Survival and Inactivation by Advanced Oxidative Process of Foodborne Viruses in Model Low-Moisture Foods

Enteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. Limited information is available regarding viral survival and transmission in low moisture foods (LMF). However, numerous foodborne  viral outbreaks associated with LMFs have been reported in recent years. Herein, we examined the survival of foodborne viruses in LMFs during long-term storage at ambient temperature and to evaluate the efficacy of advanced oxidative process (AOP) treatment in the inactivation of these viruses. For this purpose, select LMFs such as pistachios, chocolate, and cereal were inoculated with HAV and the norovirus surrogates, murine norovirus (MNV) and feline calicivirus (FCV), then viral survival on these food matrices was measured over a four-week incubation at ambient temperature, by both plaque assay and droplet-digital RT-PCR (ddRT-PCR). We observed an approximately 0.5 log reduction in viral genome copies, and 1 log reduction in viral infectivity for all three tested viruses following storage of select inoculated LMFs for 4 weeks. Therefore, the present study shows that foodborne viruses can persist for long-time in LMFs. Next, we examined the inactivation efficacy of AOP treatment, which combines UV-C, ozone, and hydrogen peroxide vapor, and observed that while approximately 100% inactivation can be achieved for FCV, MNV, and HAV in chocolate, the inactivation efficiency diminishes to approximately 90% in pistachios and 70% in cereal. AOP treatment could therefore be a good candidate for the elimination of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.