The New York Times says a commercial lab testing of "60 inches worth of Subway tuna sandwiches" purchased from three separate Los Angeles locations found the samples were unidentifiable.
In January, Subway was slapped with a lawsuit alleging that its tuna was not tuna.
The country's largest sandwich chain dismissed the case as meritless, claiming it exclusively buys skipjack and yellowfin tuna from sources that aren't overfished.
Now, The New York Times has concluded its own investigation of several samples of Subway's tuna.
"No amplifiable tuna DNA was present in the sample and so we obtained no amplification products from the DNA," according to the lab, as per the publication. "Therefore, we cannot identify the species."
According to a lab representative, the findings indicated two probable situations.
"One, it's so heavily processed that whatever we could pull out, we couldn't make an identification. Or we got some and there's just nothing there that's tuna," the representative said.
Tuna specialists also told the paper that once cooked, the protein in fish like tuna becomes broken down, or denatured, making it exceedingly difficult to detect. It also said it is not the first to investigate whether Subway's popular tuna sandwich contains 100% tuna. Inside Edition conducted its own investigation in New York and discovered that the tuna used in the sandwiches was, in fact, tuna.
Subway is defending itself against a class-action lawsuit filed in the U.S. District Court for the Northern District of California alleging that it makes misleading representations regarding its tuna meat.
The lawsuit claims that "independent testing repeatedly affirmed" that Subway manufactures the tuna product with no real tuna fish, although it does not specify the agencies that conducted such tests. According to the lawsuit, Subway benefits from mislabeling the tuna items by utilizing cheaper ingredients.