Author Topic: Oops - Skipped my diacetyl rest. Now what?  (Read 1774 times)

Offline bspisak

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Oops - Skipped my diacetyl rest. Now what?
« on: February 24, 2010, 05:15:39 PM »

I made a Kolsch with 2565 with an 8 day primary fermentation at 60F, then racked to a secondary for another 7 days at 60F then took it to 45F to get the yeast to floc. The next step is to slowly drop it to 32F. This schedule was recommended by another brewer more experienced with lagers than I.

Anyway, I somehow dumped my first hydro sample when I racked to secondary and didn't sample it again until now (at 45F.) The problem is, I can taste diacetyl. It's not strong, but definitely there and if it remains at this level, it will not be to my liking. I'm certainly more sensitive than some to diacetyl, so again, the levels aren't high, but detectable and I'd rather have them cleaned up a bit.

So, my question is what to do?  Is it too late to do a diacetyl rest? I brought the beer back up to 65F last night and the yeast were rousted a bit from me moving the carboy. I didn't want to roust too much because I've been told 2565 is a b**** to floc, and that was the whole point of the crash from 60F to 45F. Should I add some yeast nutrient to get them active again?  Or should I have just left it alone?

From what I understand about lager fermentations, the yeast stay active even at lager temps, so should I just drop it slowly to 32F and wait it out?  Will it clean up?  If so, what's the point of a diacetyl rest?  What level of diacetyl do you have to be at before you have to worry about it not cleaning up during lagering?

Brian

Offline BrewArk

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #1 on: February 24, 2010, 08:23:49 PM »
I don't have enough Kolsch experience to really say, but I think I agree w/your approach of slowly dropping to 32° and waiting longer for it.
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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #2 on: February 25, 2010, 08:45:15 AM »
Let the beer warm up and see what happens. If the diacetyl is not gone in a few days, rehydrate some dry yeast and add it to the beer.

Don’t cool down the beer. Even if you do it slowly the yeast may go dormant.

Kai

Offline bspisak

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #3 on: February 25, 2010, 10:01:09 AM »
Don’t cool down the beer. Even if you do it slowly the yeast may go dormant.

Thanks Kai.  That's one of the things I don't understand about lagers. I thought that dropping the temperature slowly was so the yeast weren't shocked.  That implies that some of them are still active during the lagering period.  Is that dependent on the yeast strain? Do some strains finish earlier than others? If they are active, what are they doing during this phase of the ferm cycle?  Same things as ale yeasts during the conditioning phase of ferm?

Brian

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #4 on: February 25, 2010, 10:30:31 AM »
I've had pretty good luck removing diacetyl by krausening....adding a qt. or so of actively fermenting wort.  Kinda like what Kai suggested, only already in action.
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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #5 on: February 25, 2010, 10:58:54 AM »
I thought that dropping the temperature slowly was so the yeast weren't shocked.

Yes, that is still true but my experience has been that they are more easily stalled than you think. Keeping the beer warm is a more reliable approach to fix your problem.

Kraeusening is another option, but it requires you to have some wort available. I’d probably do that if it was my beer, since I don’t want to buy dry yeast. In some cases kraeusening can also lead to increased diacetyl levels, at least temporary.

Quote
Is that dependent on the yeast strain? Do some strains finish earlier than others? If they are active, what are they doing during this phase of the ferm cycle?  Same things as ale yeasts during the conditioning phase of ferm?

It is very likely that there are differences between yeast strains. If they are alive but don’t do anything they likely entered the stationary phase where their main objective is to stay alive until the nutrient situation improves. I.e. new sugar, nitrogen and possibly other nutrients like oxygen. Things also happen at a much slower rate at lower temperatures.

Kai

Offline bspisak

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #6 on: February 25, 2010, 01:32:08 PM »

I understand Krausening in the context of making the same beer back-to-back and using one to start the other. I don't have that luxury (I'm not brewing another Kolsch soon - I already have 3!) but I could create a small starter to pitch. I don't think I'd want to use a different yeast strain though. I'm hoping I can get what I have to go active again. I suppose I could harvest some from the current yeast cake (if I can get to it in my carboy) and make a starter from that.  Hmmm...

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #7 on: February 25, 2010, 02:03:38 PM »
I understand Krausening in the context of making the same beer back-to-back and using one to start the other. I don't have that luxury (I'm not brewing another Kolsch soon - I already have 3!) but I could create a small starter to pitch. I don't think I'd want to use a different yeast strain though. I'm hoping I can get what I have to go active again. I suppose I could harvest some from the current yeast cake (if I can get to it in my carboy) and make a starter from that.  Hmmm...

Yes, making a starter to Kraeusen the beer is the idea for us home brewer. That's what I do. To get yeast samples from your carboy use a sanitized raking cake:

- close end with thumb
- push to bottom of beer
- release thumb to suck in beer and yeast
- close with thumb to transfer to starter vessel

repeat until you think you have enough yeast.

Kai

Offline bspisak

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Re: Oops - Skipped my diacetyl rest. Now what?
« Reply #8 on: February 25, 2010, 03:49:41 PM »

Well, the beer is sitting at 67F now, I'll taste it soon and see if I need to do that.  Thanks for the advice!!