Hygienic Zoning Control for Food and Dairy Operations: Protecting Ready-to-Eat and Sensitive Foods

Food production environments offer a shell of protection from a range of contamination sources.  Applying zoning principles to a plant design is a method to control the environment.  Through this zoning, plants can control traffic of people, materials, and air flow. Among other requirements, zoning dictates the fit and finish, level and method of cleaning, and required personal protection equipment (PPE) in each zone.  Microbes, foreign matter, chemicals, or allergens can be abated by controlling the environment.  Sensitive foods (i.e. easily spoiled) demand an elevated level of care to block against microbes.  Microbes can include pathogens or spoilage organisms inherent to the food growing to an unsafe level.

In restaurants and home kitchens food is often prepared open to the room.  Industrial scale food processing, in many cases, is a larger scale application of these practices resulting in processes, ingredients, and packaging open to the surrounding environment.  As a result, the environment around food processing equipment becomes an extension of that equipment.  A level of cleanliness to the space needs to be maintained to avoid contamination and preserve the food during the expected shelf-life and storage conditions.  

Different industries have adapted different hygienic zone designations to separate the areas of cleanliness.  For example, the pharmaceutical industry has multiple defined zoning systems.  For microorganism containment, different zones use an alphanumeric label according to the Biosafety in Microbiological and Biomedical Laboratories (BMBL).  For cleanliness levels, the International Organizations for Standards (ISO) have defined cleanliness set to numerical level.  Other groups such as European Medicines Agency (EMA) uses a similar letter designation system.  An example in the food industry includes the Preventative Controls for Human Food by the Food Safety Preventive Control Alliance (FSPCA) which introduces the need for food safety and a basic named zone system.

The diverse range of food risks without a systematic hygienic designation system has left the food industry with multiple systems creating uncertainty and confusion.  Within the food industry areas in direct contact with product, like equipment, have well defined hygienic requirements through systems like the 3-A Sanitary Standards(3-A SSI).  Defining the fit and finish of the full production environment is not as definitively spelled out.  This causes many companies to develop their own definitions.

The different levels of hygienic zoning are layered like an onion.  With the most susceptible area at the core.  In a user requirement specification or construction package a detailed definition of each care level should be given.  This should include cleaning of equipment and room plans, examples of materials of constructions, fit and finishes, personnel practices and Good Manufacturing Practices (GMP)and other related details.  The following naming example is used throughout the food industry, but no standard exists defining the levels.  For this reason, it is important for each project to outline the expected definition of each level.  Example levels in descending order:

1.      High Care

2.      Medium Care

3.      Basic Care

4.      Non-GMP

High Care is the highest level of concern including open product past its kill step (e.g. pasteurization).  For ready-to-eat products this step is the last protection step offered to the product prior to packaging and sealing it up for the consumer. This area typically includes equipment with a detailed plan for required frequencies for clean in place (CIP) and clean out of place (COP) of equipment and washdown environment.  This can require easily cleanable (i.e. 3-A SSI) equipment, smooth sealed floors, walls, and non-porous dropped ceiling.  Practices of employees are also defined such as use of hair and beard nets, gloves, captive shoe or booties, and long sleeves.

Medium Care includes open product upstream of the kill step (raw product).  Cleaning and finishes are similar to high care but adjusted to the state and nature of product.  Part of this designation is to keep it physically separated from the product in high care to prevent contamination of the final product.  

Basic Care is a generally clean area with packaged and sealed product.  Ingredients and final product in sealed containers. Where product shouldn’t be exposed but could be accidently.  This would not be washdown, but spills could be locally addressed.  This level is used as a transition point where hairnets, boot covers/shoe changes, and other personnel transitions take place.  

Non-GMP No production in these areas.  This includes other plant functions such as utilities, maintenance shop, offices, break rooms and rest rooms.  Though this isn’t a clean product space it is necessary to maintain cleanliness as a safe perimeter to the clean production space. General cleaning and pest control must be part of this space, as well as the space surrounding the building exterior.

After each separate space is identified flow through the plant must be mapped.  Air flow must be balanced so that the cleanest air is introduced with enough pressure to push air from the higher care areas towards lower care.  Personnel traffic needs to be planned to take them through gradual increasing levels of cleanliness as they work to the higher levels, with transition stations in between the zones for changing of or additional protective garments, and hand washing. Also, to minimize travel through the highest levels to essential functions.

Zones may be further subdivided by processes that need to take place or potential exposure of compounds. Identifying a space by cleaning practices, whether it requires wipe down or full foaming stations.  The walls and ceilings will need to reflect this plan. An IMP flat ceiling or smooth drop down may be needed for the space to easily clean overhead.

If the product or cleaning chemicals are acidic or basic, or if there are elevated temperatures this can lead to different surface materials and sealing practices.  Especially in higher care areas, the same considerations must be given to room as within equipment, avoid pockets cracks and crevices. If product or cleaners are high temperature or corrosive an acid brick or urethane cement finish may be required over a more basic hardened sealer used in other areas.

Overall, the hygienic zoning method of plant design offers a layered protection shell to surround and protect ingredients, packaging, in-process product and finished product. By segregating areas and controlling all flows and assigning proper fit and finishes.  Correct application gives a supportive protection to sensitive foods.

You can find extensive resources ion hygienic zoning at the 3-A SSI Knowledge Center Document Library at  https://www.3-a.org/knowledge-center/document-library.  Just enter ‘hygienic zoning’ or other subjects of interest in the search utility.