Influence of organic matters on the inactivation efficacy of plasma-activated water against E-coli O157:H7 and S-aureus

In recent years, the potential application of plasmaactivated water (PAW) in the food industry has received increasing attention as a promising alternative to traditional sanitizers. The objective of this work was to evaluate the effect of organic matters in the form of beef extract or peptone on the inactivation efficacy of PAW against Escherichia colt O157:H7 and Staphylococcus aureus. PAW was mixed with beef extract or peptone (final concentration: 0-5.0 g/L) and the mixture was allowed to stand at room temperature for 15 min. Subsequently, 100 mu L of each bacterial suspension was treated with 900 mu L of the PAW/organic matters solutions at room temperature for another 6 min. The results showed that PAW treatment without organic matters could effectively inactivate the tested bacteria, resulting in 3.70 and 2.32 log reduction of E. coli O157:H7 and S. aureus in comparison to the control group, respectively. Beef extract or peptone severely quenched the inactivation efficacy of PAW against E. coli O157:H7 and S. aureus in a dosedependent way. The addition of beef extract and peptone significantly decreased the oxidation-reduction potential and NO2- concentration of PAW, increased the pH values of PAW in a dosedependent manner (p < 0.05), but did not significantly affect its hydrogen peroxide (H2O2) content (p > 0.05). Thus, more attention should be paid to the effect of interfering substances on the disinfection efficacy of PAW before its practical application.