April 06, 2020

What is Beer Brewing Yeast?

History of Brewing Yeast

Before getting into brewing yeast here is some history on yeast itself. Yeast is a single-celled microorganism that is classified in the fungus kingdom. It is also one of the first organisms to be raised and domesticated. The domestication of yeast dates back at least 6,000 years originating in Mesopotamia. Originally yeast was primarily used for bread making, but it didn't take long before it was also used for making alcohol.

Brewing yeast is a species called Saccharomyces Cerevisiae. This species converts carbohydrates into carbon dioxide and alcohol. It’s also unique to brewing because it’s had centuries of cultivation and domestication. This domestication has enabled brewers to create yeast strains that have unique fermenting and flavor characteristics. Belgian beers rely heavily on specific “Belgian” yeast strains to give them their unique flavor characteristics. Northern Brewer sells both dry brewer’s yeast and >liquid beer yeast, each effective in brewing beer. You can also read our comparison article, Dry Yeast Versus Liquid Yeast.

Yeast is one of the four pillars of brewing, and it’s arguably the most important, if not the most interesting. Adding yeast to your wort is what converts it to beer. The alcohol transformation process for most of history was considered magical. In Norway, a “magic” stick was often used to stir every batch of beer. The stick was thought to be magic because if the same stick was not used the beer would not ferment consistently. Unbeknownst to those earth Scandinavian brewers, the magic stick was collecting and storing the yeast and would inoculate their wort each time they used it to stir their wort. It wasn’t until the invention of microscopes that scientists could start studying yeast and understanding how such a tiny little organism could make an end product called beer. Louis Pasteur, yes that Louis Pasteur, gave us our modern understanding of what we now know as fermentation. He also traveled to breweries and distilleries to help them with their yeast. Louis Pasteur, was in fact, the brewing industry’s first lab assistant!

The brewing yeast strains currently used in the United States can be traced back to German and Belgian yeast strains from the 1600s. The origin of specific yeast strains is a little cloudy, but the type of yeast we use seems to have originated from the commercial breweries of Germany and Belgium. Those yeast strains made their way to the breweries of Great Britain and eventually came over with the early European settlers of America. Our “native” yeast strains mostly resemble British yeast strains. Interestingly, the early European settlers didn’t cultivate the wild yeast found in the states naturally. Our beers are fermented by an invasive species!

Using Yeast In Your Wort To Make Beer

The science around brewing yeast has now been around for a long time. We now know how to maintain our yeast to make delicious beer. But the science behind yeast isn't even a requirement for most of us, we use off-the-shelf yeast for our beer. As mentioned earlier there are two types of pre-packaged styles of yeast, dry and liquid. When using dry yeast, you can sprinkle it directly on your wort and let it do its “magic”. Using liquid yeast is pretty much the same, all we do is shake it up and pitch it directly into the wort. The yeast laboratories have already done the heavy lifting and their packages come loaded with billions of yeast cells.

Though off-the-shelf packages are fine most of the time there is more you can do if you desire a deeper understanding of the brewing process and yeast handling. Making a yeast starter is one of the easiest ways to make better beer. A yeast starter can increase your yeast attenuation rate, and yeast cell count. The yeast attenuation rate is determined by the amount of sugar your yeast converts into alcohol. An increased yeast cell count can mean fewer off-flavors as more cells are converting the sugars and this reduces speeds up lag time. “Lag Time” is the period between the moment you pitch your yeast to the time it begins to produce alcohol.

Other ways to keep your yeast healthy are the use of nutrients and oxygen. Yeast is surprisingly complex for being a single cell microorganism. They require important minerals to live such as phosphorus, zinc, iron and many more. While wort generally provides yeast with all the key nutrients, yeast nutrients and energizers can help with stuck fermentation or unhealthy yeast. Aeration, the addition of oxygen, is also very important to the health of your yeast. While the addition of oxygen and beer may seem counterintuitive, it’s important to oxygenate your wort before adding the yeast. Oxygen makes the yeast cell walls pliable and conducive to cell growth and reproduction. Homebrewers often shake their wort in the carboy, but you can use other beer aeration techniques.

As you’ve read, yeast is a fascinating element in brewing and we’ve barely scratched the surface. If you’re ready to dive into the petri dish and learn more about yeast, “Yeast” is a fascinating book written by White Labs founder and owner Chris White along with Jamil Zainasheff who has written extensively about beer and owns Heretic Brewery and Distillery. Yeast use can be as easy or as complicated as you choose to make it, and either way that yeast is going to turn your wort into delicious beer.

Read More About Yeast:

Making A Yeast Starter - Learn how to make a yeast starter.
Yeast Nutrients and Yeast Energizers - Keep your yeast healthy. 
Dry Yeast and Liquid Yeast - Check out the pros and cons. 

Hydrating Dry Yeast -  Is pitching dry yeast directly the best method?
5 Easy Tricks For Boosting Yeast Health