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Egg is one of the most consumed food items. Currently, chlorine washing is the most common practice to disinfect shell eggs. Although chlorine washing is effective and low cost, it possesses a potentially negative impact to environment and human health. Plasma activated water (PAW) has been shown to possess antimicrobial activities. In this study, various amount (250, 500, 750, or 1000 mL) of PAW was generated by placing 1 or 2 acting plasma generator(s) in revered osmosis (RO) water at 60 watts for 20 min with 6 or 10 standard liter per minute (slm) air flow rate. After inoculated with Salmonella Enteritidis, shell eggs were placed into the PAW for 30, 60, or 90 s with acting plasma generator(s). When two generators were used, more than 4 log CFU/egg reductions of S. Enteritidis were obtained in the large amount of water (1000 mL) .In addition, concentrations of ozone, hydrogen peroxide, nitrate and nitrite were correlated with the effects of bacterial inactivity. The highest concentrations of ozone (0.9-1.36 ppm) and nitrate (55.5 ppm) were obtained at higher water amount and lower air flow rate. Higher oxidation reduction potential (ORP) and lower pH values were obtained with longer activation time, more generators, and lower flow rate. In addition, the results of ESR demonstrated that reactive oxygen species (ROS) was generated in the PAW. Observation of scanning electronic microscope (SEM) showed bacterial cells treated with the PAW were swollen or even erupted. These results indicated that cell membrane could the main attacking site for the PAW. Comparing with chlorine washing eggs, better sensory characteristics were obtained on the PAW treated eggs. This study showed that PAW was an effective method to inactivate S. Enteritidis on shell eggs even at large amount and the ozone, nitrate, and ROS could be the main cause of bacterial inactivation.
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