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What is yeast and is it vegan?

Yeasts are single-celled microscopic organisms which, as they grow, convert their food into alcohol and carbon dioxide through a process known as fermentation. Yeast is used by winemakers, brewmasters, and bakers in the making of wine, beer, and bread. The carbon dioxide from yeast is what makes beer frothy and champagne bubbly and causes yeasted bread dough rise. Pure yeast, regardless of the strain, is vegan.

In order to multiply and grow, yeast needs moisture, food (in the form of sugar or starch), and a warm, nurturing environment. Wild yeast spores are constantly floating in the air and landing on uncovered foods and liquids. They are used to promote the natural fermentation of certain foods such as sauerkraut and pickles and provide the leavening for breads that traditionally do not contain added yeast, such as sourdough bread.

The Egyptians used yeast as a leavening agent more than 5,000 years ago, and fermented beverages, including wine, were made for thousands of years before that. Scientists have been able to identify and isolate specific yeasts that are best suited for various purposes. The principal yeasts used today are baker's yeast, brewer's yeast, and nutritional yeast.

There are a number of different types of baker's yeasts, but all are considered "alive," that is, active and capable of leavening bread. Brewer's yeasts are special non-leavening yeasts used in the manufacture of beer. Brewer's yeast that is sold in natural food stores is a by-product of the brewing industry. Because it is a rich source of B vitamins, it is often promoted as a "health food," but brewer's yeast can have a very bitter taste and is therefore not recommended for use in cooking. Another product commonly found in natural food stores is torula yeast, which is a non leavening yeastlike organism that is grown on waste products from the wood pulp industry.

Brewer's yeast and torula yeast are frequently confused with nutritional yeast. Nutritional yeast is a primary grown food crop, which means it is cultivated specifically for use as a nutritional supplement. This yeast is dried at higher temperatures than baking yeast, rendering it inactive. Unlike the live yeasts used in breadmaking and brewing, nutritional yeast has no fermenting or leavening power.

The brand of nutritional yeast I recommend is Red Star Vegetarian Support Formula (VSF). This is currently the only nutritional yeast product with a consistent nutritional profile that is rich in the B-complex vitamins riboflavin, niacin, thiamin, and biotin, and includes a reliable source of vitamin B12 (cobalamine), an important nutrient often lacking in the diets of vegans. The B12 used in Red Star VSF is derived from natural bacterial fermentation, not animal products. The careful growing process used by Red Star ensures a high-quality source of protein with essential and non-essential amino acids. VSF also contains folic acid, which is important for the formation, growth, and reproduction of red blood cells, and provides several minerals including selenium, chromium, zinc, phosphorus, and magnesium.

In addition to its use as a supplement, VSF nutritional yeast adds a delicious nutty flavor to many foods. Its chameleon-like qualities make it highly adaptable, and it is prized by vegans for its uncanny ability to add poultry-, egg-, or cheese-like undertones to vegan dishes.

Some individuals who have difficulty digesting yeasted or fermented foods often find they have no problem tolerating nutritional yeast. Nevertheless, people who are allergic to yeast should avoid all the various types of yeasts and abstain from products that contain them or that have been fermented.