Soy leghemoglobin is short for legume hemoglobin -- the hemoglobin found in soy, a leguminous plant. Leghemoglobin is a protein found in plants that carries heme, an iron-containing molecule that is essential for life. Heme is found in every living being -- both plants and animals. (Heme in animals is carried by "hemoglobin" and “myoglobin” among other proteins.)
Although heme has been consumed every day for hundreds of thousands of years, Impossible Foods discovered that it’s what makes meat taste like meat. We make the Impossible Burger using heme from soy plants, which is identical to heme from animals and gives Impossible its uniquely meaty flavor.