Here’s the third of a four-part report on “10 Principles of Equipment Design for Low-moisture Foods.”


Principle 6. No Niches.

All parts of the equipment shall be free of niches such as  pits, cracks, corrosion, crevices, recesses, open seams, gaps, lap seams, protruding ledges, inside threads, bolt rivets or dead ends. All welds must be continuous and should be ground and polished smooth.

This principle means just what it says: food processing equipment should not have harborage points. Not only should equipment be evaluated to ensure that the original welding by the manufacturer is continuous and niche-free, but processors also should take care when modifying equipment in the plant environment. Often equipment is modified by the processor to make it fit into a room or to make it consistent with other designs or product lines existing in the plant, and during such modification activities, care must be taken to ensure that a hollow framework might be penetrated creating a microbial growth niche.

Principle 7. Sanitary Operational Performance.

During normal operations, the equipment must perform so it does not contribute to unsanitary conditions or the harborage and growth of bacteria.

This principle is linked to Principle 4. A processor doesn’t want anything on the production line that is going to cause microbial counts to increase throughout the course of the day. During operation, you want to minimize moisture and product buildup in all product zones. In today’s world, processors want to optimize production runs while at the same time meeting quality and food safety parameters, and meeting regulatory requirements. This is where sanitary operational performance becomes important. For example, if the processor operates in a wet environment, it is likely that moisture would be continually available for to nurture the growth of microbial counts on the conveyors. Designing the conveyor or other equipment parts to minimize product and moisture buildup would allow the production run to be maximized, while minimizing any potential for a quality defect.

7.1. Hygienic Design of Maintenance Enclosures.

Human/machine interfaces such as push buttons, valve handles, switches and touch screens, must be designed to ensure product and other residues (including liquid) do not penetrate or accumulate in or on the enclosure or interface.

This is an important principle because during the normal operation of a process or a production line, operators typically touch control panels potentially transferring allergens, pathogens and spoilage organisms. The importance of this principle is because with many equipment installations, a beautifully designed piece of equipment can be placed adjacent to an electrical box (a perfect harborage place for water leakage) and/or pushbuttons that are not cleanable negating the original sanitary design. This principle not only addresses product contact surfaces, but the entire asset represented by the piece of equipment. This moves the consideration beyond the surface to ensure that all of the maintenance enclosures and other connections to the equipment are appropriately designed and also can be cleaned and sanitized.

7.2. Hygiene Compatibility with Other Plant Systems.

Equipment design should ensure hygienic compatibility with other equipment and systems, such as electrical, hydraulic, steam, air and water systems.

Ensuring the hygienic compatibility of the equipment with other systems is as much the  processor’s  responsibility, as it is the equipment manufacturers. The processor wants to make sure that equipment that is going to be introduced into a facility is designed to be usable and cleanable within the plant systems. Processors can communicate to equipment manufacturers the established electrical, hydraulic, steam, compressed air and oil filtration and water systems information to assist in improved design strategies prior to the equipment arriving at the plant.

8. Validated Cleaning and Sanitizing Protocols.

Procedures for cleaning and sanitation must be clearly written, designed and proven effective. Chemicals recommended for cleaning and sanitation must be compatible with the equipment and the manufacturing environment. These procedures must be jointly developed with the Processor to assure that procedures and chemicals meet the capabilities of that facility.

Equipment manufacturers are not cleaning procedure experts; their manufacturing facilities resemble machine shops, with lathes and metal shaping equipment. It is a rare equipment manufacturing operation that would have the ability to wash a piece of equipment, much less sanitize it. However, food processors utilize cleaning and sanitizing systems and protocols everyday, and can provide useful insight as to the best way to clean equipment in given plant environments. This principle recommends that the equipment manufacturer work with the individual processor during the equipment design stage, so that while the equipment is being constructed, the equipment company will have a fairly good vision of how the equipment is to be cleaned and sanitized in a processing plant. When it is delivered to the processing plant, the processor also will have a clear vision of what needs to be done to successfully clean.

9. Separate Processes Wherever Possible.

Dissimilar processes in plants or on single line or equipment should be properly separated to prevent cross contamination. – i.e. raw from RTE.

This is particularly important for pathogen control in a facility and critical in any process where there is a HACCP-based microbiological kill step. Microbiological contamination could occur if raw product/dust from a raw area or even persons who work in raw areas, enter into a ready to eat (RTE) area. This was highlighted in the GMA document, which referenced Salmonella control in low-moisture foods.

10. Equipment and Personnel at installation must meet Hygiene and Sanitation requirements.

All plant personnel, contractors and visitors to processor plants must be trained and are required to follow plant hygienic and sanitation requirements - NO EXCEPTIONS. At equipment supplier manufacturing locations, used equipment being rebuilt or retrofitted must be separated from new equipment construction to comply with Principle 9.

This is important to follow while in a processor’s facilities. When suppliers and contractors come to visit or work to install new equipment they need to follow all of the GMP rules. However, it goes beyond behavior in the processors facility. In many equipment supplier locations, they repair and recondition equipment that has been in service in food processing plants for years. Some of this equipment may have been out of service for some time, or may have even been stored outside and possibly was not thoroughly cleaned prior to being sent to the Original Equipment Manufacturer (OEM) to be rebuilt. When this happens there is the potential to cross contaminate other equipment under construction in their facility. Since most equipment suppliers do not have cleaning capability, they could cross contaminate from their facility to equipment and then to a processor’s facility when they deliver a new piece of equipment. This is a potential vector that we must be aware of and prevent.

Editor’s Note: Next week, in our next installment in this series on sanitation design, Joe Stout will go the first five principles. A food scientist by education, Stout has worked for Kraft Foods for 28 years in the areas of operations, sanitation, and quality. Prior to joining Kraft Foods, he worked for Associated Coca Cola Cos. for two years. He is a registered sanitarian with the State of Pennsylvania. Stout is the facilitator of the GMA Equipment Design Group for Low-moisture Foods. In addition to having experience in equipment design in dry processes, he was also chairman of the American Meat Institute Equipment Design Task Force, and has been active with 3A and the EHEDG.

Click here to read Part I of the “Sanitary Design as an Enabler of Food Safety” white paper.  

Click here to read Part II of the “Sanitary Design as an Enabler of Food Safety” white paper.  

Click here to read Part IV of the “Sanitary Design as an Enabler of Food Safety” white paper.