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Fermenting temp

Posted: Sun Aug 16, 2020 6:30 am
by Pdunc
Brewing a Twisted Monk Witbier today. BrewDemond gives a fermenting range of 64 to 84 degrees. Is there a “best” temp for brewing this beer, and if so, why?

Re: Fermenting temp

Posted: Sun Aug 16, 2020 7:19 am
by John Sand
Yeast will ferment over a wide range, perhaps 40-100f. But it will produce different flavors at different temps, some undesirable. 64-68 is a close tolerance, I don't worry about dialing it in any closer.

Re: Fermenting temp

Posted: Sun Aug 16, 2020 7:35 am
by BlackDuck
I’ll also add that consistency can be important too. Try to avoid temp swings up and down during fermentation, even if it’s in the acceptable range. Big swings can also lead to off flavors.


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Re: Fermenting temp

Posted: Sun Aug 16, 2020 7:34 pm
by HerbMeowing
Fermenting at the high end of the temperature range will produce more esters and possible undesirable fusel alcohol.
Fermenting at the low end of the temperature range will produce a 'cleaner' tasting beer.
Fermenting below the low end of the temperature range will put the yeast to sleep.

I too aim for maintaining 64 - 68°F during the first five days after which I let it rise to room temperature (lo 70s).
Keep in mind ... fermentation gives off heat so the temperature inside the fermentor can be several degrees higher - IIRC 5-7°F - than the temperature outside the fermentor.

Re: Fermenting temp

Posted: Mon Aug 17, 2020 2:14 am
by mashani
This all depends on the yeast you are using, but if you are using the yeast Brew Demon provides in the little packs, then the ranges above mentioned (mid-upper 60s) and stableish temps are about where you want to be.

If using an actual Wit bier yeast, it might be higher though depending on the flavors you want to coax out of them. Many Belgian yeasts are good in the 70s to even 80s. Some Belgian yeast produce the best flavor profile by not doing what they said above and starting at say 68, and then letting the temperature actually rise during fermentation up to 78 or even more depending on the yeast. (actual Belgian breweries do this, not just silly home brewers like me).

Re: Fermenting temp

Posted: Mon Aug 17, 2020 5:35 am
by Pdunc
Thanks for all the great info. My new batch of Twisted Monk is now fermenting at a constant temp of 68-69 degrees. I plan on leaving it in the fermenter for 18 days, then condition in bottle for at least 3 weeks.

Re: Fermenting temp

Posted: Sun Aug 23, 2020 10:02 am
by FedoraDave
Pdunc wrote:Thanks for all the great info. My new batch of Twisted Monk is now fermenting at a constant temp of 68-69 degrees. I plan on leaving it in the fermenter for 18 days, then condition in bottle for at least 3 weeks.
That's a good temperature, and a good time frame for fermenting/conditioning. But don't chill all the bottles at once. Just the ones you plan on drinking in two days (48 hours is a good time frame to chill a bottle). See what a difference more cellar conditioning makes. You'll be surprised at the same beer from the same batch at 8 weeks.