Food Engineering logo
  • Sign In
  • Create Account
  • Sign Out
  • My Account
  • NEWS
  • PRODUCTS
  • TOPICS
  • EXCLUSIVES
  • MEDIA
  • FOOD MASTER
  • EVENTS
  • RESOURCES
  • EMAGAZINE
  • SIGN UP!
cart
facebook twitter linkedin youtube
  • NEWS
  • Latest Headlines
  • Manufacturing News
  • People & Industry News
  • Plant Openings
  • Recalls
  • Regulatory Watch
  • Supplier News
  • PRODUCTS
  • New Plant Products
  • New Retail Products
  • TOPICS
  • Alternative Protein
  • Automation
  • Cannabis
  • Cleaning | Sanitation
  • Fabulous Food Plants
  • Food Safety
  • Maintenance Strategies
  • OEE
  • Packaging
  • Sustainability
  • More
  • EXCLUSIVES
  • Plant Construction Survey
  • Plant of the Year
  • Sustainable Plant of the Year
  • State of Food Manufacturing
  • Top 100 Food & Beverage Companies
  • MEDIA
  • Podcasts
  • Videos
  • Webinars
  • White Papers
  • EVENTS
  • Food Automation & Manufacturing Symposium and Expo
  • Industry Events
  • RESOURCES
  • eNewsletter
  • Custom Content & Marketing Services
  • FE Store
  • Government Links
  • Industry Associations
  • Market Research
  • Classified Ads
  • EMAGAZINE
  • eMagazine
  • Archive Issue
  • Advertise
Food Engineering logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Food Engineering logo
  • NEWS
    • Latest Headlines
    • Manufacturing News
    • People & Industry News
    • Plant Openings
    • Recalls
    • Regulatory Watch
    • Supplier News
  • PRODUCTS
    • New Plant Products
    • New Retail Products
  • TOPICS
    • Alternative Protein
    • Automation
    • Cannabis
    • Cleaning | Sanitation
    • Fabulous Food Plants
    • Food Safety
    • Maintenance Strategies
    • OEE
    • Packaging
    • Sustainability
    • More
  • EXCLUSIVES
    • Plant Construction Survey
    • Plant of the Year
    • Sustainable Plant of the Year
    • State of Food Manufacturing
    • Top 100 Food & Beverage Companies
  • MEDIA
    • Podcasts
    • Videos
    • Webinars
    • White Papers
  • FOOD MASTER
  • EVENTS
    • Food Automation & Manufacturing Symposium and Expo
    • Industry Events
  • RESOURCES
    • eNewsletter
    • Custom Content & Marketing Services
    • FE Store
    • Government Links
    • Industry Associations
    • Market Research
    • Classified Ads
  • EMAGAZINE
    • eMagazine
    • Archive Issue
    • Advertise
  • SIGN UP!

Food Safety: Getting rid of unwanted foreign materials

By Richard F. Stier
February 1, 2009
More buyers are demanding all products be passed through a metal detector.



According to an old joke, “What’s worse than finding a worm in your apple?” The answer: “Half a worm.” No one likes finding surprises in their food. Processors devote time and effort to ensure foods do not contain unpleasant surprises. In most cases, foreign materials, such as an insect in canned vegetables or a hair in a cookie, are harmless if eaten. However, when consumers uncover these surprises, it can be traumatic and expensive for the processor.

Glass, hard plastics, stones, pieces of metal, bone, seeds, pits and wood can cause injuries to the mouth, teeth and worse if swallowed. According to FDA guidelines for hard and sharp objects, items sized between 7.0 and 25mm are deemed unsafe. Items smaller than 7mm rarely cause injuries, except with infants, and those greater than 25mm don’t fit well in the mouth.

