Water is an essential component of food structures and biological materials. The importance of water as a parameter affecting virion stability and inactivation has been recognized across disciplinary areas. The large number of virus species, differences in spreading, likelihood of foodborne infections, unknown infective doses, and difficulties of infective virus quantification are often limiting experimental approaches to establish accurate data required for detailed understanding of virions’ stability and inactivation kinetics in various foods. Furthermore, non-foodborne viruses, as shown by the SARS-CoV-2 (Covid-19) pandemic, may spread within the food chain. Traditional food engineering benefits from kinetic data on effects of relative humidity (RH) and temperature on virion inactivation. The stability of enteric viruses, human norovirus (HuNoV), and hepatitis A (HAV) virions in food materials and their resistance against inactivation in traditional food processing and preservation is well recognized. It appears that temperature-dependence of virus inactivation is less affected by virus strains than differences in temperature and RH sensitivity of individual virus species. Pathogenic viruses are stable at low temperatures typical of food storage conditions. A significant change in activation energy above typical protein denaturation temperatures suggests a rapid inactivation of virions. Furthermore, virus inactivation mechanisms seem to vary according to temperature. Although little is known on the effects of water on virions’ resistance during food processing and storage, dehydration, low RH conditions, and freezing stabilize virions. Enveloped virions tend to have a high stability at low RH, but low temperature and high RH may also stabilize such virions on metal and other surfaces for several days. Food engineering has contributed to significant developments in stabilization of nutrients, flavors, and sensitive components in food materials which provides a knowledge base for development of technologies to inactivate virions in foods and environment. Novel food processing, particularly high pressure processing (HPP) and cold plasma technologies, seem to provide efficient means for virion inactivation and food quality retention prior to packaging or food preservation by traditional technologies.

This study aimed to inspect norovirus contamination of groundwater treatment systems used in food-catering facilities located in South Korea. A nationwide study was performed in 2010. Water samples were collected and, for the analysis of water quality, the temperature, pH, turbidity, and residual chlorine content were assessed. To detect norovirus genotypes GI and GII, RT-PCR and semi-nested PCR were performed with specific NV-GI and NV-GII primer sets, respectively. The PCR products amplified from the detected strains were then subjected to sequence analyses. Of 1,090 samples collected in 2010, seven (0.64%) were found to be norovirus-positive. Specifically, one norovirus strain was identified to have the GI-6 genotype, and six GII strains had the GII, GII-3, GII-4, and GII-17 genotypes. The very low detection rate of norovirus most likely reflects the preventative measures used. However, this virus can spread rapidly from person to person in crowded, enclosed places such as the schools investigated in this study. To promote better public health and sanitary conditions, it is necessary to periodically monitor noroviruses that frequently cause epidemic food poisoning in South Korea.

With a rapidly growing urban population in Kumasi, Ghana, the consumption of street food is increasing. Raw salads, which often accompany street food dishes, are typically composed of perishable vegetables that are grown in close proximity to the city using poor quality water for irrigation. This study assessed the risk of gastroenteritis illness (caused by rotavirus, norovirus and Ascaris lumbricoides) associated with the consumption of street food salads using Quantitative Microbial Risk Assessment (QMRA). Three different risk assessment models were constructed, based on availability of microbial concentrations: 1) Water — starting from irrigation water quality, 2) Produce — starting from the quality of produce at market, and 3) Street — using microbial quality of street food salad. In the absence of viral concentrations, published ratios between faecal coliforms and viruses were used to estimate the quality of water, produce and salad, and annual disease burdens were determined. Rotavirus dominated the estimates of annual disease burden (~10−3Disability Adjusted Life Years per person per year (DALYs pppy)), although norovirus also exceeded the 10−4DALY threshold for both Produce and Street models. The Water model ignored other on-farm and post-harvest sources of contamination and consistently produced lower estimates of risk; it likely underestimates disease burden and therefore is not recommended. Required log reductions of up to 5.3 (95th percentile) for rotavirus were estimated for the Street model, demonstrating that significant interventions are required to protect the health and safety of street food consumers in Kumasi. Estimates of virus concentrations were a significant source of model uncertainty and more data on pathogen concentrations is needed to refine QMRA estimates of disease burden.

