(German) lager yeast question

MOD EDIT: Double posted threads merged.

I apologize for the double post. I didn't think my question posted the first time.

First off, my question pertains to a healthy doppelbock I put together after studying others' recipes. I measured 1.092, but I didn't stir it after topping off the fermenter, and it sat for a few minutes. Anyhow, Tastybrew puts it at 1.135 with 26 HBUs.

My question pertains to the yeast; my LHBS has some lager yeast made in Gemany with the name of Vierka. The instructions (same as the ale yeast package?) said to ferment at room temperature for 5-7 days, then age for four weeks at 50-55*. Following what appears to be a standard practice, I could be wrong here, I pitched (.5 ounces) at room temperature, then into my keezer at 55*. After five hours, I was getting bubbles every 2-3 seconds. Seventeen hours later, it is one bubble after another, with about 1.5 inches of foam on top. Do I need to give it a rest when activity subsides (room temp), then lager it in the 30s? I am really winging it with this yeast, I know. I prepped it with some nutrients, then rehydrated it before pitching.

Vierka makes 2 types of yeast, one for Alt/Kolsch/Weissbier (Obergärige Bierhefe) and one for Lagers (Untergärige Bierhefe). Assuming you got the lager yeast, it should be fermented at 6-8dC per there instructions (43-46). Which seems low, but I won't question a German Lager yeast producer. 55dF shouldn't be too bad.

Wait until it's NEAR done fermentation, do a diacytel rest for a couple days (like 60dF), then then lager it at near freezing temps. That's going to need a long lagering period... like 3 months.

I think you're on the right track.
A day or two room temp at the end of primary fermentation is usually called a 'diacetyl rest'.
Dry lager yeasts have only recently become available.
I'd love to hear a review or two.
Picking up a lagerator today.

I apologize, I double posted, didn't think it went up the first time.
Type of yeast- Vierka ( a German brand of lager yeast my LHBS had on hand.)

I rehyrdated .5 ounce of this yeast with 2.5 tsp of yeast nutrient before pitching at room temperature. I then placed the carboy in my keezer set at
55*. After activity subsides, do I need to give it a diacetyl rest, then lager in the 30s for a spell? After five hours, there was bubble every two-three seconds; after seventeen hours, it has been bubbling every second, with a 1.5 inch layer of foam on top and a thick layer of yeast on the bottom.

This beer, my fifth, is a doppelbock I concocted after studying others' recipes. After checking with Tastybrew (after all was said and done), it came out well, so far! My OG gravity reading was off, it sat awhile to cool, because Tastybrew's calculator came up with 1.135!!

Back to the yeast. The instructions said to ferment at room temperature for 5-7 days, then rack to a carboy for four weeks at 50-55*. I used an ale yeast from this same company-Vierka- and it said the same thing. The instructions also said you could then bottle or consume right from the carboy!?

I don't think I've done wrong by this yeast yet, since I have such a healthy fermentation, no sulphur smells, either. I don't know if a diacetyl rest is necessary, and if it is acceptable to lager at lower temps once activity subsides. I know, I'm really winging it with this yeast. I would hate to screw up this doppelbock now! Any help is appreciated!

menschmaschine said:

Vierka makes 2 types of yeast, one for Alt/Kolsch/Weissbier (Obergärige Bierhefe) and one for Lagers (Untergärige Bierhefe). Assuming you got the lager yeast, it should be fermented at 6-8dC per there instructions (43-46). Which seems low, but I won't question a German Lager yeast producer. 55dF shouldn't be too bad.

Wait until it's NEAR done fermentation, do a diacytel rest for a couple days (like 60dF), then then lager it at near freezing temps. That's going to need a long lagering period... like 3 months.

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What am I looking for at near end of fermentation? This is only my fifth brew, first lager. Also, what is the purpose for the diacetyl rest, and is it necessary with all lager yeasts? Please excuse my ignorance.

Pete08 said:

What am I looking for at near end of fermentation? This is only my fifth brew, first lager. Also, what is the purpose for the diacetyl rest, and is it necessary with all lager yeasts? Please excuse my ignorance.

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It's not ignorance! (at least in the bad sense) You can do a search for what diacetyl is and how it gets in your beer, but in short it is an off-flavor that will possibly (to likely) be in your beer since you fermented at the upper end (if not beyond) the optimum range for that yeast. It's generally not necessary when you start and keep your fermentation temps at the lower end of the range. Raising the temp a little near the end of fermentation will "encourage" the yeast to re-absorb the diacetyl, taking it out of your beer. The text book time to do a diacetyl rest is 6 points before terminal gravity, but since this is difficult to gauge in the homebrew setting, it's best to just do it when the krausen is nearly all fallen and/or when bubbling in the airlock is dying down.

Thanks! I see that raising it to 65* or thereabouts is acceptable? Then, lowering to the mid-30s for lagering? If I pulled a sample near the end of the fermentation, would the buttery taste be present?

Pete08 said:

Thanks! I see that raising it to 65* or thereabouts is acceptable? Then, lowering to the mid-30s for lagering? If I pulled a sample near the end of the fermentation, would the buttery taste be present?

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Yeah, that's about right. With your fermentation temps, diacetyl may be present near the end of fermentation, but I would skip that sample and just do the diacetyl rest anyway (I do them whether it needs it or not, just to clean it up). Remember too that diacetyl, esters, etc. are also cleaned up in lagering, just at a very slow rate. There isn't much in brewing that's black and white.

Even though a long conditioning time is required for a Doppelbock, I believe I would still do a 24 hour diacetyl rest. After that, let the beer condition for around 9 months to a year.

menschmaschine said:

It's not ignorance! (at least in the bad sense) You can do a search for what diacetyl is and how it gets in your beer, but in short it is an off-flavor that will possibly (to likely) be in your beer since you fermented at the upper end (if not beyond) the optimum range for that yeast. It's generally not necessary when you start and keep your fermentation temps at the lower end of the range. Raising the temp a little near the end of fermentation will "encourage" the yeast to re-absorb the diacetyl, taking it out of your beer. The text book time to do a diacetyl rest is 6 points before terminal gravity, but since this is difficult to gauge in the homebrew setting, it's best to just do it when the krausen is nearly all fallen and/or when bubbling in the airlock is dying down.

Click to expand...

So, three bubbles in 20 seconds, and less than .5 inch of krausen, though still solid. Time to raise the temp?

Personally I would wait a little bit longer, but remember with lager yeasts and diacetyl rests, it's better to be safe than sorry because the yeast don't really produce off-flavors in warmer temps on the downside of fermentation and if you let it go too far, you'll miss your chance and have to lager a little longer to try and clean up as much diacetyl as you can (if you had it in the first place).

I am in the process of my first real lager. After reading all the opinions of the rest, I did mine when I got about 75% of the way to my expected FG. Does that sound reasonable? Hope so, because it's done.