Question about esters.

So I brewed up some Caribou Slobber today, everything went quite well. It was a partial boil extract, and I used my fancy new immersion chiller to get the wort temp down to the cold break very fast (worth every $ I spent on it).

My issue comes after I added my top up water. I misjudged the temp of the water, and it ended up being about 80 degrees. I didn't think much of it, and pitched my yeast (dry yeast, danstar windsor ale) after rehydrating it.

Now in the past, it's always taken a good 12-20 hours to see fermentation, and that usually provided plenty of time for the brew to come down to the 62-64 degrees I keep the brew room at. Tonight, I had an inch thick krausen layer in 2 hours, and 2 hours after that had to yank off the air lock and hook up a blow off. The temp on the beer is still sitting very high at 76-77 degrees, and fermentation is unlike anything I have seen so far. It is going absolutely nuts in that carboy.

So my question is, do I need to give this thing an ice bath and get that temp down 10 degrees to avoid unwanted esters? I'm sure the temp will come down naturally by morning, but will this 12 hours of vigerous high temp fermentation produce noticible esters? Or is 12 hours generally to short a time to have that effect?

Any insight would be very appreciated! Thank you!

temp might not come down til fermentation is complete. fermentation generates heat. i'd try to cool it off, not with an ice bath, but a bath of water that's at your desired temp. you can keep the water cool using ice, or better yet, frozen water bottles.

I'm surprised by how quick you saw fermentation on that, even with elevated temperatures. Normally I'd say it would be fine to just let it come down in temp on its own, but surprised how fast it started.

I think the biggest worry with an ice bath is how the yeast may respond to any rapid temperature changes. Yast can be finicky about that and you wouldn't want some perhaps going dormant due to a sudden temperature drop.

I'm not familiar enough with that yeast to know what kind of esters you may get from a brief time at elevated temperatures, but after some thought I think I'd probably just let it be. You might get a little more estery production, but I think overall it should be fine.

I think that yeast throws off a lot of esters at high temps. Probably get some fusels too.

I would do everything I could to get that temp down below 70. A water bath should do it.

Yeah, was getting really worried, tossed her in a 60 degree water bath. She's already down to 72. I just hope I didn't wait to long.

pyth said:

Yeah, was getting really worried, tossed her in a 60 degree water bath. She's already down to 72. I just hope I didn't wait to long.

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sounds like you're on the right track. next time start off in the water bath and leave it there for active fermentation. most esters and fusel, along with the diacetyl precursor are produced early, during the reproductive phase.

pyth said:

So my question is, do I need to give this thing an ice bath and get that temp down 10 degrees to avoid unwanted esters? I'm sure the temp will come down naturally by morning, but will this 12 hours of vigerous high temp fermentation produce noticible esters? Or is 12 hours generally to short a time to have that effect?

Any insight would be very appreciated! Thank you!

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Don't want to come across as being alarmist, or the Harbinger of doom, but I've read a few posts stating that it's the initial few hours of fermentation where a lot of the off flavours and fusels/esters/acetylaldehyde/diacetyl are spawned.

Is Danstar Windsor Ale yeast what everyone refers to as Notty?? If so, that's supposedly particularly vulnerable to off flavours from even slightly high ferm. temps.

Good that you managed to catch and correct as soon as you did, rather than having a more prolonged high temp fermentation, though.:rockin:

Ogri said:

Is Danstar Windsor Ale yeast what everyone refers to as Notty?? If so, that's supposedly particularly vulnerable to off flavours from even slightly high ferm. temps.

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danstar windsor and danstar nitty are two different strains. but you're right, they can produce some nasty stuff when fermented too warm, as can most (not belgian) yeasts. it's always better to ferment a bit cool to limit all those nasties.

You might get a few interesting flavors you're not expecting. My advice is, once fermentation is complete, give it a few weeks in the fermenter to give the yeast a chance to clean the beer up. Then give it at least four weeks in bottles. You should have a drinkable beer. Just learn your lesson for next time and keep the fermentation temps under control early.

you should actually be pitching a lot lower. Even though fermentation doesn't start for 12 hours doesnt mean that you are free from the high temperature drama. In those 12 hours, at high temperatures, the yeast are creating all sorts of ester precursors. You need to pitch on the lower end (low 60's -63,64) and let it rise to low end fermentation temperature (66-67 ish) for the cleanest profile, or whatever your preferred temperature is (using WLP001 as an example). The damage is done fast, you need to be under control from the start.

Well she's down to a cool 63 degrees now, all I can do is hope for the best. I'll give it a lot of time in the fermentor, and since I have 2 other batches finishing before this one I can leave it to condition for a few months without messing with the pipeline. Hopefully that will give it time to smooth out whatever damage might have been done.

Live and learn I guess, won't make that mistake again.

Thanks for all the good advice everyone!

The big thing, thought, is if you do taste some off esters after a few weeks of bottling or kegging, if you can hold off, let it go for another month and you'll see those esters fade if they were present.

Once high activity has slowed down, I heard that many brewers ramp up the temps in the lower 70's to get the yeast to get back at it and clean up waste to rid the off flavors. High temp at first, not good, towards the very end, good.

My favorite summary of the yeast life cycle: http://www.whitelabs.com/beer/Yeast_Life_Cycle.pdf

Basically, the period where you get the "free pass", in so much as there is one, on temps is during the lag phase, when yeast are acclimating, as well as taking up oxygen and nutrients. Once you can see activity, they are into alcohol and ester producing mode, which means you potentially are getting unintended flavors when you're at elevated temps.

That said, there's no reason to think that this point that your beer won't be quite good. Just have to wait and see what happens.