Calculate water to add with priming sugar so ABV unchanged?

[EnglishAndy]

Here's a puzzler for the maths folks. I batch prime my beer with table sugar dissolved in boiled water before bottling. Depending on the carbonation level this can add up to 0.5% ABV to my brew. I don't want that and I know that it is possible to calculate the amount of water to batch prime with such that the final beer ABV remains unchanged. Does anyone know the formula that will do the water calculation?

 

[ajdelange]

We could do some math but I think it's simpler to just reason that if you have beer at 5% ABV and you wanted beer at 5.5% ABV (a 10% increase in the alcoholic strength) you would have added 10% more fermentables. That's how much it takes to get the extra 0.5 ABV. If you wanted 10% more beer at 5% ABV you would have used 10% more extract and 10% more water. That's effectively what you are doing here (adding extract, deferred to the priming bucket, and water to get more beer) so that makes the answer to add as much water on a percentage basis as you expect the alcohol content to increase on a percentage basis.

 

[Yooper]

Here's a puzzler for the maths folks. I batch prime my beer with table sugar dissolved in boiled water before bottling. Depending on the carbonation level this can add up to 0.5% ABV to my brew. I don't want that and I know that it is possible to calculate the amount of water to batch prime with such that the final beer ABV remains unchanged. Does anyone know the formula that will do the water calculation?

But then you are literally watering down your beer. You'd lower the ABV, but replace some of the beer with water to do so. Maybe start from the beginning, and make the beer lower ABV to begin with, and account for the priming sugar.

If you're doing a 5 gallon batch, adding 4 ounces of sugar in 2 cups of water increases the ABV by .25%.

 

[EnglishAndy]

We could do some math but I think it's simpler to just reason that if you have beer at 5% ABV and you wanted beer at 5.5% ABV (a 10% increase in the alcoholic strength) you would have added 10% more fermentables. That's how much it takes to get the extra 0.5 ABV. If you wanted 10% more beer at 5% ABV you would have used 10% more extract and 10% more water. That's effectively what you are doing here (adding extract, deferred to the priming bucket, and water to get more beer) so that makes the answer to add as much water on a percentage basis as you expect the alcohol content to increase on a percentage basis.

I think that because I'd be watering down my finished beer with over a litre of water to maintain the same ABV I'll just go brew a slightly weaker beer to begin with and accept the slight drying-out effect of adding sugar.

 

[baldm79]

I think that because I'd be watering down my finished beer with over a litre of water to maintain the same ABV I'll just go brew a slightly weaker beer to begin with and accept the slight drying-out effect of adding sugar.

Do you notice a perceivable drying out from bottling? I have noticed subtle differences in kegged -vs- bottled beers. I didn’t notice a drying effect though.

 

[EnglishAndy]

Do you notice a perceivable drying out from bottling? I have noticed subtle differences in kegged -vs- bottled beers. I didn’t notice a drying effect though.

Up until now I've only been bottling so I've not had the opportunity to try the same beer side-by-side. However my first force-carbonated kegged beer (an English bitter) is now conditioning and half a dozen bottles were done from that batch as well so I guess I'll find out soon if there's a taste difference.

 

[bucketnative]

I think that because I'd be watering down my finished beer with over a litre of water to maintain the same ABV I'll just go brew a slightly weaker beer to begin with and accept the slight drying-out effect of adding sugar.

Another option is to prime with DME, that way you are diluting your beer with wort as opposed to sugar water. This would minimize the thinning effects of using a 100% fermentable source of priming sugar.

Vw = 131.25 * (masssugar * ppgsugar * Xf) / ABV

Where:

Vw = volume of water used to dissolve the priming sugar source
masssugar = mass of the priming sugar in lb
ppgsugar = points per lb per gal of the sugar source
Xf = fermentability factor, which is a fudge factor for the % of fermentable sugars... for table sugar it would be 1.0, for DME it would be 0.68 (which is what Northern Brewer applies to DME in their priming sugar calculator).

So for a 5 gal batch at 5 %ABV primed with 5 oz of sugar source, you would use approximately 44 oz water to dissolve your sugar, and with DME, you would use approximately 29 oz water. Of course, 5 oz of DME will provide a lower VolCO2 in the beer than will table sugar.

