Battling Listeria in Produce Processing

The final and most important need is substantial time to do the job effectively. Most plants have a hard first shift start time, so it’s important to instate a hard stop time. This allows the plant to be turned over to sanitation with enough time to effectively complete duties.

The sanitation process needs to be systematic. Once all the resources are in place, sanitation should follow a consistent pattern.

Dry clean-up/dry pick-up (“rough clean”). This cleaning preparation consists of removing all product and packaging materials from the area to be cleaned. All gross soil is swept, scraped, or otherwise picked up and placed into trashcans or other appropriate disposal containers. It is strongly recommended that select production personnel pick up gross debris and trash continually during production, minimizing the amount for sanitation. This is also a good time to manually clean sensitive electrical equipment with sanitizing wipes (or other low water cleaning methods) before covering them with protective plastic bags prior to sanitation. Dismantle necessary equipment at this stage, making sure appropriate safety precautions are followed to protect employees who are cleaning the equipment.

Pre-rinse/rough down rinse/wash down. Remaining debris should be washed from equipment using hoses, if possible, reusing water from flumes. Wash down is generally performed systematically, working from top to bottom and from the perimeter toward the center of the room. Finally, equipment should be inspected to ensure it is ready for foaming. At this point, all gross debris should be gone.

Drains. Drains are a high-risk area for Listeria. It is recommended that drains be cleaned early in the sanitation process. This reduces the possibility of soil and bacteria transference from the drains to other surfaces while the drains are being cleaned. Sanitation professionals cleaning drains should have separate personal protection equipment and tools for this job that are color-coded to prevent them from being inadvertently used for other cleaning tasks. Weekly deep cleaning of drains with a drain foaming chemistry like from Sterilex Corp. is strongly recommended.

Chemical cleaning. To remove remaining soils, chemicals should be applied using either portable or wall-mount foamers. The foam allows the chemical to cling to the surfaces instead of immediately running off. As the foam breaks, the solution wets the surface and aids in the removal of soil. Self-foaming chlorinated alkaline cleaners are the most common chemicals used for sanitation. The chemistry used, however, should be selected based on the type of soils present and the material composition of the equipment. Chemicals should be mixed according to the manufacturers’ recommendations and the concentration titrated to ensure it matches the level specified in the sanitation program.

Hand scrubbing. The chemical, by itself, can only do so much; mechanical action is necessary for removing all soils from a surface. After the chemical has been sitting on the surface for a few minutes, all surfaces should be scrubbed by hand using a scrub pad. All surfaces need to be cleaned, not just the direct food contact surfaces.

In many circumstances, additional chemical cleaning may be necessary. In hard water regions, periodic acid cleaning may be needed to remove hard water scale and mineral buildup. Other specialized cleaning protocols should be used to address specific cleaning challenges.

Rinsing. Potable water should be used to rinse away cleaning chemicals and soil before they dry. If the chemicals are allowed to dry, surfaces will need to be re-foamed before they can be rinsed properly. As with the initial wash down, rinsing should be performed systematically working from top to bottom and from the perimeter toward the center of the room.

Inspection of cleaned surfaces (re-clean if needed). After rinsing, all surfaces are inspected. If residual soil is found, the area should be re-cleaned as needed. In addition to visual verification of cleanliness, this is the appropriate point to use adenosine triphosphate (ATP) testing to verify the removal of soils from the surfaces. The results of ATP testing and the observations of the QA team should be provided to the sanitation team on a regular basis as feedback on their performance.