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sudndeth · 02-17-2011, 01:31 PM

If your yeast states 85% attenuation, how much can you really have? 97% seems impossible. I did the calculations according to whitelabs. (attenuation = [(OG-FG)/(OG-1)] x 100. Is this right and is 100% attenuation possible?

I don't think so and I'm rechecking my gravities. OG 1.084 FG 1.000 and .998. Wyeast 1214 and an Allagash Tripel cultured yeast.
Grain:
24lbs Belg Pils
1lbs Belg Bisc
1lbs Belg Aromatic
2lbs Inverted table sugar
2lbs table sugar(both added 10 min end of boil)
Mashed at 148 for about 70min

sudndeth · 02-17-2011, 01:32 PM

my calc was 100% and 102%

**motobrewer** · 02-17-2011, 01:44 PM

apparent attenuation and real attenuation are different things.

http://www.realbeer.com/spencer/attenuation.html

how do you have two final gravities?

***Yooper*** · 02-17-2011, 01:48 PM

I'm not sure how you have different FGs, but table sugar and corn sugar are 100% fermentable, and alcohol has a lower gravity than water so it's possible to have an apparent attenuation that is very high.

For my wines, I routinely get .990 as a FG.

sudndeth · 02-17-2011, 02:47 PM

I brewed a 10g batch and split it pitching two separate yeast in two 5g carboys. I figured the sugars a lot to do with it, but I figured the yeast would reach a certain point and just die off leaving me with a FG of around 1.010 - 1.005. Maybe I'm not understanding this too well.

McGarnigle · 02-17-2011, 03:34 PM

I wouldn't be surprised if those were inaccurate measurements. Yes, it's possible to go below 1.000 for non-beer. But it seems unlikely that you'd get that low.

**motobrewer** · 02-17-2011, 04:05 PM

low mash temp, lots of sugar

***Yooper*** · 02-17-2011, 06:55 PM

Quote:

Originally Posted by sudndeth

I brewed a 10g batch and split it pitching two separate yeast in two 5g carboys. I figured the sugars a lot to do with it, but I figured the yeast would reach a certain point and just die off leaving me with a FG of around 1.010 - 1.005. Maybe I'm not understanding this too well.

Well, the yeast don't die off- they're still alive but just dormant when the fermentable sugars are gone. In most beers, that's usually 1.008-1.016 or so. But in a beer with fermentable simple sugars, you could get lower. A low mash temp also creates a more fermentable wort (more easily fermentable sugars vs. long chained sugars). With a recipe with 4 pounds of simple sugars, and mashed at 148, it would be possible to get a low FG and a super dry beer.

remilard · 02-17-2011, 07:48 PM

The maximum possible real attenuation is 100%. The maximum possible apparent attenuation is higher.

Wort fermentability is a much larger factor than yeast selection. The range of attenuation quoted for yeast is apparently assuming a wort typical for the style the yeast might be used for. If all yeast were tested on a standard wort you would find that they do not very much in terms of terminal gravity.