How long until high temperatures affect taste?

Hey guys,
I brewed my first batch of Caribou Slobber last night and cooled it outside in the snow... I made a yeast starter and pitched it at about 70 degrees which I figured would cool down by the time the yeast started-and it did.

This afternoon I checked on the fermenter and it was bubbling like mad (some of the krausen started bubbling out of the airlock so I put the blowoff tube on). At this point the fermenter was sitting at 74-76 degrees which is a little high but I figured it would stay around there. The weather has been so cold here in Chicago but today its pretty warm out so the room I ferment in was warmer than usual. When I got back around 3-ish I saw the temperature was at 78-80 degrees..WAY too high... so I decided to move the carboy to the basement where its about 64..

My question is, How long does it take for high temperatures to affect the beer? Do you think about 6 hours at 76-78 degrees is enough to create that banana/ester flavor?

I'm hoping I didn't **** it up! Especially during the crucial adaptive/attenuation stage..

I'd say there is no hard answer. Some will tell you that you will have off flavors. I've had two batches over warm for half a day in high activity with no ill effects. You'll just have to wait and see. But if it has fruity esters, call it a Belgian.

Just record all these details and see what happens when you finally taste it. At least you will have a baseline to work off of if something isn't good.

I think a distinction between fruity esters (which is not always bad, but sometimes out of style and personal preference) and superior alcohols (which is almost always not enjoyable) should be made..

Anyway - I'd say expect some fruitiness and not completely clean ale. I doubt there's detectable fusel alcohols in your brew.. I recently brewed a batch with S-04 and it got a bit high 73-76 F (for the entire fermentation) and it has an ever so slight hint of turpentine.. (Perfectly drinkable, but none the less a detectable flaw.. )

Your 64° basement would have been the ideal place to have your fermentor. Ferment would have been better if you cooled the wort to 60°. Yeast work better pitched cool and then warmed to fermentation temperature.

Beginning with a 60° wort in a 64° basement, the highest fermentation temperature may have only reached 70°. After active fermentation was over the fermentor could have been brought into your living area to finish.

flars said:

Your 64° basement would have been the ideal place to have your fermentor. Ferment would have been better if you cooled the wort to 60°. Yeast work better pitched cool and then warmed to fermentation temperature.



Beginning with a 60° wort in a 64° basement, the highest fermentation temperature may have only reached 70°. After active fermentation was over the fermentor could have been brought into your living area to finish.

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I will definitely remember this for my next batch! The room I ferment in usually stays at a perfect temperature at night while the basement gets pretty cold during the winter.

Will moving the carboy in the morning/night affect fermentation at all?


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McLovinBeast57 said:

Will moving the carboy in the morning/night affect fermentation at all?

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Not at all.. Some people even swirl their carboys to resuspend yeast that has drop out prematurely or to get hop pellets to settle.

McLovinBeast57 said:

I will definitely remember this for my next batch! The room I ferment in usually stays at a perfect temperature at night while the basement gets pretty cold during the winter.

Will moving the carboy in the morning/night affect fermentation at all?


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Leave your fermentor in the basement for about three days. Since you are using a sealed carboy bubbles in the airlock is an indicator of fermentation activity. When the bubbling slows to about one per 30 seconds return the fermentor to living quarters temperature. Let the beer warm and the yeast will finish and clean up natural off flavors of fermentation.

Slosh as little as possible to retain the CO2 layer and the krausen ring. If you slosh or swirl, the krausen ring (dried gunk) will break loose and forever float. Some of these floaties can end up in keg or bottling bucket.

Fusel alcohols produced by a short time at high ferment temp may not be noticeable after four weeks of bottle conditioning. 70° to 75° is a good temp for conditioning.

I agree with Flars. I ferment 5 gallon batches in my basement until the ambient temp drops below 60. Then I ferment them in the basement near the furnace, where it is a few degrees warmer. If I have any doubts whether it is finished, I bring it upstairs for a few days and set it by the baseboard.

flars said:

Leave your fermentor in the basement for about three days. Since you are using a sealed carboy bubbles in the airlock is an indicator of fermentation activity. When the bubbling slows to about one per 30 seconds return the fermentor to living quarters temperature. Let the beer warm and the yeast will finish and clean up natural off flavors of fermentation.



Slosh as little as possible to retain the CO2 layer and the krausen ring. If you slosh or swirl, the krausen ring (dried gunk) will break loose and forever float. Some of these floaties can end up in keg or bottling bucket.



Fusel alcohols produced by a short time at high ferment temp may not be noticeable after four weeks of bottle conditioning. 70° to 75° is a good temp for conditioning.

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Thanks man! I put it in the basement and it cooled off but now it isn't bubbling nearly as much... Since I added a whirlfloc tablet I'm not too worried about the clarity at this point so I spun the carboy around a few times to re-suspend some of the yeast...

It went from 78 to 66 within a few hours, so I'm hoping it doesn't drop below 60 overnight.


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If the temperature drops, many yeasts will keep on chugging along, albeit a bit more slowly.

McLovinBeast57 said:

Thanks man! I put it in the basement and it cooled off but now it isn't bubbling nearly as much... Since I added a whirlfloc tablet I'm not too worried about the clarity at this point so I spun the carboy around a few times to re-suspend some of the yeast...

It went from 78 to 66 within a few hours, so I'm hoping it doesn't drop below 60 overnight.


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The temperature change will slow the yeast some, but fermentation should continue. Longer time in the primary will not be detrimental to the beer.