Poor Attenuation- Stouts

[HopSong]

I've brewed McQuakers OM Stout from BCS' twice now and have had poor attenuation. Reading the forum, in MANY posts I've read, people seem to get poor attenuation with stouts. Is this a common problem?

The first one had an OG of 1.051 and finished at 1.021. Tastes great.. but, not what I expected for a FG. Some grain substitute/additions.. but, basically the recipe in BCS.

The latest which is still in the primary for a few more days had an OG of 1.055 and is reading 1.023 temp corrected. Slightly different recipe than the first.. a little simpler as far as fermentables but more oatmeal and Black Roasted Barley.

That said.. in both cases I built a good starter.. the first with WLP-002 and this latest with WLP-001. Temps were held between 67 and 68*F the whole time and I am now letting it finish at room temp which seems to be holding at about 71-72* throughout the day/night. The fermentation.. bubbling ceased about 5 days ago and I'm letting things 'clean up' a bit before bottling/kegging which I expect to do mid next week. I also paid good attention to pH in the mashing process.

I should also mention, in the current brew, I wanted it to be more like a Velvet Merlin (Firestone) and Matt suggested mashing at ~158*. I expect that may have something to do with the second batch.. but both batches seem like they would finish at a higher gravity then expected.

The taste of the sample is flavorful but a bit 'thin' (?) which will probably improve with some carbonation. So it is turning out to be a very sessionable beer at about 4.4%. I sort of like that... but, I'd like to get my oatmeal stouts to ferment out.. if that is not out of the question for the style

 

[BlueHouseBrewhaus]

It seems 158F is pushing it. I had a batch last year that I mistakenly mashed at 160 (badly calibrated thermometer). It ended up at 1024 and never was quite right.

 

[HopSong]

The first batch mentioned was at 153*.. The only reason I did this one so high was a the recommendation of the brew master at Firestone... else I would have tried a couple degrees lower.

 

[pdxal]

OK, somebody has to ask: are you measuring gravity with a refractometer?
How about posting recipes so we can help you more? If you have a lot of unfermentables in there plus the high mash temperature on the more recent one FG may be higher...

 

[HopSong]

Thanks..

nope.. I don't feel comfortable doing a refractometer conversion at FG.. or close to it OG taken with both Refractometer and Hydrometer; FG hydrometer.

The recipe, as mentioned, is Jamil's McQuaker OM Stout... which I have slightly modified..

68% 2-Row
7% Maris Otter
10 % flaked oats
6% Chocolate malt
6% Crystal 80
10% Black Roasted Barley
Hops are Fuggles
Mash at 158 90 min
Boil 90 min
WLP-001
Whirlfloc; yeast nutrient; touch of NaCl and CaCO3

 

[pdxal]

Sorry, had to ask about the refractometer So many of these poor attenuation/high FG/is my fermentation stuck threads are resolved with this question.
Easy answer to your problem, based on your recipe you have 107% grist.
There are a lot of unfermentables in the recipe, which could give you a higher FG. How long has the McQuaker recipe you listed been fermenting? Time might help it if you aren't too far in. Bubbles in the airlock aren't the best sign of fermentation. WLP is pretty solid with attenuation if given a chance, I'd expect at least 75% with most beers unless a mistake has been made.

 

[Hammy71]

I always seemed to have a problem with my stouts attenuating properly until I concentrated on aerating my wort. Nothing fancy or expensive. Just a cheap wine degasser at my LHBS. For me shaking just wasn't cutting it. The darker, the longer I aerate. No high FGs or stalled fermentations in probably 5 years (knock on wood).

 

[HopSong]

Thanks.. I did EDIT my grist.. It's now 100%

pdxal.. I made one glaring error in my grist.. 2-Row should have bee 61.8% The rest were generally rounded up the the next whole number.. Now, they are to the 10th :rockin:

Today is only day 12 in the fermenter and I'll typically leave it in place for another 8-10 days. It is still bubbling.. maybe once every 1.5 minutes.. which could simply be outgassing of CO2.. I'm sure there is a bit of cleanup going on.. and I may gain 1-2 points.. getting me down to 1.020.. We'll see.

Hammy71. I think I have that well covered.. I bubble pure O2 for 60-90 seconds.. so the yeast should be pretty happy with that.

Again, I've added yeast nutrient as well. Also, using tap water that has good minerals, etc for dark beers. Should have had PLENTY of yeast.. especially for a beer that started out at 1.055... maybe too much

I'd like to soak a little oak in some bourbon and toss it in the mix for an added flavor complexity.. I think that's what Firestone does.. I'm not sure if they do that with Velvet Merlin or only with Velvet Merkin. Do that for the remaining 10 days and then transfer to the keg and bottle a few 22's.

 

[pdxal]

Aw heck, only 12 days in is plenty early. Give it lots of time.
You've got pitch rate, oxygenation, fermentation temperature covered. Mash temperature and water chemistry are the other factors to look at. If you don't have enough alkalinity in your water to balance out all that acidic C80, chocolate, and roasted barley you'll have an overly acidic wort/beer and impair yeast performance. Chalk is probably not a good way to up your alkalinity, you might look into another method.

 

[HopSong]

I have to start keeping better records.. I'm hazy on this one.. For this brew, I followed what I remember hearing in BeerSmith's interview with Gordon Strong. I adjusted the strike water to 5.4 and mashed in only the 2-row, maris otter and oatmeal... I mashed for 90 minutes and added the dark grains at 10 minutes. What I don't remember if I did/didn't is a pH at about 30 minutes into the mash.

My next big project is to sit down and make sure I have a good process sheet that tells me what I need to have on hand, what I need to do.. step by step.. including volume, gravity and pH measurements at various points in the process.

 

[CyberBob]

HopSong, I know what you mean about attenuation. I just bottled a high gravity winter warmer, partial mash kit. OG was 1.080 and after one week in a primary the gravity was 1.024. I racked it to a secondary fermenter per the instructions and it was still 1.024 the last three times I checked it. Never dropped while in the secondary. I'll know in a month or so but I'm hoping it doesn't turn out too sweet.

 

[pdxal]

-

 

[pdxal]

Hopsong, It might be interesting to try the same recipe with your water cut with 1/2 reverse osmosis or distilled water and see how it turns out.
Good luck!

 

[HopSong]

Might be a good try.. altho, the brewery in town doesn't cut water. I asked both Martin and AJ.. both said the water should be very good for dark beers.

 

[pdxal]

If Martin Brungard and AJ Delange say your water would be fine, I'm not going to say any more about water.

 

[HopSong]

On a further note.. I have a friend who is a brewer at a nearby brewery.. and they do stouts. His comments were.. It is NOT unusual to get that FG.. due the the un-fermentables in the grist.. namely the dark malts. He said I might get lucky and get down to 1.015.. But I know this batch won't get that far down.

I know there have been some experiments I've seen on HBT(?) that say they do ferment.. but, probably at a much lesser degree than base malts.. I didn't mention in my OP that I modified my process using Gordon Strong's method of either steeping the dark grains and adding them to the wort.. or simply adding the dark grains at the end of the mash.. supposedly to minimize the bitter tastes.. similar to coffee that has been in an electric pot warming all day. It was in a BeerSmith podcast.