Attenuation - much more than expected

[ArcLight]

I mashed a 2 row pale ale at 152 for an hour using BIAB with no mashout.
I collected my wort (65F and well mixed) and took a gravity reading of 1.062.
After 5 days my White Labs 002 English Ale yeast had dropped the gravity down to 1.011. Thats an 82% attenuation rate, while the white labs website says attenuation should be 63-70%.

How can the attenuation be so high?
There is no sign of infection.
It's not like I mashed at 144 for 3 hours to make a very fermentable wort.
I pitched the right amount of yeast (having made a starter)

 

[poislb]

Is your thermometer calibrated? What temp did you ferment at?

 

[ArcLight]

Is your thermometer calibrated? What temp did you ferment at?

I have a Thermapen, and it also matched the thermometer on my Brew kettle, and was about the same as the temperature strip on my bucket.
So 65 +/- 1 degree was the correct temperature (one degree isn't going to have much impact on a hydrometer reading).

I fermented at 70F for a day and then it cooled down in my basement to 65F.
Its not like it was 80F for 5 days.

 

[tgmartin000]

Did you perform a mash-out? Most of my beers attenuate more than white labs says they will. I like my beers drier, so I have absolutely no problem with this.

 

[ArcLight]

Did you perform a mash-out? Most of my beers attenuate more than white labs says they will. I like my beers drier, so I have absolutely no problem with this.

No mashout. I'm not unhappy with the results, just surprised.

A few months ago I had a lager using Wyeast 2124 that went from 1.06 to 1.006
Again with an appropriate starter and yeast nutrient.
I'm curious how there is so much variation in attenuation?

 

[ArcLight]

Did you perform a mash-out? Most of my beers attenuate more than white labs says they will. I like my beers drier, so I have absolutely no problem with this.

What about Wyeast, do they also over attenuate sometimes? Like my Pilsner 2124 yeast?

 

[broadbill]

What was your temp at the end of the mash? How long did you mash?

Also, this could be a semantic discussion, but you could say by doing BIAB you automatically do a mash-out...after you pull the bag and start heating the wort to boiling, once that wort hits 170F that could be considered a mash-out. I argue this as the main function of a mash out is to set the sugar profile in the wort by heat-denaturating the enzymes.

What is your time between end of mash and when the wort temp reaches 170F? Since enzymes are still active in that range, you may want to consider that part of your mash time, at least when considering how fermentable of a wort you would like.

I've had similar issues as you have with high attenuation, and have started doing a mash-out to lock the sugar profile. Seems to be working for me (n=1 batch). Very fermentable wort is good for some styles, but not others.

 

[broadbill]

Another thought...today's 2-row is super modified, so it doesn't take long to convert it. We still say we should give a mash an hour to do its thing, but if you really check for converstion its probably done in 20 minutes.

So if you are giving the mash a full hour, then there is extra mash time built in to where you are trying to get the wort over 170F as you do with BIAB...that is a long time for enzymes to be working on the starch and sugar chains, especially when there is high-levels of them as in highly-modified 2-row.