Reduction of Norovirus Surrogates Alone and in Association with Bacteria on Leaf Lettuce and Tomatoes During Application of Aqueous Ozone

This study evaluated the efficacy of ozonated water on the inactivation of viruses, bacteria, and viruses in association with bacteria on produce surfaces. Boston bibb lettuce (BB) and cherry tomatoes were spot inoculated with viruses (murine norovirus (MNV) and MS2 bacteriophage), bacteria (Enterobacter cloacae andBacillus cereus), or MNV associated withE. cloacae orB. cereus. Following inoculation, produce was held at 4  °C for 90 min (virus, virus + bacteria) or 24 h (virus, bacteria) prior to treatment. A batch wash ozone sanitation system (BWOSS) was prepared with ice (3–5 °C) and 0.5 ppm initial ozone concentration or no ozone. Produce samples were treated for 40 min with an ozonated water (0.86– 0.99 ppm) or water-only wash with samples taken every 10 min. Samples were processed for microbial recovery, and plaque forming units (PFU) and colony forming units remaining on the produce were determined. Although microbial reductions of 99 to 99.99% were achieved during ozone treatments, few st atistically significant differences (P >  0.1) were detected when comparing the ozonated water to water-only wash. Notably, a significant difference (P = 0.009) in log reduction of MNV + bacteria and MNV alone on BB was observed after 40 min ozonated water wash. Specifically, MNV withB. cereus achieved a 1 −log greater reduction (2.60 log PFU/ml) compared to MNV alone (1.63 log PFU/ml). Overall, washing produce in ozonated water did not significantl...
Source: Food and Environmental Virology - Category: Virology Source Type: research