One of the effects of the pandemic on consumers’ habits has been a higher consumption of frozen seafood, in the form of ready-to-cook fillets or pre-cooked fish burgers and sticks. For most consumers (81%), eating more seafood is a way to improve their diet and health. According to a 2023 report by the Food Industry Association, in 2019 sales of fresh seafood were higher than frozen. In 2020, they switched places: frozen seafood ranked first, and it was still the leader in 2022, despite a 2.8% decline in sales due to rising food prices.

Bone Detection Challenges in Fish vs. Meat Inspection

The ramp-up of frozen seafood production brought new challenges to processors. One of them is removing fish bones. While consumers may be accepting to find some bones left when they eat fresh seafood at home or at a restaurant, when it comes to frozen seafood products, the expectation is to find no bones at all.

With two goals in mind—increasing production and keeping quality and safety standards as high as ever—, it has become increasingly important for processors to use an in-line X-ray system that can reliably catch fish bones that were left behind after the deboning step.

Why Fish Bone Detection Is More Difficult Than Meat Bone Detection

Bone detection with X-rays, however, can be challenging. In food inspection, X-ray systems detect foreign material thanks to the difference in density between the product and the contaminant. Bones tend to be low-density, which makes them harder to detect.

That, at least, is the general rule. In fact, with animals that are slaughtered at a more mature age, bones will have a higher content of calcium, making them denser and therefore easier to detect via X-rays. That’s the case for beef products, where X-ray systems can find bones as small as 0.5 mm to 1.5 mm. With broilers, on the other hand, the minimum detectable size is higher, because they’re usually slaughtered when still quite young.

Although the same age factor applies to fish bones (larger species, such as salmons, tunas, or swordfish are caught when they’re more mature and have relatively denser bones), detecting bones in seafood adds another level of difficulty.

The Impact of Product Density on Bone Detection

One reason is its much lower density overall, compared to land animals. For example, the density of boneless pork meat is typically 1.090 g/cm³, while Atlantic salmon is between 0.01 g and 0.015 g/cm³, which equals to 0.92% - 1.38% of pork meat. Density of rainbow trout can be even lower: 0.008 g - 0.015 g/cm³. Such low density in seafood also makes reinspection and rework more difficult, as the product could easily lose its shape the more it gets handled.

Anritsu’s DualX+ Fish System for Advanced Bone Detection

Anritsu has responded to the quality and safety needs of seafood processors with DualX+ Fish. It’s an X-ray system based on the DualX technology, which was developed fifteen years ago to improve bone detection in chickens. DualX+ Fish is equipped with an HD sensor and IP69K build, and it’s designed to detect bones in raw fish fillets while surviving the harsh environment of fish processing plants.