https://en.wikipedia.org/wiki/Impossible_Foods#Technology_and_food_safety
Unlike most plant-based products intended to emulate meat, the Impossible Burger contains large quantities of heme. Heme is the molecule that gives blood its red color and helps carry oxygen in living organisms.[14] Heme is abundant in animal muscle tissue and is also found naturally in all living organisms.[15] Plants, particularly nitrogen-fixing plants and legumes, also contain heme.[16] The plant-based heme molecule is identical to the heme molecule found in meat.[17][18]
To produce heme protein from non-animal sources, Impossible Foods selected the leghemoglobin molecule found naturally in the roots of soy plants.[19] To make it in large quantities, the company’s scientists genetically engineered a yeast and used a fermentation process very similar to the brewing process used to make some types of beer.[20] In 2014, Impossible Foods declared leghemoglobin is Generally Recognized As Safe after testing under FDA oversight,[21] and filed updates with the FDA in 2017 and 2018.[22] The U.S. Food and Drug Administration issued a “no questions” letter in July 2018, accepting the unanimous conclusion of a panel of food-safety experts that the protein that carries heme is safe to eat.[23] This acceptance letter was limited to products cooked in restaurants because soy leghemoglobin required safety review as a new food colorant for uncooked products.[24] An FDA rule change that accepted the colorant and allows the sale of Impossible Burgers in grocery stores took effect on September 4, 2019.[25]
LightLife, a brand of meat analogues, criticized its competitors Beyond Meat and Impossible Foods in an open letter published in The New York Times, asking that these companies reduce their use of “hyperprocessed” ingredients.[26] Impossible Foods responded by calling it a “disingenuous, desperate disinformation campaign”.[27]
The Center for Consumer Freedom (CCF), a nonprofit advocacy group that has received funding from the meat industry, has targeted Impossible Foods and other meat analogue producers through advertising, including a commercial during Super Bowl LIV, criticizing meat analogues for using additives. Impossible Foods quickly answered with a parody commercial.[28]
“...genetically engineered a yeast and used a fermentation process very similar to the brewing process ...”
Sounds yummy. And indigestible.