Plasma-activated water for inactivation of Salmonella Typhimurium avirulent surrogate: Applications in produce and shell egg and understanding the modes of action

Abstract

Plasma-activated water (PAW) is gaining interest as a novel sanitizer for foods. However, the sanitizing efficacy of PAW varies under different conditions, and its modes of action and impacts on food quality need further investigation for it to be applied in the food industry. This study evaluated the inactivation efficacy of PAW against a Salmonella Typhimurium avirulent surrogate, investigated the underlying mechanisms, and assessed the impacts of PAW on the safety and quality of cherry tomatoes and shell eggs. PAW was effective in inactivating S. Typhimurium in a planktonic state (1.5–5.8 log CFU reduction in 2–5 min) and on the food surface (>5 log CFU reduction in 5 min). PAW prepared with deionized water vs. tap water did not differ significantly in sanitizing efficacy. Various reactive oxygen and nitrogen species (RONS) contributed to the antimicrobial property of PAW, with nitric oxide playing the most significant role. The acidic nature of PAW might synergistically affect bacteria by disrupting cell membrane and enhancing RONS permeation. PAW did not modify the visual appearance and internal pH of the treated foods. This study demonstrates that PAW has the potential to be applied as a novel sanitizer for fresh produce and egg washing.