Tip of the Week: Keeping Foreign Material Out of Consumer Products

Foreign material devices are a vital part of food production. If a food product including a piece of foreign material is released into the consumer market and there is an issue, it can resonate just as much with consumers as foodborne pathogen contamination. Along with the consequences of a recall, the consumer "word-of-mouth" spread can damage a company’s reputation and sales. Consumers often remember these types of events and the food company behind the issue.

As with all food production, there is always a risk of foreign material contamination. Foreign material is defined as anything that doesn’t belong in the food product. So basically if the ingredient is not listed on the label, it is foreign material. Here are some examples to give you an understanding of how much variety there is of foreign material:

  • Floor dirt
  • Particles or residue from yesterday’s ingredient
  • Dirty or greasy particles blown around by air hose cleaning
  • Slivers of wood
  • Cleaning materials
  • Pesticides
  • Insects, rodents, birds, and their excrement
  • Other particles that should not be in the finished product
  • Paint chips
  • Dust, mold, and bacteria

The goal for any food facility is to keep food pure, or unadulterated. Facilities often use foreign material devices to reach this pure food goal.


Magnets remove magnetic metals from incoming ingredients, protect sensitive equipment such as grinding units, and check finished products for metal prior to packaging.

Magnets are grouped in three ways:

  1. Primary – these are used in the receiving stage to screen incoming material
  2. Secondary – these are used at various stages in the process
  3. Finishing – these are used as a final check of materials before they are packaged or shipped


Strainers separate foreign material from liquid by allowing the liquid to pass through small openings while blocking items that are larger than the openings.

Strainers will vary in size and location depending on the needs in the process.



Metal detectors will determine if any metal is in the product. The detector will recognize metal and activate a rejection mechanism to remove the metal. Metal detectors should be routinely checked. This is sometimes done by intentionally placing a small (usually round piece of metal) into the product to determine if the detector catches it.

Careful examination of ingredients, machines, production practices, and your habits will improve foreign material control to help you manufacture safe, clean products for the consumer.

Most importantly, these efforts ensure that you are complying with the law.

Foreign material control devices are not perfect, so you must still exercise other preventive controls such as GMPs, preventive maintenance, and employee training for reducing foreign material contamination. We recommend Food Safety Essentials Training for your line workers and personnel training. Our 15 unique lessons allows you to cross train all your workers and reduce training costs.

AIB is leading a movement in food safety training. Become part of the movement to grow our industry.