Listeria-related outbreaks and recalls are a persistent problem for the produce industry, according to the CDC’s listing of foodborne illness outbreaks and the FDA recall list. However, unlike other foodborne pathogens such as E. coli or Salmonella, which are usually brought into the plant on incoming raw material, Listeria can become resident in a processing facility, subsequently contaminating produce with each processing.
Listeria is a particularly challenging problem for produce processors. Much, if not all, of their product will reach consumers’ plates without undergoing additional processing, such as cooking, that could kill pathogens. This ready-to-eat status requires that produce coming into the plant be free of contamination, and that processing is carried out in a manner that minimizes the potential for contamination.
Produce is frequently processed in facilities that are cold and wet, an ideal environment in which Listeria can become a persistent issue if cleaning and sanitation practices are not thorough and consistent. Though seeming to be but an added cost to the food processor, effective sanitation can lead to long-term savings. Recalls are expensive, both in terms of lost product and, more importantly, in damaged brand reputation. A safe food product is a quality food product; no one wants consumers getting sick or sharing negative experiences. Additionally, the increasing involvement of the Department of Justice in outbreak investigations raises the potential for facility owners and management involved in outbreaks to become subject to criminal prosecution.
Proper sanitation, as a component of a robust maintenance program, can increase operational efficiency. Clean equipment breaks down less frequently, a sanitary environment increases product yield, and a cleaner workplace is safer for employees.
Components of Effective Sanitation Program
Sanitary design of facilities and equipment is a major challenge for the produce industry. An effective program starts with a plant and equipment that can be cleaned properly. Oftentimes, equipment is not designed or built to be cleaned. Equipment may be made from porous materials that trap soil and bacteria. Floors may be in poor condition with eroded concrete or cracked and peeling epoxy coatings. These issues cannot be fixed overnight, but they need to be addressed whenever possible. Of course, sanitary design principles should be used for any new construction or equipment installation.
A detailed discussion of sanitary design is outside the scope of this article, but it is important to review the American Meat Institute Sanitary Equipment Design Principles. Here’s a list of the 10 essential equipment characteristics:
- Cleanable to a microbiological level;
- Made of compatible materials;
- Accessible for inspection, maintenance, cleaning, and sanitation;
- No product or liquid collection;
- Hollow areas should be hermetically sealed;
- No niches;
- Sanitary operational performance;
- Hygienic design of maintenance enclosures;
- Hygienic compatibility with other plant systems; and
- Validated cleaning and sanitizing protocols.
It is vital to develop an operational cleaning and sanitation program. A master sanitation schedule must cover and document the following:
- What needs cleaning, with each item listed separately;
- How each item should be cleaned, including safety precautions such as lock out/tag out; how and what to dismantle (if necessary); what chemicals to use; how to mix and apply the chemicals; how to verify that the item has been properly cleaned; and how to sanitize the item;
- How often the cleaning should occur (e.g., nightly, weekly, or monthly); and
- Who is responsible for cleaning the item.
For a successful sanitation program, an adequate number of properly trained sanitation personnel are needed. Sanitation professionals must be provided with ongoing training in effective and safe job performance. Also, adequate supervision is vital to ensure the job is properly completed.
The sanitation team needs the right personal protective equipment: rain suits, safety glasses, goggles, gloves, rubber boots, and hard hats/bump caps. The right tools are also key: wash-down hoses, foamers, buckets and scrub pads, flashlights, ladders to reach elevated equipment, measuring jugs for chemicals, and chemical test kits. Additionally, an abundant supply of potable water, at appropriate pressure and temperature, is critical to the endeavor—soft water is ideal but not essential.
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.
Sanitizing. When all surfaces have been cleaned and any required verification testing completed, the final cleaning and sanitation step begins—the application of sanitizer, an EPA-approved compound that is intended to kill all bacteria remaining on the surfaces. Many ready-to-eat facilities use a three-step process—disinfection, rinse, sanitize—for greater efficacy. A sanitizer is applied at a higher concentration, rinsing happens after appropriate contact time, and a no-rinse concentration is applied prior to starting production.
Sanitizers, applied at a “no-rinse” concentration, should be drained but not rinsed off the surfaces prior to the start of processing. Because some produce items can be damaged upon contact with certain sanitizers, it is essential that sanitizers be compatible with the products being processed. Furthermore, rotating, or changing, sanitizers on a regular basis is recommended to provide an additional challenge to resident microbes.
The steps described above can be applied to all produce processing facilities, whether they run conventional or organic products. Differences occur at the sanitation step, where the final sanitizer must be one that is approved for organic production.
Listeria represents a growing challenge for produce processors, who are concerned about both their brand and their consumers’ health. There is no single “silver bullet” that can prevent Listeria contamination on fresh produce. However, a robust cleaning and sanitation program with multiple interventions can allow effective control of Listeria in produce processing facilities.
Dr. Owens is the director of technical services at Birko in Henderson, Colo. Reach him at 800-525-0476.