Fermentation: Range Fermented vs. Absolute FG

[Andrew82]

I am several days into brewing a Munich Helles. I sloppily brewed it and as a result overshot my OG by a fair bit (mashed too high, then boiled off too much water that I never replaced). I had some issues with temp early on, so the yeast seem to have fermented quickly. The stats are below:

Batch Size: 5.25 gal

Fermentables:

8 lbs 9.7 oz Pilsner 2-Row
12.7 oz Munich Malt
1.4 oz Melanoiden Malt

Hops: 1.39 oz Saaz (3.1%) 60 mins

Yeast: 1 pkg Saflager (W-34/70)

OG: 1.055 (target: 1.046)
SG (3/25): 1.018 (target: 1.008)

Here's my dilemma: I've fermented exactly the number of gravity points I estimated I would from the recipe, but just overshot the target OG & FG by .01 due to, I assume, the considerably lower volume of water I sent to the fermenter. Does the fact that I've bridged the estimated range between OG & FG indicate that's all I'll get from the yeast, or should I take steps to try to restart them?

 

[McKnuckle]

How high of a mash temp in this case was too high? That's going to be the key here. Also, the number of days you've been waiting. Lager yeast is slower than ale yeast.

W-34/70 is a reliable 80% attenuator, and you're at 67% at the moment. If you pushed the mash temp into the 158º+ range, you are probably looking at attenuation in the low 70% range, but I'd think it's not quite done yet. If you were at 160º or higher though, all bets are off and it could be done.

The other thing is that lager yeast is capable of fermenting longer chain sugars (dextrins etc.) over an extended period of time, that being the lager phase itself (cold storage on at least some of the yeast). So if you are following a more or less standard lagering process, you should be very patient and allow that slower fermentation to happen.

If you are trying to get this into bottles soon, vs. a keg, then I would raise ambient temp by a couple of degrees per day into the high 60s, and leave it for another 5-7 days. You might get another point or two out of it.

Bottom line, though, you won't restart the fermentation if you have a dextrin-heavy beer due to very high mash temps.

 

[RPh_Guy]

lager yeast is capable of fermenting longer chain sugars (dextrins etc.) over a longer period of time, that being the lager phase itself

That's not correct. Only diastaticus variants of Saccharomyces ferment dextrins.

you won't restart the fermentation if you have a dextrin-heavy beer due to very high mash temps.

I agree.

 

[Andrew82]

How high of a mash temp in this case was too high? That's going to be the key here. Also, the number of days you've been waiting. Lager yeast is slower than ale yeast.

W-34/70 is a reliable 80% attenuator, and you're at 67% at the moment. If you pushed the mash temp into the 158º+ range, you are probably looking at attenuation in the low 70% range, but I'd think it's not quite done yet. If you were at 160º or higher though, all bets are off and it could be done.

The other thing is that lager yeast is capable of fermenting longer chain sugars (dextrins etc.) over an extended period of time, that being the lager phase itself (cold storage on at least some of the yeast). So if you are following a more or less standard lagering process, you should be very patient and allow that slower fermentation to happen.

If you are trying to get this into bottles soon, vs. a keg, then I would raise ambient temp by a couple of degrees per day into the high 60s, and leave it for another 5-7 days. You might get another point or two out of it.

Bottom line, though, you won't restart the fermentation if you have a dextrin-heavy beer due to very high mash temps.

This is very helpful! I had the water at ~165 when the water hit and it got down to about 156 when the 60 minute mash was complete. After what you said about mash temp I went and reread Palmer's chapter on mashing and can totally see what you mean. I definitely mashed too high and got a less fermentable wort as a result.

If the wort stays at its current SG (it's been at the same level for ~ 3 days), do you think it's worth bottling given that it's a good deal higher than the recommended FG for the style?

 

[RPh_Guy]

do you think it's worth bottling given that it's a good deal higher than the recommended FG for the style?

Yes, all is well.

FG is just a number, and it being out of range for the style certainly doesn't ruin the beer.

 

[McKnuckle]

Consider me corrected about the dextrins. Diastaticus, pastorianus, let's call the whole thing off...

But yeah, 165 dropping to 156 is a high mash, so your yeast is definitely done. It's actually kind of a cool thing to have inadvertently experienced. Now you know that W-34/70 gives about 67% attenuation even at such a high temp. That can be used intentionally if one likes to brew a full bodied, relatively lower ABV beer. I've been experimenting a lot with those lately. Haven't mashed over 160F yet, though.

 

[Andrew82]

Consider me corrected about the dextrins. Diastaticus, pastorianus, let's call the whole thing off...

But yeah, 165 dropping to 156 is a high mash, so your yeast is definitely done. It's actually kind of a cool thing to have inadvertently experienced. Now you know that W-34/70 gives about 67% attenuation even at such a high temp. That can be used intentionally if one likes to brew a full bodied, relatively lower ABV beer. I've been experimenting a lot with those lately. Haven't mashed over 160F yet, though.

I agree--a very good experience to keep in mind for my next mash. It was really a crash course in mashing and the resulting beer with the Saflager strain. I'll make a note about what you've said in my records.

Regarding the beer itself: should I just let it settle a few more days (six days at current SG) in primary then move to bottles for a couple weeks then to cold storage for "lagering"? I'm trying to dial in when to move from primary to bottles.

 

[McKnuckle]

If the gravity hasn't moved in 3 days, then it's stable and I would feel comfortable waiting just a wee bit more, then proceeding with 2 weeks carbonating at room temp, and finally to cold storage. Sounds like a plan!

BTW, I know that people here talk a lot about beer being "sweet" at an FG like 1.018, but I rarely pick that up. I would be hard pressed to guess the FG of most beers I brew if I didn't already know it. It's subtle to me. Perhaps I'm just different and not very sensitive to that particular variable? Maybe you'll be the same.

 

[Andrew82]

If the gravity hasn't moved in 3 days, then it's stable and I would feel comfortable waiting just a wee bit more, then proceeding with 2 weeks carbonating at room temp, and finally to cold storage. Sounds like a plan!

BTW, I know that people here talk a lot about beer being "sweet" at an FG like 1.018, but I rarely pick that up. I would be hard pressed to guess the FG of most beers I brew if I didn't already know it. It's subtle to me. Perhaps I'm just different and not very sensitive to that particular variable? Maybe you'll be the same.

Agreed. Looking forward to trying this one out.

I'll try to remember to circle back to this thread to give some commentary for how it turned out re: the sweetness and the overall product.