The best temperature for fermenting

Andy F. has sent us the following email about fermentation temperatures:

“I want to make my own cider from scratch this year. I intend to use a sectioned off part of a timber workshop which is well insulated. I was thinking off standing the fermentation bin on a heated mat that winemakers stand their demijohns on. Please can you let me know what the ideal temperature I should keep the mix at?

Many thanks.

Andy F”

Well Andy, that is a great question. Yeast is a living organism and like us, when it’s too cold it just goes dormant and stops doing anything.

Of course when the environment is too hot, the yeast also suffers. The good news is that most yeasts will work across quite a broad range of temperatures without too much complaint. Anywhere between about 9 degrees centigrade and 40 degrees and you should still be able to brew cider.

yeast

By Masur – https://commons.wikimedia.org/w/index.php?curid=1069017

But if you have the opportunity to control the temperature precisely, then you can give the yeast their equivalent of paradise which will mean they will work exceptionally hard for you.

However that might not be the best idea. Although the yeast  may multiply fastest when close to blood heat,  generations of brewers have handed down the wisdom that with cider, the colder the better is the rule.

As long as it is warm enough that the yeast doesn’t stop working altogether, a long slow cool fermentation at a constant temperature seems to produce the very best results.

We ferment in an unheated room at a fairly constant 17 degrees. I wish it  was a couple of degrees cooler than that to be honest.