Lager yeasts differ from ale yeasts in the flavors and other important characteristics they produce and the primary factor which makes the difference is the fermentation temperature.
Lager yeasts prefer the colder temperature and if you wonder what happens when you ferment with lager yeasts at room temperature also known as the ale yeast fermentation temperature you need to know the following.
If you ferment with lager yeast at ale temperature the beer will be high in fruity and harsh alcoholic flavors. Fruity flavor comes from high esters production and harsh alcohol flavor comes from diacetyl which is the group of alcohols that are created at warm fermenting temperatures.
Yet, there are unique lager yeast strains that are cultivated for fermentation at ale temperature! Some beer styles such as steam beer are brewed this way.
Understanding Lager Yeast
What Makes Lager Yeast Unique
Lager yeast, scientifically known as Saccharomyces pastorianus, is known for its ability to ferment beer at lower temperatures compared to ale yeast. Lagers are typically fermented at temperatures ranging from 44°F (7°C) to 55°F (13°C). This cold fermentation process contributes to the clean, crisp, and smooth characteristics associated with lagers.
The Role of Ale Yeast
Ale yeast, or Saccharomyces cerevisiae, is commonly used for ales and operates at warmer temperatures, typically between 60°F (15°C) and 75°F (24°C). This yeast strain imparts a wide range of flavors and aromas, often resulting in fruity and estery notes.
The Trend of Fermenting Lager Yeast at Ale Temperatures
Brewers worldwide are increasingly intrigued by the idea of fermenting lager yeast at ale temperatures. This trend challenges traditional brewing norms and allows for the creation of hybrid beer styles that blend the characteristics of ales and lagers.
Benefits of Fermenting Lager Yeast at Ale Temperatures
If these benefits sound good to you, perhaps you should forget about the traditional way of brewing lagers and instead be different.
- Enhanced Flavor Profiles: Fermenting lager yeast at ale temperatures can lead to unique flavor profiles not typically associated with lagers. Brewers have reported hints of fruity esters and a more pronounced hop presence, resulting in complex and exciting beer experiences.
- Reduced Fermentation Time: One practical advantage is the shortened fermentation time compared to traditional lagering. Ales ferment faster, and typically most yeast strains are more active in warm temperatures which can be advantageous for breweries looking to produce lager-like beers more quickly.
While the concept of fermenting lager yeast at ale temperatures is intriguing, it comes with its fair share of challenges. Brewers must carefully manage several factors to achieve the desired results.
Warm Temperature Lager Yeast Strains
Choosing the right lager yeast strain is crucial for success. Some strains are better suited for warmer fermentations, and brewers should consult yeast suppliers for recommendations or go with a few proven picks we’ll share with you.
Warm-temperature lager yeast strains are specifically bred to thrive in ale-like fermentation conditions while imparting lager-like characteristics to the beer. Some popular strains include:
1. Saflager W-34/70
- Fermentation Range: 53°F to 59°F (12°C to 15°C) ideally. However, it can ferment at up to 68°F (20°C) quite well.
- Characteristics: Clean, neutral flavor with a mild ester profile. Ideal for lagers brewed at warmer temperatures.
2. Imperial Yeast L17 Harvest
- Fermentation Range: 50°F to 60.8°F (10°C to 16°C)
- Characteristics: Produces a crisp and clean lager with subtle esters. Works well in hybrid styles.
3. Mangrove Jack’s M54 California Lager
- Fermentation Range: 64°F to 68°F (18°C to 20°C)
- Characteristics: Delivers a clean and malt-forward lager profile, suitable for warmer fermentations.
4. WLP810 San Francisco Lager Yeast
- Fermentation Range: 58° – 65° F (14° – 18° C)
- Characteristics: Used for California Common beer and steam styles when fermented at ale temperatures, and used for märzens, pilsners, and helles style lagers at lower temperatures.
Possible complications
Fusel alcohol off-flavors
Unless you brew with some of these high-quality yeast strains or accidentally ferment too warm due to poor temperature control, it’s possible to create a harsh alcoholic flavor profile. Hopefully, the harsh alcoholic off-flavors can be filtered out by long conditioning times as with time the harsh flavors will mellow.
High esters (fruity flavors)
Similarly, brewing with some other lager yeast strains not suited for fermenting at ale temperature or messing up with the temperature can lead to high production of esters responsible for strong fruity flavors that can be overwhelming in a lager.
The best you could do to save such a high-ester beer is to mix it with another beer style that will benefit from an ester profile like Belgian ales.
However, you won’t have a crisp, refreshing lager any longer but rather a new style. Moreover, I am a big believer in experimenting with different beer styles and recipes because sometimes the weirdest ideas can come true as very unintentional but pleasant brews.
Raise the temperature for the last few days
It’s suggestible to increase the fermentation temperature by the end no matter the strain. When fermentation is above 90% from complete or in other words, the last few days before you are certain it’s complete, you can raise the temperature by a few degrees.
By doing this you’ll often enter the ale fermentation range even when fermenting with true lager yeasts fermented at cold. You see, the fermentation is almost complete anyway, so all important processes are pretty much done, and by increasing the temperature you can give the lager a nice finish which will take care of certain harsh flavors and help the conditioning.
One of these harsh flavors is diacetyl (fusel alcohols) which will occur during normal lager and ale fermentation to some extent. The removal of diacetyl is done by increasing the temperature and waiting a few days for the alcohol to evaporate, also called diacetyl rest.
Diacetyl rest is achieved by raising the temperature to 68°F (20°C) for the last 2-3 days in the primary fermenter.
After the diacetyl rest you can bottle or keg and if you are naturally carbonating the room temperature is ideal.
Diacetyl rest is not necessary if there are no obvious weird alcoholic off-flavors present when you take a sample.
Lagering temperature VS fermeting lager temperature
When we talk about lager yeasts, fermentation temperature, and logging temperature it’s important to call the difference between these two terms.
Lagering temperature isn’t the same as fermenting lager temperature. Fermenting lager temperature is the temperature optimal for fermentation of lagers but once the lager is complete with fermenting, it’s bottled, canned, or kegged and put in a colder room for conditioning.
The lagering temperature is even lower than the temperature used for the fermentation of lagers and it can be as cold as 30°F – 36°F. The purpose of lagering is to let the lagers condition at cold and establish the desired character as no freshly fermented beer tastes as good as a beer that matured a bit.
Frequently Asked Questions (FAQs)
Can I ferment any lager yeast at ale temperatures?
While it’s possible, not all lager yeast strains are suitable for warmer fermentation. Consult yeast suppliers for recommendations.
What are the most common off-flavors when fermenting lager yeast at ale temperatures?
Off-flavors can include fruity esters, diacetyl, and fusel alcohols if not managed carefully.
Do I need specialized equipment for fermenting lager yeast at ale temperatures?
Precise temperature control equipment is essential to maintain consistency during fermentation.
Can I still achieve a clean lager profile when fermenting at ale temperatures?
With the right yeast strain, temperature control, and conditioning, it’s possible to achieve a clean lager-like profile.