is there a tool available ($hundreds not thousands) that can accurately measure abv in finished beer? I will be experimenting with de-alcoholizing some of my beers. Thanks.
Tool to measure abv?
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VikeMan
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Hundreds? I could be wrong, but I don't think so.
You could distill off a known quantity from a known quantity and weigh the distillate. I have watched the procedure but don't know all the specifics. It's accurate enough.
(the appropriate labware should only be a few hundred bucks)
If you went to spend as little as possible then distillation is the only way. The drawback is that it's time consuming but it won't cost you thousands of dollars in sophisticated equipment. You'll need a lab scale distillation kit that you can buy for as little as $100. You'll also need a pair of volumetric flasks to accurately measure the sample's and the distillate's volume. This are a bit more pricey but not unbearably so since we're talking about only 50-100 ml sample size. You'll also need a hydrometer to measure the distillate's density and the cost here depends on how accurate you want the measurement to be.
In practice you'll need to measure a known quantity (say 50 ml) of your beer (it will have to be filtered as solids will affect the results, you can do that with a simple paper filter). You'll then add distilled water to get to 70-80 ml and distill the diluted sample until you have about 40 ml in the receiving flask. You'll then top up the distillate to exactly 50 ml (or whatever the sample volume was) with distilled water. You can then measure the density of the distillate and this will give you the ABV of the distillate which will be equivalent to the ABV of the product sample. You can also measure the density of the sample post-distillation after topping it up with distilled water to the original volume and this will give you the actual residual extract of the beer.
The idea basically is to get all the volatiles, which in the case of beer or wine will be made up to 99,99% of alcohol, on one side of the distillation while leaving the dissolved solids (a.k.a. the actual residual extract) on the other side.
In practice you'll need to measure a known quantity (say 50 ml) of your beer (it will have to be filtered as solids will affect the results, you can do that with a simple paper filter). You'll then add distilled water to get to 70-80 ml and distill the diluted sample until you have about 40 ml in the receiving flask. You'll then top up the distillate to exactly 50 ml (or whatever the sample volume was) with distilled water. You can then measure the density of the distillate and this will give you the ABV of the distillate which will be equivalent to the ABV of the product sample. You can also measure the density of the sample post-distillation after topping it up with distilled water to the original volume and this will give you the actual residual extract of the beer.
The idea basically is to get all the volatiles, which in the case of beer or wine will be made up to 99,99% of alcohol, on one side of the distillation while leaving the dissolved solids (a.k.a. the actual residual extract) on the other side.
With a precise enough scale and volumetric flask, you can simply *weigh* the distillate, to get the density. In this quantities that seems more practical than using a hydrometer.
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It really depends on the equipment but with the weighing method you'll be adding three separate errors:
- tare weight measurement error
- gross weight measurement error
- flask volume error
With the hydrometer you just have the hydrometer as a source of measurement error, so if it's a good (i.e. expensive) one chances are the measurement will be more accurate. But of course which method is acceptable also depends on how accurate you'd like your measurement to be.
- tare weight measurement error
- gross weight measurement error
- flask volume error
With the hydrometer you just have the hydrometer as a source of measurement error, so if it's a good (i.e. expensive) one chances are the measurement will be more accurate. But of course which method is acceptable also depends on how accurate you'd like your measurement to be.
Silver_Is_Money
Larry Sayre, Developer of 'Mash Made Easy'
And also density vs. specific gravity error. Density and specific gravity are not precisely one and the same.
https://www.thoughtco.com/density-and-specific-gravity-differences-606114https://www.differencebetween.com/difference-between-density-and-specific-gravity/
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Ultimately unless you're incredibly accurate in your volume reading of your distillate, which if I understand correctly is the most critical error point, how you accurately measure the density thereafter depends on that first accuracy anyway. The method I saw derived ABW from the weight of distillate and then calculated ABV from there.
I haven't had a chance to try it hands on yet but it's on my to do list.
I haven't had a chance to try it hands on yet but it's on my to do list.
Thank you everyone for your responses. A question about weighing the distillate, how would I take into account any water vapor that came along with the ethanol?
Most of what you distill off will be water. But because it'll be distilled water and volatiles (which as said above will be almost entirely alcohol), no extract, you can determine the ABV from that. Distillers are able to directly read ABV for this reason, where brewers and winemakers are not.
OK, that makes sense now. Thanks!
TheBudBuddy
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I've recently tried the following online ABV calculator ABV Calculator | Find The Alcohol Content Of Your Beer and it has worked just fine for me..!
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Won't work in this case. This calculator works only by calculating the difference between OG and FG. Not FG and FG minus alcohol removed from the beer, as he intend to do.
By way of update, I ended up just brewing very low gravity milds and apa's. Simple, easy. 2.5-3.5% abv. Works well. Makes a good alternative tap to my IIPAs, lol.
VikeMan
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I don't think that wouldn't help @Dan K for what he was originally wanting to do. Refractometer "FG" readings have to be corrected to compensate for the presence of alcohol. I don't think the carefully tuned refractometer calculator formulae would work with a beer where the alcohol has been partially removed.
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Correct... unfortunately... the measurement problem ended up being a giant PITA, but brewing ultra low abv is actually working pretty well.
Distillation as elaborated in whatever the relevant ASBC procedure it is , is considered accurate for US regulatory purposes, IIRC. Law may be different in Italy.
I read somewhere that the ebulliometer was required by law for the labeling of wine and beer, but that, in fact, allows some slack, so it is not necessarily precise. Also an ebulliometer gives best results whithing the alcohol ranges which are typical for wines.
