Volatility of Fresh Wash

Any hardware used for mashing, fermenting or aging.

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Twisted Brick
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Volatility of Fresh Wash

Post by Twisted Brick »

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Today I finished squeezing a 12gal gumballhead made from 14lbs of spent grain (wheat single malt) and 16lbsof sugar in 12gal of water. After filling a 6.5gal carboy and three one-gallon jugs with clear, I squeezed the remaining wash from the spent grains into my conical fermenter.

My questions are: with only four gallons of a 9% beer in a 13gal vessel (with lid), how much alcohol might be lost to the conical headspace while I wait for the grain to separate from the beer? Since this is destined to be refluxed for a faux-wheat vodka, would it be advisable to strip it cloudy ASAP presuming my CCVM will clean up any yeast notes?

Thanks in advance.

Twisted
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cob
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Re: Volatility of Fresh Wash

Post by cob »

2 days and not able to find the expansion ratio of ethanol.

So lets assume it's close to water 1x liquid = 1700x vapor.

you have 9 gallons of vapor in your fermenter = .0052 gal.

which is .8528 oz. At 9% etoh. it won't even wet a shot glass. :lol:
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Twisted Brick
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Re: Volatility of Fresh Wash

Post by Twisted Brick »

cob wrote: Thu Jun 10, 2021 5:00 pm 2 days and not able to find the expansion ratio of ethanol.

So lets assume it's close to water 1x liquid = 1700x vapor.

you have 9 gallons of vapor in your fermenter = .0052 gal.

which is .8528 oz. At 9% etoh. it won't even wet a shot glass. :lol:
Thanks for the input, cob. From my limited research, it seems the evaporation rates of certain types of alcohols are a function of many things, temperature, presence of oxygen and/or heat, whether or not there is water to bind to (ie: food) etc, therefore is a complex process with many variables. Reducing these variables to a relevant common denominator, I discovered a like alcohol (in ABV anyway) in an open beer can evaporate in as little as 8 hours.

I was successful in not disturbing my clearing ferment but once, and noticed there was a mass of tiny bubbles on the surface, indicating a possible release of C02 from residual yeast activity. How much C02 was released and if it was sufficient to cover the entire surface of the vessel in unknown, but on my second ferment I will fill a carboy instead of the conical and compare the actual alcohol realized from each batch. I fully expect this batch to have evaporated all of its alcohol, but hey, it's a sugar wash.
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cob
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Re: Volatility of Fresh Wash

Post by cob »

So my napkin math could be questionable. I had never contemplated your question until your post

please keep us posted as to what you find in real life.
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NZChris
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Re: Volatility of Fresh Wash

Post by NZChris »

Most of the alcohol that evaporates will condense on the sides and lid and drip back into the ferment. According to my refractometer, I got 14% abv condensate from the lid of a fermenter at 8%. Working this stuff out is interesting and can be part of the hobby, but at hobby scale, any potential increase isn't worth chasing.

As for ethanol that is trapped in the head space, I doubt Cob's calculation is wrong and, even it is wrong, it can't be so wrong that I would care, or would change something that I already do.
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Re: Volatility of Fresh Wash

Post by Hügelwilli »

The mass of vaporous ethanol is around 2.5 times the mass of vaporous water per liter volume, because the molar mass of ethanol is around 2.5 times the molar mass of water and because in a given volume (same temperature and same pressure) is always the same number of molecules.

I don't see that the headspace is a problem. It will be filled mostly with CO² or air, not with ethanol vapor.
But in general there is the I think unsolved question, why we get much less alcohol from sugar than we should get stoichiometricly. Theoretically, if we have 100 grams sugar made up to a volume of 1 liter wash, we should get 6.85%abv, if yeast was a simple scissor, that cuts sugar molecules into alcohol molecules. But from practice we know that we get around 1%abv less. This means we loose around 14% of the sugar or of the ethanol.
Possible answers:
1. The yeast needs some "energy". But actually the energy comes from the conversion of sugar into ethanol.
2. Not all sugar gets converted to ethanol. But why not?
3. The yeast builds something else from it. But what? The yeast cannot simply build proteins or something else important for multiplying from sugar. Like humans it is only able to get energy from it. And after the energy is taken, mainly ethanol and only a few esters, aldehydes and other alcohols remain. But those congeners don't sum up to such a loss. And probably our alcoholmeter measures them as ethanol.
4. Ethanol gets driven out the wash together with CO². But if this was responsible for such a loss, the alcohol industry would try to condense the ethanol out of the CO². I have never heard of something like a cooling jacket around an airlock. But for me this answer sounds more plausible than the other answers. And this is, why I think the headspace volume is not important. If there is a loss caused by ethanol flying out of the fermenter, it is the volume of the CO² what causes this problem, not the volume of the headspace. 1kg of sugar produces 280 liter of CO².
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Twisted Brick
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Re: Volatility of Fresh Wash

Post by Twisted Brick »

Hügelwilli wrote: Sat Jun 12, 2021 12:15 am
Ethanol gets driven out the wash together with CO². If there is a loss caused by ethanol flying out of the fermenter, it is the volume of the CO² what causes this problem, not the volume of the headspace. 1kg of sugar produces 280 liter of CO².
Thank you for your most informative post, Hügelwilli. In an earlier email Mars (Stillerboy) echoed your comments, recommending to make sure I degas the clearing squeezin's in addition to keeping it covered and at a cool temp.
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jonnys_spirit
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Re: Volatility of Fresh Wash

Post by jonnys_spirit »

One thing the yeasties definitely produce that dissipates into the surrounding environment is heat.

Cheers,
-j

EDIT:
Just sayin - that making heat’s gotta consume a couple carbs and contribute to a little evaporation. Probably fairly insignificant in the scope though?
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i prefer my mash shaken, not stirred
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