Session: General Poster:

Salmonella, which causes salmonellosis, is a major pathogen in food-borne disease related to fresh produce and its contamination rate is a significantly influenced by the surface properties of fresh produce. Epicuticular waxes present on the outer layer of the leaf surface provide water repellency to the leaves thereby they reduce the rate of Salmonella attachment. Damage or deformation of epicuticular wax crystals by external action, such as pesticide spraying, may increase the rate of Salmonella attachment. Meanwhile, the hydrophobic nature of epicuticular wax crystals may possibly reduce the effectiveness of Salmonella inactivation in fresh produce. The main purpose of this study is to investigate whether the rate of Salmonella attachment increases as pesticides denature epicuticular wax crystals and to test that antibacterial effect of ozonated water can be improved on waxy produce surface by adding surfactant to ozonated water. Leaf disks of three different surface conditions (waxy; with the epicuticular wax crystals, glossy; without epicuticular wax crystals, pesticide-treated waxy) were inoculated with a S. Typhimurium inoculum. As a result, significantly lower (P < 0.05) S. Typhimurium attached to waxy leaf surface than glossy and pesticide-treated waxy leaf surface (3.28 as opposed to 4.10 and 4.32 Log CFU/cm²), suggesting that the pesticide (surfactant) application increased the rate of S. Typhimurium attachment on waxy leaf surface. This was confirmed to be the influence of the surfactant per se which deformed the structure of epicuticular wax crystals. The surviving population of S. Typhimurium on waxy leaf surface washed with ozonated water was no significant difference when compared with unwashed waxy leaf surface (2.91 as opposed to 2.82 Log CFU/cm²). On the other hand, S. Typhimurium were not detected in surfactant-added ozonated water washed waxy leaf surface. These results imply that the surfactant can effectively improve the efficiency of ozonated water on plants with epicuticular wax crystals. Furthermore, disinfection strategy proved in this study will reduce the risk of cross-contamination by maintaining the quality of the washing solution safe and will become an environmentally friendly alternative for washing fresh produce in the food industry.

Kang-Mo Ku

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