How do commercial breweries measure ABV

[bobtheUKbrewer2]

I ask this because in a recent thread we established that refractometers can't be used once alcohol is present.

If they use hydrometers I do not understand how the "reading on day 2" can take account of less maltose plus some alcohol.

OG 1.045 FG 1.007 measured with a hydrometer, ABV ?

Answers from professional brewers particularly welcome!

 

[temple240]

I'm no expert on the matter but I know that breweries aren't using a hydrometer to get their abv. That's the homebrew way. The proper way involves lab testing from an in house lab or a contracted lab. I have no idea what the actual process is.

 

[wailingguitar]

No brewery I ever worked for sent beer off to a lab to determine ABV (Bell's, Rogue, Breckenridge and a few others that no longer exist) except in cases where it was required from states that had ABV limits on beer. It was always calculated from gravity drop in fermentation.

 

[temple240]

No brewery I ever worked for sent beer off to a lab to determine ABV (Bell's, Rogue, Breckenridge and a few others that no longer exist) except in cases where it was required from states that had ABV limits on beer. It was always calculated from gravity drop in fermentation.

What do you do that allowed you to work for so many breweries, including Bell's and Rogue?

 

[FATC1TY]

They use hydrometers like we do.


You can figure abv at any point in fermentation.

 

[VladOfTrub]

Here's how it's done. A certain volume of beer is measured out. A gravity reading is taken @ 60 or 68F, depending on what temp the hydrometer is calibrated at. Then, the sample is ran through a de-carbonating filter or placed under a slight vacuum. After the sample is completely de-carbonated, the sample is heated to 173 F for an hour, stirring constantly. After the alcohol in the sample is boiled out, the sample is cooled to 60 or 68F, de-gassed, distilled water is used to top up the sample to it's original volume. The volume of distilled water that was added to the sample, divided by the original volume equals ABV. True attenuation can be figured out at the same time. Or, a formula with many numbers and decimal points, along with a chart that is available, can be used.

 

[bobtheUKbrewer2]

Thanks vlad, in the UK small microbreweries would not go to that trouble. I will see if our customs and excise people have any info.

 

[bobtheUKbrewer2]

In the uk breweries have to use the process described by vladoftrub ONCE PER YEAR to ensure their ESTIMATE of ABV is accurate. The prescribed way to determine ABV for each batch of beer is (OG-FG) x factor

Factor is .125 for "drop" up to 6.9
.126 for drop 7 - 10.4
.127 for drop 10.5 to 17.2
.128 for drop of 17.3 - 26.1
.129 for drop of 26.2 - 36 (approx 3.3 to 4.6 ABV)
.130 for drop of 36.1 to 46.5

I shall use .129 in the future.

 

[bobtheUKbrewer2]

It seems to me that if I take refractometer and hydrometer reading at the start and end of fermentation for each of the beer styles I brew, I can "calibrate" my refractometer readings in some way and use them to determine ABV.

Probably the refractometer drop against the hydrometer drop.

 

[ajdelange]

Large breweries, some small ones and even the occasional home brewer use the ASBC's methods of analysis Beer-4A, European brewers use the similar MEBAK procedure. I don't know what they do in the UK.

100 mL of beer is measured into a volumetric flask and then transferred quantitatively to a distilling flask using two 25 mL aliquots of DI water to rinse the volumetric flask. The volumetric flask is washed with DI water and placed at the end of a condenser to act as the receiver in the distilling apparatus. Close to 100 mL of distillate is collected. This is attemperated and made up to 100 mL. The flask now contains all the alcohol in 100 mL of beer but it is in 100 mL of water now. The density of the solution in the flask is determined by the use of a pycnometer or digital density meter and the density referred to the AOAC tables in the US and, I presume, the OIML tables in Europe to give the ABV and/or ABW. The digital meters have the tables built in and read alcohol content directly.

TTB does not require this procedure of brewers in the US. I believe it is sufficient for them to WAG ABV from estimated OE (original extract) and AE (apparent extract).

 

[ajdelange]

It seems to me that if I take refractometer and hydrometer reading at the start and end of fermentation for each of the beer styles I brew, I can "calibrate" my refractometer readings in some way and use them to determine ABV.

You can indeed and the procedure is spelled out in ASBC MOA Beer-4C. The relevant paragraph is

"To construct calibration curve, analyze a number of
samples of beer of the same type that cover the alcohol
range of interest, both by distillation (Beer-4,A) and by
refractometric procedure given below. Plot results..."

Beer 4A is the procedure I described in my previous post. MEBAK has a similar procedure.

 

[wailingguitar]

What do you do that allowed you to work for so many breweries, including Bell's and Rogue?

Brewer. Well, when I started at Bell's (then called Kalamazoo Brewing Co.) in '89 I was the packaging director, moved to brewing about 6 months later. Brewed for them and Rogue as an assistant brewer. Was head brewer at Breckenridge in Birmingham, AL and also brewed at the Memphis, TN location as well as both the Blake St and Kalamath locations in Denver (Breckenridge had this idea in the 90s to open pubs across the country, it didn't work out). Was company brewmaster for City Breweries (not to be confused with a similarly named, currently existing company), was brewmaster at their Magic City location in Birmingham, AL, also brewed at their Port City and Lexington City pubs, as well as hiring, training and overseeing brewers in those locations. Was brewmaster for Little Star/Mad Monk for a while. Have done industry consulting from time to time, not start-up stuff but "will this system work for us?", "Are these tanks worth repairing?", "What is this system worth?", etc.

 

[bobtheUKbrewer2]

Can this be figured out theoretically? Assuming only maltose solution with a SG of 1.050, if it is dilutes to 1.040 with distilled water, then the maltose "lost" has turned into ethanol. If the weight of this ethanol can be worked out, so can its SG in one litre of water. This can then be averaged with the 1.040. Repeat for 1.030 1.020 etc

 

[ajdelange]

Yes. That is the basis for the Balling formula. He found that 2.065 grams of extract produced 1 gram alcohol, .11 grams of yeast biomass and 0.955 grams of CO2. The formula derives from that. See Vol II of deClerck.

 

[bobtheUKbrewer2]

can you give me full reference to declerck please - google didn't find anything.....

 

[bobtheUKbrewer2]

A maltose solution with SG of 1.050 ferments down to 1.010. This produces 9.678 gm of ethanol per litre. This will depress the SG by .004. So the original maltose solution only fermented down to 1.014 .

 

[bobtheUKbrewer2]

A beer with OG 1.050 and FG = 1.010 in reality has a FG of 1.014 for the purpose of calculating ABV

(1.050 - 1.014)*1000* .129 = 4.644 ABV

 

[ajdelange]

can you give me full reference to declerck please - google didn't find anything.....

I'm away from home base and so can't look at the books but it is Jean deClerck and I think the title is Textbook of Brewing. Brewers just refer to it as deClerck.

Try http://www.carlsbergdanmark.dk/Prod...er/Documents/Balling formula - origin agk.pdf

That's got some of the history and the basic equations but not the table of Balling Factors I referred to in a much earlier post in this thread.