I have done 9 beers since I started brewing and that was in January, so I am still pretty new to this. All of the beers I have made turned out very well, except one which was an over carb issue. Every one of these beers was fermented in a closet that was at an ambient temp of 66F. I didn't use a swamp cooler or anything of this sort so each of these beers most likely got too warm during primary fermentation. By the 8th beer I started to realize that this was a problem. I have now been taking precautions and trying to keep the beer consistently at 65 or so. Even though the majority of the beers I have made thus far got too warm at one point, they all turned out great. Some, better than expected. I have only been able to detect warm fermentation flavors in my wheat beer because it had a distinct banana flavor. As for as the others, there were no detectable off flavors. Is temp control make a night and day difference or am I just not able to detect these off flavors. I am starting to get the feeling that it really doesn't have a whole lot of affect. My latest beer is a Citra Pale Ale, and I've kept it at 60-65 with wyeast 1272. I am curious to see if the temp control really makes a difference or not. I'm not sure if its me not being able to taste/identify them or it really not being as big of an issue as its made out to be? If it doesn't make a noticeable difference, I may not sorry about it too much in the future. Thoughts anyone?
Off flavors from warm fermentation & being able to identify them
- Thread starter SurlyBrew
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Im as green as you still. I always take mine to my friend try. Hes been brewing for I think about 20 years so he has some solid feedback on my brews and can identify any issues if there are any like your mentioning. Find someone with good brewing wisdom and they should be very helpful.
Warmer fermentation temperatures certainly do have an effect, and I can speak to this from personal experience. Is it night and day? Not necessarily ... more like a spectrum of gradually increasing off flavors the higher you go. The flavors can range from banana/clove flavors from ester production, to "fire-water" boozy flavors from higher order alcohols like fusels. Some of these age out; some don't. And while I'm sure it's possible to ferment warm without any of these ill effects just by sheer luck, it's a very important variable that should be controlled if possible. 
But IMHO, an ambient temperature of 65-66°F is really not that risky ... which is why you're probably not tasting off flavors. It's hard to know exactly how much warmer the beer itself is than the ambient temperature of the room ... it could be 2° higher, it could be 10°. But I know many brewers who would call an ambient temperature of 66°F good enough.
If you don't taste any off flavors, I wouldn't worry too much about it. But if you ever start fermenting ales in rooms with an ambient temperature of 72°F like we get here in Texas in the summer, you'll notice the difference.
But IMHO, an ambient temperature of 65-66°F is really not that risky ... which is why you're probably not tasting off flavors. It's hard to know exactly how much warmer the beer itself is than the ambient temperature of the room ... it could be 2° higher, it could be 10°. But I know many brewers who would call an ambient temperature of 66°F good enough.
If you don't taste any off flavors, I wouldn't worry too much about it. But if you ever start fermenting ales in rooms with an ambient temperature of 72°F like we get here in Texas in the summer, you'll notice the difference.
OP
OP
SurlyBrew
Well-Known Member
Once I started to pay attention to the temps, I did notice some getting upwards of 10+. Still no noticeable off flavors. The yeast for my Amarillo pale ale was pitched at an accidental 85F and it turned out great.
Did you keep it at 85°F during the entire fermentation? Or did you pitch it at 85°F and then get it cooler? In my experience, the temperature at pitching time is less important (unless of course it's too hot and kills the yeast!). What matters more is what temperature it sits at for the first few days.
OP
OP
SurlyBrew
Well-Known Member
I'm sure it cooled down some what after, but not immediately. It most likely cooled down and once fermentation started probably go into the mid 70's for a bit. I was surprised at how well it turned out after the high fermentation temps. I am curious what it would have tasted like if it remained in the 60's.
The majority of fusels, diacetyl, esters and other byproducts are created during the growth phase. This means that your pitching temp is extremely important. Try pitching a lager warm, as some people suggest, and you will find this out in a hurry. Best practice is to pitch slightly below your desired fermentation temperature let it rise to your ferm temp early on and hold it until fermentation slows at which point you can raise it if desired. This all depends on the individual yeast of course.
Agree with this 100%
And yeah, OP, temp control's pretty important and you will definitely have off flavors if you ferment too warm for the yeast you're using. It sounds like your temps are pretty decent, which is why you're not getting a ton of off flavors. But try letting a beer ferment at 75 degrees, and you'll see what can happen when it gets too warm.
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