Shedding Some Light on Inactivation of Foodborne Viruses

The majority of non-bacterial gastroenteritis is caused by norovirus, which is transmitted primarily through surfaces, food and water. Most household disinfectants are ineffective against these viruses with the exception of the bleach which, however, loses partially its activity and generates toxic residues in the presence of organic matter. Alternative, effective and safer methods of disinfection are necessary to hamper the spread of norovirus. This presentation will focus on the work of our research team on two promising approaches, namely peroxycarboxylic acids and pulsed light.

First, four peroxycarboxylic acids were evaluated based on their concentration and contact time. Monoperoxycarboxylic acids, namely peracetic and perpropionic acids, were the most effective by reducing the viral load of about 4 log₁₀ after a treatment with 50 mg L^-1 for 5 minutes. These molecules maintained their activity against noroviruses attached on stainless steel and PVC, clean or dirty, and entrapped in an artificial biofilm. In the case of peracetic acid, we showed that this inactivation was mainly due to damages on the RNA, probably through free radicals. At high concentrations, the capsid was also altered.

On the other hand, noroviruses were treated with pulsed light (200-1000 nm; 0.69 J cm^‑2 per pulse). Three pulses (1.6 seconds) decreased viral load of approximately 4 log₁₀ in all media tested (buffered saline, hard water, mineral water and sewage treatment effluent) with the exception of turbid water. At the maximum turbidity (1000 NTU), the reduction was 2.4 log₁₀. This technology is also effective to disinfect clean surfaces even in the presence of an artificial biofilm (4 log₁₀ after 7 pulses), but is affected by the presence of proteinaceous material. We demonstrated that the pulsed light inactivated norovirus by inducing damage to both the RNA and the integrity of the particles.

In conclusion, these results demonstrate the effectiveness of these approaches and