Temp swing during Fermentation... ugh

[Kornssj]

PG&E decided to shut off the power and this was 38 hours into fermentation of my newly racked blonde ale.

I have a Fermzilla set at 2PSI inside my kegerator with an inkbird set to 66F with a 1 degree delta.

I moved the batch inside and let it sit on cool kitchen tile. Temp gradually rose to 76F during the 38 hour to 45 hour mark as the sun got higher in the sky. I came home and placed everything back since the power was restored. It's now getting back to 66F.

How bad is the damage in terms of flavor and Final Gravity?

 

[day_trippr]

What was the yeast strain used?
FG is unlikely to change at all, and I don't think that brief excursion to 76°F will hurt the beer.
Carry on!

 

[Kornssj]

White lab WLP029. German ale kolsch.

 

[day_trippr]

It'll be fine. That strain actually is a bit unique as a kolsch yeast in that it prefers to be run as warm as 69°F so a handful of degrees over for a few hours is unlikely to be noticeable in the end. Classically kolsches were fermented in the 50s°F with ale yeasts and then laagered even colder but this strain is decidedly unhappy when run that cool...

Cheers!

 

[IslandLizard]

Keep in mind the air temp measured inside the kegerator may have been warmer than that of the beer itself inside the fermenter. Liquids have a much higher thermal mass, resisting temp changes.

 

[jdauria]

I feel for you, brewed a Hefeweizen last week and tried to ferment it at 62F and my mini-fridge I use to chill glycol/water to pump to a chilling jacket was not handling the heat and humidity at all (I have a hole in the fridge door for the tubing), and the beer got up to 76, meaning I am probably going to be left with a banana bomb of a beer.

With WLP029, I think you will be OK. plus at 38 hours with an ale, you may have already had a decent amount of fermentation completed (assuming a proper pitch of yeast) and been past the danger zone of off-flavors.

 

[tracer bullet]

One of those things where you let it finish fermenting and find out. I really think it'll be fine with a good chance you won't even notice.

 

[hotbeer]

Even if everyone told me my beer was going to be nasty, I'd still wait and see.

Keep notes on your temp excursion. And add to those notes what the final product tastes like when ready for the glass.

Let us know too if you don't mind.

 

[Kornssj]

Thanks all. I will take some flavor notes and report back. I appreciate everyones input. Puts my mind at ease.

 

[tracer bullet]

I've been amazed how many ways I can mess up the fermentation temperature and how the beers always turn out fine. I'm working on a keg of ESB right now that was in the mid 70's for practically the whole first day and was happy to find that it tastes great. I don't think I'd do it again on purpose at any point but it was one of the times to be occasionally reminded about "RDWHAHB".

 

[MaxStout]

Never give up on a beer. Wait until you know for sure. That max air temp was a peak, I doubt it was that high the whole time. And as @IslandLizard noted, the beer is a much bigger thermal mass. Its temp increase would've greatly lagged behind the increase in air temp. I'd be surprised if it exceeded the 69F recommended temp range.

 

[Bramling Cross]

At thirty-six hours into the fermentation you must've been nearing (if not already past) half gravity. You're good, the bulk of your yeast flavors were locked in during the first 48hrs. You might hit TG a little earlier than expected, but that's a good thing, right?

Edit: Having given it a bit more thought, assuming it's a normal blonde ale gravity and that you pitched right, you're clearly in the back half of the fermentation, cool it down slowly. Don't give your yeast any excuse to punk out early. Frankly, I wouldn't cool it below 70F.

 

[Bramling Cross]

I've been amazed how many ways I can mess up the fermentation temperature and how the beers always turn out fine. I'm working on a keg of ESB right now that was in the mid 70's for practically the whole first day and was happy to find that it tastes great. I don't think I'd do it again on purpose at any point but it was one of the times to be occasionally reminded about "RDWHAHB".

A long-held and long-languishing goal that I've had for my brewery is exploring the Fullers and T. Taylors strains north of 70F. But I keep chickening out because I'm a big chicken.