Viruses as an Invisible Threat to Food Safety
Fresh fruits and vegetables are commonly considered a healthy and safe dietary choice. However, despite their nutritional value, they can be a potential source of foodborne viruses—especially if they haven’t been properly cleaned or have been contaminated during production and distribution.
The viruses most commonly associated with such infections include noroviruses (NoV) and hepatitis A virus (HAV). Increasingly, cases are also being linked to hepatitis E virus (HEV), rotaviruses, and sapoviruses. These viruses can be found on the skins of fruits and vegetables, and although invisible to the eye, their presence can lead to serious health consequences.
Why Do Viruses “Cling” to Fruits and Vegetables?
Fresh and minimally processed products are sold ready-to-eat, without prior heat treatment and without protective substances against microorganisms. This makes them particularly vulnerable to contamination—both during production and at later stages of the supply chain.
Contamination can occur at the cultivation site, for example, through contact with wastewater or contaminated soil. It may also happen later—during transport, storage, packaging, or preparation by individuals not following proper hygiene practices.
Importantly, unlike bacteria, viruses do not multiply in food products but can survive on their surfaces for a long time. Even a low dose may be enough to cause an infection.
What Characterizes Foodborne Viruses?
Viruses are extremely small particles containing genetic material (DNA or RNA) enclosed in a protein capsid. They require living cells to replicate but can remain infectious for days or even weeks in environmental conditions.
They are highly resistant to external factors—they can survive contact with the acidic environment of the stomach, low temperatures, and common cleaning agents. They do not die during freezing and can persist on work surfaces, kitchen tools, and hands.
Does Heat Treatment Eliminate Viruses?
Not always. In the case of frozen or fresh products that are not subjected to prolonged heat treatment, the risk of infection still exists. Simply heating to 60°C is not sufficient, as enteric viruses require higher cooking temperatures for effective inactivation.
This makes not only proper washing essential, but also quality and food safety monitoring at various stages of production.
Modern Detection Methods – How to Find What’s Invisible?
Virological diagnostics in food products is one of the more demanding tasks in laboratory analysis. Due to the very low number of virions in samples and their irregular distribution, methods with very high sensitivity and precision are necessary.
In our laboratories, we use advanced molecular techniques—primarily RT-PCR (reverse transcription polymerase chain reaction). The process includes:
- elution of viruses from the sample surface and their concentration,
- isolation of genetic material (RNA),
- amplification and detection of viral material.
RT-PCR makes it possible to detect even trace amounts of norovirus, HAV, and HEV genetic material with high specificity.
If you have any questions or concerns, J.S. Hamilton Experts are at your service.