What is attenuation ?

[Empty bottle]

Hi there ive just noticed when i was using the brewers friend abv calculator that the attenuation was 87%. On the yeast label it says between 72-83%. So i was just wondering if this is a good or bad thing as i have never checked this before with any previous brews that i have done as im not a very technical brewer and just go with the flow. The sg was 1047 and its now at 1006 been 8 days. So i was just curious as to what the attenuation means in simple terms. Cheers

 

[LeeH]

How much sugar the yeast can consume in % of the total available (which you have measured in SG)

 

[Empty bottle]

How much sugar the yeast can consume in % of the total available (which you have measured in SG)

Ah ok cheers for replying so basically it means that according to the readings it has consumed 87% of the sugars and so i take it that this is a good thing and you dont want to have a low figure as that would mean less alcohol?

 

[Caramel Ox]

It will impact the mouthfeel of the final beer as well. More attenuation puts it towards dry/thin, less attenuation more full/sweet. Overshooting your expected attenuation is more likely if your beer has some simple, non-malt sugars in.

 

[Sandimas]

Yeast attenuation = (OG - FG) / (OG-1) x 100

So using your example from your brew (1.047 - 1.006) / (1.047 - 1) x 100 = 87%

So you have hit the target for your recipe, but exceeded the attenutation spec of the yeast.....interesting, what yeast was it? I've never got anywhere near 87% in 250 brews, best I've got is 80% with Safale US-05, most mine tend to be in the 70s.

 

[Empty bottle]

Yeast attenuation = (OG - FG) / (OG-1) x 100

So using your example from your brew (1.047 - 1.006) / (1.047 - 1) x 100 = 87%

So you have hit the target for your recipe, but exceeded the attenutation spec of the yeast.....interesting, what yeast was it? I've never got anywhere near 87% in 250 brews, best I've got is 80% with Safale US-05, most mine tend to be in the 70s.

I never had a target to hit. I just brew and drink it. I don't plan recipes or take notes etc. The yeast is from crossmyloof and its just their cheap ale yeast. £9 for 10 packets. cheers

 

[Stu's Brews]

The level of attenuation specified for any given yeast typically assumes a mash temperature of 67.5degC (e.g. for Wyeast that would be the middle of the specified range for one of their yeasts).

If you decrease mash temperature you will start to get higher levels of attenuation as you are creating a wort with a higher proportion of sugars that are fermentable. The opposite is true for higher mash temperatures.

I achieve >80% quite regularly if I mash at 65degC or lower.

The above all assumes you have healthy yeast, well oxygenated wort and good fermentation temperature control. If any of those are off the mark then attenuation may drop.

 

[Sadfield]

Other variables to add to @Stu's Brews post.

Mash thickness. β-amylase activity decreases in thinner mashes at higher mash temperatures.

Wort quality. Satisfactory levels of Nitrogen and Zinc are important to yeast performance.

High attention makes beers more drinkable. YMMV.

 

[LeeH]

Other variables to add to @Stu's Brews post.

Mash thickness. β-amylase activity decreases in thinner mashes at higher mash temperatures.

Wort quality. Satisfactory levels of Nitrogen and Zinc are important to yeast performance.

High attention makes beers more drinkable. YMMV.

OP asked in simple terms. :-)

 

[Sadfield]

OP asked in simple terms. :-)

It wasn't a reply to the OP. Their question was already answered.

 

[Twopan]

I brew Belgian-style beers and use the Mangrove Jack Belgian Ale yeast or Tripel yeast. 90% attenuation with those is common.

 

[dmtaylor]

You can think of attenuation as the ability to ferment sugars, or as the ability to produce alcohol. If you think of it that way, a yeast with for example 70% attenuation will give you less alcohol than a similar yeast with 80% attenuation.

The higher the number, also will give you a thinner bodied beer at the end, in theory, since alcohol is thinner and more "watery" than sugar.

I use attenuation ratings as a tool to select the right yeast and/or mash profile when designing the recipe.

 

[Foggie]

I never had a target to hit. I just brew and drink it. I don't plan recipes or take notes etc. The yeast is from crossmyloof and its just their cheap ale yeast. £9 for 10 packets. cheers

Is that a new supplier in Glasgow Southside?

 

[Empty bottle]

Is that a new supplier in Glasgow Southside?

I think they have been on the go for a while. They don't have a shop that you can just turn up and buy stuff as its all done online. I think they do it from home on Dumbarton road, Partick. You can arrange with them to go and pick up large sacks of grain like 25kg sacks. They provide a great service at good prices, just type in on google crossmyloof brew and it will take you to their site. I buy my yeast and hops from them and never had a problem as i say they provide a good service. Cheers

 

[Foggie]

Thanks for the info, I'll have a look.

I lived in Glasgow for about 25yrs before the move down. No one mentioned them and I'd never seen anything in the Crossmyloof area. Guys used to visit the Homebrew shop on Dumberton Rd, but then started to use the recipe maker from The Malt Miller.

Anyway all good.

 

[Empty bottle]

The Homebrew shop on Dumbarton road is still open, well it was a year ago as i was in buying some hops while i was up in Partick for a few swally's. I think they are the uk distributor for the Coopers kits so they must do lots of online sales as wee shops like that are fast becoming things of the past sadly.

 

[hoppyscotty]

How much sugar the yeast can consume in % of the total available (which you have measured in SG)

But specific gravity is only a measure of total sugars in solution and doesn't tell you anything about fermentable and non fermentable sugars. There must be a basic assumption around the proportion of fermentable vs non-fermentable in the abc calc? how is that taken into account?

 

[crescent city Mike]

Here's a little article which brings out some basic facts on attenuation. Worth a read.
https://crescentcitybrewtalk.com/attenuation-2/

 

[Python15]

Here's a little article which brings out some basic facts on attenuation. Worth a read.
https://crescentcitybrewtalk.com/attenuation-2/

Just read your article their and it saved me from asking a silly question regarding non-fermentable sugars leaving you with a high FG, thanks!