Autolyzed yeast extract is a substance that results when yeast is broken down into its constituent components. It naturally contains free glutamic acid, or monosodium glutamate, and is often used as a less expensive substitute for MSG. As a natural component of autolyzed yeast extract, MSG does not have to be listed separately in the ingredients, so look for the yeast extract on the label if you're sensitive to MSG.
Autolyzed yeast extract results from the breakdown of yeast cells. The cell wall gets disrupted as the yeast’s enzymes break down proteins, releasing amino acids, salts and carbohydrates. The soluble portions are separated from the insoluble components and referred to as autolyzed yeast extract.
Baker’s or brewer’s yeast goes through a series of steps to break it down and release its contents. First salt or mild heat is applied, causing the cell walls to lose integrity but maintain the integrity of enzymes. Through autolysis, the enzymes break apart the proteins into constituent amino acids, now referred to as free amino acids. Next, the cell wall and other insoluble components are removed, followed by concentration and pasteurization of what remains. The final product is either stored in liquid or paste form or may be spray dried to a powder.
Autolyzed yeast extract is used primarily as a flavor enhancer in a variety of processed foods such as soups, meats and vegetarian “meats.” Some products include yeast extract in addition to other flavor enhancers such as MSG, hydrolyzed protein or substances labeled only as “natural flavor.” Like MSG, it is valued for its ability to stimulate taste receptors that are sensitive to the umami or savory type of taste.
If you follow a gluten-free diet you'll need to avoid autolyzed yeast extract because it's a source of hidden gluten, according to Colorado State University. Another possible concern about consuming autolyzed yeast extract is that it naturally contains monosodium glutamate. Even though the U.S. Food and Drug Administration considers MSG to be a safe substance, some people are sensitive to it and experience side effects after eating MSG-containing foods. Symptoms of MSG syndrome include headache, flushing, sweating, chest pain and numbness around the mouth. While gluten must be shown on the label, MSG does not have to be listed separately when the only source is autolyzed yeast extract, according to the USDA Food Safety and Inspection Service.