Foreign Body Detection in Frozen Food by Dual Energy X-Ray Transmission

Foreign bodies of different types may find their way unnoticed into frozen food during processing or while packing. These contaminating objects show a great variety of materials, but consist most likely of glass, plastics, metal or (fish-) bone. The contaminants may cause considerable product recalls because of their hazardous nature for the consumer, leading to suffocation or shortness of breath. Eventually, the reputation of the respective manufacturer is long-termed harmed. Dual energy X-ray transmission is a powerful tool in nondestructive testing and thus may provide a solution to detect different foreign bodies in frozen food. We used this method for studying different frozen foods like mixed berries or vegetables and convenience food contaminated with aluminum, synthetic bones, Teflon, steel and glass test objects of different diameters in the range from0.3 mm to 10 mm. The study shows that dual energy X-ray transmission is suitable to detect certain contaminants in frozen food while it reveals weakness in reliably discovering plastics. A general limitation of a contaminants size that can be detected with this method is the spatial resolution of the measurement setup. Especially in highly heterogeneous environments, dual energy outperforms conventional X-ray transmission.