Can yeast heat beer???

[Iowa Brewer]

So, I did my first yeast starter and boy did it work!

4hrs after I pitched into an English Ale, a small kreutzen had formed and the bubbler was going 12 hrs later, and the bubbler was flying off the handle. Now, 26hrs after first bubbling, down to about 1/sec.

But here’s the thing... I pitched at 68F, put it in ferm chamber at 70F with a witbier that’s 5days in. This morning, at frantic bubbling, the ale was reading 74F and the wit at 70F

Since the Omega British Ale I had a 64-72F range, I dropped the chamber to 66 to start cooling it down; took all day to get the English Ale to 72F. All the while, the wit was responding as I’d expect.

Anyone know why? Faulty carboy thermometer? A hyper-active yeast heated up the wort? I’m very curious as to any insights you might have.

Also, there was quite an astringent aroma. Burned my nose to smell (glad that’s shaking out of the beer!).

As always, thanks!

 

[NGD]

Your thermometer is likely fine. Yeast will create exothermic heat. Looks like you had a good starter going. Nice job.

 

[FatDragon]

A very active ferment can easily warm the wort up by 5+ degrees Fahrenheit. I prefer to err on the side of caution by setting my temp controller on the low end of the recommended temperature range unless I want certain yeast characteristics that come with higher temperatures.

 

[EnglishAndy]

Also, there was quite an astringent aroma. Burned my nose to smell (glad that’s shaking out of the beer!).

You probably got a nose full of CO2. It really burns if you do that.

 

[Northern_Brewer]

It's quite normal - breaking down sugar molecules releases energy which ends up as heat, it's the yeast equivalent of running a marathon.

Traditionally British breweries would do pretty much what you've done so far - pitch cool (low 60s) then let the temperature free-rise to 70F or so for ester development for 24-48h, then cool it back down to 65F or so to stop the yeast cleaning up after itself too much. See this thread for a discussion of temperatures.

 

[RM-MN]

So, I did my first yeast starter and boy did it work!

4hrs after I pitched into an English Ale, a small kreutzen had formed and the bubbler was going 12 hrs later, and the bubbler was flying off the handle. Now, 26hrs after first bubbling, down to about 1/sec.

But here’s the thing... I pitched at 68F, put it in ferm chamber at 70F with a witbier that’s 5days in. This morning, at frantic bubbling, the ale was reading 74F and the wit at 70F

Since the Omega British Ale I had a 64-72F range, I dropped the chamber to 66 to start cooling it down; took all day to get the English Ale to 72F. All the while, the wit was responding as I’d expect.

Anyone know why? Faulty carboy thermometer? A hyper-active yeast heated up the wort? I’m very curious as to any insights you might have.

Also, there was quite an astringent aroma. Burned my nose to smell (glad that’s shaking out of the beer!).

As always, thanks!

You can take the witbeer out of the chamber. It is already past the time when it needs to be kept cool and will benefit from warming to room temp. If you have a controller with a probe to control your fermentation chamber it should be affixed to the actively fermenting beer as that is what needs the temperature controlled, not the rest of the chamber. If you have the probe fastened to the active fermenter with a bit of insulator over it, the chamber temp might go down into the 40's or 50's trying to keep the fermenter temp where it should be but you shouldn't care about that, only the beer temp matters.

 

[Iowa Brewer]

Your thermometer is likely fine. Yeast will create exothermic heat. Looks like you had a good starter going. Nice job.

Thanks, NGD!

 

[Iowa Brewer]

A very active ferment can easily warm the wort up by 5+ degrees Fahrenheit. I prefer to err on the side of caution by setting my temp controller on the low end of the recommended temperature range unless I want certain yeast characteristics that come with higher temperatures.

Sounds good FatDragon, and thanks. What are some of those characteristics that might be wanted at higher temps?

 

[Iowa Brewer]

It's quite normal - breaking down sugar molecules releases energy which ends up as heat, it's the yeast equivalent of running a marathon.

Traditionally British breweries would do pretty much what you've done so far - pitch cool (low 60s) then let the temperature free-rise to 70F or so for ester development for 24-48h, then cool it back down to 65F or so to stop the yeast cleaning up after itself too much. See this thread for a discussion of temperatures.

Thanks so much, Northern Brewer! There's nothing better for a newbie to read that I've accidentally done something right!
Thanks for the thread on temps, too. I lived in Sheffield for 5yrs and love the English ales I had over there and always scoped out the CAMRA pubs. It's fun to try to make them, now, and this is my first go at it. That link will be a big help. Cheers!

 

[Iowa Brewer]

You can take the witbeer out of the chamber. It is already past the time when it needs to be kept cool and will benefit from warming to room temp. If you have a controller with a probe to control your fermentation chamber it should be affixed to the actively fermenting beer as that is what needs the temperature controlled, not the rest of the chamber. If you have the probe fastened to the active fermenter with a bit of insulator over it, the chamber temp might go down into the 40's or 50's trying to keep the fermenter temp where it should be but you shouldn't care about that, only the beer temp matters.

That's a terrific idea and makes perfect sense, RM-MN! I've just affixed the sensor to the English ale carboy and removed the wit.
Much obliged for the tip!

 

[FatDragon]

Sounds good FatDragon, and thanks. What are some of those characteristics that might be wanted at higher temps?

It depends on the yeast and the style of beer. Saisons are the most common example - many strains of saison yeast produce their most characteristic saison flavors at much higher temps than most ale yeasts are suited for.