Impossible Foods tested a key ingredient in its flagship product, the Impossible Burger, on rats - it has been revealed.
According to a report published in July, the brand's famous 'heme' ingredient - that is used to make the burger 'bleed' and give it a meat-like taste - was consumed daily by rats in amounts 'well above' those in the burger. The rats' behavior and organs were then analyzed.
Heme, which is made from genetically modified yeast, consumption reportedly had no impact on either.
A memo written by agency officials in preparation for a phone conversation with Impossible Foods said: "F.D.A. believes the arguments presented, individually and collectively, do not establish the safety of soy leghemoglobin for consumption, nor do they point to a general recognition of safety."
But a statement released by Impossible Foods spokesperson Rachel Konrad said: "The Impossible Burger is safe.
"A key ingredient of the Impossible Burger — heme — is an ancient molecule found in every living organism."
New ingredients do not require the FDA's approval - instead, under a process known as self-affirmation, companies are able to hire consultants to conduct tests on the ingredients. They have no obligation to inform the FDA of the findings.
Impossible Foods followed the self-affirmation process, but wanted the FDA' s stamp of approval for heme.
According to Rachel Konrad: "We respect the role the F.D.A. plays in ensuring the safety of our food supply, and we believe the public wants and deserves transparency and access to any information they need to decide for themselves whether any food they might eat is safe and wholesome."
This led to the company feeding the ingredient to rats.
Konrad told the New York Times: "We are taking these additional steps because the public wants and deserves full transparency about the foods they eat and because transparency is a core part of our company’s DNA."
She added that the burger is 'entirely safe to eat' and 'fully compliant with all F.D.A. regulations'.
But the FDA wants proof the product is safe for humans in particular, and wanted to see Impossible Foods to assess a number of ingredients further.
Despite the FDA's rejection of Impossible Food's petition to approve the safety of heme, the company can still sell its burgers.
It currently plans to resubmit its petition to the FDA.