ABV of Barrel Aged Beer?

[cb341982]

Hi all. I'm hoping someone can help with this. I brewed a Russian Imperial Stout and a Dubbel that where both put in to 25L ex distillery whisky barrels which I purchased through my homebrew club. The barrels where pretty wet when I filled them. I'm just wondering if anyone knows of a test I could do at home or somewhere I can send the beers to be analysed to determine the ABV content?

 

[MHB]

The standard methods that the ATO accepts are Distillation and Near IR Spectroscopy.
Distillation isn't all that hard and a lot of the larger wineries use this method, NIRS on the other hand needs some pretty expensive kit ($20K+) so would probably only be found in really big wine or brewing companies.
If you had any wineries around where you live it might be worth making some phone calls.

I would need to do a bit more digging but I think if you can take both a Hydrometer SG and a Refractometer reading you should be able to interpolate the answer, maybe not well enough to keep the excise man happy but close enough for home brew. (have a look at this)
Otherwise if you took your OG and FG readings and calculated your alcohol in the normal way. Having a look at your current SG, if its gone back up, you should be able to make a fair guess as to how much alcohol you have lost. in Scotland, in a cellar (so stored around 10oC) whiskey is said to loose about 4% of its alcohol/annum (the so called "Angles Share").
Here its hotter but your alcohol is lower than cask strength spirit and a lot less volatile, so I wouldn't be too worried, there will be plenty left.
Mark

 

[Roosterboy]

From memory I think it's humidity, either higher or lower than 65% that really makes a difference if ethanol or water is lost from the barrel. You can get it tested but it will cost around $40. eg vintessential.com.au.

 

[cb341982]

If anyone is interested, I finally got around to sending some samples away to be tested at Vintessential and the results are in!
Dubbel went in to a barrel @ 8% ABV and came out @ 14.8% ABV
RIS went in to a barrel @ 10% ABV and came out @ 15.7% ABV

Cheers Roosterboy for the heads up on getting the beers tested

 

[MHB]

I'm having trouble believing those results.
If your Dubbel went in at 8% and came out at 14.8% you have gained 6.8%, in the barrel.
To get that you need to have converted a lot of sugar into alcohol (from ABV=change in gravity/7.5) 6.8*7.5 = 51 points, you already had 8% so another 60 points. means your OG had to be 1.110, that's assuming the beer finished at 1.000 which is unlikely so the OG would have to have been 1.110 + your FG more likely something like >1.120

Something isn't adding up, a bit more information on the beer might help, just double check the lab results, they haven't given you the answer in ABW or something similar.

 

[cb341982]

I didn't convert any more sugar to alcohol. The dubbel went in an extremely wet barrel,5.2kg over tare weight. So my 8% dubbel was drawing barrel strength whisky (60%+ABV?) out of the wet staves for approx 4 weeks. Hence 14.8%ABV.

 

[MHB]

Might have been worth mentioning that in the OP

 

[cb341982]

I said they were ex distillery and pretty wet. Surely that's enough info without going into too much detail

 

[captnhaddock]

I didn't convert any more sugar to alcohol. The dubbel went in an extremely wet barrel,5.2kg over tare weight. So my 8% dubbel was drawing barrel strength whisky (60%+ABV?) out of the wet staves for approx 4 weeks. Hence 14.8%ABV.

That's rather amazing really. But it does lead to one question, how sure are you of the pre-barrel ABV?

 

[cb341982]

4 week fermentation with the Dubbel and 5 weeks with the RIS. Both beers reached expected FG (according to beersmith) and multiple hydrometer readings. Even if there was the slightest bit of fermentation it wouldn't have accounted for much in the way of ABV. I don't know about you, but once I reach expected FG I wouldn't test again unless I could see more fermentation taking place. Plus the 4 and 5 weeks respectively of fermentation was enough to call it done in my mind

 

[captnhaddock]

4 week fermentation with the Dubbel and 5 weeks with the RIS. Both beers reached expected FG (according to beersmith) and multiple hydrometer readings. Even if there was the slightest bit of fermentation it wouldn't have accounted for much in the way of ABV. I don't know about you, but once I reach expected FG I wouldn't test again unless I could see more fermentation taking place. Plus the 4 and 5 weeks respectively of fermentation was enough to call it done in my mind

No offense meant, just wondering how sure you were of FG pre barrel. I do find that I struggle with my gravity readings, so more often than not, it's an approximation (ironically, I work in brix rather than gravity and even have a digital brix meter, so I shouldn't be struggling but I do).