Abstract
Enteric viruses, such as human norovirus (NoV) and hepatitis A virus (HAV), are the major causes of foodborne illnesses worldwide. These viruses have low infectious dose, and may remain infectious for weeks in the environment and food. Limited information is available regarding viral survival and transmission in low-moisture foods (LMF). LMFs are generally considered as ready-to-eat products, which undergo no or minimal pathogen reduction steps. However, numerous foodborne viral outbreaks associated with LMFs have been reported in recent years. The objective of this study was to examine the survival of foodborne viruses in LMFs during 4-week 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) using the modified ISO-15216 method as well as the magnetic bead assay for viral recovery. 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 the examined foodborne viruses can persist for a 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% (4 log) inactivation can be achieved for FCV, and MNV in chocolate, the inactivation efficiency diminishes to approximately 90% (1 log) in pistachios and 70% (< 1 log) in cereal. AOP treatment could therefore be a good candidate for risk reduction of foodborne viruses from certain LMFs depending on the food matrix and surface of treatment.
Highlights
Gastroenteritis outbreaks and illnesses due to the consumption of contaminated low-moisture foods (LMFs) are recently emerging as a food safety burden in developed countries, with norovirus and hepatitis A virus being important causes of LMF-associated outbreaks (Carvalho et al 2012; Donnan et al 2012; Anonymous 2019; Park et al 2015; Sakon et al 2018)
We have developed a magnetic bead-based assay for the isolation of hepatitis A virus (HAV) and norovirus surrogates, feline calicivirus (FCV) and murine norovirus (MNV), from LMFs and compared its efficacy against the adapted ISO 15216–1 method (Nasheri et al 2020)
We examined the survival of FCV, MNV and HAV in LMF by inoculation of pistachios, chocolate, cereals, and storage at room temperature (RT) for four weeks
Summary
Gastroenteritis outbreaks and illnesses due to the consumption of contaminated low-moisture foods (LMFs) are recently emerging as a food safety burden in developed countries, with norovirus and hepatitis A virus being important causes of LMF-associated outbreaks (Carvalho et al 2012; Donnan et al 2012; Anonymous 2019; Park et al 2015; Sakon et al 2018). A norovirus outbreak in 2008, which led to 117 symptomatic infections in Korea was attributed to dried radish (Yu et al 2010), another norovirus outbreak in 2017, which involved 2094 cases in Japan was linked to dried seaweed (Sakon et al 2018), and sun-dried tomatoes were identified as the vehicle for a large hepatitis A outbreak in Australia (Donnan et al 2012) Due to their low water activity (aw), LMFs are considered less susceptible to the growth of foodborne pathogens. The environmental stability of foodborne viruses together with their low infectious dose and resistance to conventional antimicrobial treatments, could lead to their persistence in LMFs and cause serious implications on public health
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