Fermentation Temps

On ales I've heard 66-70 is the ideal temperature, any higher than that and you get off flavors.

So what off flavors do you get if your ale is over a specific range? Would too cold of a temperature produce off flavors too, or just a slower fermentation?

Too hot: Esters, phenols, and fusel alcohols. Esters have banana/clove-like flavors, phenols have peppery/spicy notes, and fusel alcohols have a harsh alcoholic taste. And BTW, 66-70 is the higher part of the range, I would try to keep it well away from 70 if you can. I now ferment at an ambient temp of ~59-62F (I don't have temp control, so it's whatever my basement is, but it's pretty consistently within that 3-degree range) and I am very pleased with the results. Also remember that the ambient temp could be a solid 5 degrees cooler than your active fermentation.

Too cold does not produce off flavors, but as you say, it could slow or even halt your fermentation. It also could in theory prevent the production of esters, which are desirable in some styles of beer (although this point is a matter of some controversy... I have no experience with it, but some people say that even for those styles, they have the best luck fermenting it in the cool end of the yeast's range, and get plenty of esters and such anyway)

Story: My 2nd batch was a pale ale that I brewed too hot, and it's really phenol-y. I really don't care for it. It wasn't even that hot, either, about 72F ambient, but that could have fermented as hot as 77F or more.

Now, remember how I said that those biproducts are desirable in some styles? My wife, who is much more into Belgians than me, thinks that beer's actually not so bad. We both agree it's not great, but she rather likes it -- it reminds her of a Belgian that's a bit rough around the edges. Actually, I see exactly what she means, I just don't care for it. So how much it bothers you may depend on your personal taste preference.

To be clear, I am NOT suggesting fermenting hot to get a Belgian-like flavor! You are better off using a Belgian-style yeast and fermenting at an appropriate temperature, which will give you more controlled production of those trace compounds and a much more pleasant beer.

For most fermentations I go right at the bottom end of the yeast strain's temperature range. There are some exceptions, such as Belgians, where I pitch cool then let 'er go. One day I will get a bit more careful with ferm temperatures.

Since I built my fermentation chamber I hold a steady 64 and have not had any off flavors since. Sure its a little slower fermentation but I keep my beers in the primary for a minimum of 3 weeks (Unless something comes up) so its usually done fermenting by then anyways.

Depends on the yeast.

I use US-05 a lot for beers that don't depend on yeast for flavor(IPA, APA etc) I like that at about 65ish.

Belgian yeasts I like to pitch low end of the range and hold it there for a day or two and let them go up to high 70's.

For my Saisons I use 3711 and hold that near 70-72. Love that yeast.

So get to know the yeast you are using and what temp it likes. It usually is better to err on the lower end of the range most of the time.

The worst ferm temp mistake I made was fermenting a belgian yeast too low, made the beer too sulfury, and even though other people liked it, all I could taste was the sulfur.

I use the proper yeast for the proper style, and at the proper temperature. If I make an ESB or a Mild, I like to ferment a bit on the high side, say around 70-72F with an English style yeast.

M_C

So there ya go, 7 brewers, 7 different answers. (Though I guess osagedr, Coldies, and myself more or less said the same thing... Mostly... )

In any case, the one thing we all seem to agree on is that it depends on the yeast, the style, and your own personal preference. As a rule, though, I would start out fermenting most "typical" ales (i.e. not Belgians or other specialty yeast) at the cooler end of the range, and then experiment from there to see what you like. I'll reiterate that the only beer I've brewed that I was really grossly unhappy with, it was because I let it ferment too hot...

The first piece of advice I can give you is to pick a strain, and stick with it. Learn how that yeast reacts to different temperatures, and continue to play with temperature until you maximize the characteristics you are looking for. Other than a real specialty, like a Cal Common or a Belgian, one house ale yeast and one house lager yeast will suffice.

I say this, because every yeast has a sweet spot, and finding that sweet spot with change from brewery to brewery. A lot of that change will depend on what you consider fermentation control.

Let me explain. You hear the number 65F thrown out a lot for an ale. Rarely do you then hear if that is 65F ambient, a fridge set to 65F, or a probe reading 65F in the fermenting wort. They are very different things.

And that brings me to my second piece of advice. Get your temperature control as precise as your budget allows. A one way temp controlled fridge trumps ambient, and a 2 way temp controlled wort trumps a fridge. It will make heaps of difference in the repeatability and overall quality of your beers.

Joe

I'm dumping ice in the bathtub each morning before I leave, so the carboy is hovering between 62-66 throughout the day. So I think my temperatures should be ok for this american brown ale.

In other good news...the airlock held and didn't explode (SWMBO didn't know she was supposed to check it more than once)