In agricultural processing, operations are designed to remove foreign materials during receiving. Harvesters pick up everything: birds, rodents, snakes, glass, rocks, etc. Plus, systems such as wash tanks, air blowers, destoners, float tanks using a compound like salt to alter the specific gravity of water, magnets, flumes and other devices help ensure undesirable items are removed. A final wash or rinse before processing helps remove even small materials. However, despite these efforts, sometimes items manage to get though. For example, the produce industry has occasional problems with small frogs that stick to the greens and end up in bagged products.

Over the past decade, food processors have focused their attention on foreign material detection due to the desire to ensure food quality and safety while meeting buyer requirements that include all products be passed through a metal detector. The exception is fluid products and powders that may be passed through in-line detector systems. These detectors are used when processing bulk materials, although some operations utilize detectors with gates large enough to handle 50-pound sacks.

When installing a metal detector, food processors should work closely with the equipment manufacturer to ensure the unit is not only properly installed, but operating at optimum sensitivity limits. For example, if a processor decides to use a metal detector on 50-pound bags of powder or cases of frozen entrées, minimum sensitivities may start at 4.0mm for ferrous metals. This would meet FDA guidelines for hard and sharp objects, but might not satisfy a buyer. Operating at lower sensitivities may result in false positives. Consequently, processors should have the manufacturer provide a letter defining minimum sensitivities for the system. The system should also be validated so there is supporting data that demonstrates performance.

Of course, many products, such as items using metalized film for packaging and some recycled paper products used for secondary packaging, cannot be passed through a metal detector. In these cases, as well as other applications, X-ray technology is a viable option. These machines not only find bits of metal, they also detect stones, glass and bone. Other available detection tools include in-line screens, sieves and magnets.

Food processors need to select the equipment for foreign material control that best meets their needs and the demands of their buyers. However, if a buyer’s demands are too extreme, the processor must be able to demonstrate that its system is equal to or better than what the buyer demands.

Share This Story

Looking for a reprint of this article?
From high-res PDFs to custom plaques, order your copy today!

Richard stier 200px
Richard Stier is a consulting food scientist who has helped food processors develop safety, quality and sanitation programs. He believes in emphasizing the importance of how these programs can help companies increase profits. Stier holds degrees in food science from Rutgers University and the University of California at Davis. He is a Contributing Editor for Food Engineering. Email: rickstier4@aol.com

Recommended Content

JOIN TODAY
to unlock your recommendations.

Already have an account? Sign In

  • Global Organic Food & Beverage Market to Grow

    Global Organic Food & Beverage Market to Grow

    With a CAGR of 12.07%, Bonafide Research estimates this...
    Latest headlines
  • skilled MEP worker

    Predicting Food and Beverage Manufacturing Trends for 2024

    The two words that should be kept in mind are labor and...
    Automation
    By: Derrick Teal
  • cleaning and sanitation

    The basics of cleaning and sanitation in food plants

    Sanitation maintains or restores a state of cleanliness...
    Food Safety
    By: Richard F. Stier
Subscribe For Free!
  • eMagazine
  • eNewsletter
  • Online Registration
  • Manage My Preferences
  • Customer Service

Food Plant Openings and Expansions May 2025

Food Plant Openings and Expansions May 2025

OT Cybersecurity Vulnerabilities in Food Manufacturing Facilities

OT Cybersecurity Vulnerabilities in Food Manufacturing Facilities

Understanding Impacts of OT Cybersecurity Events in Food Manufacturing

Understanding Impacts of OT Cybersecurity Events in Food Manufacturing

Food Plant Openings and Expansions April 2025

Food Plant Openings and Expansions April 2025

More Videos

Popular Stories

Vilter IHP in plant

Industrial Heat Pumps: Sustainable Energy Solutions for Now and the Future

FMTE Formed by Four Food Manufacturing Companies

Coalition Unites Europe’s Food Manufacturing Technologies and Equipment Sector

Sanitation worker spraying water

Fighting the Foodborne Bacteria War with Cleaning and Sanitation

CHECK OUT OUR NEW ESSENTIAL TOPICS

Alternative ProteinAutomationCleaning/SanitationFabulous Food Plants

Food SafetyMaintenance StrategiesOEE

PackagingSustainability

Events

June 17, 2025

Refrigerated & Frozen Foods’ State of the Cold Chain

Kelley Rodriguez, Editor in Chief of Refrigerated & Frozen Foods, will be joined in this 60-minute webinar by industry experts to help unpack the latest research.

