The Impossible Burger presents a plant-based alternative designed to replicate the sensory experience of ground beef. A central component enabling this realistic quality is a unique ingredient known as “heme.” This article explains what heme is and its contribution to the Impossible Burger.
Understanding Heme
Heme is an iron-containing molecule found widely in all living organisms, including animals, plants, and even microorganisms. It forms a ring-shaped structure with an iron ion at its core, which enables it to bind with other molecules. In animals, heme is a part of proteins like hemoglobin, responsible for carrying oxygen in the blood, and myoglobin, which stores oxygen in muscle tissue.
Heme is a tightly bound, non-protein component that assists in protein function. While animal-derived heme is notably concentrated in red meats, plants also produce heme, often associated with proteins like leghemoglobin found in the root nodules of legumes. Though structurally similar, heme forms are found in diverse biological contexts and perform varied functions.
Heme’s Role in Impossible Burger
Heme is incorporated into the Impossible Burger to mimic the sensory attributes of cooked beef. It is largely responsible for the distinctive savory flavor, rich aroma, and reddish color that transitions to brown when cooked. During the cooking process, the heme acts as a catalyst, promoting the Maillard reaction. This reaction creates the savory notes and browned crust characteristic of cooked meat.
The presence of heme also contributes to the visual and textural qualities that consumers associate with beef. It helps the burger patty appear to “bleed” when raw and sizzle in a manner similar to traditional ground meat. This replication of the beef experience is a primary reason for heme’s inclusion.
Source and Production of Impossible Burger’s Heme
The heme used in the Impossible Burger is derived from soy leghemoglobin. This protein naturally occurs in the root nodules of soy plants. Impossible Foods identified soy leghemoglobin as an ideal plant-based source of heme due to its ability to impart a meaty flavor and appearance.
To produce soy leghemoglobin on a large scale, Impossible Foods employs a fermentation process. The gene encoding soy leghemoglobin is introduced into a genetically engineered yeast, specifically Pichia pastoris. This yeast is then grown in large fermentation tanks, similar to the process of brewing beer, to produce large quantities of the protein. After fermentation, the soy leghemoglobin is filtered and concentrated, then incorporated into the burger mixture.
Safety and Nutritional Considerations
The safety of soy leghemoglobin in the Impossible Burger has undergone evaluation by regulatory bodies. The U.S. Food and Drug Administration (FDA) has issued a “Generally Recognized As Safe” (GRAS) notice for its use as a color additive and flavor enhancer in plant-based meat alternatives. This determination followed extensive safety testing, including studies for allergenicity, mutagenicity, and potential toxicity. Studies examining consumption levels far exceeding typical human intake found no adverse effects.
From a nutritional perspective, the heme in the Impossible Burger differs from animal heme in some aspects. Plant-based heme does not introduce cholesterol or the saturated fat often found in animal meat. The Impossible Burger’s heme contributes to its iron content, providing a source of this mineral.