FAQs of X-ray Product Inspection

Author Guido Mahnke R&D Engineer

Face-to-face interview with x-ray inspection expert, Guido Mahnke, to answer the most commonly asked x-ray product inspection questions. Guido has 10+ years’ experience in the x-ray inspection industry and has been with Eagle for the past 8 years. He’s currently working as the company’s R&D Systems Engineer. We had a moment to sit down together to get the answers you want to know regarding x-ray product inspection and its detection capabilities.

Q. Is x-ray equipment for food inspection safe?

A. Yes, x-ray systems are safe. Machines don’t carry radiation sources. X-rays are generated in the machine by shooting electrons at a Tungsten target that generates x-rays. When the x-ray is off, there is no radiation present.

Using an x-ray machine is also 100% safe for food inspection. X-rayed food is not radioactive. In fact, food that’s been inspected by x-ray is indistinguishable from food that hasn’t. Flavor and nutritional value are unchanged. Our infographic illustrates more of these interesting x-ray safety facts.

Q. What can an x-ray system detect?

A. X-ray systems can detect objects that are denser than the surrounding product. Typically the density of food is comparable to that of water. The general rule is if a contaminant floats on water, it is less dense than water and hence it is hard to detect. If a contaminant does not float on water, chances are that it can be detected in an x-ray image. So generally contaminants such as bugs, wood or plastic are not detectable. However, there is a lot of variability when it comes to plastic because plastics containing Fluorine or Chlorine are detectable, however others like Polyethylene, Polypropylene etc. are not. There are exemptions to the “floats on water” rule, for example, an x-ray system can find hollow hearts in potatoes because the void is less dense than the surrounding potato. These will come up as a lighter area in the x-ray image and therefore can be detected.

X-ray inspection systems can detect all types of granite and ceramic stone because they have a high density and can absorb more x-rays than typical food products. However, stones have varying sizes and the detectable size depends on the density of the stone, as well as the surrounding food product. X-ray equipment for food inspection can detect ferrous and non-ferrous metal easily because the metal is dense and absorbs x-rays very well. Aluminum is harder to detect because it is less dense than other metals. So its smallest detectable size is larger than that of other denser metals, for example iron.

Another common contaminant is glass. X-ray inspection systems can detect glass contaminants quite well. However, the minimum detectable size varies on the mineral content for glass. Because x-ray technology is sensitive to some chemical elements from minerals used to make glass, “glass-in-glass detection,” or the detection of glass fragments in glass jars, is made possible. The minimum detectable size will vary with the type of glass used, for high mineral glass, for example soda lime glass, much smaller pieces can be detected, than for low mineral glass.

We all know bones have calcium. But did you know that calcium build-up actually grows during the entire life of an animal and stops at point of death. When x-raying an animal food product, standard x-rays will detect the calcium in the bones at time of death. When animals, such as poultry or fish, only have a short lifespan there is not much calcification to detect. Only advanced x-ray inspection systems with enhanced dual energy technology can detect bones from young animals which have not had much time to build up calcium during their short life span.

Click here for a detailed list of detectable contaminants and their density levels.

Q. Can an x-ray machine weigh product?

A. X-ray systems can provide a weight value of the product. However, an x-ray machine doesn’t have a weight sensor such as a load cell—it’s not a scale or checkweigher. X-ray inspection systems provide a weight by “teaching” the density of the product to a weight algorithm. This algorithm converts product density to a mass or weight value.

Q. Can x-ray inspection systems see if a package is open or closed?

A. X-ray in rigid applications with jars on a conveyor can verify if a lid is present. On boxed products, it all depends on the package. For non-rigid packaging such as foil or plastic bags, the x-rays will not be useful to check for open or closed packages.

Q. What additional quality checks are possible with x-ray technology?

A. Besides superior contaminant detection, x-ray systems also provide additional quality checks simultaneously and at high-line speeds. X-ray can check the head space or fill level which is used as a gauge after sealing products such as canned goods, yogurts or ready meals. Inspection equipment can also count products, as long as what needs to be counted is denser than the surrounding products. Additionally, x-ray can count whether there is product in divisions within packaging. And when it comes to checking product and package integrity, x-ray technology can do both. For example, x-ray software can identify broken cookies in packages, misshaped burger patties in boxes, reject dented cans and detect dense food trapped in seals.

Q.  How accurate is an x-ray inspection system?

A. X-ray product inspection has a 95% probability of detection also known as POD. Why not let Eagle test your products in our lab? Book a complimentary product analysis to discover how x-ray inspection technology can transform your line.

Q. How can x-ray systems assist red meat processors and slaughterhouses with their inspection needs?

A. There are three main benefits an x-ray inspection system provides, with the first being detection of foreign contaminants to ensure product safety. Secondly, both red meat processors and slaughterhouses need to produce high-quality products to their desired specifications consistently and, in order to do that, they need to be able to measure 100% of all the meat products that run through their production line. Fat analysis x-ray systems can quickly and accurately measure the chemical lean (CL) or fat content.

The third benefit is the ability to optimize their production processes to maximize profits. By taking into account the variation of the fat content of raw materials and also the associated costs of these raw materials, along with the prices that red meat processors and slaughterhouses get for the final products they take to market, FA x-ray systems can play a key role in optimizing production.

Q. Where is the best location to place an x-ray product inspection machine on my poultry line?

A. There are a few different areas poultry processors can place an x-ray system depending on their critical control points. An x-ray machine can be placed at the start of the line where raw poultry enters to check for contaminants. This ensures the removal of foreign bodies as well as stops hazards earlier in the process before they can cause problems to downstream product or equipment.

By the time poultry product gets to the end of a production line where it’s packaged, invariably that’s the final check any supplier can do to ensure product is safe for consumption. At this inspection point, an x-ray machine can check for contaminants and simultaneously check a package’s weight as well as ensure that it contains the right number of products. In the video below, follow poultry product through an entire production line to see how Eagle x-ray machines can provide multiple points of inspection.

Q. What are some contaminant detection challenges when it comes to inspecting seafood products?

A. Bones are a consistent challenge. Fish bones are long but very narrow. You must have sufficient x-ray software resolution to detect such tiny objects. Another challenge is the low x-ray absorption of fish bones by nature—the contrast between bone and fish flesh is very low. Discerning between bone and fish requires a highly sensitive detector, like Eagle’s PXT™ detector. Exclusive to Eagle, this technology captures more detailed information about a product being inspected than has been previously possible. In addition to small bones in fish, x-ray systems can be used to find shell fragments and fish hooks, which impact both food safety and quality. Other contaminants can be introduced during processing, such as wire, machinery shavings and even small pieces of glass that could accidently get into a product if a lamp breaks on the line.