Most beer drinkers know about hops, but not many consider how yeast can affect the flavor, taste, and feel of their beer too. One type of beer in particular is known for its high levels of yeast.
Hefeweizens tend to have more yeast than other beers. This is because they have very low flocculating yeast that tends to stay in suspension. Bottled beers will also have more yeast than their draft or canned counterparts as well.
In this article, we will take a look at the different types of yeast found in beer, the influencing characteristics of yeast, and the types of yeast common beers are made with.
What Is the Role of Yeast in Beer?
Yeast is an important ingredient in beer, as it's an essential part of the fermentation process. It eats the unfermented sugars in liquid that is referred to as 'wort'. As the yeast consumes these sugars, it converts them into alcohol and CO² gas.
The type of yeast used will affect the flavor and aroma of the beer significantly (more on that later).
Does Yeast Affect the Alcohol Percentage of a Beer?
Yes, the yeast plays a huge factor in determining the alcohol percentage of the beer. Each strain has a different threshold for the amount of alcohol it can sustain before it will stop fermenting. The more alcohol the yeast can sustain, the higher the alcohol percentage of the beer.
What is attenuation?
Attenuation is the amount of sugars in the wort that end up being converted into alcohol. This is what makes beer alcoholic.
The attenuation of yeast is divided into three classifications with the following percentages:
- Low attenuation: 72% and lower
- Medium attenuation: 73% to 77%
- High attenuation: 78% and higher
Can Yeast Impact the Flavor of a Beer?
Yeast has a major impact on the overall flavor of your beer. A strand of yeast can help add a sweetness, a fruity flavor, or dry flavor to a beer.
Yeast can also help highlight the maltiness or hoppiness of a beer.
Which Types of Yeast Are Found in Beer?
There are two types of yeast commonly found in beer:
- Ale yeast (top-fermenting)
- Lager yeast (bottom-fermenting)
Why is ale yeast considered top-fermenting?
Ale yeast is referred to as a top-fermenting yeast because it creates a thick, yeast head early in the fermentation process.
Ale yeasts are typically fermented at a temperature range between 10° and 25° Celsius.
Why is lager yeast considered bottom-fermenting?
Lager yeast is considered bottom-fermenting because it sits at the bottom during the fermenting process. This is in part because the lager yeast ferments at a much lower temperature than ale yeast.
Lager yeasts ferment at a temperature range between 7° and 15° Celsius. This results in inhibiting the production of some chemical flavors that are associated with ale yeast beers. Therefore, a lager yeast beer typically has a cleaner taste.
Which types of beer use ale yeast?
Some types of beers that commonly use ale yeast include:
- Pale ales
- Wheat beers
Which types of beer use lager yeast?
Some types of beers that commonly use lager yeast include:
Are There Other Strains of Yeast Used in Beer?
Even though yeast used in beer is mainly divided into two categories there are an endless variety of different strains of yeast.
Each strain of yeast can present a different flavor profile and also affect the alcohol percentage of the beer. In the following sections, we will look at the different characteristics of yeast.
Does Fermentation Temperature Affect the Flavor of Beer?
Yes, the temperature during the fermentation process plays a huge role in the overall flavor of the beer.
If a beer is fermented at too low of a temperature, the yeast may never actually ferment. This leaves you with a non-alcoholic yeast slushie.
If a beer is fermented at too high of a temperature, it will cause the flavor to be off resulting in a bad tasting beer.
What is Flocculation?
Flocculation happens towards the end of the fermenting process and is when yeast cells clump together. The flocculation rate determines how quickly yeast will sink to the bottom of a fermenter to give a clear beer.
Therefore, beers that are very cloudy or yeasty (like wheat beers) typically have very low flocculation rates.
Are There Other Types of Yeast?
There are some beers made with yeast that does not fall into the ale or lager yeast category. These include:
- Brettanomyces bruxellensis – This is often used to make sour beers. It has a really high attenuation rate, which provides a very sweet flavor.
- Saccharomyces cerevisiae variety diastaticus (STA1) – This strain also has a very high attenuation rate and is commonly used when making a saison.
- Bacteria-positive yeast – Often used in making sour beers, because the added bacteria adds the sour flavor.
- Bacteria – Also added to sour beers to add sour, but since bacteria alone won’t make a beer alcoholic, it is added when the beer is put in the kettle.
What are the Common Types of Ale Strains?
Different types of ale strains produce very different types of beers. Some of the most common strains of ale yeast you will see around include:
- American Ale – A very neutral yeast with medium attenuation and medium flocculation.
- Belgian Ale – An extremely high alcohol tolerance with a fruity flavor that often includes hints of clove.
- British Ale – Produces a woody, yet tart flavor.
- Barleywine/Imperial Stout – very high alcohol tolerance with a malty flavor.
- India Pale Ales – A wide variety of flavors intended to pair well with a large amount of hops.
- Brown Ale – comes in a wide variety, but almost always produces the brown color that the category is known for.
- Kölsch – Good attenuation giving the beer a crisp and clean finish.
- Stout – That smooth, dark flavor and color associated with stouts.
- Wheat Beer – low flocculation providing a very cloudy and dense look.
Why Should You Care About Your Beer's Yeast Levels?
The yeast levels in your beer are important because they play a role in the overall taste, mouthfeel and appearance of your brew. Different strains of yeast create different flavors and can also affect the alcohol percentage of the beer. Understanding yeast is key to making great beer!
If you're not a brewer and instead just enjoy drinking beer, it's still useful to know about the various types of yeast used in different types of brews. This way, you can order a beer that will best suit your taste—and discover other similar beers you may like based on their yeast profile.