Use of ozone in a lettuce-washing process: An industrial trial

Bacteria such as Escherichia coli and Salmonella spp. may cause serious problems for the quality maintenance of pre-packaged lettuces. The aim of this study was to evaluate the bactericidal effect of ozonated water in the washing of iceberg lettuce. For this purpose an ozone generator was integrated into a commercial lettuce-washing facility. Lettuce samples were removed from this process and analysed for mesophilic total viable count (TVC), E. coli, Salmonella spp., vitamin C and sugar content. The analyses were carried out either directly after washing or at the end of best-before date (BBD), in which lettuces were stored at 4 °C for 6 days. Water samples were analysed for total organic carbon (TOC) content and pH. Through the addition of ozone to the wash water the quality of lettuce during storage time was unaffected while there was only a limited observed decrease in populations of microorganisms.