Thermal Inactivation of Human Norovirus Surrogates and Hepatitis A Virus in Foods

Foodborne enteric viruses are the leading cause of gastroenteritis in humans. In particular, human noroviruses and hepatitis A virus (HAV) are the most important foodborne viral pathogens with regard to the number of outbreaks and people affected. Therefore, studies are needed to bridge existing data gaps and determine appropriate parameters for thermal inactivation methods for human norovirus and hepatitis A virus. Due to the absence of appropriate cell culture systems to propagate these viruses, cultivable surrogates (feline calicivirus, FCV-F9 and murine norovirus, MNV-1) are commonly used based on the assumption that they can mimic the viruses they represent. The objectives of this study were to determine thermal inactivation behavior of human norovirus surrogates and hepatitis A virus (HAV) in buffer, mussel, spinach and turkey deli meat, to compare first-order and Weibull models in describing the data in terms of selected statistical parameters, to discuss inactivation mechanism during thermal treatment and to provide insight for future studies and industrial applications. Temperature had a significant effect on both tD and D-values for the range from 50 to 72°C for all virus surrogates (p<0.05). In general, HAV was more resistant to thermal treatment than FCV-F9 and MNV-1 at all temperatures studied suggesting that it would require a more severe treatment than the tested human norovirus surrogates for inactivation in food. Results also revealed that the Weibull model was more appropriate to represent the thermal inactivation behavior of all tested surrogates. The thermal inactivation of viruses was found to be associated with HAV capsid structural changes and denaturation of proteins. This study provides useful information on the thermal vi inactivation behavior of viruses and will contribute to the development of appropriate thermal processing protocols to ensure safety of food for human consumption.