Homebrewers are well aware of the importance of yeast in the fermentation process. It can get confusing, however, in determining at exactly what temperature beer yeast will die.
The maximum temperature at which all beer yeast will die is 122℉/50℃ but some strains might be much lower. Each strain of yeast has its own ideal temperature range as well as a recommended wort temperature when pitching – typically between 40-54 °F for lagers and 55-70 °F for ales.
Continue reading for more on the temperature that will kill yeast, the heat ‘danger zone’ for yeast health and viability, and the ideal temperature range for pitching yeast. Also included is a chart detailing various yeast strains and their temperature ranges.
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At what temperature will beer yeast die?
While different strains of yeast have different heat tolerances, the absolute maximum temperature for any beer yeast is 122℉ according to Overview on Brewing Yeast Stress Factors.
In its research, the University of Galati found that number by determining the thermotolerance of brewer’s yeast. Thermotolerance is defined as “cellular capacity of surviving the exposure to high temperatures, usually having a lethal effect”.
Most yeast, however, will suffer at temperatures much lower than 122℉. While yeast strains and their temperature tolerances vary, what they all share in common is that temperatures that are too high will begin producing off-flavors in the beer in addition to running the risk of killing the yeast off altogether.
In fact, this is a great way to elongate the life of dry beer yeast. It’s even perfectly good to use long after the expiry date if stored in a freezer. Less extreme temperatures, like a wort that is not hot enough, will not kill the yeast but it will mean a sluggish or altogether delayed fermentation.
If this happens to you, you can gently warm your wort and then pitch a starter.
At what temperature is beer yeast at risk?
Some yeast strains thrive in cooler temperatures, where others can withstand much higher temperatures during the fermentation process.
Ale yeasts prefer warmer temperatures (usually in the 55-70℉/12-21℃ range) and lager yeasts need it to be cooler, around 40-54℉ (4-13℃). To complicate things, some ale yeasts will not prompt fermentation below 65℉/18℃, and some lagers are fine above 70℉/21℃.
The ‘danger zone’, while not a perfect science, can be as much as thirty degrees above the high-end of the stated range. The yeast is still alive, but it will be suffering from heat damage if exposed to temperatures drastically higher than recommended.
Damaging the health of the yeast can create undesirable flavors and aromas as well as cause your beer to be hazy.
Keep in mind that the metabolic activity of the yeast will create heat during fermentation, adding a few degrees to the initial wort temperature. Yeast is also finicky about dramatic temperature swings, so cooling your wort to an appropriate range before pitching is highly recommended, rather than pitching the yeast, finding the wort is hotter than you would like (or the yeast would like!) and then attempting to rapidly chill the wort.
What is the ideal temperature range for beer yeast?
Although it is quite a task to list the ideal temperature range for every strain of yeast, here is a good general answer.
The ideal temperature range for beer yeast is between 60 and 70℉ (15-21℃). This takes into account the general high-end temperature preference of lagers and the mid-range for ales.
Pitching your yeast at an appropriate temperature for the particular style and strain you are using but ensures fermentation will happen. Look at the yeast’s packaging or the producer’s website to get it right and avoid the need to repitch.
What temperature should my wort be when I pitch the yeast?
Since yeast creates heat as a byproduct of fermentation, it is advisable to pitch yeast into a wort that is a few degrees cooler in order to give yourself some wiggle room.
A wort temperature between 50 and 70℉ (10-21℃) is generally considered the best practice. If you pitch your yeast into a wort that is too hot, it will kill the yeast and fermentation will not start.
As has been discussed at length here, it is best practice to consult the specific yeasts’ packaging in order to determine at what wort temperature your yeast will thrive.
Use the chart below as a general guide to appropriate pitching temperatures.
|Yeast Strain||Beer Style||Temperature Fahrenheit||Temperature Celsius|
|Wyeast Rogue Pacman||Stout||60-72||15-22|
|Wyeast Denny’s Favorite 50||Stout||60-70||15-21|
|Wyeast Belgian Schelde Ale||Pale Ale||62-74||16-23|
|Mangrove Jack US West Coast||Pale Ale||59-74||15-23|
|Wyeast Northwest Ale||IPA||65-75||18-24|
|Wyeast London Ale III||IPA||64-74||17-23|
|Wyeast PC Staro Prague||Lager||50-58||10-14|
|Wyeast PC Hella Bock||Lager||48-56||9-13|
|White Labs Copenhagen Lager||Pilsner||50-58||10-14|
|Wyeast Bohemian Lager||Pilsner||45-68||7-20|
|Wyeast Belgian Abbey II||Belgian||65-75||18-24|
|White Labs Belgian Ale||Belgian||68-78||20-25|
|White Labs Burton Ale||Porter||68-73||20-23|
|Mangrove Jack British Ale||Porter||57-72||14-22|