Will Yeast Ferment in the Fridge? Your Complete Guide
The fermentation process is a fascinating one, and it often begs questions about temperature, conditions, and important details not to miss.
Particularly when it comes to beverages, is there such a thing as too cold? Or too hot?
While yeast is amazing and natural and will do much of its work without interference, there are important factors to consider if you want yeast to be at its best.
Yeast
A single celled, eukaryotic organism, yeast is a type of fungus. It has been on earth probably since the very first signs of life, and it has made its way through history serving one function, and one function only: to ferment.
Yeast is all around us, in the air, on surfaces, on our skin, and even in our bodies. It is only outnumbered by bacteria, but yeast is much larger than bacteria, by a factor of 10, so it manages to take up more space.
The fermentation process occurs because yeast basically sits around waiting for some action.
And action in this case is sugar.
When yeast notices sugar, it attacks: it consumes all the sugar and converts it to alcohol and carbon dioxide. This conversion, called fermentation, has been going on for as long as sugar and yeast have been in existence.
Wine
Wine was likely the first food or drink to be fermented, as scientists have shown that monkeys make their own wine, which means we have been making wine at least as long as our cousins, and probably even before that, back when we had a common ancestor.
Yes, cavemen probably made wine.
Picture it: a nice cave lady was probably picking fruit for her family, left the fruit out to sit, at which point it ripened, attracted yeast, and fermented.
Now she and her cave hubby had a delightful buzz over their campfire lit dinner.
Beer
After wine came beer.
Anthropologists think beer has been around for several millennia, and that it was, again, a happy accident.
A mother was likely out gathering grain, left her grain to sit exposed to the elements while she wandered off to do other chores. A storm struck, soaking the grain and leaving liquid in the bottom of the container.
Days later, the mother would have found the grain, soft and doughy now, and the liquid at the bottom, and never one to waste food or drink, served both to her family.
There you have the discovery of ale.
The Critical Element for Yeast: Temperature
Notice the most important factor in the stories here is the elements. In order to be harvesting fruit or grain, the weather had to have been relatively nice.
The weather was warm enough to produce food, which means the yeast was naturally alive and attracted to the sugars in both the grains and the fruits, and fermentation could take place.
For thousands of years, then, fermentation likely only took place in warmer climates and under warm weather conditions.
We know now that most yeast needs a relatively warm environment to ferment, somewhere between 60 and 70 degrees Fahrenheit.
It would not be until the 1300s that Bavarians monks would discover a slight exception to this rule.
Lager
These ale brewing monks lived up in the mountains, in a colder climate, and rather than leave their barrels of brew out to ferment in the open air, they stored their barrels in caves in those mountains.
Lo and behold, the beer attracted a cold weather yeast, which quite different from ale, came to be known as lager.
The yeast that makes lager prefers a lower temperature than that of ale, between 48 and 55 degrees Fahrenheit.
The same is true of white wine, which ferments at a colder temperature, as compared to red wine, which ferments at a much warmer temperature, all the way up to 86 degrees Fahrenheit.
Refrigeration and Yeast: Will Yeast Ferment in the Fridge?
Thus, when it comes to refrigeration and yeast, you are unlikely to get fermentation to occur.
Most refrigerators run between 36 and 38 degrees Fahrenheit, which is much too cold for yeast to ferment, but it is a great temperature to keep your live yeast alive and active without having to feed it for a couple of weeks if you are in between batches of beer, wine, bread, or whatever you happen to be fermenting.
Stuck Fermentation
In fact, not only will yeast not ferment when refrigerated, if your temperature is too cold, you might find your fermenting process stops.
Too cold of a temperature will put most yeast to sleep.
Which is why, when brewers or vintners complain of stuck fermentation, temperature is the first question that gets asked.
Stuck fermentation occurs when all the correct steps have been taken to brew beer or make wine, the yeast is added, all seems to be going well, and suddenly fermentation stops.
You notice the bubbling and fizzing is not longer occurring, and your yeast may even collect, or flocculate, as if it is done.
But you know it is not.
This stagnation often happens because of a temperature drop. Typically, you can simply raise the temperature of the room or move your barrel or tank to a warmer location, stir the liquid to activate your yeast again, and notice it will jump right back into action.
In the end, yeast will either ferment very slowly or not ferment at all in the refrigerator, which is why, quite often, putting your beer in the fridge pretty much insures against continued fermentation, and the alcohol level remains low. With wine, the yeast can continue to ferment slowly at cooler temperatures, and will have a higher alcohol content.
So, if it does ferment, like in the case of bread or white wine or lager, at those colder temps, it will do so very slowly.
Cheers!
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