Efficacy of Oxidizing Disinfectants at Inactivating Murine Norovirus on Ready-to-Eat Foods

Introduction: Noroviruses are the leading cause of foodborne illness, and ready-to-eat foods are frequent vehicles of transmission. Studies of the disinfection of fruits and vegetables are becoming numerous. It has been shown that strong oxidizing agents are more effective than other chemical disinfectants for inactivating enteric viruses.

Purpose: The aim of this study was to evaluate the efficacy of oxidizing disinfectants at inactivating noroviruses: (1) in suspension and, (2) on fruits and vegetables.

Methods: Sodium hypochlorite, chloride dioxide and peracetic acid were used against murine norovirus in suspension and spiked on strawberries, blueberries and lettuce. Artificial feces were also tested for their potential protective effect against disinfectants. The viruses were recovered after each treatment and the viral reduction (log PFU/ml) was determined by plaque assays.

Results: Solutions of peracetic acid (85 ppm) and chlorine dioxide (20 ppm) reduced the infectivity of the virus in suspension by at least 3-log units after 1 min, while sodium hypochlorite at 50 ppm produced a 2-log reduction. On the surface of blueberries, strawberries and lettuce, chlorine dioxide was less effective than peracetic acid and sodium hypochlorite, which reduced viral titers by approximately 4 logs. A surprising increase in the efficacy of sodium hypochlorite on surfaces fouled with artificial feces was noted.

Significance: These results will help targeting the active ingredients in the formulation of disinfectants for washing fruits and vegetables to reduce the incidence of these pathogens.