W-34/70 underpitched, stuck FG?

[Matt_man]

Ended up underpitching W-34/70 due to a few things. 2 one year old packs into 6.5 gal of 1.048 Pilsner. We'll call this a "learning opportunity". Beersmith said I should be around 1.012 but seems to be stuck around 1.016 after a d-rest with a few days in between measurements and some slight agitation. Normally, I would shrug it off but I am concerned that I am going to be creating bottle bombs once I get some primer into the mix. What is everyone's thoughts? Maybe it will just be not as clean as it should be?

 

[Yooper]

A good thing to remember is that the predicted FG is not a rock solid goal- it's just an average attenuation percentage of the yeast strain.

So, say the yeast strain you're using has an average attenuation of 68-75% Beersmith might have gone with 71%, but you got 76%. Or vice versa. So that's more than .004 of a difference right there. We can do a little math and see, but first look up the yeast strain's average attenuation. (I'm a little rushed at the moment, but I can help with this later if you need help).

Plus, many other things go into attenuation- ingredients, mash temperature, mash time, the pH of the mash, etc. So you're not off at all from a good FG for your beer. That's a totally acceptable FG, and I would NOT slosh or agitate and ruin the beer.

 

[kh54s10]

I don't see a problem here. Yeast cannot read a hydrometer. They stop when there is nothing left for them to feed upon. Beersmith is making a calculation based on the expected attenuation, it is not an exact measurement or calculation,

If the gravity was 1.020 or higher I would be worried. Four points is within my margin of error. YMMV.

The website says storage is 36 months. 2 packs that old should be about right.

 

[Silver_Is_Money]

If you mashed at the high end of the temperature spectrum, you generated a noticeably higher degree of unfermentable sugars. Does Beersmith attempt to account for this?

 

[Matt_man]

I guess my concern is that Mr malty is telling me that I'm about about a package short. 2/3 just seems like a bit of a red flag. While four points does seem reasonably negligible, when combined with underpitching, I'm just curious as to what I can expect from this point going forward. Especially since I'm bottling.

 

[Matt_man]

If you mashed at the high end of the temperature spectrum, you generated a noticeably higher degree of unfermentable sugars. Does Beersmith attempt to account for this?

Mashed at 150 and fermented at 53.

 

[Yooper]

I guess my concern is that Mr malty is telling me that I'm about about a package short. 2/3 just seems like a bit of a red flag. While four points does seem reasonably negligible, when combined with underpitching, I'm just curious as to what I can expect from this point going forward. Especially since I'm bottling.

While you may have underpitched, the attenuation doesn't seem to be affected overmuch. I think the average attenuation is 73-77%.

You started at 1.048, and ended at 1.016 which is only about 66%. That's lower than the average, but it could be ingredient related as well.

1.016 is an acceptable FG. You don't risk bottle bombs or anything at all, as long as the gravity is stable. It's fine.

It's really fine.

 

[passedpawn]

FYI:

Saflager W-34/70, Real World attenuation results?

 

[kh54s10]

I guess my concern is that Mr malty is telling me that I'm about about a package short. 2/3 just seems like a bit of a red flag. While four points does seem reasonably negligible, when combined with underpitching, I'm just curious as to what I can expect from this point going forward. Especially since I'm bottling.

I checked MrMalty before I responded and it gave me 2 packs. MrMalty is also considered to be conservative on the high side for pitching.

IMO, your gravity is close and it is stable. I am sure there is no problem for you to proceed.

Underpitching alone, unless extreme, is not usually a cause for a stalled fermentation. The yeast will reproduce to cell counts sufficient to ferment the beer.

 

[Silver_Is_Money]

I had a batch fermented with W-34/70 finish at 1.020 (OG was 1.059). I bottle primed and carbonated it a few months ago and it is doing just fine. Moderate carbonation that has not perceivably changed since week 2. Flavor is still improving.

 

[saltymirv]

I don't think 2 packs is an underpitch, at least according to this calculator: http://www.mrmalty.com/calc/calc.html

I've found that 34/70 doesn't like to ferment larger chain sugars and thus, is very susceptible to higher than expected FG. This is especially noticeable with higher mash temperatures. This might be the reason why a lot of German brewers use the Hockhurz mash schedule.

It sounds to me like the beer is done. If you are still concerned, bring the temp up to 70F or so and give it another couple of days.