Hygienic zoning is a key critical preventive control that often does not get the attention that it deserves. The basic concept of hygienic zoning is to divide a food or feed manufacturing facility into defined areas based on food safety risks. This is commonly used to control microbiological risks but also for other segregation needs, such as allergen control, physical hazards or GMO versus non-GMO.

Different industries are at varying stages of maturity when it comes to hygienic zoning. Infant formula manufacturers have been using these concepts for decades, as well as the RTE meat and poultry industry. Pet food facilities have been working to implement hygienic zoning after some significant Salmonella outbreaks were linked to dry pet food and pet treats a number of years ago. More recently, facilities manufacturing frozen blanched vegetables have reevaluated their hygienic zoning due to a Listeria outbreak, which caused a refinement to the definition of RTE. The fresh produce industry is also working diligently to validate pathogen reduction interventions, and as such, it is beginning to reevaluate hygienic zoning. To help you evaluate your hygienic zoning practices, we’ve put together three key considerations:

1) Creating a Divide

The hygienic zones within your facility can be divided physically, such as with a wall, or they can be divided using special practices, such as a requirement for employees to wash their hands or wear special shoes or clothing. Commonly, manufacturers would prevent microbial cross-contamination by dividing the raw side of their facility from the cooked side. Divisions could also be made between dry and wet areas, treated versus untreated areas or allergen-containing versus non-allergen areas. Most facilities also have non-manufacturing areas, such as offices, locker rooms and cafeterias, which would be a third defined hygienic zone.

The degree of hygienic control in each zone is based on the risk of product cross-contamination. A plant could have a fourth zone if it is producing a high care item, such as ready-to-eat (RTE) foods with an intended use of consumption by the general public, or a high, high care item, such as items designated for consumption by infants or other higher-risk groups. Another term often used in connection with hygienic zoning is the Primary Pathogen Control Area (PPCA). The product passes through this area after the pathogen kill step and is exposed to the environment here before being sealed in the final package. The stringency of controls in the PPCA depends on the intrinsic characteristics of the product (pH, water activity, etc.), the degree of exposure of the product to the environment and the degree of handling or processing of the product.

There is often confusion between hygienic zones and environmental monitoring zones. They are related, but the two are separate concepts. Hygienic zones are created within the facility based on the risk of cross-contamination to the product. Environmental monitoring zones are commonly divided into zones 1 – 4 for the purpose of targeting environmental sampling for pathogens such as Listeria or Salmonella. Environmental sampling zones 1 – 3 are sampling sites within the hygienic zoning PPCA, while zone 4 is designated for sampling sites outside of the PPCA.

2) Movement Between Zones

Obviously, you can’t design a manufacturing facility as a series of sealed boxes; people and items need to be able to move between the zones. This requires manufacturers to establish a buffer or transition zone between the hygienic zones. All of these devices and practices function to reduce the risk of contaminants moving from a dirtier or lower risk zone to a cleaner or higher risk zone. Hover over the circles on the image below for some examples of areas to consider for movement between zones:

3) Employee Training and Practices

When a solid physical barrier does not make sense, employee training and practices are key. A running joke at our North American Meat Institute Listeria Control Workshop is, “where do you buy yellow paint for lines on the floor that Listeria can’t cross?” When zone segregation depends on employee practices, it is always a great challenge to ensure that the practices are adhered to diligently. The success of this method is often directly related to the food safety culture within the facility.

The ideal plant layout would have raw, potentially contaminated ingredients entering one end of the facility, a place for processing in the raw area, and then product undergoing a scientifically validated kill step as it is piped or conveyed through a wall into the PPCA. After packaging, the product would be conveyed through another wall into the storage area. Employees designated to work in the PPCA would have their own locker room, cafeteria and maintenance area with PPCA-designated tools and equipment. Raw side employees would never see the PPCA employees during work hours. Clean, filtered air would flow from the PPCA to the other zones, and wastewater lines would run from the PPCA to the other zones.

I have seen facilities that painted the walls in each zone a different color and required employees to wear colored smocks to match the color of their work zone. These practices may seem extreme, but there are some newer or remodeled facilities that use these controls as part of their hygienic zoning plan. Unfortunately, most facilities do not have such an ideal layout, so well-designed practices must take the place of solid walls. Science-based risk evaluations can help determine the most impactful remodeling projects, training initiatives and practice changes.

Mérieux NutriSciences can provide assistance in a number of areas to help you improve your hygienic zoning practices. Our Food Science Center offers challenge studies to provide the scientific validation of pathogen reduction interventions and formulations. Our expert consultants team can assist in conducting facility risk assessments and provide input on hygienic zoning. To map the PPCA for environmental monitoring and delineation of hygienic zones, our EnviroMap software provides helpful functions such as mapping, scheduling, documentation and flexible reporting. Our laboratories provide testing services for microbial and chemical contaminants as well as indicators for environmental, ingredient and finished product testing. Contact us now to learn how we can customize our services to meet your hygienic zoning needs!


Meet the Author

Tim Freier, Ph.D
Division Vice President, Scientific Affairs and Microbiology, America, Mérieux NutriSciences

Tim Freier is the Division Vice President, Scientific Affairs and Microbiology, North America at Mérieux NutriSciences. He has over 25 years of experience working in various food safety and quality related positions in food facilities and in the microbiology lab. Tim has worked extensively in the area of pathogen environmental monitoring and exploring and implementing new food safety technologies.

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