WLP002 Attenuation

[bierhund]

So I've brewed two variations on an English Brown ale using WLP002 and both times I've gotten attenuations 80% - 83%. White labs gives a range of 62% - 70% attenuation for this year. BeerSmith estimates 66.5%. Basic details of the brews are as follows:

Estimated O.G. = 1.054
Estimated F.G. = 1.017
Measured O.G. = 1.054
Measured F.G. = 1.009.
Mashed between 150 - 154 degrees F for 60 minutes
Fly sparge water temp = 168 degrees F
Yeast starter of 0.75 L
Fermented at 66 degrees F for 7 days.

I'm OK with the higher attenuation as the beers have been delicious but it makes it troublesome when planning a recipe. Has anyone else experienced this with WLP002? Or know what I'm doing to cause this higher attenuation?

 

[j1n]

whats the grain bill look like?

 

[bierhund]

I don't have the grain bill in front of me but I believe it was like 9 lbs 2-row malt, 1 lb crystal 20, 8 oz chocolate malt. Might have been something else but I don't think so. I'd have to check.

 

[chisena]

So many variables can contribute to your scenario. Great input can be found here:

http://homebrew.stackexchange.com/questions/2862/what-factors-can-lead-to-a-higher-attenuation

 

[bierhund]

Very helpful, but many of those factors figure into under attenuation. According to some of the reviews on white labs website, this is not unheard of. My only thought right now is that the sparge water isn't hot enough to mash out and therefore the mash actually is continuing during lautering.

But then again if this was the case, would I have hit my estimated O.G.?

 

[dmtaylor]

This seems odd to me. First thing I would do is calibrate your mash thermometer and your hydrometer. If using a refractometer, ensure you are using the associated correction tables for alcohol for the final gravity reading. In both cases for refractometer and hydrometer, ensure either your wort is at about 60-70 F, or that you have applied the appropriate temperature correction factors.

 

[bierhund]

We had concerns over our old thermometer so just recently bought a thermopen (actually their economy version). I always adjust the gravity reading for temperature. I'll admit I haven't checked the calibration on my hydrometer in a long time. It just throws me off that I hit the estimated O.G.

 

[dmtaylor]

FWIW, my hydrometer reads high by 0.003. Yours might read low by a similar amount. You never know until you check.

 

[jeremy0209]

+1 on calibrating the mash thermometer. I used to get 63-66% attenuation from 002, then I found out that my thermometer was off and I was actually mashing 5 degrees higher than I thought. Now, I'm getting 68-70% from 002. It's possible that you're mashing way lower than you think you are, and that's why you're getting attenuation in the 80s. In my experience, predicted OG is not affected by mash temp or time (as long as conversion has taken place), but FG is.

 

[dmtaylor]

+1 on calibrating the mash thermometer. I used to get 63-66% attenuation from 002, then I found out that my thermometer was off and I was actually mashing 5 degrees higher than I thought. Now, I'm getting 68-70% from 002. It's possible that you're mashing way lower than you think you are, and that's why you're getting attenuation in the 80s. In my experience, predicted OG is not affected by mash temp or time (as long as conversion has taken place), but FG is.

Bingo!! Give this man a prize.

 

[bierhund]

Makes sense. The amount of sugar stays the same, but how fermentable it is will change.