Finding horse DNA in a beef burger does not necessarily mean the burger actually contains horse meat or had any contact with it, a leading expert on DNA testing has warned.

As urgent investigations continue to determine how horse and pig DNA could have found its way into beef burgers sold in the UK and Ireland, Dr Konstantin Rizos – technical manager at international DNA test provider Global ID – said it was important to keep an open mind about the possible source of contamination.

The idea of horse DNA in beef burgers tended to conjure up images of horse meat being mixed into the burger, but other scenarios were possible, Rizos said. “The presence of DNA doesn’t mean meat has to be involved. For example, with horse DNA the contamination could be down to horse hair brush tools being used for cleaning.”

Rizos added Global ID worked on a contamination case in Germany back in 2011, which involved pig DNA being found in paper used to pack halal products. “In the end, it turned out this was due to animal fat being used as a machine lubricant,” he said.

The three suppliers implicated in the horse meat scandal – Silvercrest Foods, Dalepak Hambleton and Liffey Meats – have said they believe they have traced the source of contamination to third-party suppliers from the Continent, most likely Spain and the Netherlands. The third parties under suspicion have not yet been named, nor their products identified, but there is speculation in the meat industry that bulking agents could have been responsible for the contamination.

Asked about Rizos’s comments, Dr Patrick O’Mahony, chief specialist for food technology at the Food Safety Authority of Ireland – whose tests first uncovered the contamination scandal – said it was indeed possible the horse DNA could have been introduced to the burgers through a “dirty” horse brush cleaning meat processing equipment. “But that would raise other red flags of a hygiene nature, I’m sure,” he added.

He stressed although such an explanation – or similar scenarios – could be behind burgers in which  trace amounts of horse DNA were found, but would not explain the one burger product – a Tesco Everyday Value frozen burger – which was found to contain 29.1% horse DNA.

Rizos stressed he had no personal theory or insight on what the most likely explanation was and agreed the 29.1% burger was likely to have a different explanation than the ones containing just trace amounts.

Rush for tests

Rizos said the contamination scandal had already sparked plenty of new business for DNA testing companies such as Global ID. “We have been picking up new UK and Irish clients, and tests are due to commence next week,” he said, although he declined to name them. Depending on sample size and the exact nature of the tests, they cost between €120 and €200, according to Rizos.

Tests such as those provided by Global ID have long been used to test foods for the presence of genetically modified materials and came into their own on animal DNA in the wake of the BSE crisis.

O’Mahoney at the FSAI said the current scandal could prompt acceptable contamination levels for meat products being introduced, similar to official EU tolerance levels that already exist for GM materials. “There may be a need to set some acceptable limits for the presence of various meat species in meat-based products, so that there are clear EU labelling tolerances similar to those for GM foods, but that is a job for the EU and possibly Codex,” he said.