Looking back at food recalls in 2024, listeria monocytogenes appears to be the leading cause of food contamination and foodborne illnesses. It is a change from prior years where Salmonella was historically the primary agent. There are number of reasons for this change with the main one being some high-profile product recalls due to listeria contamination. Boars head or chicken made for school lunch program are just the two that made the headlines in 2024.
This causes the regulatory agencies to tighten inspections and tests for listeria in refrigerated ready-to-eat products more often. Food facilities must build their HACCP food safety systems in a way to prevent cross contamination with pathogens with the focus on Listeria. This is not just the way facilities clean their equipment, but also the state of the facility’s repair including machinery and structures. It is required that food facilities have adequate verification activities including environmental monitoring programs as a default verification activity in ready-to-eat and high-risk plants.
Refrigerated RTE facilities with wet washing process are prone to Listeria contamination from the environment. There are many ways those facilities can prevent cross contamination with environmental pathogens. The methods include not only cleaning and sanitizing procedures but also the GMPs with hygienic zoning, Preventive Maintenance Programs and most importantly verification activities including swabbing procedures.
Cleaning and Sanitizing – Facilities must properly design their SSOPs including careful determination of frequency for cleaning, chemical sitting / contact times, tools used for cleaning and selection of sanitizers. Since Listeria becomes immune to the same type of active ingredient in a sanitizer over time, your cleaning procedures should include provisions for sanitizer rotation. Training for cleaning personnel should be carried out and be fitted specifically to the assigned cleaning tasks. Sanitizer application methods depending on the type of surface should also be part of a “hands on” training. Very often we don’t realize that the way you spray the sanitizer on the surface will depend on the structure (flat surfaces versus interlock conveyors). The bottom line is that if the sanitizer solution is not on the surface, there is no agent removing the bacteria (including pathogens) from your environment.
GMPs – Good Manufacturing Practices for people working in high-risk zones. Your Program should differentiate between low and high – risk zones depending on where the potential for cross contamination with listeria is the highest. Typically, ready-to-eat areas with exposed food pose the highest threat to product contamination. Hygienic practice requirements for personnel working in those areas should be elevated to adequately protect food from cross-contamination. High risk hygienic zones are the ones you should focus most of your resources on and address in your Environmental Monitoring Program. Those are your primary pathogen control zones and people or material going to those areas must be subject to adequate hygienic practices and requirements.
Preventive Maintenance – the state of repair for equipment and structures within a food facility is important. Broken or rusty equipment is not easily cleanable and could become a harborage for environmental pathogens. Listeria in the environment travels with water and could get to the smallest cracks and crevasses. Ready to eat, wet processing facilities must follow sanitary design principles for their equipment and structures to minimize the risk. Equipment and structures must be maintained in a good state of repair to allow for cleaning. Those are very important factors that must be considered when designing your PM Program.
Environmental Monitoring Programs – EMPs must be crafted specifically for the facility. There are some common elements that must be addressed. Those include the frequency of swabbing, swabbing surfaces / zones, target organisms, timing and corrective actions. It does happen quite often that facilities only collect swabs pre operation. Those swabs verify the effectiveness of cleaning and sanitizing within the facility. Since environmental monitoring must assess the risk associated with product contamination, the swabbing must also occur during production hours. It is recommended that environmental swabs are collected at least 3 hours into a steady production run. The frequency of collecting swabs can be based on two factors. The primary factor should be the volume of food produced. The more food you make the more frequent swabbing should be. The other factor could include historical data from prior swab results or the results from baseline testing. Calculating positivity ratio could be a great indicator for swabbing frequency. The number of swabs you collect with each cycle is typically based on the complexity of your operation, i.e. the size of the facility with the number of production lines and pieces of equipment. It is expected that your swabbing will be randomized and covers all equipment and structures in high-risk areas within a year. For swabbing surfaces the requirement is to cover a variety of zones. Food contact, indirect food contact and nonfood contact zones. Areas outside of your ready-to-eat rooms can also be covered in the EMP but perhaps on a less frequent cycle (i.e. once per year) or when investigating many out-of-limit results in the production room.
In conclusion, to prevent food contamination with listeria monocytogenes, the facilities must look at their HACCP food safety system from a broader perspective. All elements in your system including SSOPs, GMPs, Preventive Maintenance and EMPs must work together to ensure the food is safe.
If your facility needs any assistance with enhancing your food safety system through training or program development, feel free to reach out to our team at BD Food Safety Consultants LLC. You can fill out a contact form on our website at https://bdfoodsafety.com/contact-us/ or call 815-641-6404.