Food safety experts have suggested that freezing chickens during processing for human consumption could vastly reduce the chances of people catching a food poisoning bug. In the UK, around 60,000 cases of campylobacter infections − an illness that can be caught from poultry − are reported to health authorities every year.
The real figure is thought to be closer to half a million as people often choose not to visit their doctors when they are ill.
Freezing chickens found with campylobacter cells in them could reduce the rate of passing the infection on to humans by up to 90 per cent, according to Frieda Jorgensen, from Public Health England.
In Iceland, chickens found to be infected with campylobacter when they reached an abattoir were not allowed to be sold as fresh or chilled chickens, but instead frozen.
She said: “Freezing does bring about a reduction in the number of (campylobacter) cells. We believe that they can reduce that by 90 per cent if you are undertaking this freezing process.
“And that reducing the number of campylobacter cells on the chicken can matter in terms of the public health risk.”
A survey carried out by the Food Standards Agency (FSA) previously found that almost three fifths of shop-bought chickens tested positive for campylobacter.
The bug was present in 59 per cent of birds tested, and in 4 per cent of samples it was identified on the outside of the packaging. But Jorgensen said that freezing chickens was unlikely to resolve the problem in the UK because of the high demand for fresh or chilled produce.
She said that it was “pointless” if chickens were frozen and then could not be sold but said processors were looking at other methods of interventions, such as using steam, ultrasound and ‘quick-blast chilling’, which are known to reduce the number of campylobacter cells on chickens.
But she said: “All of those cost money to put in place in the big, busy processing plants, but they are looking at whether it does bring a sufficient amount of reductions ... and if it is worth putting in place.”
Chris Elliott, chairman of food safety at Queen’s University Belfast, said two large UK poultry processing organisations were carrying out pilot studies on the use of ultrasound and ‘rapid surface chilling’.
The chilling, he said, was a new technique not used anywhere else in the world and invented in the UK.
“What the industry are doing, they are comparing these two methodologies at the moment to see which is the most effective and the most cost-effective as well.”
But he said he was concerned about the chilling method because it involves bringing large quantities of liquid nitrogen on to farm facilities. He said: “I think the industry have to be very clear that it works and brings about a very large-scale reduction before that is what should be advised for the whole industry.”
It is during their slaughter that infected matter can transfer to the chicken meat, Jorgensen said, which is how contaminated chicken meat can end up being sold in shops.
She said that some European countries have ‘substantially’ lower contamination rates. This could partly be explained by climate, but she said: “It is clear that industry practice and consistent application of biosecurity and slaughterhouse hygiene can have a real impact.”
Campylobacter bacteria do not normally grow in foods as they cannot multiply in air or below 30˚C, so reducing their levels rather than their complete elimination would present a “real improvement” in food safety.
Human infections from campylobacters are more common in the spring and summer months than in the winter.