Hepatitis A virus inactivation in phosphate buffered saline, apple juice and coconut water by 254 nm and 279 nm ultraviolet light systems

Novel ultraviolet light emitting diodes (UV-C LED at 279 nm) are being investigated for broad-spectrum antimicrobial activity in addition to traditional mercury-lamp 254 nm UV-C systems. The goals of this study were to determine the doses required for hepatitis A virus (a resilient foodborne virus) inactivation in phosphate buffered saline (PBS, pH = 7.2), apple juice (AJ, pH = 4), and coconut water (CW, pH = 5), when treated with traditional 254 nm UV-C compared to 279 nm UV-C LED. For each tested liquid, 500 μL of HAV (∼5 log PFU/mL) was mixed with 4.5 mL liquid within glass beakers and treated for 0–15 min with 254 nm UV-C (maximum dose of 33.89 mJ/cm²) or for 0–10 min with 279 nm UV-C LED (maximum dose of 7.03 mJ/cm²) with continuous stirring. Mixed model analysis of variance (SAS v 9.4) was used to statistically analyze the recovered viral counts of three replicates. HAV in PBS and CW showed significantly lower D₁₀-values (dose required for a 1-log PFU inactivation) of 4.37 ± 0.61 and 5.59 ± 1.16 mJ/cm² with 279 nm UV-C LED than 15.27 ± 2.01 and 10.46 ± 0.53 mJ/cm² with 254 nm UV-C, respectively (p ≤ 0.05). However, D₁₀-values for HAV in AJ of 4.02 ± 0.27 mJ/cm² by 279 nm UV-C LED and 3.31 ± 0.61 mJ/cm² by 254 nm UV-C were obtained. HAV showed the highest sensitivity to 254 nm UV-C treatments in AJ followed by CW and PBS. Overall, 279 nm UV-C LED systems show potential for HAV inactivation in the tested fluids without visual changes at the target doses, which warrants further investigation for scale-up operations.