A 2D-Hollow-Air-Based Cold Plasma Generation Unit for Inactivation of a Human Norovirus Surrogate on Food Contact Surface

Introduction: Non-thermal decontamination of food contact surfaces from foodborne viruses, particularly human norovirus (NoV), is important in food service industry. We have found that a 15 second exposure to Ar+1%O₂ cold atmospheric pressure plasma jet was able to completely inactivate feline calicivirus (FCV), a surrogate of human NoV. Unfortunately, this plasma jet is capable of point exposure only and cannot be used on an industrial scale for decontaminating food contact surfaces.

Purpose: In the present study we evaluated and optimized the use, for the first time, of an atmospheric pressure two dimensional hollow-air-based high voltage cold plasma generation unit for FCV decontamination from food-grade stainless steel (grade 304) surface.

Methods: The effects of dry and wet plasma exposure, plasma generation power, exposure distance, air flow rate, and exposure time on the reduction of FCV titer (projected as log TCID₅₀/100 µl of the elution buffer) were studied.

Results: No significant (P<0.05) inactivation of FCV was observed in dry exposure while > 3 log reduction was attained when the surface was wetted by spraying water on the surface prior to plasma exposure. The highest virus inactivation (>3 log reduction in FCV titer) was observed at a 10 W plasma generation power, 3 mm exposure distance between the stainless steel surface and the hollow surface of plasma generation unit, 10 slm air flow rate, and 4 min exposure time.

Significance: The results showed that this 2D- hollow air-based plasma generation unit is more advantageous than the plasma jet unit since it is suitable for treating areas of surfaces plus it generates plasma from air with no need for using expensive pure gases. The results show that this novel plasma unit is promising in industrial application for decontaminating food contact surfaces from foodborne viruses.