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%.

agusus said:

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%.

Click to expand...

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

remilard said:

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

Click to expand...

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?

remilard said:

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

Click to expand...

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.

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.

Edited due to stupid post

My bad

Where'd you get this book?

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

http://www.amazon.com/dp/1607740559/?tag=skimlinks_replacement-20

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).

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

I'm getting that book.

Great book, I just started reading it a few days ago. It had to go on the back burner because I wanted to learn more about using casks.

EricCSU said:

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

Click to expand...

That's a good question. I checked some of the others and here are the divergences:

13th = 0.6% ABV
9th = 1.3% (1.079->1.010 = 9.1% but they say 7.8%, on an imperial wheat)
8th = 0.1%
7th = 0.6%
6th = .4%
stone smoked porter = 0.3%
stone pale ale = 0.3%
stone levitation = 0.2%

So it's interesting that some recipes have effectively no divergence (<=0.3%), which means that their recipes are consistent with the ABV estimation formula, while other recipes have very high divergence (9th Anniversary, 12th Anniversary, both > 1%).

The FG on the 9th Anniversary is particularly questionable. My guess is the recipe is correct but the FG is overly aggressive. On a 1.079 imperial wheat there's no way my FG would get down to 1.010. It's english ale yeast, and there's no sugar in the recipe. Another odd thing is it calls for a 30 minute mash @148F - so highly attentuative wort, but at 30min you might not even get full conversion. Some other recipes call for 90min mash @148F, which makes more sense.

Maybe I will email him.

agusus said:

That's a good question. I checked some of the others and here are the divergences:

13th = 0.6% ABV
9th = 1.3% (1.079->1.010 = 9.1% but they say 7.8%, on an imperial wheat)
8th = 0.1%
7th = 0.6%
6th = .4%
stone smoked porter = 0.3%
stone pale ale = 0.3%
stone levitation = 0.2%

So it's interesting that some recipes have effectively no divergence (<=0.3%), which means that their recipes are consistent with the ABV estimation formula, while other recipes have very high divergence (9th Anniversary, 12th Anniversary, both > 1%).

The FG on the 9th Anniversary is particularly questionable. My guess is the recipe is correct but the FG is overly aggressive. On a 1.079 imperial wheat there's no way my FG would get down to 1.010. It's english ale yeast, and there's no sugar in the recipe. Another odd thing is it calls for a 30 minute mash @148F - so highly attentuative wort, but at 30min you might not even get full conversion. Some other recipes call for 90min mash @148F, which makes more sense.

Maybe I will email him.

Click to expand...

The book is on my xmas list, so I have not seen it yet unfortunately. Does the recipe list the FG?

Don't underestimate the power of WLP007, that yeast is a monster. It is my house yeast so I have used it about 40 times. My IPA regularly goes from 1058 to 1009-1010 and I mash at 152F with an all malt wort. I made an extra pale ale that went from 1068 to 1010 when I mashed at 149F. I have wondered before how low that yeast could go if I used a 145F mash, then bumped it to 154F, then 168F.

Also, you are correct on the mash length. I would be surprised if you could get complete conversion at 30 minutes. When I go under 150F, I usually rest for 60 minutes, mash out to 158F, then 168F.

Eric

Which recpies are in the book?

I GOT THE BOOK!

I'm especially happy that it has food recipes in it as well. Overall, a great book (and an extremely beautiful book too!)