Designing Food Safety Into Your Plant

Don't make food safety an afterthought. Carefully planning the design and materials used in your plant can help insure the safety of your food production.

By Mike Pehanich, Plant Operations Editor

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Air can be the primary source of mold, bacteria and other microbes as well as allergens and other potential contaminants. It also carries heat and moisture, which can endanger the quality or safety of the food product under some conditions. Good airflow and filtration is essential to a food-friendly plant design.

Filtering air at 0.1 micron will remove bacteria, yeast, mold and most viruses.

“One of the primary areas [of focus] in facility design is the air, the air handling system,” says Don Graham, president of Graham Sanitary Design Consulting Ltd., Chesterfield, Mo. “So many plants are built with negative air pressure. You open the door and draw air, along with dust and microbes, into the plant. So one of the key areas I focus on is the incorporation of positive air pressure — and a well-filtered system — into the design.”

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Air quality should be at its highest level where the food product is most sensitive. That area is where the processed product enters the package, according to Graham, who held top technical and quality assurance positions with Green Giant of Canada and Pet Inc. as well as serving as senior food/sanitation technologist for Sverdrup Facilities.

“It’s a product/air counterflow,” says Graham. “As the production line moves from raw product through processing to packaging, the cleanest air commences at the point of packaging and flows backward to where product is microbiologically the least clean, the raw product stage. The point is, once the product is sterilized, you don’t want to re-contaminate.”

Maintaining sufficient positive air pressure is critical as well.

“You want to have enough positive air pressure so that air is blowing out the door and the plant is not sucking air in,” adds Graham. “Restrooms and personnel facilities are the only areas that should have negative air pressure. Their exhaust fans should blow to the outside.”

6. Site elements facilitate sanitary conditions. Provide site elements such as exterior grounds, lighting, grading and water management systems to facilitate sanitary conditions for the site. Control access to and from the site.

A cockroach infestation could really mess up your day. To keep roaches out of your plant, read this section and follow the recommendations closely.
The outside area of the plant should be kept neat with bushes and trees  — any object that might harbor pests — located away from the building. Employ bait boxes and traps where safe and practical and where regulations allow. Keep grass well trimmed and away from the plant.

Keep pests out with adequate door seals. Door and window screens should use 22-mesh or finer material. Air curtains add an extra layer of protection. Outside lights should be situated away from the building so they do not attract insects to the facility. Carefully position insect electrocutors so they will not draw insects to food areas.

If you are building a new facility, don’t locate near areas offering high risk of contamination, such as sanitary landfills, refineries, sewage treatment facilities, junkyards, etc. Surround the facility with fences and gates to limit access of outsiders.

People access also should be controlled from the front gate and/or other key entry points.

“Start thinking about sanitation at the property line, your first line of defense,” says Kramer. “Specify materials that are easy to clean. Design also for the expected life cycle of the facility. Your cost of control increases as you move closer to your intensive hygiene areas.”

7. Building envelope facilitates sanitary conditions. Design and construct all openings in the building envelope (doors, louvers, fans and utility penetrations) so that insects and rodents have no harborage around the building perimeter, easy route into the facility or harborage inside the building. Design and construct envelope components to enable easy cleaning and inspection.

This seventh principle focuses on the skin or envelope of the food plant and involves effective control of what small invaders get in.

Caulk or seal gaps at windows and doorways to prevent cavities where material build-up or pests can gather.

“Get away from the stone-ballast-over-tarpaper-type roofs, especially over processing areas where you have vents,” advises Graham. Contaminants can and will gather in these vents, which are also very difficult to clean and welcome insects, rodents and birds. Such roofs interfere with draining and tend to leak easily.

“There are a lot of good single-membrane materials available today,” adds Graham. “Stick with them. Just make sure that they are pitched correctly.”

8. Interior spatial design promotes sanitation. Provide interior spatial design that enables cleaning, sanitation and maintenance of building components and processing equipment.

“Equipment placement is important,” notes Graham. “Don’t shoehorn equipment into tight places. Leave space for cleaning, sanitation and maintenance, at least 30 inches between the machinery and the wall, so the equipment can be cleaned.”

Sara Lee’s Kramer recommends 360-degree access and good spacing of equipment.

All wall-mounted objects, including signs, sinks, electrical boxes and pipes, should have sufficient space — at least one to two inches — between them and the wall to make effective cleaning possible. Don’t leave nooks and crannies for material and organic build-up to occur.
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