Underattenuation in London Ale III (Wyeast 1318)?

[luckybeagle]

I brewed an Oatmeal Stout with an OG of 1.050 on Monday, mashing at 154F for 60 minutes followed by a 170F mashout. I pitched a 1.3L starter of Wyeast 1318 into well aerated wort and put the carboy into a 66F fermentation chamber. The yeast was fresh--just a week old from Wyeast according to the package's date.

Yesterday I took a hydrometer reading since the airlock stopped bubbling. It came in at 1.019. Tasted fine, albeit young. I then bumped the temperature up to 68F to encourage it to finish. Today, my gravity hasn't budged, though it does taste better, so I tried to rouse the yeast with my wine thief a little. I guess we'll see what this does.

50 - 19 = 31 gravity points chewed through. 31/50 = 62% apparent attenuation. Seems crazy low, even for a hotter mash. I primarily brew Belgians and routinely achieve 80+% attenuation on those styles with step mashes and low temps, so maybe this is par for the course for this yeast and mash temp? Just seems incredibly low--I was expecting a FG of 1.012-1.014 tops. Any thoughts on my process or what might've happened?

FWIW: I'm brewing on a 15 gallon, 3 vessel eHerms system utilizing a recirculating mash and PID temperature control via Auber Cube 2E and 2x5500w elements in my HLT and BK.

Thanks

 

[Andre3000]

What was your grain bill? I've had lower attenuation with my stouts too due to all the roasted / crystal malts those grain bills tend to have.

 

[luckybeagle]

What was your grain bill? I've had lower attenuation with my stouts too due to all the roasted / crystal malts those grain bills tend to have.

Here's a screenshot from my Brewersfriend recipe (ignore the cost part--it was definitely more than that!). Also, instead of Crystal 45, I used Crystal 40:

 

[VikeMan]

I put your recipe and parameters into BrewCipher. It predicts an FG of 1.018. You might already be done, or very nearly. One thing to remember...most brewing software doesn't care about the makeup of the grist when predicting attenuation, which is silly.

 

[day_trippr]

I've only used a couple of recipe builders but they both had a notion of relative fermentability of ingredients, as well as strain-specific yeast attenuation ranges...

Cheers!

 

[VikeMan]

I've only used a couple of recipe builders but they both had a notion of relative fermentability of ingredients, as well as strain-specific yeast attenuation ranges...

Okay, there are bacically four major knobs that influence attenuation:
- Grain Bill
- Mash Temp
- Mash Length
- Yeast Strain

BrewCipher is the only tool I know of that considers grain bill. Before BrewCipher, there were none, and that's a big reason why I developed it. If you know of another one that gives a different Attenuation % prediction based on Grain Bill, please tell me about it. The easy test is take any recipe you have, switch out your base malt for, say, Roasted Barley, and see if the predicted attenuation percentage changes.

Over the years, people have occasionally told me that the software they use does this. In every case, it didn't. But if there is one, I'd like to know about it!

 

[day_trippr]

Beersmith

 

[VikeMan]

Beersmith

Did you verify that?

ETA: I just downloaded and tested. Beersmith does not change attenuation percentage based on grain.

If you check this, be sure to adjust both OGs to be the same through "Adj Gravity" so both examples start with exactly the same gravity (beyond 3 decimal places), so that the (rounded) OG and FG you use to compute attenuation aren't subject to different rounding errors.

 

[luckybeagle]

Good to know! And I will be mindful of that--come to think of it, I've always been +/- a few gravity points on FG, even when I hit all other numbers on the dot. This could also explain the attenuation differences between brewing, say, a dubbel (more dark malts and more complex grain bill) than a tripel, when using the same yeast slurry/cake.

Since I know I got a healthy pitch, had good control over the mash schedule and fermentation temperature, I will assume it's done if gravity hasn't changed when I check it later today.

I was a day off when I mentioned brewday in my first post--I actually brewed it Sunday (not Monday). So today makes for day 6. It's been reading 1.019 since day 4.

On that note, given the forgiving style of the beer and very low ABV (4%), would you advise crashing this now and kegging it in a couple days? Most of the beers I've been brewing have been 7-8+% ABV and I usually give them 2 weeks or longer in the carboy followed by a cold crash and "lagering" (in the keg in the keezer) before tapping them around week 3-4 from brewday. They're drinkable at that point, but most get better around week 6-8 with the exception of a tripel that took until week 12 to hit its stride.

Since this is literally half-strength and a dark beer where clarity is less of a concern, do you see any reason I can't do a "grain-to-glass in 10 days" on this one? I do that with my 4.5% ABV hefeweizen, though Wyeast 3068 seems to produce a very tasty beer very early, but have never tried this fast of a turn on any other beers or with this yeast.

Reason for the rush: I'm sick of the other beers I've had on tap and an oatmeal stout seems like the perfect compliment to our current spate of rainy weather. Thoughts?

 

[VikeMan]

On that note, given the forgiving style of the beer and very low ABV (4%), would you advise crashing this now and kegging it in a couple days?

If you're happy with the taste, no off flavors, etc., I don't see why not.

Since this is literally half-strength and a dark beer where clarity is less of a concern, do you see any reason I can't do a "grain-to-glass in 10 days" on this one?

You'll have to fast force carb it, but if you're comfortable with that process, go for it. Personally, I tend to not rush any beers, but it's entirely up to you. It doesn't sound like you're going to hurt anything in this case (assuming it's tasting good now).

 

[smata67]

I would also be concerned with 1.019 after 5 days given the low OG. The yeast is highly flocculant, so it is mostly done. All I can contribute is that for highly flocculant yeasts you want large populations and ideal conditions up front. You say the yeast had a fresh date and you made a 1.3L starter. But did you take a hydro of the starter prior to pitching? I have been doing this lately and I was shocked once to see that a re-pitch that I was sure was healthy and had made a sizeable starter for had barely fermented out. These things happen, so best to take measurements when you can and a starter is hard to tell if it has fermented out on the stir plate. I'm actually using a refractometer, but the point is the same. Anyway, stir a few times and wait it out for 3 weeks, you will probably drop a couple of more points. And even finishing at 1.019 will result in a fine beer.

 

[thehaze]

It's done: 30% Crystal and Roasted malt, 10% Flaked oats which have a very low enzimatic power and Dark Munich - same -, I think it's fine your FG got under 1.020. LAIII can get up to around 75-76% apparent attenuation, but not with 30% Crystal+Roasted.

 

[day_trippr]

[...]ETA: I just downloaded and tested. Beersmith does not change attenuation percentage based on grain.
If you check this, be sure to adjust both OGs to be the same through "Adj Gravity" so both examples start with exactly the same gravity (beyond 3 decimal places), so that the (rounded) OG and FG you use to compute attenuation aren't subject to different rounding errors.

Hmmm...Vexing, but it appears you are correct. Interestingly, if I set a particular grain to "not fermentable" it clearly affects the %attenuation, but otherwise it doesn't appear that BS understands %dextrin vs %fermentable ratios wrt any particular grain. Base malts or Black Patent, it doesn't matter.

Thanks for the heads up

Cheers!

 

[VikeMan]

Hmmm...Vexing, but it appears you are correct. Interestingly, if I set a particular grain to "not fermentable" it clearly affects the %attenuation, but otherwise it doesn't appear that BS understands %dextrin vs %fermentable ratios wrt any particular grain. Base malts or Black Patent, it doesn't matter.

I'd estimate that (on a different forum) I answer at least one "Help, my stout fermentation is stuck" type post a month. It's good that there's a "non fermentable" option, but there's a whole lot of "semi-fermentable" left hanging.