X-ray machine ensures bone-free chicken pieces

AT THE Haerland factory of Nortura, an agricultural co-operative and the largest supplier of meat and eggs in Norway, three Ishida IX-G2 Dual Energy X-ray machines are installed to ensure quality control of chicken breast fillets and deboned thigh meat.

Unlike ordinary X-ray detection equipment which obtains an image using X-rays of one energy, the IX-G2 uses rays of two different energies to produce two images. These images are then compared to eliminate the background effect that is caused by the product itself, and this improves the detection of low-density contaminants such as bone fragments.

While cutting equipment for poultry has become more and more accurate over the years, there is still a need to ensure maximum quality and safety. Nils Olaf Vikmark, Process Engineer at Nortura explains:

“If the cutter removes a piece of the wishbone along with the breast, then we need to be aware of it: to find it and remove it. If left in, either arm of the wishbone is long enough and strong enough to cause trouble for anyone swallowing it.”

Other ‘floating bones’, which can include the scapula (shoulder blade) or even pieces of rib, may present a lesser danger, but would certainly lower the quality of the product in the mind of the consumer.  These too Nortura can now consistently pick up, down to a size (for fully calcified bone) of 3 mm or 4 mm.

The IX-G2 from Ishida compares two images to eliminate the background effect that is caused by the product itself. This improves the detection of low-density contaminants such as bone fragments

At Nortura the individual fillets emerge from the cut-up to the inspection stage well separated from each other, but the G2 has been shown to be capable of picking up small fragments even in packs of overlapping fillets.

Breast fillets, with their consistent-density fibers all running in the same direction, do not present  as great a challenge to X-ray inspection as deboned thighs, whose muscle and fat vary considerably in density.  A single IX-G2 is enough to monitor the combined output of deboned thighs at Haerland, ensuring that they are fully up to standard.

The bigger the customer, the more likely they are to have their own specific limits for size and density of bone fragments, says Nils Olaf Vikmark.

“We deal with a major international fast-food company, for example, that has its own set of criteria for X-ray detection, just as it had for metal detection before.  With the G2, we can in fact do significantly better than those standards.”

A full truck load of birds undergoes processing and packing in just 20 minutes at the Haerland factory. This is reflected in a belt speed of 25m per minute on the fillet lines and is well within the capacity of the G2. Nortura also considers the Ishida X-ray system, with its width of just 800mm excluding reject systems, to be reasonably compact.

X-rays are the favored approach to the detection of a wide range of solid contaminants, with Ishida now the major supplier of inspection systems to the food industry worldwide. Machine set up is simple and takes place automatically when a product sample is passed through several times.

The X ray can capture small fragments even in packs of overlapping fillets

“The operators are very pleased with the G2, as they get good results without excessive preparation,” said Mr Nils. Back in the day 50% of fillets had to be rejected in order to achieve acceptably bone-free product, he said. Nowadays very few will have significant bone fragments, which makes it all the more important to be able to decisively remove these from the product stream.

Mr Nils believes that Advances in X-ray inspection of poultry are not just driven by retailer and consumer demands but also by automation itself.  “We used to cut the fillet with a knife and check it by hand, while another person would put it in the tray. Now we have automatic cutting at high speed, with robots packing the fillets into trays. There is very little close human eye or hand contact with each piece. Reliable X-ray detection at speed has therefore become essential.”