Keeping Listeria out of your production facility


With the Listeriosis break out being a world record in terms of numbers reported, we as food professionals need to proactive.  Ready to eat foods have been named as a high risk, but we should all be doing whatever we can to ensure we manage the risks in all facilities, to the best of our abilities.


We are not alone though - an outbreak involving the same serotype 6 is also happening in EU countries; a multi-country outbreak was announced at the beginning of Dec 2017, but they have also not identified the source of the Listeria monocytogenes cross contamination causing the outbreak. From 2012 – 2016 between 1 754 and 2 555 cases were reported annually, and most of these cases were caused by serotype VIb; mainly from domestic origin.


During November 2017 Finland reported ST6 and four other countries were also being investigated. During 2017 there were 14 cases reported by Finland, Denmark, Sweden, Austria and United Kingdom; and 4 consumers passed away. Our reported numbers are significantly higher.


The question is – to act or not to act, rather than to investigate all methods and means of prevention. In primary processing there might be an impression amongst us that we cannot contribute to the prevention of infestation into the further processing facilities, which is the route the product takes on its way to the plate of the end user. But if ever there was a time in our history to stand together, it is now. We all need to come together, take hands and do whatever we can to prevent cross contamination from farm to fork.


Supplier approval and control

The suppliers of goods shall be approved by taking set criteria into consideration. To do this, one needs to be knowledgeable on the hazards associated with the product, produce or live animals which are purchased.


You must take these identified hazards into consideration when supplier approval criteria are compiled, as well as when systems are designed to assess compliance of goods (including animals).


The supplier must be aware of the organism and the applicable control measures for the respective industry and activities. Purchasing from the open fresh produce markets make supplier assessments a challenge. A good place to start would be to identify farmers who are known for goods agricultural practices and who deliver into these markets.


Slaughtering practices and cutting facilities

  1.  Heavy soiled hides must be rinsed before slaughtering - the cross contamination of soil to the carcass to be prevented at all cost.
  2. Handling of soiled carcasses not including rinsing - the contaminated surfaces should be trimmed off.
  3. Dropped meat protocol must be effectively implemented at all times. No rinsing of carcasses should take place; and contact surfaces must be trimmed off.
  4. No condensation in cold rooms should take place – it creates a potential cross-contamination between the ceiling (a non-food contact surface) and the carcass.
  5. If carcass washing is considered, it must be done with a food safe and food grade product. Ideally this practice should be eliminated over a period of time.
  6. Good food handler controls and practices must be in place - protective clothing must not be worn on the outside of the facility at any point in time.
  7. Dirty and clean side of the facility must be segregated with no potential cross flows inside the abattoir as well as on the premises. Food handlers, management, and other trafficking should be taken into consideration.
  8. Drainage of water inside the abattoir, as well as on the premises, must be taken into consideration.
  9. Tools and the like, which might enter the area, should be clean and neat.
  10. If ice is used, it could provide a harbour for Listeria spp. This equipment should be regularly cleaned and disinfected.


Cutting and processing practices

If the Listeria monocytogenes pathogen (or any other pathogen for that matter) is not internalised, then washing the produce down with a sanitiser solution can help to eliminate the pathogen count or at least reduce it to an acceptable level.

Sources of contamination in the packing plant include:

  1. Hands, gloves and personal protective equipment.
  2. Slicers and knives.
  3. Conveyors and table surfaces.
  4. Washing tanks and wash water.
  5. Holding containers.
  6. Shelving for packaging and packaging equipment.

 With all these sources of contamination in play, cleaning and personal hygiene practices must always be implemented to such extent that cross contamination is prevented during processing activities.


Cross Contamination points to be considered are:

  1. Condensation in cold rooms - potential cross contamination between ceiling (a non-food contact surface) and exposed product.
  2. Protective clothing – this must not be worn outside of the facility, and forms part of good food handler control and practices, which should be adhered to.
  3. High care practices – these must be fully implemented. No item should be transferred into the section without sanitation and segregation must be well-planned and fully implemented.
  4. Movement of tools and utensils - this can cause cross-contamination and they should be kept clean.