Norovirus (NoV) is a major cause of acute non-bacterial gastroenteritis in all age groups worldwide. To detect NoV from foods, polyethylene glycol (PEG) precipitation or ultracentrifugation methods are generally used with reverse transcription (RT)-PCR. These methods need to use complicated procedures and varied buffers depending on the kinds of food matrices. In this study, we suggested a universal method to recover NoV in food and water samples as a prior step to real-time RT-PCR. As a NoV surrogate model, feline calicivirus (FCV) was used. FCV was artificially inoculated to samples, and then concentrated by the adsorption-elution method using negatively charged membrane filters. The detection limit was 4.3×10¹ PFU/250 mL for distilled water, 4.3×10² PFU/250 mL for environmental waters, and 4.3×10² PFU/15 g for lettuce and oyster. We were able to identify the possibility of one universal and time-saving method to detect NoV in food and water samples without modifications.

Norovirus infections are one of the most prominent public health problems of microbial origin in the U.S. and other industrialized countries. Surveillance is necessary to prevent secondary infection, confirm successful cleanup after outbreaks, and track the causative agent. Quantitative mass spectrometry, based on absolute quantitation with stable-isotope labeled peptides, is a promising tool for norovirus monitoring because of its speed, sensitivity, and robustness in the face of environmental inhibitors. In the current study, we present two new methods for the detection of the norovirus genogroup I capsid protein using electrospray and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. The peptide TLDPIEVPLEDVR was used to quantify norovirus-like particles down to 500 attomoles with electrospray and 100 attomoles with MALDI. With MALDI, we also demonstrate a detection limit of 1 femtomole and a quantitative dynamic range of 5 orders of magnitude in the presence of an environmental matrix effect. Due to the rapid processing time and applicability to a wide range of environmental sample types (bacterial lysate, produce, milk, soil, and groundwater), mass spectrometry-based absolute quantitation has a strong potential for use in public health and environmental sciences.

Consumer preference for minimally processed foods has steadily increased for several years, while foodborne outbreaks from under-processed foods continue to be reported worldwide. We investigated the combination effect of ohmic heating with various essential oil components for inactivation of foodborne pathogens in buffered peptone water and salsa. We choose carvone, eugenol, thymol, and citral to combine with ohmic heating, which are registered for use as flavorings in foodstuffs. Combination treatment of ohmic heating with citral showed the most synergistic bactericidal effect against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes in buffered peptone water followed by thymol, eugenol, and carvone. When enumerated on selective media, the reductions were 4.8, 5.7, and 4.3 log CFU/ml for E. coli O157:H7, S. Typhimurium, and L. monocytogenes, respectively. Cell membrane destruction by combination treatment and the loss of cell membrane potential by essential oil components were proposed as the bactericidal mechanism. When applied in salsa, inactivation of bacterial pathogens was the greatest with the ohmic and thymol combination treatment followed by citral, eugenol, and carvone. A synergistic virucidal effect was observed for MS -2 bacteriophage, which was used as a norovirus surrogate. Color (b* values) of salsa were improved by combination treatment of ohmic heating and thymol compared to ohmic treated samples. Therefore, the combination treatment of ohmic heating and thymol could be used effectively to pasteurize salsa.

Noroviruses (genogroup I (NoV GI) and genogroup II (NoV GII)) and the hepatitis A virus (HAV) are frequently involved in foodborne infections worldwide. They are mainly transmitted via the fecal–oral route, direct person-to-person contact or consumption of contaminated water and foods. In food virology, detection methods are currently based on identifying viral genomes using real-time reverse transcriptase PCR (RT-qPCR). One of the general requirements for detecting these viruses in food involves the use of a process control virus to monitor the quality of the entire viral extraction procedure as described in the ISO/TS 15216-1 and 15216-2 standards published in 2013. The selected process control virus should have similar morphological and physicochemical properties as the screened pathogenic virus and thus have the potential to provide comparable extraction efficiency.The aim of this study was to determine which virus should be used for process control, murine norovirus (MNV-1) or Mengovirus, when testing for the presence of HAV, NoV GI and NoV GII in bottled water, lettuce and semi-dried tomatoes. Food samples were spiked with HAV, NoV GI or NoV GII alone or in the presence of MNV-1 or Mengovirus. Recovery rates of each pathogenic virus were compared to those of both process control viruses using a multiple comparison procedure. Neither process control virus influenced the recovery of pathogenic virus regardless of the type of food matrix. MNV-1 was the most appropriate virus for validating the detection of HAV and NoV GII in all three food matrices as well as NoV GI in lettuce. Mengovirus proved to be the most appropriate control for NoV GI detection in bottled water and semi-dried tomatoes.The process control virus is essential for validating viral detection in food and the choice of virus depends on food type and the screened pathogenic virus.