January 1, 2030

Webinar Sponsorship Information

For webinar sponsorship information, visit www.bnpevents.com/webinars or email webinars@bnpmedia.com.

View All Submit An Event

Products

Recent Advances in Ready-to-Eat Food Technology

Recent Advances in Ready-to-Eat Food Technology

See More Products

Plant of the Year

Related Articles

  • Food Processing

    Managing foreign materials

    See More
  • handwashing and sanitizing station

    Getting handwashing right

    See More
  • receiving dock

    Food defense has become a critical aspect of food safety audits

    See More

Related Products

See More Products
  • composites.jpg

    Composites Materials for Food Packaging

  • 9780367351052.jpg

    Food Process Engineering: Safety Assurance and Complements

  • small-occ.jpg

    Occupational Health and Safety in the Food and Beverage Industry

See More Products

Events

View AllSubmit An Event
  • November 8, 2012

    Food Plant of the Future: Hazardous Materials Storage and Use

    On-Demand Concerns over food safety, reliability, and traceability get a great deal of attention within plants.  Yet the highly regulated – but often-overlooked – concern for the storage and use of hazardous materials is also important.
View AllSubmit An Event
×

Elevate your expertise in food engineering with unparalleled insights and connections.

Get the latest industry updates tailored your way.

JOIN TODAY!
  • RESOURCES
    • Advertise
    • Contact Us
    • Food Master
    • Store
    • Want More
  • SIGN UP TODAY
    • Create Account
    • eMagazine
    • eNewsletter
    • Customer Service
    • Manage Preferences
  • SERVICES
    • Marketing Services
    • Reprints
    • Market Research
    • List Rental
    • Survey/Respondent Access
  • STAY CONNECTED
    • LinkedIn
    • Facebook
    • YouTube
    • X (Twitter)
  • PRIVACY
    • PRIVACY POLICY
    • TERMS & CONDITIONS
    • DO NOT SELL MY PERSONAL INFORMATION
    • PRIVACY REQUEST
    • ACCESSIBILITY

Copyright ©2025. All Rights Reserved BNP Media.

Design, CMS, Hosting & Web Development :: ePublishing

Food Engineering logo
search
cart
facebook twitter linkedin youtube
  • Sign In
  • Create Account
  • Sign Out
  • My Account
Food Engineering logo
  • NEWS
    • Latest Headlines
    • Manufacturing News
    • People & Industry News
    • Plant Openings
    • Recalls
    • Regulatory Watch
    • Supplier News
  • PRODUCTS
    • New Plant Products
    • New Retail Products
  • TOPICS
    • Alternative Protein
    • Automation
    • Cannabis
    • Cleaning | Sanitation
    • Fabulous Food Plants
    • Food Safety
    • Maintenance Strategies
    • OEE
    • Packaging
    • Sustainability
    • More
  • EXCLUSIVES
    • Plant Construction Survey
    • Plant of the Year
    • Sustainable Plant of the Year
    • State of Food Manufacturing
    • Top 100 Food & Beverage Companies
  • MEDIA
    • Podcasts
    • Videos
    • Webinars
    • White Papers
  • FOOD MASTER
  • EVENTS
    • Food Automation & Manufacturing Symposium and Expo
    • Industry Events
  • RESOURCES
    • eNewsletter
    • Custom Content & Marketing Services
    • FE Store
    • Government Links
    • Industry Associations
    • Market Research
    • Classified Ads
  • EMAGAZINE
    • eMagazine
    • Archive Issue
    • Advertise
  • SIGN UP!