High attenuation or something else?

[ScotchMist]

So on the 29th I attempted my first BiaB brew. It was a pale ale/EKG SMaSH (based on a thread from here), aiming roughly for a golden/blonde type ale.

Unfortunately, the resulting beer is the colour of **** - **** from a healthy, well hydrated animal, but **** nontheless. It tastes fine, so I'll drink it with my eyes shut, and adjust the next iteration of it to make it look less like ****.


The thing that puzzles me about this beer is this - the FG (1005 - OG 1044) seems really low. The specs for the 'five' yeast on the CMY website give attenuation of around 78% - the apparent attenuation here is 88%!

Now, to my mind there are 3 potential reasons for this;

1) The yeast overperformed.
2) I was over-enthusiastic with finings, maybe?
3) Someone has replaced my beer with ****.

Am I thinking along the right lines, or is there something I'm missing?

It doesn't taste particularly strong to me (4%ish feels about right - not the 5% the readings would suggest)... I could be wrong though.





RECIPE

GRAIN
2.5kg of crisp's pale ale, mashed for 60 mins at 66/67 degreesish (hard to be precise on my analogue thermometer) in 17.5L of tap water.

HOPS
- EKG (6.8%AA) - 15g at 60mins
- 15g at 15 mins
- 20g after the temperature had dropped below 80 degrees.

ADDITIONAL
- Pinch of irish moss (around 5g) at 10 mins.
- Pack MJ Vegan finings >24 hours before bottling

YEAST - CMY Five

Pre-boil gravity = 1030
OG1 = 1051

- this was well above what I wanted - I'd underestimated efficiency significantly.
I left 1-2l of wort in the bottom of the mash kettle (it had bits in), then added a further 2l of water giving a volume of 12L in the FV.

OG2 = 1044
FG = 1005

Brewed on 29/01/2022
Bottled on 09/02/2022

Added MJ Vegan finings a day before bottling.

 

[Dazzelknight]

Start with your hydrometer, these are often not accurate, they can be out by a few points,, mine is !.. stick it in 20’c of water, see if the reading is. 0.000..

 

[foxbat]

Attenuation figures written on the packet are just a guide. The real attenuation depends on your ingredients and process (particularly the mash temperature). I'll regularly get 80-90% attenuation from a healthy fermentation mashed between 65 and 68 so I don't think you've anything to worry about.

If you'd like it to finish higher next time then the best thing you can do is to raise your mash temperature a few degrees. Over time you'll work out the effect that each increment in the temperature has on FG.

 

[ScotchMist]

Start with your hydrometer, these are often not accurate, they can be out by a few points,, mine is !.. stick it in 20’c of water, see if the reading is. 0.000..

Thanks! It's accurate enough for me to know that this is unusual.

Attenuation figures written on the packet are just a guide. The real attenuation depends on your ingredients and process (particularly the mash temperature). I'll regularly get 80-90% attenuation from a healthy fermentation mashed between 65 and 68 so I don't think you've anything to worry about.

If you'd like it to finish higher next time then the best thing you can do is to raise your mash temperature a few degrees. Over time you'll work out the effect that each increment in the temperature has on FG.

That's really helpful advice! Thanks :)

I'll try varying the temperature in future.

 

[dmtaylor]

Five = repacked US-05, which for me has given an average attenuation of 83%. So starting with 1.044, I would expect FG of about 1.007. If your hydrometer is in fact reading 0.002 too low (check it in plain water) then THIS would certainly explain the apparent oddity.

Plus, since it's a SMASH so you didn't add any less fermentable malts such as crystal or dark roasted malts, that can play a role as well, maximizing fermentability in this batch.

Maybe next time use Four or something less attenuative instead. US-05 is one of the most highly attenuative dried yeasts available.

And/or, yeah, raise your mash temp significantly, and mash for a shorter time, as little as 30-40 minutes would make a noticeable difference.

 

[Agentgonzo]

Start with your hydrometer, these are often not accurate, they can be out by a few points,, mine is !.. stick it in 20’c of water, see if the reading is. 0.000..

Water should read 1.000
A vacuum should read 0.000

 

[ScotchMist]

Water should read 1.000
A vacuum should read 0.000

Only if you're assuming that the hydrometer was subject to earth-standard gravity whilst in the vacuum, right?

 

[ScotchMist]

Five = repacked US-05, which for me has given an average attenuation of 83%. So starting with 1.044, I would expect FG of about 1.007. If your hydrometer is in fact reading 0.002 too low (check it in plain water) then THIS would certainly explain the apparent oddity.

Plus, since it's a SMASH so you didn't add any less fermentable malts such as crystal or dark roasted malts, that can play a role as well, maximizing fermentability in this batch.

Maybe next time use Four or something less attenuative instead. US-05 is one of the most highly attenuative dried yeasts available.

And/or, yeah, raise your mash temp significantly, and mash for a shorter time, as little as 30-40 minutes would make a noticeable difference.

Thanks - good point about it being a SMaSH, this hadn't occurred to me.

The mash temperature differences are really interesting. I think I'll come back to this recipe in a month or so and try varying that... see what difference it makes :)

I've got a packet of m36 for the next guy.