Virucidal Activity of Lemon Juice Against Feline Calicivirus, Surrogate of Norovirus

Abstract

Noroviruses are a major cause of acute gastroenteritis, often transmitted through contaminated food and water. In this study, lemon juice (LJ), rich in citric acid (CA) and flavonoids, was tested against Feline Calicivirus (FCV), used as a surrogate of human norovirus. Significant virucidal activity was observed for pure LJ (pH = 2.3), with a reduction in viral titers as high as 4.50 log₁₀ TCID₅₀/50 µL after 30 s and complete inactivation after 1 min. LJ also showed limited virucidal activity at a dilution of 1:2000 (pH = 6.7), with a reduction in viral titer of 0.75 log₁₀ TCID₅₀/50 µL. CA (at the same molarity as CA in pure LJ and adjusted to pH = 2.3) exhibited virucidal effects comparable to pure LJ, with a decrease in viral titers as high as 3.75 log₁₀ TCID₅₀/50 µL, whilst diluted CA (pH = 6.7) did not show significant effects. This study demonstrated the virucidal efficacy of LJ, suggesting the role of pH and, eventually, of LJ bioactive compounds against a norovirus surrogate. Due to its large use in food preparation, LJ has the potential to enhance the safety of raw food. Also, broader applications in personal hygiene and surface disinfection could be devised.

Keywords: citric acid; disinfection; lemon juice; norovirus; virucidal activity.

Figure 1

Cytotoxicity of the CrFK cells treated with LJ and CA at 72 h post-treatment and calculated using the XTT assay.

Figure 2

Virucidal effect of LJ incubated with Feline Calicivirus (FCV) for 30 s, 1, 3, 5, 15, and 30 min at room temperature and subsequently titrated in Crandell-Rees Feline Kidney (CrFK) cells. Viral titers of FCV were expressed as log10 TCID₅₀/50 μL, and treated virus titers were plotted against the control virus (CV). The bars in the figures indicate the means. The error bars indicate the standard deviation.

Figure 3

Virucidal effect of citric acid incubated with Feline Calicivirus (FCV) for 30 s, 1, 3, 5, 15, and 30 min at room temperature and subsequently titrated in Crandell-Rees Feline Kidney (CrFK) cells. Viral titers of FCV were expressed as log10 TCID₅₀/50 μL, and treated virus titers were plotted against the untreated control virus (CV). The bars in the figures indicate the means. The error bars indicate the standard deviation.