The effect of essential oils on norovirus surrogates

Abstract

Essential oils (EOs) have long been applied as flavoring agents in foods, and due to their content in antimicrobial compounds, they have potential as natural agents for food preservation. In this study the effect of three EOs, clove, oregano and zataria, was evaluated on the infectivity of norovirus surrogates, i.e. feline calicivirus (FCV) and murine norovirus (MNV).Different concentrations of EOs were individually mixed with each virus at titers of ca. 7–8 log TCID50/ml and incubated for 2 h at 4 °C and 37 °C. The infectivity of the recovered viruses after triplicate treatments was evaluated by cell-culture assays. 2% of oregano EO at 37 °C decreased the FCV titers by 3.75 log TCID50/ml, with decreasing effects at lower concentrations, and also decreased MNV titers by 1.04–1.62 log TCID50/ml, with respect to the concentration used. Clove and zataria EO effects on FCV showed similar trends in titer reductions to those obtained with oregano EO, achieving the maximum titer reduction when FCV was treated at 37 °C with 0.1% of zataria EO. These results represent a step forward in the understanding of EOs as antimicrobials and their possible application in the food industry as alternative natural compounds to reduce viral contamination and, therefore enhancing food safety.