I found the method here: Determinazione del grado alcolico nella birra
Yet I don't understand how that works, as it doesn't consider the alcohol which necessarily remains in the kettle. There will always be a mixture of alcohol and water in the condensate and in the kettle. You can derive the proportion, probably, with some equations, which must assume zero reflux along the vapour path (thinking about it, that is, in fact, easy to obtain, so it must be possible to infer the residual alcohol in the kettle). The alcohol which is collected in the receiving vessel is never all the alcohol which was present in the kettle.
Yes, of course: in an ideal distillation there is a known correlation between the alcohol in the receiving vessel and the alcohol in the kettle:
https://www.chemguide.co.uk/physical/phaseeqia/idealfract.html
The method, for what I understand, must not rely solely on the collection of the alcohol in the product vessel (which is what I got from the post by @Vale71) but must also consider the alcohol remaining in the kettle, which is derivable.
An ebulliometre might be an interesting instrument for the OP though, if the beer is not intended for sale.
I found the method here: Determinazione del grado alcolico nella birra
Yet I don't understand how that works, as it doesn't consider the alcohol which necessarily remains in the kettle. There will always be a mixture of alcohol and water in the condensate and in the kettle. You can derive the proportion, probably, with some equations, which must assume zero reflux along the vapour path (thinking about it, that is, in fact, easy to obtain, so it must be possible to infer the residual alcohol in the kettle). The alcohol which is collected in the receiving vessel is never all the alcohol which was present in the kettle.
Yes, of course: in an ideal distillation there is a known correlation between the alcohol in the receiving vessel and the alcohol in the kettle:
https://www.chemguide.co.uk/physical/phaseeqia/idealfract.html
The method, for what I understand, must not rely solely on the collection of the alcohol in the product vessel (which is what I got from the post by @Vale71) but must also consider the alcohol remaining in the kettle, which is derivable.
An ebulliometre might be an interesting instrument for the OP though, if the beer is not intended for sale.
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bracconiere
Jolly Alcoholic - In Remembrance 2023
i thought the refractometer reading compared to a hydrometer reading was good enough? now i'm wondering?
I found this document, the ebulliometre is not good enough for the beer, because it is influenced too much by sugars
https://www.rivistadiagraria.org/ar...l-grado-alcolico-del-vino-via-ebulliometrica/
Sorry
https://www.rivistadiagraria.org/ar...l-grado-alcolico-del-vino-via-ebulliometrica/
Sorry
The original poster wants to brew a beer and then de-alcolize it with some method. The refractometer and hydrometer method will not work because they are based on the notion that sugars are converted into CO2 and alcohols according to a certain law, so the "missing" sugars in the beer are mathematically linked to the CO2 and alcohol which have been produced during the fermentation. That law allows to link the difference of density between OG and FG with the alcohol present in the beer.
If then one eliminates the alcohol from the beer, the equations don't work any more.
bracconiere
Jolly Alcoholic - In Remembrance 2023
hmm,...i thought it was a measure of the difference of SG reading between the two, that's how you can calculate the OG from the two together? i could be off? i was thinking of getting a refractometer so i could calculate ABV this way, let me know if i'm off on that.....
You absolutely can get a refractometer to evaluate the FG or the OG, and with the usual equations (or the usual calculators) you will then calculate the ABV of your "natural" beer, your non-dealcoholized beer.
The determination of the OG with the refractometer is practical but it has a small error due to the different refraction index between wort and a sugar solution;
The determination of the FG with the refractometer is practical but it has two small errors, one described above, and the other that you must know the OG and then apply an equation (several have been proposed) to arrive to the FG.
So, the hydrometer gives you the "physical" result, a direct measure of density, while the refractometer always gives you an indirect measure, with a small margin of uncertainty, but it's good enough for most purposes.
bracconiere
Jolly Alcoholic - In Remembrance 2023
That can only work if you use a hydrometer (which can be graduated in Plato or Brix or other measures). Actually not even because it doesn't ask you the OG so how can that infer the ABV from the FG? This is not something possible or I don't see part of the page for some reason.
If you use a refractometer and you want to know final gravity, you must know the original gravity and use a calculator like this:
https://www.brewersfriend.com/refractometer-calculator/
Many computer programs or apps give you the same possibility.
Once you know your OG and FG you can calculate the ABV
https://www.brewersfriend.com/abv-calculator/
You can use a refractometer for OG, FG and ABV using these two pages.
The first page, upper part, will convert your °Brix value of the refractometer (identical for our purposes to °Plato) to SG.
The first page, lower part, will convert your °Brix value of the refractometer to a FG.
The second page will allow you to know ABV by inserting OG and FG.
If you have an hydrometer you only use the second page, if you have a refractometer you use both pages. But you save beer
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bracconiere
Jolly Alcoholic - In Remembrance 2023
i thought it worked on the basis that alcohol effects a refractomometers FG reading? but not a hydrometer, thus comparing the two, you can calculate what the OG 'was', and thus ABV? or vice versa...but alcohol effects a refractometer, so comparing a refractometer reading to a hydrometer one, will tell you how much ABV? or so i'm convinced?
Alcohol affects a refractometer reading and that is why, while you can have a decently accurate density measure by measuring a wort (no alcohol, you are measuring an OG) with a refractometer, you cannot use a refractometer to measure density of a fermented beer (with alcohol, you are measuring an FG), unless you also know the OG of that beer.
If you know the OG, it is possible to use the refractometer to measure FG, because there are equations which exploit the fixed relation which exists between sugars consumed (OG - FG) and alcohols produced. This means that it is possible to infer how much alcohol there is in the sample, and how it affects the refractometer reading.
