A Head-to-Head Test of 3 Foreign Material Inspection Technologies 

The many benefits associated with removing foreign materials from your product stream are obvious – from controlling chargebacks to reducing downtime spent cleaning contaminated equipment to, ultimately, protecting your brand. 

What’s often less obvious is which specific inspection technology will be most effective for finding the foreign materials that impact your operations. Foreign materials vary widely in size, composition, and shape impacting which inspection technology will best identify them. 

Chart comparing the effectiveness of X-rays, Vision Systems and Hyperspectral imaging in finding foreign materials.
  • Vision systems are great at finding objects when there’s strong contrast with the background. This is perfect if your poultry line is contaminated with bright blue pieces of plastic, but it’s not going to be effective if those same plastic pieces are white or you have a problem with wood.
  • X-ray can see inside the product, which is handy as long as the foreign materials are high density. It’s not an effective solution for finding many of the low-density materials that processing plants have in their operations, like plastic and cardboard. 
  • Hyperspectral imaging, like the technology used in PPO’s Smart Imaging System, is great at finding low-density materials on the surface of product, even at miniscule sizes. You might be wondering how small. We’re so glad you asked! 

The Test: Foreign Material Detection in a Pork Production Plant 

The pork producer put parameters in place before running their head-to-head foreign material detection test. The technologies they were testing had to meet the following criteria: 

  • Be able to handle 30,000+lbs/hr.
  • Operate in the washdown environment of a meat plant.
  • Process a variety of product forms, including coarse ground trims. 
  • Pass the foreign material testing protocol on materials deemed critical by the processor.
  • Provide any bonus applications that could be beneficial to the processor.
  • Fabricate and install multiple systems throughout the US.

The producer planted a wide variety of foreign materials of various sizes on coarse-ground pork trims running through their line, moving from largest (7 mm?) to smallest (1.0 mm). The findings were eye-opening.

Cotton Glove 2.0mm tested using hyperspectral imaging

The Results: Hyperspectral Imaging Detects the Widest Variety of Foreign Materials

The chart below summarizes which inspection technologies were able to detect which foreign materials on the surface of the pork products. 

Chart of what x-ray, vision and hyperspec systems can find with hyperspec being able to find everything except glass and cartilage

While all technologies accurately detected some foreign materials, PPO’s Smart Imaging System detected the highest number of foreign materials, regardless of size, color and density. 

  • Unsurprisingly, x-ray was effective at finding all the metals and glass. 
  • The vision system performed the poorest, finding only brightly-colored hard and soft plastic materials. 
  • PPO Smart Imaging System found a wide variety of foreign materials regardless of color and density. It also detected material as small as 1 mm in size. The only two materials hyperspectral imaging didn’t detect were glass and soft cartilage. In the chart below you can see the materials and sizes that PPO’s system easily found during the test.
Table of in-plant findings by a pork processor including green rubber glove, wood, cardboard, blue combo liner, aluminum, stainless steel, clear plexiglass, blue acetal, blue thermoplastic, cotton glove

What Makes Hyperspectral Imaging So Effective?

Low-density foreign materials are more challenging to detect with traditional methods because they often blend in with the product. Hyperspectral imaging is fundamentally different from camera-based or multispectral inspection systems. It can detect subtle differences in the spectral characteristics of foreign materials, even if they are not apparent to the naked eye. This makes it more precise and sensitive than other detection solutions.

  • Hyperspectral imaging reflects light from specialized lamps onto the product being inspected as it travels on a conveyor belt.
  • The reflected light is then sent through a high-efficiency holographic grating in the spectrometers (think of it like a prism).
  • The information generated by the reflected light is recorded by a high-speed camera in 500 different continuous wavelengths.
  • This creates “chemical fingerprints” of whatever is on the conveyor belt, including the product and any foreign materials present. 
  • Advanced machine learning software allows for rapid identification of foreign materials in real time, at line speed. The system can then use the captured data to keep learning and optimizing performance over time.

Multispectral imaging is NOT the same as hyperspectral (even though some multispectral solutions are positioned as hyperspectral). It’s important to understand there is a big difference in the number of wavelengths each system uses for inspections. Hyperspectral imaging relies on thousands of light bands to capture all the available information in the material being inspected. Multispectral imaging relies on a much smaller number – a dozen at most – which results in a less complete inspection. Since the data captured by a multispectral system is limited to the smaller number of wavelengths it uses, these systems also have a limited ability to learn over time.

Don’t be fooled. A true hyperspectral imaging solution will check all the boxes outlined in the bullets above.

Quote from Chris Sawyer from Brakebush Brothers. It reads: With PPO, we routinely find previously undetectable materials, as small as two millimeters – really small pieces of plastic. Even things like clear stretch wrap…it has delivered on and exceeded our expectations on the promises PPO was making.

Get Help With Choosing the Best Inspection Technology

The issue of foreign material contamination in our food supply is not going away any time soon. The US Department of Agriculture (USDA) Food Safety and Inspection Service (FSIS) website reveals that over 300,000 pounds of product has been recalled in 2023 alone due to possible foreign material contamination. That doesn’t account for foreign material that slipped through and didn’t result in a recall. 

If budget and approvals weren’t a factor, implementing a multi-hurdle approach that relies on more than one inspection technology would be the best course of action for many processing plants. In reality, many plant leaders need to bet on one technology that maximizes ROI. 

If you have a persistent problem with a known foreign contaminant then choosing the right technology for the job is much easier. If you need a solution that will find the widest variety of foreign materials then the data shows hyperspectral imaging is a sound bet. 
The head-to-head inspection technology results from a major pork producer shared in this article clearly demonstrate that PPO’s Smart Imaging System is worth a closer look. Reach out to book your personal demo today.

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