Cleaning practices

  1.  A master cleaning schedule and cleaning procedure must be in place to address good cleaning practices. Key areas for inspection must be identified; those difficult-to-clean sections must be identified for the visual verification of cleaning.
  2. No food contact surfaces (e.g. containers, trolleys, utensils) should be cleaned on the outside of the facility, to avoid potential cross contamination from outside.
  3. During cleaning operation prevent splashing of water from the floor onto equipment, from the drain onto the floor and also between equipment. This is a vehicle for cross contamination and can result in the organism being spread over the facility. This means you should avoid cleaning with high pressure washing equipment. Even medium pressure can contribute to this risk, if it causes splashing. Brushes used to clean drains can also be a culprit – you must ensure that the brushes do not touch the floor and the drain during cleaning.
  4. Ensure that no food contact area ever comes into contact with the floor. This includes hose pipes nozzles, which must never be placed onto the floor.
  5. It is necessary to perform a validation study to ensure that your cleaning is effective.
  6. Chemical sanitisers like iodophor, QAC, peracteic acid, peroctanoic acid are recommended; chlorine-like sanitisers are found to be too unstable and become too quickly inactivated. Floors, drains, waste and storage containers should be cleaned daily, with an acid; and walls, condensate drip pans, and coolers must be cleaned weekly or monthly.
  7. Use the maximum dilution level of the sanitiser which you are using, and do deep cleaning with peracetic acid.
  8. Overspray from one items/section to another can cause cross contamination. When using hoses, one should avoid contaminating equipment with water or chemical overspray while cleaning the adjacent items/line.
  9. Condensation should be sufficiently exhausted out of the area. Condensate can originate from steam, fog, or mist generated from cleaning and sanitizing activities. The formation of condensation over equipment that is operating must be prevented.
  10. Drainage cleaning should be done in such a way that it does not create drain backups in shared floor drains. Cleaning chemicals should not drain to equipment that is operating
  11. Cleaning activities should not take place in a way that does not adversely affect room temperature, relative humidity, or air pressure balance.
  12. Traffic patterns and potential cross contamination should be the same during cleaning as it is during operations and production.
  13. Listeria spp can thrive in brines. The re-use of brines can contribute to potential hazards. The organism might thus also survive in the injector. Ensure that the clean-in-place is effectively implemented
  14. Drain cleaning and regular cleaning are of utmost importance -  see guidelines below.


Steps to be followed during drain cleaning

  • Avoiding cleaning floor drains during times when foods are processed or exposed or when unused packaging is present;
  • Avoiding use of high-pressure hoses to clear or clean a drain, because use of such hoses could create aerosols that could spread contamination throughout the room;
  • Use brushes that are at least 0.8 cm smaller than the diameter of a drain opening to prevent splattering during cleaning of floor drains;
  • Using a splashguard to prevent splashing during cleaning; and
  • Dedicate tools used for cleaning drains to that purpose only and ensure that tools used for cleaning drains are easily distinguishable from utensils used for other purposes (e.g., by color-coding).


Steps to be followed during cleaning:

  • Dry Clean – Using appropriate tools (such as brushes, scrapers), remove heavy soils or debris from equipment, then floors;
  • Pre-Rinse – Working from the top of the equipment down, rinse and scrub equipment to remove visible soils. Using appropriate tools, remove any additional debris from the floors and drains, and then rinse the floor;
  • Apply detergent and scour – Apply foam cleaner to ensure adequate coverage by first foaming walls (if applicable), floors, and then the equipment from the bottom of the equipment to the top. Clean drains using appropriate tools. Scour equipment to remove any residues. Avoid the drying of the foam cleaner. Clean from top to bottom.
  • Post-Rinse – Remove the foam cleaner by flood rinsing the walls (if applicable), floors and equipment in the same order that the foam cleaner was applied;
  • Prepare for Inspection – Remove any possible overhead condensation or standing water and prepare the equipment for inspection;
  • Sanitize and Assemble – Sanitize the equipment, floors, and (if applicable) walls and prepare the equipment for operation, using ATP bioluminescence or other appropriate testing as a sanitation check.

Equipment standards

  1. This pathogen can infiltrate vacuum packing equipment. Ensure that the air system and filters are cleaned.
  2. The refrigeration units and drip trays can be a source and provide habourage. Regular cleaning and disinfection must be in place. Drainage of the unit must take place into the drainage system; no pooling of water should occur.
  3. No bubbled welding or similar grooves and niches are allowed, as they create areas where cleaning is very difficult. Any opening or similar construction which might be difficult to clean can provide habourage.
  4. Equipment must not be installed over drainage.
  5. It is advisable to inspect and clean all drip trays (refrigeration units); these items and the connected drain pipes can also provide a potential risk.

Construction standards

  1. Floors must not provide habourage areas. They must be impervious, smooth and cleanable.
  2. The design of the facility shall prevent any standing water due to incorrect floor sloping or any other causes.
  3. Sewage lines must never run through any production areas.
  4. All inside surfaces must be cleanable; impervious and smooth.
  5. Catwalks, if they exist, should not contribute to cross contamination.
  6. The production area must be fully enclosed.
  7. When a ready to eat product is packed, high care/risk facilities should be well constructed to prevent any possible cross contamination. Necessary control measures will include air control, personnel hygiene practices to be separated from that in the low risk/care areas.


If we all commit to following these best practices and reducing risks, we can play our part in saving lives.




Rika Le Roux Kemp