CML Beòir Yeast Overattenuating

[An Ankoù]

This is the first time I've used Beòir yeast with a stated attenuation of 73-75%. Made a batch of Summer Lightning OG 1050 mashed at 66C and pitched Saturday. Came to rack into secondary this morning and the RG is 1004 giving an apparent attenuation of 92%! I'm aware of the limitations of my hydrometer, in fact water at 20C gives a reading of 1000 at the top of the meniscus rather than the bottom. I wonder if anyone else has had a similar experience with this yeast. Otherwise, it's amazing at dropping our of suspension and forming a dense deposit the bottom of the FV.
I should add that the my recipe uses all M O and hops with no additional sugars and fermentation temperature was about 16-17C throughout.

 

[marshbrewer]

Mmm, that's odd - I've used it quite a bit and have always had fairly consistent attenuation around 75%.

 

[Dads_Ale]

I have used this yeast quite a bit recently and it has always finished about 1013. It does work quick and as you say packs down nice and tight.
My mash would have been about 66c but fermentation temp would have been 19c

 

[An Ankoù]

In an unwonted moment of self-doubt, I've measured the gravity again, and yet again with a different hydrometer. 1004 both times. I've no idea what's going on. Even if my mash temperature was a bit out, it wouldn't attenuate that much, would it?
It's the sort of gravity I would expect if I'd chucked a bucketload of amyloglucosidase in there. But I didn't.

I've got a brew on now and I was going to use some of the yeast cake to ferment it. Again, 66C mash and quite a similar composition to the Summer Lightning: 80% M O, 10% wheat malt, 10% Gambrinus honey malt and a pinch or two of acidulated malt to adjust the pH. Let's see what happens this time round.

 

[Cheshire Cat]

This is the first time I've used Beòir yeast with a stated attenuation of 73-75%. Made a batch of Summer Lightning OG 1050 mashed at 66C and pitched Saturday. Came to rack into secondary this morning and the RG is 1004 giving an apparent attenuation of 92%! I'm aware of the limitations of my hydrometer, in fact water at 20C gives a reading of 1000 at the top of the meniscus rather than the bottom. I wonder if anyone else has had a similar experience with this yeast. Otherwise, it's amazing at dropping our of suspension and forming a dense deposit the bottom of the FV.
I should add that the my recipe uses all M O and hops with no additional sugars and fermentation temperature was about 16-17C throughout.

I've used it 4 times on stouts and the best attenuation I've had was 71% twice. But these were milk stouts so the Lactose may have lowered it.

 

[Pezza24]

I got 88.2% attenuation off it on my batch of bitter I've just bottled. I think you need to catch it early to get the attenuation I want because that was after 7 days for me.

Pitched a lump of the slurry into my Oatmeal stout this morning and it's already blipping away.

 

[Chico1980]

This is the first time I've used Beòir yeast with a stated attenuation of 73-75%. Made a batch of Summer Lightning OG 1050 mashed at 66C and pitched Saturday. Came to rack into secondary this morning and the RG is 1004 giving an apparent attenuation of 92%! I'm aware of the limitations of my hydrometer, in fact water at 20C gives a reading of 1000 at the top of the meniscus rather than the bottom. I wonder if anyone else has had a similar experience with this yeast. Otherwise, it's amazing at dropping our of suspension and forming a dense deposit the bottom of the FV.
I should add that the my recipe uses all M O and hops with no additional sugars and fermentation temperature was about 16-17C throughout.

I’ve used this yeast twice. First time dropped from 1.045 to 1.006, second got stuck on 1.014 eventually got down to 1.012. Two different packets, was expecting the 2nd brew to drop as far until I actually read the attenuation levels. Strange.

 

[The Baron]

Same here when I have used it finishes in 1.013/14 range. Looks like it was the Twilight zone batch you got

 

[Benfleet Brewery]

I’ve used it a few times now but couldn’t comment on attenuation. I just leave my brews for 14 days regardless and don’t measure the FG anymore. I agree it packs down really well though. Here’s a bitter in the FV after 3 days cold crashing. I could have probably poured that last bit of beer out without disturbing the yeast cake.

 

[An Ankoù]

Thanks all. It seems a mixed bag of experiences, even with the same brewer using two different batches. I'll see how the next one goes. I might drop crossmyloof a line to see if they can throw any light on the matter. Apart from that, it seems to be decent yeast.

 

[marshbrewer]

Apparently, it's 'very similar' to Mauribrew draught, so it might be worth checking the Aus forums to see if they have experienced similar attenuation?

 

[NPi]

Weirdly enough I had the same thing with a current brew. All malt wort, and 90% attenuation. Added a percentage point to my ABV as well! I do find CML yeast do attenuate more than they state but not normally this much more?

 

[Pezza24]

Just bottled a stout and that's the second brew with the same yeast. Pitched some slurry into the wort. And I've got 80% off it.