Listeria monocytogenes (Lm) is main cause of death from foodborne illness in the EU. It is huge problem for the food sector, capable of surviving freezing (-18°C), relatively heat resistant (70°C/2 mins for 6-log reduction), and highly tolerant of salt (aw 0.92): survives in >20% salt solution – growing even in cured foods.
It’s worth noting that although it’s the most common cause of food-related death in Europe, the UK case numbers are much lower compared with the EU, which saw a reported hospitalisation rate of >95% in 2021.
In the same year, across Europe, the top five foodborne diseases were campylobacteriosis (which recorded the most cases), then salmonellosis, yersiniosis, STEC infections and listeriosis. However, the fatality rate was by far the highest for listeriosis at 13.7%.
The top countries impacted by listeriosis include Spain, Finland, Iceland, Denmark and Sweden (rates recorded between 2016-21).
The risk of becoming infected by one of these foodborne illness-causing pathogens can be lowered by consumers and businesses implementing hygienic practice (clean, cook, chill, separate) and consumers and foodservice following on-pack instructions (i.e. don’t eat frozen sweetcorn or other frozen vegetables without cooking as they are not ready to eat (RTE) products!). However, there are also a number of regulations in place for manufacturers to follow too and by doing so well, the risk of listeriosis becomes much lower.
Yet, in a recent webinar (Listeria: the law and best practice), Karin Goodburn, director general of the Chilled Food Association (CFA), affirmed the epidemiology shows that current law when applied and enforced is effective. The issue is when it’s not employed well.
“The law has not been implemented properly across the EU,” Goodburn argued, pointing to varied interpretations from each Member States.
Now, the EU is believed to be on the cusp of proposing new law (updating EU Microbiological Criteria for Foodstuffs Regulation 2073/2005) for the Listeria monocytogenes legislation – most likely in response to high rates of listeriosis; but it has yet transpired as to how this will manifest and impact those trading with or within EU Member States.
But do we really need another legislative change or just a refresher on best practice – and if law does change, what impact could this have on the industry?
Potential EU Listeria law amendments
The timeline for regulatory changes has not yet been determined, but Goodburn predicts the European Commission may convene in the third quarter of 2023. If that’s the case, there will be a four-week online consultation.
Possible changes for RTE could include the introduction of mandatory challenge testing to set shelf life, a limit of 100 cfu/g (criterion 1.2a) changed to Lm not quantified (10 or 20cfu/g), or criterion 1.2b changed so that Lm are not detected throughout life.
Challenge testing to determine RTE shelf life
The issue for Goodburn when it comes to challenge testing is that “it doesn’t tell you how clean your factory is” which is where Listeria is likely to be living – on the floor, on the slicer etc.
She explained that this is a costly lab test, wherein the product is subjected to inordinate levels of rapidly-growing bacteria to determine shelf life. However, she contends that it ignores controls within the factory and supply chain.
“You can see through historic ‘End of Life’ sampling and modelling using e.g., pH data what the Lm will do in a product. There is no need to challenge test a fish [for example]! Storage trials are proven to be effective in setting shelf life.
“This [challenge testing] is an expensive test and there are a lot of better things you can spend money on, such as temperature and hygiene controls.”
Moreover, right now there is insufficient lab capacity to even deliver on this. This could result in foods disappearing off shelves, even if safety substantiated through DOP, EOL and environmental data.
Shelf life would also be set by a third party with no knowledge of raw materials, manufacturing areas or processes. However, food safety is the responsibility of the FBO and its technical experts must be involved as they have a detailed knowledge of all aspects of the product.
Despite these potential issues, according to Goodburn, most Member States are in favour of challenge testing.
“A fallback position could be applying it just to EFSA-identified high risk foods such as RTE meat, fish and dairy.”
With regards to the proposal of 100cfu/g (criterion 1.2a) changing to not qualified (10 or 20cfu/g), Goodburn pointed to previous Food Standards Agency (FSA) analysis of CFA data which showed no public health benefit in reducing 100/g limit. This is because counts occur so rarely when best practice is in place.
In addition, 10/g will double the cost of plating methods and could therefore reduce the amount of sampling undertaken by FBOs and enforcers.
Looking at the possibility of criterion 1.2b changing to ‘zero tolerance/not detected’ limits, Goodburn warned of the unintended ripples this could cause throughout the food sector.
She elaborated that the 100/g limit allows FBOs to actively search for L. spp in the manufacturing environment, in components, in raw materials and to verify control of Lm by testing finished product. The levels of Lm associated with ‘unavoidable’ contamination of minimally processed products are very low, and the risks are minimal if multiplication does not, or cannot, occur during storage, distribution and preparation. Zero tolerance does not reflect ubiquity of L. spp in the environment and their resultant occasional presence in minimally processed foods and chilled wet manufacturing environments, nor its control.
“Assurance requires proactive monitoring,” stated Goodburn. “Not detecting Listeria in a 25g sample does not guarantee absence in a whole batch, and if Listeria is detected in a 25g sample, it does not imply that the whole batch is contaminated.”
By changing these limits, it could deter FBOs from testing as often because they’re worried about finding Lm and what the consequences of that will be. For example, a factory shutdown and reputational damage.
“Flexibility is needed,” urged Goodburn. If no (safe) leeway is offered in law, we may see a spike in recalls. She nodded to the US as an example of where such limits have been set and consequently reduced testing. This she suggested has led to mass recalls across the pond.
“The law has to facilitate people doing the right thing.”
Best practice for Listeria management in the plant
Summarising her thoughts on the possible routes new EU law could take, Goodburn was adamant that challenge testing should not become mandatory.
She also argued that enforcer and FBO training is needed to ensure a thorough understanding of the necessary controls and how to validate and verify their continual effective application.
For the non-UK industry, she added that EU federation buy-in and action is needed when new regulatory proposals emerge from the European Commission.
For Goodburn, best practice of the current law is the prudent move forwards, which she outlines as follows:
- Regular environmental swabbing and food sampling, included targeted environmental sampling, sampling of RTE food components at intake (in particular high risk commodities), and trend results.
- Environmental swabbing should be used to validate cleaning methods and verify ongoing efficacy of such processes.
- Food sampling should be undertaken at day of production and end of life to signal hygiene and shelf-life appropriateness.
All of these points are the agreed position of UK and European industry represented in the Industry Listeria Group chaired by Goodburn.
“There is a lot of guidance on Listeria – and these can give a good indicator on what is worth spending your money on,” Goodburn concluded.
Read more about the CFA’s report on controlling Lm in food manufacturing here.