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agusus 11-11-2011 03:50 PM

Mistake in The Craft of Stone Brewing
 
Hi,
So I purchased the new Stone brewery book. It's great! But there seems to be a mistake in the recipe for their 12th Anniversary Bitter Chocolate Oatmeal Stout.

The beer was 9.2% ABV (stated in the book, and on their website http://www.stonebrew.com/12th/ale/) but the recipe says OG 1.099 to FG 1.022. That would produce a 10.3% beer. That's a pretty big difference, can't be just a rounding error. Their website also says the beer was 23.5 plato, which is about 1.099.

According to BeerSmith with a 1.099 OG you'd need it to ferment down to only 1.030 to get 9.2% ABV. I'm pretty sure the beer did not have that high of an FG - it would have been super sweet.

So does anyone have any idea what might have happened? Does Stone have some magical exemption to the laws of chemistry where their beers get thinner without producing alcohol (add water to the fermenter? haha)?

I think I'm going to shoot for 1.091 to get about 9.2%.

remilard 11-11-2011 04:34 PM

Quote:

Originally Posted by agusus (Post 3477548)
Hi,
So I purchased the new Stone brewery book. It's great! But there seems to be a mistake in the recipe for their 12th Anniversary Bitter Chocolate Oatmeal Stout.

The beer was 9.2% ABV (stated in the book, and on their website http://www.stonebrew.com/12th/ale/) but the recipe says OG 1.099 to FG 1.022. That would produce a 10.3% beer. That's a pretty big difference, can't be just a rounding error. Their website also says the beer was 23.5 plato, which is about 1.099.

According to BeerSmith with a 1.099 OG you'd need it to ferment down to only 1.030 to get 9.2% ABV. I'm pretty sure the beer did not have that high of an FG - it would have been super sweet.

So does anyone have any idea what might have happened? Does Stone have some magical exemption to the laws of chemistry where their beers get thinner without producing alcohol (add water to the fermenter? haha)?

I think I'm going to shoot for 1.091 to get about 9.2%.

Alcohol production is not a function of the difference in beginning extract and apparent residual extract. Beersmith's estimate is wrong, Stone is right.

xjmox14x 11-11-2011 04:41 PM

Quote:

Originally Posted by remilard (Post 3477681)
Alcohol production is not a function of the difference in beginning extract and apparent residual extract. Beersmith's estimate is wrong, Stone is right.

Would you care to elaborate on this statement?

EDIT: upon further research, realbeer has the following equation: real extract = 0.1808 * original extract + 0.8192 * apparent extract

Being that there is an equation that can obtain real extract, does Beersmith not have a setting that allows for this? Do the typical equations used by homebrewers to determine ABV account for this discrepancy?

agusus 11-11-2011 06:02 PM

Quote:

Originally Posted by remilard (Post 3477681)
Alcohol production is not a function of the difference in beginning extract and apparent residual extract. Beersmith's estimate is wrong, Stone is right.

But it is mostly a function of the change in original density to final density isn't it? My impression was that ABV calculated from OG/FG might have say a 1-5% deviation from a lab test of alcohol level, but I wouldn't expect it to be 10% (error deviation from actual) like it is in this example.

This calculator - http://pint.com.au/calculators/alcohol/ - agrees with the BeerSmith estimate, and they use a variable 'f' factor (it scales as OG increases).

If you're really saying that OG/FG estimation can't approximate ABV within 5% of actual, then is there any way to do it based on ingredients list? Otherwise it sounds like a laboratory alcohol test is the only way to get within 10% accuracy?

What other chemicals contribute to decreasing a liquid's density without being a form of alcohol? Proteins increase liquid density I believe, so that's out. Polyphenols (phenolics) and esters might, but I wouldn't think those are present in high enough volume to significantly affect measured density. Hop oils probably have a lower density than wort too, but those are present in extremely tiny proportions compared to the other wort components.

vespoli 11-12-2011 12:53 AM

Apparent vs. real extract is another big player. Hydrometers are great tools, but they are not anything compared to a digital density meter, refractometer or GC.

FloatinAway 11-12-2011 03:54 AM

Edited due to stupid post

My bad

r8rphan 11-12-2011 12:23 PM

Where'd you get this book?

Sounds like something I want... Didn't know I wanted it, but now I do...:D

agusus 11-12-2011 03:25 PM

http://www.amazon.com/Craft-Stone-Br...dp/1607740559/

For big fans of Stone it's a must have. Makes a good coffee table book too. (though I still recommend reading parts of it - the history of how they got started is pretty interesting).

EricCSU 11-14-2011 02:56 AM

Is there a discrepancy with the rest of the recipes or just that one? You should email Greg if there are errors. I bet he would want to know about it.

Eric

FatherJack 11-14-2011 06:51 AM

I'm getting that book.


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