In summer 2018, it was announced that frozen corn was the likely source of a widespread Listeria monocytogenes outbreak that has been affecting many European countries, dating as far back as 2015.
Source: Microbiology Insider magazine
Whole genome sequencing was able to trace the same strains of L. mono in frozen vegetables processed by a Hungarian company over a three year period; suggesting that the strains have persisted in the processing plant despite cleaning and disinfection procedures.
Increase in Environmental Monitoring
In response to this, frozen vegetable manufacturers have taken a systematic approach in reviewing their sites including zone segregation, factory layout, process flow and cleaning practices to assess and reduce the risk of Listeria within their sites. The frequency of monitoring the factory environment and finished products for Listeria was also increased significantly.
Auditing Service Implemented
To determine the efficiencies of these improved control measures, Campden BRI Hungary, a founding member of the Hungarian Freezing and Canning Industry Association (MHKSZ), were appointed to perform factory audits; based on their extensive industry knowledge and experience in frozen food technology. Following initial ‘fact finding’ audits during the 2018 production season, non-conformities were reported and further corrective actions deployed.
Best Practice to Avoid Cross Contamination
As there are so many possible routes of pathogen transmission within a food processing site, it is important for manufacturers to be aware of potential cross contamination risks. “Best practice to avoid cross contamination issues include frequent testing of the environmental samples and finished products” says Dr. Sebõk, “The speed, accuracy and reliability of the testing methods is also important for basing timely corrective actions, as well as regular internal audits by the companies”.
Continuous Improvement
For the 2019 processing season, Campden, supported by MHKSZ, are leading a working group of participating companies to create a voluntary standard for the ‘Control of Listeria monocytogenes in Frozen Vegetables and Fruit Products’. This joint bid brings together industry partners, and gives processors the opportunity to share experiences of both failures and successful practices within their sites, to continually improve conformity and reduce the risk for future outbreaks.
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