Food processors have been caught on video boasting that they have developed undetectable methods of adulterating the chicken that goes into hospitals, schools and restaurants with cheap beef waste and water.
Tests by a television programme have also shown samples of British supermarket Sainsbury's Blue Parrot chicken nuggets to contain both bovine and pork DNA. The company says the bovine DNA comes from milk protein and the presence of pork DNA in one sample may be the result of contamination in the laboratory.
In what is likely to be a major food scandal, secret filming for BBC TV's Panorama has revealed that vast quantities of frozen chicken coming into the UK each week have been injected with beef proteins.
The programme went undercover to find the source of the beef proteins. BBC reporters were told by Dutch manufacturers that beef DNA can now be manipulated in such a way that none of the safety authorities' tests can detect it.
Adulterated chicken has been imported widely by British wholesalers. Brakes, a leading supplier to schools, hospitals and restaurants, has unwittingly imported chicken with beef DNA, according to laboratory tests for the BBC.
On Panorama today, a German protein supplier for huge Dutch chicken companies tells undercover reporters his firm, Prowico, has developed secret high-tech methods to break down the DNA of the proteins so much that no government tests can detect the beef.
The proteins are hydrolyzed and mixed into additive powders which are then injected into chicken meat to hold extra water, thus vastly increasing profits. Tests have found that some chicken fillets are as much as 50% added water.
The director of Prowico, Theo Hietbrink, says that his beef proteins are guaranteed to be "PCR-negative" -- polymerase chain reaction (PCR) is the test authorities use to find DNA from totally different species.
He also says that at least 12 companies are using his new hydrolysed proteins.
The owner of Surplus, the Dutch company which blends the Prowico proteins into powder, tells the undercover reporters the industry has been extracting hydrolyzed beef proteins to inject into chicken and other meats, including ham, for more than 10 years.
Prowico says the original source of the beef is cow hides from Brazil. It admits it does not test its beef for BSE and would not show reporters the process by which the proteins are extracted. But it says that Brazil is BSE-free and that hides do not carry a BSE risk.
Panorama sent 12 samples of Dutch chicken to the laboratory used by British authorities but it did not find any beef DNA. Several of the same samples were then sent to a private Irish lab, which, using more sensitive techniques, detected beef DNA in several samples.
But if the protein manufacturers have now managed to make the beef PCR-negative, no one will be able to detect it.
Tim Lang, professor of food policy at City University, London, said: "My response to the food standards agency saying this is just a matter for labelling is `pull the other one'. How naive can you get? We expect the FSA to not say `put the information on the label', but `sort it out please'."
Brakes said it had conducted its own independent PCR tests on chicken it imported but they were negative.
Its specification with its Dutch supplier was for chicken that was 70% meat. Its own tests revealed that the chicken had more water than was declared and it has now recalled it all.