Setting the scene for contamination control

An intelligent facility design can inhibit the entry, growth and spread of harmful microorganisms during food production. Pablo Coronel, Director Food Processing, and Dennis Collins, Architectural Practice Manager, CRB, look at the layout, construction materials and environmental controls

It is important to plan a large enough space to accommodate
the current production level and future growth potential

Producing safe, quality food products depends on many factors, starting with the design and construction of the manufacturing facilities. If the environment in which these foods are produced is not clean and does not promote cleanliness, the food products are at risk of contamination and of being poor quality.

There are many reasons why cleanliness and food safety should be the primary focus when designing and constructing a food manufacturing facility. Any product that does not meet the high-quality standards of consumers will not only alienate customers, but will also negatively impact a company’s reputation and bottom line.

Contaminated foods also pose a threat to public health, so it is imperative to have a clean design that will inhibit the entry, growth and spread of harmful microorganisms. This is accomplished through an intelligent layout of facilities, careful selection of materials and construction techniques, proper air handling, pressurisation and temperature control.

When starting to design the facility layout, it is important to have the final product in mind, and to consider both the ingredients and the process

Creating a clean design starts with the food itself. The type of product that is produced will drive the design decisions. For example, refrigerated products require very different staging, production, warehousing, environmental controls and cleaning procedures than baked goods.

When starting to design the facility layout, it is important to have the final product in mind, and to consider both the ingredients and the process.

A clean layout

Segregation may be necessary based on the risk of cross-contamination. Raw ingredients cannot be mixed with the final product and some ingredients contain allergens that should not come into contact with other products. Another consideration, which may necessitate space segregation, is whether wet-cleaning or dry-cleaning is required. It is also key to consider how materials, personnel, waste and air will move through the facility. Each should flow from areas of high risk to low risk.

A careful design and proper barriers will prevent raw ingredients, airborne pathogens and personnel in a low-risk area from crossing back into areas of higher risk.

Next, points of entry to the facility should be separated from production and packaging areas. Docks can pose a hazard to a clean environment if they are not designed properly. First, they should be high enough off the ground to deter rodents from entering the facility. Second, since there is potential for outside contaminants to enter while the dock is open, they should not open directly into production areas; the same goes for exterior doors. And third, the drivers and truck crews must not be allowed into production areas, so breakrooms and restrooms should be considered.

Finally, the most common layout mistake is not allocating a large enough warehouse space. When a facility runs out of warehouse space, finished products or materials usually get stored in other areas. This creates contamination risks and fire hazards, so it is important to plan a large enough space to accommodate the current production level and future growth potential.

Construction materials

The right materials and construction methods ensure the cleanliness of a facility. They should reduce areas that collect dust, debris and bacteria and make necessary cleaning easy.

The first consideration is the flooring. The material should be impermeable and washable so that dust and debris either cannot collect or can be easily removed. If a flooring material has too many joints, it is too difficult to keep clean. Most facilities have sealed concrete floors with either an epoxy or urethane coating. Drains also need to be placed strategically in the floor so cleaning solutions, water and debris can be washed away.

Another common place where contaminants like mould and dirt collect is the joint where walls meet the floor. Typically, a 4-6 inch high seamless coved or cant base is created with the flooring material. This aids cleaning, and prevents dirt and dust buildup.

The wall materials are equally important because any sort of cavity or joint can create a potential harbour for contaminants. Food facilities commonly use insulated metal wall panels for their lack of cavities and limited number of joints; the same principle applies to ceilings. Therefore, many facilities do not have ceilings but rather an open space with structural detailing that reduces areas for dust to collect.

Tube steel beams or girders with plating on the sides eliminate dust ledges. Precast construction is another option. Using precast concrete planks for roof decking also eliminates cavities in the decking and reduces the number of joints.

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Finally, consider how the equipment will be installed. If it rests on the floor, it creates spaces that are difficult to clean. Equipment can either be raised off the floor or hung from the ceiling.

Environmental control

In addition to keeping the surfaces in the facility clean, environmental conditions are also key to ensuring food safety and quality. The right air quality, pressurisation and temperature will help inhibit harmful contaminants.

Incoming air must be filtered to remove dirt, spores and microorganisms from the outside environment. Some facilities require further filtration, such as high-efficiency particulate air (HEPA), to prevent the ingress of additional microbial contaminants.

Temperature plays a very important role in food processing facilities. Not only is it imperative to keep cold products cold and to heat raw products to cook them; proper ventilation, for example to cool down a baking facility, allows the staff and machines to run more efficiently.

Allowances should be planned to maintain the correct level of humidity in the production and storage areas to prevent contamination. Humidity encourages the growth of microorganisms, so dryer air helps prevent this growth. For example, if food products are heated with steam, ventilation must be in place to evacuate the steam from the process areas. Otherwise, it can turn to condensation that collects on the food products, potentially jeopardising their integrity and safety.

Finally, positive air pressure is crucial in clean food production facilities. This means that the air pressurisation matches the level of cleanliness of each area so that air from a ‘dirty’ area cannot flow to a ‘clean’ area. This should also keep outside air from entering processing areas.

The human factor

Even the best designed facility can have issues with food quality and safety if the operators within the facility are not trained to follow proper procedures. Management must allocate enough resources to continually train personnel, especially if frequent turnover occurs. Design can compensate for human errors in some ways, but training is essential.

Design must include soft or hard barriers to keep people from moving against the flow of the facility to prevent cross-contamination. Hurdles like railings around hand and shoe washing stations and gowning areas help slow people down, making them think twice about the procedures they must follow. Even little things, like colour coding the floors to indicate areas that require different levels of care help make workers more aware.

Ultimately, food can only be as clean as the facility in which it is produced. Facility design is important to ensure cleanliness and enable easier long-term maintenance.

Food contamination can be prevented by focusing on proper layout, appropriate construction materials and building methods as well as correct environmental controls.

This article appeared in the September issue of Cleanroom Technology.

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