I’m not going to lie to you – I’m no expert in homebrewing and still learning the ropes myself.
However, I do want to blog a bit more often and recently I’ve been thinking and reading up on the importance that maintaining the right temperature during fermentation has on beer. In particular the direct impact it has on yeast performance.
It’s no secret that yeast is an exceptionally important, nay vital, part of the brewing process. Ensuring that the yeast that you use is “comfortable” plays a major role in getting the best results from the microorganisms.
Just like people, yeast becomes volatile and unpredictable in temperatures which it finds uncomfortable – be it too warm or too cold. A nice even temperature is extremely important if you want the fermentation process to go cleanly and without any nasty surprises.
The production of ester alcohol mainly takes place within the first 3 days of fermentation. So in the early stages you want to make sure that the yeast, when pitched, has time to acclimatize to your wort. Try and stop it from charging off like the bolder in Indiana Jones.
One way to do this is to lower the temperature to a couple of degrees below your target (i.e. if you want your beer to ferment at around 20C then prior to pitching the yeast, lower the temperature to around 18C).
As the yeast get used to their environment, they will begin to multiply. This in itself raises the temperature of the wort – another reason to aim a bit lower than your ideal fermentation temperature.
If you hit that temperature spot on to begin with, the wort will get warmer as the yeast start to do their thing.
I keep an eye on the temperature of my wort before I add the yeast using a HYGIPLAS multi-purpose stem thermometer.
I think normally this is used to check the temperature of meat when cooking, but it does the same job for my brewing and is accurate.
Keeping Temperature Consistent
This can be tricky. Especially if you are like me and do not have room for a kegerator/keezer in your home.
Finding a method that works for you is important. I’ve read online of people freezing water bottles, wrapping fermentation bins in cold wet towels or just placing a fan nearby.
Living in Scotland I find that my main issue is keeping the temperature high enough – especially in the latter half of the year.
To begin with I would just wrap it in a blanket (all tucked in ready for bed) but I stepped up a gear recently and bought a heating tray.
The next stage in evolution for this is to build a temperature controlled unit which knows when to switch the tray on or off.
However, that’s another blog post for another time – once I actually get around to building it really! Anyway, I’ve digressed a bit.
The temperature of the beer during the fermentation process will alter as the yeast works and will come to a peak before slowing and cooling down.
Different yeast strains will act differently, and then activity will start to slow down. Towards the end of their job, the yeasts activity will begin to abate. With less activity the heat generated lessens.
Some brewers at this point find it useful to slowly warm the worst up artificially. The reason being that by doing this you’re giving the yeast a bit of a life line and some more time to clean up after themselves.
They will consume some of the diacetyl in the beer and also other by products they produced during the early days which could create some undesirable flavours if left in the beer.
So, that’s that for now. Temperature is important.
Don’t let it get away from you when fermenting your beer. Too high and you’ll likely be left with overly fruity smelling (and tasting) beers.
Too low and the yeast may drop out prematurely, leaving you with a beer that is not completely fermented.
What a waste of time, energy and hope that would be.
What Do You Reckon?
Any thoughts on temperature? Have you had any disasters? Think I’ve got this whole thing wrong? Found your own way of dealing with temp control?
If so, leave a comment below and let me know your thoughts.