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Docthorjp 12-20-2011 02:38 PM

Alcohol free attempt fail...
 
Hi,
I tried to produce an alcohol free beer for my step-sister who is pregnant. It didn't work and I don't really understand why. I need your suggestions. There are the processes I used :

1) Canadian 2 row malt + carafoam = OG: 1.042
2) Mash at 83C (181F) for more body and less fermentable sugars
3) Only primary (wyeast Abbey ale) for 7 days = FG: 1.011
4) Final alcohol supposed to be 4.1%ABV
5) Heat primary to 80C (176F) for 1h30 to evaporate ethanol and mixing 4-5 times
6) Bottling with dextrose and adding fresh yeast
7) After 3 weeks, samples were tested on a GCMS (gas chromatography - mass spec) by a specialized company
8) Result : 5.1%!!

So, I don't really know what happened. There is more alcohol than it suppose to be. The only mistake I have done, I think, it's that I didn't stir continuously when I heated it to evaporate alcohol...

wilserbrewer 12-20-2011 03:06 PM

I would guess that you didnt get hot enough to drive off the ethyl. 176 is only 3 degrees above boiling, so if you had any error, the alchohol remained. I would bring it up to 185 - 190 to be certain.

audger 12-20-2011 06:10 PM

mashing at 181F is how you extract tannins from the grain and immediately denature all your enzymes. there would have been no starch or long chain sugar conversion at all in that mash. at that point you were really just steeping the grain in hot water, not 'mashing'.

and when you are distilling off the alcohol, instead of heating the beer to 176F or higher, normally you pull a vaccuum on the container to lower the boiling point enough so that you dont change the flavor of the beer. heating it again after fermentation can add considerable amounts of negative flavors. normally you pull enough of a vacuum on it so that the boiling point of ethanol is lower than 120-140F.

from those gravities, you only had about 60% attenuation, which is low for that yeast. which is probably explained by lack of available sugars for it to eat. you should also have 4% ABV, which means that either your annalysis company was wrong, or your measured OG and FG numbers arent accurate (more likely).
pint.com.au - Brewing Calculator - Alcohol and Attenuation

if you are really going non-alcoholic for someone pregnant, you should force carbonate, as bottle conditioning will add even more alcohol (albeit a small amount).

Denny 12-20-2011 07:05 PM

Quote:

Originally Posted by audger (Post 3587509)
mashing at 181F is how you extract tannins from the grain and immediately denature all your enzymes.

Denature enzymes, yes. Tannin extraction is much more dependent on pH than temp, though. If it wasn't, you couldn't do decoctions. In a decoction mash, you boil the grain, yet you don't get excessive tannins from it.

Yuri_Rage 12-20-2011 07:10 PM

Post your exact recipe as well as mash and boil volumes. Your stated measurements seem a bit off.

dcp27 12-20-2011 07:21 PM

sounds like broken thermometer was the problem. a 181F mash would never get close to 74% attenuation.

Misplaced_Canuck 12-20-2011 08:07 PM

Quote:

Originally Posted by Docthorjp (Post 3586829)
2) Mash at 83C (181F) for more body and less fermentable sugars

That's a double mistake. 1) 181F is too high and won't have any enzymatic activity. 2) While you want residual sugars, mashing soooo high will create too much of it.

If you mash at normal temperatures (say 153F), and evaporate the alcohol, the body will increase. Alcohol is, by nature, "thinner" than the normal body of a beer.

I might actually consider mashing LOWER to prevent too much residual sweetness, say 150-151F.

M_C

Lennie 12-20-2011 08:40 PM

I don't think you can effectively remove ethanol from a water solution by heating it to the BP of ethanol. Or at least it would take a lot longer than 1.5hrs.

You might be better off doing something like steeping some specialty grains, crystal and a generous amount of dextrine malt, then boiling that for a bit with some hops to approximate a beer without fermentation.

BrewKnurd 12-20-2011 08:56 PM

Quote:

Originally Posted by Lennie (Post 3588026)
I don't think you can effectively remove ethanol from a water solution by heating it to the BP of ethanol. Or at least it would take a lot longer than 1.5hrs.

This. I mean, it sounds simple, but if you're not boiling, you're not boiling. You're just doing hot evaporation. And while that is faster than a cool evaporation, I don't think you can expect to drive of a significant amount of ethanol in a reltively short period of time without boiling it.

I don't know what the actual boiling point of a 5-6% ethanol solution is, but its probably up around 205 deg F.

Lennie 12-20-2011 09:03 PM

Plus when you do boil, the steam coming off is the same ratio as the solution at first, and only ratchets towards the 95% ethanol (the azeotrope) as the distilation progresses.


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