effectively maintained the quality of kiwifruits during their shelf life. This study could provide reference basis for controlling the propagation of Psa and developing a new and natural kiwifruit preservative.