Subway says a media report claiming its chicken is half soy is "wildly inaccurate".
The Canadian Broadcasting Corporation claims that an independent DNA analysis found Subway's chicken to contain only about 50% actual chicken.
Subway vehemently denies these claims, and says its own lab results found less than 1% soy protein.
"Our chicken is made with 100% chicken + spices and marinade," the fast-food sandwich chain tweeted.
The CBC Marketplace report sent samples of fast-food chicken products, including Subway, to Trent University's Wildlife Forensic DNA Laboratory.
Earlier this week, CBC reported that the lab found that Subway's chicken was only about half animal protein. The rest was soy protein.
"The oven roasted chicken scored 53.6 per cent chicken DNA, and the chicken strips were found to have just 42.8 per cent chicken DNA. The majority of the remaining DNA? Soy," CBC wrote.
The story ruffled feathers all over the world, but Subway says it isn't accurate, and cited the results of its own DNA test as proof.
Subway did not did not share the DNA analysis with the media, and CBC is standing by its story.
Steven Newmaster is familiar with the type of testing CBC used to come to its conclusions. The botany professor at the University of Guelph caused his own media firestorm when he published a 2015 paper claiming that many herbal supplements contain unlabeled plant ingredients and filler.
Prof Newmaster used DNA barcoding to analyze the samples, which is the same method employed by CBC's Trent University lab. The methodology works by scanning organic material for short DNA sequences. The test can show the DNA percentage of a product, says Newmaster, but "it is very difficult" to translate that to the product's mass. That makes it hard to say how much of a product is actually chicken and how much is actually soy.
He said people shouldn't take too much stock in CBC's report yet.
"I do not think Subway should be scrutinized without another lab validating the results of this study as the standard operating protocols and analysis must be clearly defined, reproducible and statistically accurate without any error due to lab personnel, instruments or improper experimental design," he said.
How CBC got its results:
"Marketplace initially tested three samples from Subway: two from the oven-roasted chicken and one from the chicken strips. Each piece of chicken was broken down into three smaller samples, which were individually tested. The lab also retested these samples a second time.
Since the results were so markedly different from the DNA composition of the other sandwiches, the lab tested 10 new samples, five of the oven-roasted chicken and five of the chicken strips. The samples were obtained from multiple locations across Southern Ontario.
The repeated tests all reinforced the lab's initial assessment."