Longer shelf life for some RTE foods contributes to Listeria rise, expert

By Rory Harrington

- Last updated on GMT

Related tags Listeria monocytogenes Cheese Rte

An industry expert has raised concerns about the lengthy shelf-life of some listeria-prone ready-to-eat foods (RTE) in come countries as the EU said it would help fund a pan-regional study on the issue.

Kaarin Goodburn, of the UK Chilled Food Association (CFA), said increasing incidents of Listeria monocytogenes could be linked to longer shelf lives allowed for foods such as RTE smoked salmon, meats and specialist cheeses in many continental European countries compared to the UK. In some cases, she said these can be up to twice as long.

Euro survey

The worries were voiced as the European Commission agreed last month to contribute more than €1.5m to a survey on the prevalence of Listeria in some RTE foods across the economic bloc, an official told FoodProductionDaily.com.

The decision to provide cash for the project was unanimously backed by member states after the Commission reported there had been a “significant increasing trend in cases of listeriosis”​ in humans since 2001. The body said RTE foods could “be an important source of contamination”​ and that “illness is often severe and mortality is high”.

According to the European Food Safety Authority (EFSA), the highest frequency of Listeria-tainted products are found in RTE fish, cheese and meat products because they no longer “undergo any treatment” before consumption - such as reduction before cooking," ​added the Commission official.

She added: "Cheeses, meat products and sandwiches were most often identified food vehicles in food-borne listeriosis. Microbiological risk assessment studies have also shown a relatively high risk for listeriosis caused by consumption of smoked fish."

Longer shelf lives

CFA secretary general Goodburn said she believed the longer shelf lives allowed in some countries for RTE meat, fish and cheese products was also a factor.

“The shelf life of smoked salmon in the UK is usually around three weeks, whereas many other European counties allow it to remain on shop shelves for up to six weeks,”​ she explained.

“If you give certain foods such as RTE fish, meat and cheeses that have a potential Listeria presence an excessively long shelf life, then it gives the bacteria longer to grow.”


The Commission confirmed the survey will be carried out next year with the findings from individual countries due to be reported by the end of May 2011. The final report is scheduled for release by the end of 2011.

As human exposure to Listeria is food borne, the study will look at packaged (not frozen) hot or cold smoked or gravad fish; soft or semi-soft cheeses, excluding fresh cheeses and packaged heat treated meat products in a harmonised way across Europe.

The Commission said: “The growth of Listeria monocytogenes in a ready-to-eat product is influenced significantly by the pH, water activity and storage temperature of the product. A modelling can be used for the estimation of the growth of Listeria monocytogenes in a ready-to-eat product under various temperature conditions.”

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