Designing food safety into your plant

The essence of the “hygienic zones” principle is the strict control of the movement of people and materials through the plant to prevent contamination and its spread. People can be intentional or unintentional carriers, staff personnel or visitors, involved or uninvolved in the direct manufacture of food product. Materials include: raw materials, packaging materials, trash, rework, inedible matter, uniforms and clothing, maintenance materials and parts, and sanitation chemicals.

This principle incorporates hazard analysis of critical control points (HACCP), places where the food product is most vulnerable to contamination or where contaminants are most likely to build up or make entry. From that analysis should flow a plan to reduce the likelihood of contaminants entering the facility, let alone the food product.

Sara Lee’s Kramer emphasizes the concept of having “zones of control.” Identifying such zones as raw processing, clean room area, packaging, cook/chill, etc. is Step One. A logical process flow and control of movement from one zone to another will help determine prevention capability.

Personnel facilities — particularly locker rooms, showers and restrooms — should not open directly into a process area. Add an ante-room or hallway for separation.

2. Personnel and material flows controlled to reduce hazards. Establish traffic and process flows that control movement of production workers, managers, visitors, QA staff, sanitation and maintenance personnel, products, ingredients, rework and packaging materials to reduce food safety risks.

Once you have established control zones in the plant, you can introduce controls to manage the flow of materials and people between these zones.

“You need to consider how personnel move in the plant,” advises NFPA’s Henry. This is particularly important in a plant with multiple processes, and particularly in a plant where you have two very different processes, such as a process for raw product and a second for cooked product. When personnel and materials move freely from one process to another, the odds of contamination rise exponentially.

“When you have movement of personnel, tools and parts from one area of the plant to another — say maintenance — you have a disease vector,” notes Henry. “Some facilities have elected to dedicate tools to one part of the plant. They may have dedicated employees, too. The tools, even uniforms of personnel, may be color-coded.”

What would your USDA inspector find if he were to swab your equipment tomorrow? Photo courtesy of USDA.

Sara Lee’s Kramer advocates clear and active separation between areas, where feasible, to pose more formidable barriers to the migration of potential contaminants. Recommended measures include separating chambers, magnetic locks and controlling access to areas with card readers.

“Equipment moving from one process or part of a plant to another poses an even greater risk,” adds Henry. “Listeria, pests, molds, etc., can easily be transferred. This is especially true with material handling equipment. All equipment that moves between different parts of the plant needs to be considered for sanitation. When you move equipment, especially during weekend maintenance, you should have your HACCP team involved. Don’t move any equipment into a critical area of the plant without cleaning it first.”

Heat treating equipment prior to its entry into a critical region is one way of ensuring safe transfer. Henry suggests “tenting” where possible — a process in which disassembled equipment is wrapped in polyethylene and blasted with steam as a sanitary measure.

“The steam source must also be dedicated,” Henry emphasizes. “Plan the time, the people, and make sure you have enough steam!”

3. Water accumulation controlled inside facility. Design and construct a building system (floors, walls, ceilings and supporting infrastructure) that prevents the development and accumulation of water. Ensure that the water positively drains from the process area and that these areas will dry during the allotted time frames.

Temperature and moisture are critical to the growth of microorganisms. The drier your facility, the easier it will be to control microbial growth and dispersal.

But keeping a plant dry is easier said than done in food processing environments where water is an essential part of product, process and sanitation.

“If you are designing a wet process, you need to manage the water flows to control the risks,” says Kramer.

A sanitary design allows water to drain freely. “Pooling is a sign of trouble,” Kramer adds.

4. Room temperature and humidity controlled. Control room temperature and humidity to facilitate control of microbial growth. Keeping process areas cold and dry will reduce the likelihood of growth of potential airborne pathogens. Ensure that the HVAC/refrigeration systems serving process areas maintain specified room temperatures and control room air dew point to prevent condensation. Ensure that control systems include a cleanup purge cycle (heated air, make-up and exhaust) to manage fog during sanitation and to dry out the room after sanitation.