Battling Listeria in Produce Processing

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.

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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:

1. Cleanable to a microbiological level;
2. Made of compatible materials;
3. Accessible for inspection, maintenance, cleaning, and sanitation;
4. No product or liquid collection;
5. Hollow areas should be hermetically sealed;
6. No niches;
7. Sanitary operational performance;
8. Hygienic design of maintenance enclosures;
9. Hygienic compatibility with other plant systems; and
10. 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.