We recently wrote about how inspection of meat products with multiscan metal detection technology is ideal for finding buckshot, hooks or other large metal contaminants that will damage grinding and slicing machines downstream.
However, not all contaminants found in the meat processing environment are metallic. Sometimes bones, stones, plastics and even glass can be present. In these cases, the foreign objects will pass through a metal detector undetected because the contaminants are not conductive.
X-ray inspection is therefore the only possible option for foreign object detection. Food X-Ray detection and inspection systems utilize X-rays, similar to those used in medical technology, X-rays have a very short wavelength, which corresponds to very high energy. As an X-ray penetrates a food product, it loses some of its energy. A dense area, such as a contaminant, will reduce the energy even further. As the X-ray exits the product, it reaches a sensor. The sensor then converts the energy signal into an image of the interior of the food product. See the image below.
Food X-ray inspection systems are considered safe as they do not use radioactive materials to generate X-rays. Instead they use X-ray tubes that are run at very high voltage where electrons are accelerated across a gap bombarding a tungsten material to generate images. When the tube is turned off no X-ray energy is emitted. (Read Is X-ray Inspection of Packaged Food Safe?)
In an X-ray system, the beam passes through a product as it is conveyed through the aperture. The detector creates a line-by-line image of the product for vision analysis before the product leaves the system. The computer makes a good/bad decision and automatically rejects contaminated product. While there are numerous ways to configure an X-ray system, the fundamental operation is always the same: scan, analyze, and pass or reject. (Read How Do Food Safety Metal Detectors and X-Ray Inspection Systems Work?)
Since X-ray inspection works by detecting differences in density and thickness within the product, they can find many common conductive AND non-conductive contaminants. Sensitivity, however, requires a detailed product test because some contaminants like bones and plastic can be challenging due to their low density.
Many times X-ray technology is combined with metal detection for better overall performance. Given the challenges to meat processors in protecting consumers and their brand, it is prudent to ensure that the most effective inspection technology is in place to avoid recalls and ensure the products they deliver to market are safe.
For more details about inspection in the meat processing industry, read our application note, Foreign object detection challenges in meat processing.