Preventing Microbiological Contamination with Product Inspection Equipment

Hygienically designed product inspection equipment can play a critical role in helping to prevent the growth and spread of microbiological contamination in manufacturing plants.

Every year almost 1 in 10 people worldwide fall ill after consuming contaminated food, according to the World Health Organization's (WHO) first global estimates of the burden of foodborne diseases in 2015¹.

Approximately 90 percent of all foodborne illnesses are caused by microbiological bacteria, with insufficient cleaning and sanitizing programs, as well as poor equipment design, construction and maintenance to blame for many outbreaks.

Hygienically designed product inspection equipment can play a critical role in helping to prevent the growth and spread of microbiological contamination in manufacturing plants but, despite this, many manufacturers continue to take risks by purchasing less hygienic equipment.

Outbreaks of Foodborne Illness

Several serious foodborne illness outbreaks have occurred in the U.S. and other parts of the world in recent years. Examples include a Listeria Monocytogenes outbreak in cantaloupe melons in 2011 which was caused by equipment that had been inadequately cleaned, poorly maintained and was not of cleanable design and construction. Prior to this, an extensive and well-publicized Salmonella Typhimurium outbreak was associated with peanuts in 2009. Investigations revealed that equipment design and maintenance, as well as cleaning and sanitizing programs were major causative factors.

In addition to endangering consumers' lives, the repercussions of microbiological outbreaks include loss of production caused by unplanned downtime and facility shutdowns, reductions in revenue and long-term brand damage resulting from adverse publicity. The average cost of a recall to a food company is believed to be U.S. $10 million in direct costs, with some recalls resulting in losses of more than US $100 million². What's more, the long-term reputational damage to companies can have an even steeper price tag, with around 57 percent of consumers revealing they would stop buying an affected product for at least a year³.

As recalls become more frequent and costly, and food safety laws become increasingly stringent, it's more important than ever that product inspection equipment not only performs well, but is designed to prevent bacterial growth and facilitate proper cleaning.

What Defines Hygienic Design?

Hygienic design helps to minimize microbiological contamination risks by enabling easy, cost-effective and reliable cleaning of manufacturing facilities and processing equipment. Several organizations are involved in the hygienic design of equipment used for food processing. The main ones are:

  • The European Hygienic Engineering and Design Group (EHEDG)
  • The U.S. Food and Drug Administration (FDA)
  • 3-A Sanitary Standards Inc. (3-A SSI)
  • National Sanitation Foundation (NSF) International
  • The North American Meat Institute (NAMI)


In 2002, NAMI's Equipment Design Task Force (EDTF) established a list of 10 sanitary design principles aimed at improving food safety by reducing the contamination risk from Listeria in ready-to-eat meat and poultry products. In 2014, the American Meat Institute Foundation (AMIF) updated these principles.

Sanitary Design Criteria for Product Inspection Equipment

To reduce the risk of microbiological contamination outbreaks, all product inspection equipment should be designed with due consideration to the application, operating environment and cleaning regimes likely to be encountered, and should adhere to the following 10 principles of sanitary design:

1. Cleanable to a Microbiological Level

Food equipment must be constructed to ensure effective and efficient cleaning over its lifespan. It should be designed to prevent bacterial ingress, survival, growth and reproduction on both product and non-product contact surfaces.

2. Made of Compatible Materials

Construction materials used for product inspection equipment must be completely compatible with the product, environment and cleaning/sanitizing chemicals, as well as the methods of cleaning and sanitation. Product contact surfaces should be made from materials that are corrosion-resistant, non-toxic and non-absorbent.              

3. Accessible for Inspection, Maintenance, Cleaning and Sanitation

All parts of the product inspection equipment should be readily accessible for inspection, maintenance, cleaning and sanitation without the use of tools. Clean-in-place (CIP) is preferred over clean-out-of-place (COP) to avoid time-consuming disassembly and re-assembly.

4. No Product or Liquid Collection

Equipment should be self-draining to ensure that liquid, which can harbor and promote the growth of bacteria, doesn't accumulate, pool or condense on the equipment.

5. Hollow Areas Should Be Hermetically Sealed

Hollow areas of equipment such as frames and rollers must be eliminated, wherever possible, or permanently sealed. Bolts, studs, mounting plates, brackets, junction boxes, name plates, end caps, sleeves and other items must be continuously welded to the surface of the equipment, not attached via drilled and tapped holes.

6. No Niches

Equipment parts should be free of niches such as pits, cracks, corrosion, recesses, open seams, gaps, lap seams, protruding ledges, inside threads, bolt rivets and dead ends. Welds should be flush and free of pits, cracks and corrosion.

7. Sanitary Operational Performance

During normal operations, the product inspection equipment must perform so that it doesn't contribute to unsanitary conditions or the harborage and growth of bacteria. The characteristics of the product being produced will have the greatest impact on the equipment's operational construction specifications.

8. Hygienic Design of Maintenance Enclosures

Maintenance enclosures and human machine interfaces (HMIs) such as push-buttons, valve handles, switches and touchscreens must be designed to ensure that product residue or water doesn't penetrate or accumulate in and on the enclosure or interface. In addition, the physical design of the enclosures should be sloped or pitched to avoid use as a storage area or residue accumulation point.

9. Hygienic Compatibility with Other Plant Systems

Product inspection equipment should be designed to ensure hygienic compatibility with other equipment and systems, such as electrical, hydraulics, steam, air and water.

10. Validate Cleaning and Sanitizing Protocols

Procedures for cleaning and sanitation must be clearly written, designed and proven to be effective and efficient. Chemicals recommended for cleaning and sanitation must be compatible with the equipment and manufacturing environment, and capable of removing product residue as non-aggressively as possible.

The Benefits of Hygienically-designed Equipment

Although the initial upfront cost of purchasing hygienically designed equipment can be more than non-hygienic equipment, the benefits are multitudinous. As well as helping to protect consumer welfare and a company's brand reputations by increasing food safety and reducing the risk of recalls, hygienic equipment can help with regulatory and Hazard Analysis and Critical Control Points (HACCP) compliance.

But that's not all — investing in hygienically designed product inspection equipment can also lead to long-term cost savings and increased operational efficiency by allowing run times to be extended, shortening cleaning times, reducing cleaning chemical and water usage and lowering maintenance costs.

Learn more about METTLER TOLEDO'S Inline Product Quality Inspection today.