What is Yeast in Beer?

What is Yeast in Beer

Credit: GTF Chromium Blog


We know from the beer flavor wheel that the four components of beer are hops, grain, water, and yeast. But what is yeast? What are the kinds of brewer’s yeast? Is yeast in beer good for you? And what flavors that you taste in your beer were a byproduct of yeast?

What is Yeast?

Yeast for brewing (also called brewer’s yeast) is a single-celled microorganism that reproduces by budding. Biologically classified as fungi, they are responsible for converting fermentable sugars into alcohol. Yeast for brewing should not be confused with baker’s yeast or nutritional yeast.

Is Yeast Good for You?

Yeast for brewing is rich in minerals, particularly:

  • Chromium – a mineral that helps the body maintain normal blood sugar levels. Chromium is low in other types of yeast.
  • Selenium
  • Protein
  • B-complex vitamins

What are the Kinds of Brewer’s Yeast?

Top-Fermenting Yeast

Also known as ale yeast, top-fermenting yeast got its name from how they rise to the surface during fermentation that creates a very thick, rich yeast head. Because they ferment at warmer temperatures, this produces a beer high in esters, giving the brew a distinctive character in taste.

Examples of brews with top-fermenting yeast: ales, porters, stouts, Altbier, Kölsch, and wheat beers.

Bottom-Fermenting Yeast

Sometimes called lager yeast, bottom-fermenting yeast grows less rapidly than ale yeasts. They also produce less surface foam and tend to settle at the bottom of the fermenter as fermentation nears completion. The strain of this yeast and the temperature of fermentation determine the final flavor of the beer.

Examples of brews with bottom-fermenting yeast: Pilsners, Dortmunders, Märzen, Bocks, and American malt liquors.

Flavorful Byproducts of Yeast

Just as water, hops, and grain impact the flavor of beer, so does yeast. In addition to CO2 and ethanol as byproducts, yeast can produce other flavorful compounds including:

  • acetaldehyde (green apple aroma)
  • diacetyl (taste or aroma of buttery or butterscotch)
  • dimethyl sulfide (DMS) (taste or aroma of sweet corn or cooked veggies)
  • clove (spicy character reminiscent of cloves)
  • fruity / estery (flavour and aroma of bananas, strawberries, apples, or other fruit)

One thought on “What is Yeast in Beer?

  1. How Beer is Carbonated – Flagstaff-Grand Canyon Ale Trail

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