Stouts and Attenuation

[JeffoC6]

I've only brewed 3 stouts thusfar, but have noticed a similar trend when checking FG. My stouts finish higher (sometimes by 5 or so points) than the target FG of a recipe. Why would this be?

All other beers I brew seem to attentuate down where they need to be, but not the 3 stouts I've brewed. I aerate very well (only 1-gallon AG batches so I literally shake the carboy for 2 minutes) and I pitch more than enough yeast (per Mr. Malty).

What would cause my FG to finish high on stouts, yet, finish where it should be on all other beers?

PS- Even a normal gravity stout that I brewed finished high

 

[RmikeVT]

What is your grain bill, Mash Temp, Yeast strain?

 

[BobBailey]

What would cause my FG to finish high on stouts, yet, finish where it should be on all other beers?

Most stout recipes contain ingredients to increase body and are generally mashed at higher temperatures, also to increase body. Less fermentable grains, adjuncts, lower mash temperatures and lower attenuating yeasts are designed to give beers more body. More body = lower attenuation.

Bob

 

[Yooper]

There are a couple of reasons for stouts (and other darker beers) to finish a bit higher. The first is mash temperature- most stouts tend to be mashed at 154+ degrees. I mash one of my stouts at 158, so that it has a fuller body and "thicker" mouthfeel. That also makes the wort less fermentable as it has more long-chained sugars. Secondly, stouts (again, and other darker beers) tend to have more dark crystal malt in them. That means that they also would have more of those less fermentable sugars in the wort. The third thing I can think of is yeast strain choices (but probably not as significant as the first two things I mentioned). Often, I like the character of a less-attenuative yeast strain (like Windsor) for a stout and so I will use that. The last thing is ingredient related as well- sometimes people make "milk stouts" and use lactose in the recipe. Lactose is unfermentable and will cause a higher FG and a sweeter finish.

If you feel that these stouts are too sweet and full bodied, you could try mashing at a cooler temperature, decreasing the darker crystal malts, and using a more attenuative yeast strain. That should have the beer finish up at a lower FG. If you post a typical recipe where the FG is too high, we can help you troubleshoot it.

 

[JeffoC6]

Alright, here's an example. I followed this recipe to a T, dividing my grain bill by 1/5 (5 gallon recipe) and adjusting for brewhouse efficiency of 70%

Malts and Fermentables
Pale 2-Row- 1.50 lb
Caramel/Crystal Malt 60L- 0.30 lb
Roasted Barley- 0.20 lb
Pale Chocolate- 0.15 lb

Hops
Chinook- 0.09 oz @ 60 min. (11.8 AA's. Recipe calls for 24 IBU's).

Misc.
1/5 Whirlfloc tablet @ 15 min.

Yeast
US-04- Per MrMalty, pitch: 0.2 packets (rounded to .5)

(Based on 70% efficiency)
Target OG: 1.055
My OG: 68* @ 1.052 = 1.053 (68% efficiency)
Target FG: 1.015
My FG: 1.021

Strike temp 158
Mash temp 154
Covered and put in pre-warmed oven for 60 min.
After 60 min, took out and took temp. Temp was around 154/153
Heated wort to 170 and cut the heat, covering and let sit for 10 min.
Removed bag after 10 min and squeezed out all remaining wort and brought to boil

Added hops/etc as per above

After 60 min., cooled down to 70 degrees, strained, and took OG reading (see above)

Pitched yeast at 4:30 PM

Added a few drops of Fermcap S.

Put into fermentation chamber. Ferment at 66 degrees for 21 days.

 

[kwingert]

154*F is about right for a stout unless your making a dry stout. Calibrate your thermometers. Make sure they are right. Like it was mentioned earlier, lower your mash temp. One thing the remember is you have to adjust for your equipment. A recipe may call for a certain mash temp on a certain set of brewing equipment, you have to make that recipe work on your equipment.

 

[JeffoC6]

154*F is about right for a stout unless your making a dry stout. Calibrate your thermometers. Make sure they are right. Like it was mentioned earlier, lower your mash temp. One thing the remember is you have to adjust for your equipment. A recipe may call for a certain mash temp on a certain set of brewing equipment, you have to make that recipe work on your equipment.

I'm not sure I understand. My thermometers are all accurate and calibrated, so I'm not worried about that (as is my hydrometer).

How on earth do I determine what's right for my equipment? Is it possible I may have to brew this stout 3, 4, maybe 8 times before I find out what I should be mashing at? Sounds a bit in-efficient, no? Isn't there an easier way to hit my numbers?

 

[kwingert]

I'm not sure I understand. My thermometers are all accurate and calibrated, so I'm not worried about that (as is my hydrometer).

How on earth do I determine what's right for my equipment? Is it possible I may have to brew this stout 3, 4, maybe 8 times before I find out what I should be mashing at? Sounds a bit in-efficient, no? Isn't there an easier way to hit my numbers?

Yep, the easiest way to hit your numbers is to use extract. Brewing is knowing your equipment and making recipes work on it. If you give 10 brewers the same recipe you will get 10 different beers. Home brew clubs do this all the time to show how different equipment makes different beer.

And what's wrong with brewing a stout 8 times? Sounds like a problem I'd like to have. Besides, brewing is like anything else, you only get better through repetition. If your looking to brew a consistent stout, which I think many of us try to have one beer that is their go to beer, you have to brew it often.

Finally, the most important thing is how does the beer taste. If your stout comes out at 1.021 instead of 1.015 and you enjoy it then who cares what it finishes at. Don't worry so much about numbers and worry more about flavor. Brewing is part science and art.

I hope this helps.