Attenuation Efficientcy Query

[rude]

I have been brewing mainly pommy bitters, a couple of wheats & a stout all up 14 Ag's.

With my setup keep cool mash tun with braid I have worked out on beersmith that I get 80% efficientcy

Recently I did my first APA using 1272 yeast attenuation 72 - 76%

4.5kg ale malt

munich 0.5kg

crystal 200g

OG was 1050 FG after 2 weeks was 1015 - 1014 69-70% attenuation

I used 1.5litre starter with a stir bar, refrigerated then poured off & pitched, it took 24 hours to get a good krausen on it slow start

Fermented at 18c & after primary it dropped to 16 -15c

I then poured an American brown on the cake both were no chilled OG was 1050 only got 69% eff ? was after1057

Ale malt 5kg

crystal400g

wheat500g

It took off really early krausen went through the lid racked off after 3 days same as the apa & it was 1012 1011 75% attenation

I recon its done but will leave it for a week, temp was high though at 20 -22c initally but is now at 18c

so my questions are do bigger grain bills effect youre efficientcy & does temp effect youre attenuation

 

[levin_ae92]

How big is your mash tun, and what was your liquor to grain ratio on each of these occasions? Ferment temp shouldnt have an effect on attenuation, but mash temp will.

 

[MHB]

Well there are a couple of things that come to mind

The beer (American Brown) on the yeast cake has shown 75% attenuation, about what you would expect from the yeast, the same yeast underperformed in the first brew indicating that either.

1/ Your initial pitch wasn't up to snuff, and the population breed up giving better results on the second beer.

2/ The first wort (APA) wasn't as attenuative as you expected (likely mashed a bit too hot).

Checking your mash temps and having a good hard look at your yeast propagation methods would be the first steps toward a solution.

Hope this is of some help

MHB

 

[Screwtop]

so my questions are do bigger grain bills effect youre efficientcy

YES!

Screwy

 

[chappo1970]

YES!

Screwy

:lol:
:lol:
Isn't it past your bedtime?

 

[rude]

Thanks for the replys my Apa was 5.2 kg of grain, mashed in with 15 litres strike with 73c got 66-65c.

Mashed out with 10litres at 93c got 75c then sparged with18litres at 83c got 76c total of 34litres in the kettle

Mash tun is KeepCool round esky

American Brown 6.1kg of grain,mashed in with 18litres at 75c got 68-69 added a litre & stirred got 66c

Mashed out with 10 litres at 95 got 76c then spargedwith 15litres at 85c got 77-78c total of 34litres in the kettle

With the smack pack I pitched into a starter of 1.5litres & used a stirr bar used this on the APA

MHB I was'nt happy with the way the yeast took so long to start on the APA so you are probably right.

Thats why it under attenuated cheers all

Still not sure about my efficientcy will have to check the mash tun I spose

 

[Screwtop]

:lol:
:lol:
Isn't it past your bedtime?

Thought one old lady was enough :angry:

Screwy

 

[rude]

So a bigger grain bill effects efficiency thanks Screwy

Will adjust eff for next bigger beer

 

[The King of Spain]

I mash using a similar esky and cannot mash >6kg at 3:1. I resort to using some DME for double bocks etc

 

[rude]

No worries KOS

Just trying to think here I just did 6.1kg @ 3 to 1 with 10 litre mash out esky was full to the brim

I even added a litre of cold to hit target, I know bad strike temp

sorry not sure what you mean?

 

[rude]

this is the one you use KOS

A bit of dex to get there OK

 

[goomboogo]

Rude, I've got the same mash tun with a 9" false bottom and it's big enough to do 6kg @ 3:1. I normally go around the 2.7/2.8 litres/kilo and do a mash-out and there is plenty of room for a 6kg grain bill. Going up to 3:1 would still allow enough space for a mash-out. As you already know. All I can think is that KOS has a smaller Keep Cool. Mine is labelled as 36 Litres.

 

[Fourstar]

Recently I did my first APA using 1272 yeast attenuation 72 - 76%
...
OG was 1050 FG after 2 weeks was 1015 - 1014 69-70% attenuation

I then poured an American brown on the cake both were no chilled OG was 1050 only got 69% eff ? was after1057
It took off really early krausen went through the lid racked off after 3 days same as the apa & it was 1012 1011 75% attenation

Well actually they where both within the attenuation range. the first was actually 72% app attenuation while the second was 78% (slightly higher)

Atleast this was my understanding of how to work it out. App Attenaution % = (OG-FG)/OG * 100

MHB I was'nt happy with the way the yeast took so long to start on the APA so you are probably right.
Thats why it under attenuated cheers all

I would agree with what MHB has noted, either under pitching or a less attenuative wort.

With this yeast (which is pretty much my house yeast) i usually end up with 72-74% attenuation with mash temps between 64-67deg.

Majority of my beers are re-pitches from krausen with the exception of the first (up to 3 repitches) and built up from a slant following the method ThirstyBoy uses to get to smack pack cell counts (or there abouts) and then built to my expected pitch rate.

Cheers.