The effectiveness of ozone, ultrafiltration, and low pH on Escherichia coli inactivation in fresh-cut endive process wash water at a pilot setting

Abstract

During the processing of fresh-cut produce, any pathogenic contamination that could occur must be prevented so that uncontaminated produce does not become contaminated via the washing water(cross-contamination). Thus, there is a need to disinfect water during processing.This study evaluated three disinfection technologies – ozone, ultrafiltration (UF), and lowering the pH to 4.0 using processing aid T128 – when used singly during fresh-cut endive washing. The goal was to investigate the effect of these technologies on the reduction of Escherichia coli in the process wash water (PWW) and identify potentials for saving water and energy on an industrial washing line. The study focused on disinfecting the PWW of fresh-cut endive, with the first two technologies applied in a bypass and the third directly in the wash tank. The study provided the first proof of application for three different water disinfection technologies during pilot-scale fresh-cut endive washing. The main conclusions were that no E.coli reduction was found in the PWW during the experiments with ozone, UF or T128. Water and energy could be saved, although these savings were in the same order of magnitude as the technology costs. Furthermore, the pilot experiments allowed us to compare microbial and chemical aspects in the PWW and on the endive. This showed that although some chemical hazards like cadmium, lead, and nitrate accumulated over time, the final levels after two hours of recycling did not lead to an exceedance of legal limits in the PWW and endive. Future research should examine a modified bypass setup to allow treatment of higher water volumes. Especially ozone appeared interesting given that it is a more economical application than UF. The dosing needs to be adjusted, as the primary limitation was the insufficient dose applied. A possible combination of ozone and another technique, like UV, may be of interest to further research to achieve a higher log reduction.