Purpose: The purpose of this study was to determine the efficacy of several natural antimicrobials alone and in combination with surfactants, against hepatitis A virus (HAV) and murine norovirus (MNV-1), a surrogate for human norovirus.
Methods: Grape seed extract, white vinegar, pycnogenol, pomegranate juice, cranberry juice, and sodium bicarbonate were evaluated for efficacy against MNV-1 or HAV at a 1 to 10 (virus to sanitizer) ratio in suspension. Antimicrobials with a pH below 4 were tested with sodium dodecyl sulfate (SDS) and basic compounds were combined with benzalkonium chloride. Following 1 minute contact time at room temperature, antimicrobials were neutralized using 10% FBS in PBS and an acid/base neutralizer. Antimicrobial activity was quantified following plaque assay (n = 3).
Results: MNV-1 (average inoculum titer was 6.17 log PFU/ml) was reduced by 2.33 and 2.65 log PFU/ml when treated with 0.01% or 0.1% grape seed extract, respectively, and by 1.59 log PFU/ml in 0.1% pycnogenol. Undiluted cranberry juice, pomegranate juice, and white vinegar were not effective (< 1 log PFU/ml reduction) alone. Combined with 0.1% SDS, reductions of 1.48 and 1.38 log PFU/ml were observed for cranberry juice and white vinegar, respectively. Reductions of HAV (average inoculum titer was 5.98 log PFU/ml) in 0.01% grape seed extract, 0.1% grape seed extract and 1% pycnogenol were 0.75, 2.00 and 1.33 log PFU/ml, respectively. Sodium bicarbonate (5%) did not inactivate HAV alone, however combined with benzalkonium chloride, a 1.22 log PFU/ml reduction was observed.
Significance: Results suggest the antiviral properties of some natural antimicrobials against foodborne viruses can be enhanced when paired with surfactants. Such combinations could be used as produce washes or food-contact surface disinfectants to help prevent transmission of foodborne viruses.