What Temperature to Pitch Yeast at?

In brewing, the process seems at face value to be quite simple. After all, our ancestors were making beer 10,000 years ago with cereal grains and water. The result was so amazing that we have continued the tradition for generations, finding our own ways to tweak ingredients, flavors, and aromas to our benefit. Today, the process is not necessarily more complicated as it is what it has always been, complex. Because so much is happening with the few ingredients we work with, it is essential we understand what is happening so that we can properly guide the process. One of those complexities involves what temperature to pitch yeast at.

The Role of Yeast in Beer

Before we discuss the issue of temperature, it is helpful to understand what we are working with here. Notice I said our ancestors worked with cereal grains and water. I didn’t mention yeast. That’s because they had no idea what yeast was, regardless of the fact that yeast then, as now, played a critical role in the production of beer.

But what happened was that yeast managed the fermentation process all on its own.

Brewers literally only had to soak grains in hot water for a bit, strain out the grains, and leave the water, now called wort, exposed to the elements.

Yeast would get right to work.

Why?

Well, yeast is a single celled, living organism that has been on earth for millions of years. It has been around as long as there has been a sugar source, as sugar is the source of energy for yeast.

In nature, there are thousands of strains of yeast, and they all hover in the air, rest on surfaces, and even inside of other living organisms, feeding off fermentable sugars.

Then, as a natural byproduct, yeast release alcohol and carbon dioxide, along with hundreds of other micronutrients, as waste.

That’s right. Yeast consume sugar and expel alcohol and carbon dioxide. That’s how we get beer, wine, liquor, and any other alcholic beverage. In fact, we could not get alcohol if yeast did not exist.

As to bread, which also calls for yeast, the alcohol is burned off during the baking process and the highlight is on the carbon dioxide, which expands the bread from within the dough. That’s why, before the discovery of yeast, bread was flat – or unleavened. Think of tortillas, pita bread, and even pizza.

Once bakers realized they could leave bread out overnight and it would rise, we had the invention of leavened bread. This fluffier, more flavorful bread was a hit thanks to yeast.

But yeast did not need any help, you see.

Because it is everywhere in nature, with the exception of super hot environments like volcanoes, where it will burn off and die, or frigid environments where it will go dormant, it simply awaits the arrival of a sugary source and starts consuming.

Thus, even today, if you were to toast your chosen cereal grain, crack it open, and steep it in hot water for the mash-in, then strain out the grain for lautering and leave the wort in an air tight vessel for a couple of days, you would find it fermenting.

That’s how amazing yeast is.

The Egyptians called it a miracle when grape juice turned to wine over and over with little human interference.

Indeed, many small craft brewers today do follow the ancient practices and work with wild yeast instead of commercial yeast, in which case temperature is of very little concern.

Why Temperature Matters

So why does temperature matter?

Well, if you’re using a commercially cultivated, packaged, and shipped yeast, you will have to follow the guidelines designated for that yeast. Today, we have over 400 yeast strains that have been commercially grown, both ale and lager, and when you buy a specific yeast strain in order to make a certain kind of beer, you want to be sure you are pitching according to the needs of that yeast, or you will have wasted your money on yeast that won’t ferment at the wrong temperature.

In nature, of course, the local yeast will ferment at whatever the current “room” temperature is because that is the temperature at which the yeast is currently surviving.

However, if you are a brewer in Chicago during the winter, and you hope to brew an ale, it is unlikely you will find ale yeast occurring naturally in the wild. You will need to buy ale yeast, or harvest it earlier in the year and save it for yourself for later, and then pitch it at an ale yeast temperature.

The same goes for a brewer in the Arizona desert attempting to make a lager in the heat of summer. You’ll need to control the temperature of your lager before pitching, or your lager yeast will die.

To sum up, you typically need to pitch yeast at the temperature at which that particular yeast thrives, which is different for different yeasts.

In general, ale yeast strains all ferment in one warm temperature range and lager yeast all ferment at another, lower range.

What Temperature to Pitch Yeast at

Ale

The generally agreed upon range at which to pitch ale yeast is from 68- to 80- degrees Fahrenheit. Lower than that and your yeast might stagnate. Any higher, and your yeast may create unwanted off flavors in your beer. It is also important to remember that fermentation is yeast consuming sugar for energy, which creates heat. So aim for the lower end of 68 degrees to allow room for excess heat to be added.

Lager

Lager yeast ferments naturally at much cooler temperatures, so you can shoot for between 45- and 55- degrees Fahrenheit. If you notice that your fermentation is stuck, you can always try mixing the ingredients up a bit to activate the yeast, moving your vessel into a warmer room, or raising the temperature of the room slightly.

Cheers!

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Sources:

1. https://www.morebeer.com/questions/210
2. https://www.homebrewersassociation.org/forum/index.php?topic=7980.0
3. https://www.youtobrew.com/mead-making-101/how-to-pitch-yeast-properly

 
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