Control of Listeria within ready-to-eat foods

Why are we undertaking this project?

Approaches that demonstrate control of Listeria monocytogenes in ready-to-eat foods have different values in terms of the strength of evidence they provide. It can be difficult to predict how the competent authorities view the various pieces of evidence and exactly what a food business operator must do to demonstrate effective control where challenge testing, for example, suggests growth can occur.

What are we doing as part of this project?

Evaluating the growth potential of Listeria monocytogenes in ready-to-eat foods with the use of challenge test and durability studies at the potential to develop a scoring system for showing effective control of this organism. If this proves not to be possible a guideline covering aspects that can be used in Listeria monocytogenes will be produced.

Current status of the project

Survey
A survey has been carried out to find out if people are aware of the EU regulation 2073 in relation to Listeria monocytogenes control in products and following on from that how effective control is demonstrated. The results showed that 87% of respondents used environmental monitoring in order to demonstrate Listeria monocytogenes control, 69% used routine testing and 40% used predictive modelling and 40% challenge testing. A large proportion 94% would like some help and guidance on Listeria monocytogenes control.

Practical testing

A number of Listeria monocytogenes challenge studies have been carried out. This includes cooked meat products- two products from two sites, two raw fish products for use in sushi; milk, cream, two cheese products, three dairy desserts and three smoked fish products. Predictions have been run for these products and the routine and environmental monitoring data supplied and analysed. The findings have been written up and will be published as an RD report in the near future.

Steering group and guideline

A steering group was formed consisting of 23 members. These include manufacturers, retailers and relevant authorities. An online meeting was held where the production of a scoring system was discussed. At the meeting it was clear that a scoring system would be very complex and many factors would need to be considered even in something which appears simple such as environmental monitoring or routine testing. It was therefore decided that a guideline giving a summary and descriptions of the ways in which control can be demonstrated. These are historical data, predictive modelling, challenge testing and durability studies. Some case studies are included that describe findings in each of these categories and how they can be used to show Listeria monocytogenes control.

This guideline will be published in the near future.