One of the key things to take into account when you’re making a home brew is the temperature…
If the temperature is too high you run the risk of producing off-flavors, or, worst case scenario, killing the yeast off altogether.
And if the temperature is too low, you run the risk of the fermentation being too sluggish, which can result in the growth of contaminants such as bacteria or wild yeast.
To get it just right can be something of a balancing act, but I can safely assure you that it can be done. And this article is here to help…
In this article, we’re going to cover temperatures that can kill yeast, the temperature danger zone that can affect yeast health, and the perfect temperature for pitching yeast for your home brews.
We’ve even got a chart that specifies the ideal temperature ranges for a range of different popular strains of yeast.
So please read on to find out more. And feel free to scroll ahead if you so wish. Here goes!
What Kind Of Temperatures Kill Off Beer Yeast?
In their paper titled “Overview On Brewing Yeast Stress Factors”, which can be accessed on this link, the University of Galati studied the thermotolerance of brewer’s yeast.
Where thermotolerance is described as the “cellular capacity of surviving the exposure to high temperatures, usually having a lethal effect”.
Hope I haven’t lost you already! Basically, the thermotolerance of brewing yeast is what kind of temperatures it can tolerate before the yeast is killed.
And they found that the absolute maximum temperature for any beer yeast is 122 degrees Fahrenheit. Or, in other words, 50 degrees Celsius.
But that doesn’t mean that you can go right ahead and turn the temperature all the way up to 122 degrees Fahrenheit! Most strains of yeast will start to suffer at much lower temperatures.
Even if the temperature of the brewing yeast isn’t so high that it could kill it off, high temperatures can cause the brew to start producing off-flavors.
But interestingly, it turns out that extreme low temperatures are not harmful to dry beer yeast.
And this is great news because it means that you can really elongate the lifespan of dry beer yeast. Freezing your dry beer yeast makes it perfectly safe to use for long past the expiry date.
But, once you have started mixing to form your wort, you still have to be careful that your wort isn’t at too low a temperature…
As we mentioned earlier, if the temperature is too low, you run the risk of the fermentation being too sluggish, which can result in the growth of contaminants such as bacteria or wild yeast.
If such a scenario rears its ugly head, you can simply warm up the wort a little and then pitch a starter.
What Temperature Is The Danger Zone For Yeast?
The truth is, the temperature tolerances of yeast can really vary between different strains.
For example, ale yeasts are usually better with warmer temperatures, between 12 and 21 degrees Celsius (55-70 ℉), while lager yeasts do better in cooler temperatures, usually between 4 and 13 degrees Celsius (40-54 ℉).
And just to complicate things further, some ale yeasts won’t work til you get to 18℃/65 ℉, and some lagers can do well at 21℃/70 ℉.
The temperature only needs to be about 30 degrees Fahrenheit above the ideal range before you start to damage the health of the yeast, and start giving you unwanted flavors and aromas.
And another thing to remember is that the metabolic activity of the yeast during fermentation will create heat, adding a few degrees onto the initial temperature of the wort.
So, it’s best to cool your wort a little before pitching the yeast.
What Is The Perfect Temperature For Beer Yeast?
As I mentioned earlier, the temperature tolerances of yeast can really vary between different strains. Which is why I’ve included a handy little chart for you on the ideal temperatures for different popular strains.
However, as a general rule, it’s pretty safe to say that the ideal temperature range for beer yeast falls between 15 and 21 degrees Celsius (60 – 70 ℉).
This temperature range takes into account both the high-end temperature ideals for lagers, and the mid-range temperature ideals for ales.
However, if in any doubt, please refer to the instructions on your packet of yeast.
When I Pitch Yeast At What Temperature Should My Wort Be?
As I mentioned earlier, it’s best to cool your wort ever so slightly under the ideal temperature before you pitch your yeast because heat is a byproduct of the fermentation process. And you don’t want to risk the health of the yeast before you even start.
Unless your particular strain has different instructions, I would recommend that you pitch your yeast when the wort temperature is between 10 and 21 degrees Celsius (or between 50 and 70 degrees Fahrenheit).
In this guide, we have taken a look at what temperature will kill beer yeast, and lots more. So, if you want to find out more, check out the guide above.
Thanks for reading! We hope that the information in this guide has helped you.