 

[bucketnative]

So for a 5 gal batch at 5 %ABV primed with 5 oz of sugar source, you would use approximately 44 oz water to dissolve your sugar, and with DME, you would use approximately 29 oz water. Of course, 5 oz of DME will provide a lower VolCO2 in the beer than will table sugar.

So looking at the Northern Brewer priming calculator, I assumed a 5 gal batch of beer at 5 %ABV, and I assumed I wanted to get 2.5 vol CO2 in the beer. I looked at sugar and DME:

msugar = 4.1 oz (0.256 lb)
ppg sugar = 0.042
Xf = 1
Vw sugar = 36 oz

mDME = 6.0 oz (0.375 lb)
ppg DME = 0.036
Xf = 0.68
Vw DME = 31 oz

 

[kh54s10]

IMO, the minor amount that the priming sugar is going to raise the ABV is not even worth thinking about. Are you sure the .5% is accurate? Seems high to me.

 

[dylpik]

Use c1v1=c2v2

Try
((5.5x litres you currently have)\5.5) - litres you currently have= amount of water to use for priming

So it’ll be around 1.9 litres for a 5G batch

I really feel like that much increase will result in bottle bombs though.. I’d double check that and then you can change the percentage in the equation to whatever it should be. If that’s right though hope this helped!

 

[EnglishAndy]

IMO, the minor amount that the priming sugar is going to raise the ABV is not even worth thinking about. Are you sure the .5% is accurate? Seems high to me.

For higher carbonated styles, yes. In your recipe builder (I use Beersmith) add your carbonation sugar to the grist to see the effect for yourself.

 

[hammy1983]

I recently screwed up and watered down my beer. unintentionally. I personally would just except the slight bump from the priming sugar calculator and keep the taste.

 

[kh54s10]

The simple way of dealing with priming sugar bumping up the ABV is to get a recipe .5 ABV lower than you want or design your recipe that way. I have never worried about a .5 difference. I don't know that I could tell the difference anyway, even if drinking them all evening.

 

[cactusgarrett]

I would posit the idea that the amount of ABV that the priming solution changes your batch by is less than the error in reading your hydrometer at various stages of the brewing process. I know we like to think we got this down to a science, but in my opinion, so many variables make the accuracy of ABV in our finished product unreliable at the the nearest 0.1 level.

 

[bucketnative]

I would posit the idea that the amount of ABV that the priming solution changes your batch by is less than the error in reading your hydrometer at various stages of the brewing process. I know we like to think we got this down to a science, but in my opinion, so many variables make the accuracy of ABV in our finished product unreliable at the the nearest 0.1 level.

The fact is that the priming process can add to the ABV, and we can accurately know how much ABV will increase because we can accurately measure the amount of sugar added to the beer for priming purposes. I think given the proper equipment, like accurately calibrated scales and pipettes, as opposed to a bobbing hydrometer, you could be accurate to within the 0.1 % ABV. On the federal side of things, I believe that BATFE requires that commercial beer be labeled accurately within +/- 0.5 %. I think that may be mostly to account for batch-to-batch variation in production beers. But, you're right, how can we expect to be held to a greater accuracy what is applied to the industry.

 

[EnglishAndy]

The fact is that the priming process can add to the ABV, and we can accurately know how much ABV will increase because we can accurately measure the amount of sugar added to the beer for priming purposes. I think given the proper equipment, like accurately calibrated scales and pipettes, as opposed to a bobbing hydrometer, you could be accurate to within the 0.1 % ABV. On the federal side of things, I believe that BATFE requires that commercial beer be labeled accurately within +/- 0.5 %. I think that may be mostly to account for batch-to-batch variation in production beers. But, you're right, how can we expect to be held to a greater accuracy what is applied to the industry.

EU law also permits +/- 0.5% to account for seasonal variations.

[*] There was a recent case in the UK where one of the megabreweries deliberately took advantage of this and labelled their cans at a higher level than the actual content in order to take advantage of a lower tax band applied at the actual brewed level while at the same time misleading the consumer into thinking they were getting a stronger brew.

They were sued by the tax authorities and they won.

[*] Link.

 

[ajdelange]

I think given the proper equipment, like accurately calibrated scales and pipettes, as opposed to a bobbing hydrometer, you could be accurate to within the 0.1 % ABV. .... But, you're right, how can we expect to be held to a greater accuracy what is applied to the industry.

I used to regularly check the actual alcohol content of my beers using the ASBC prescribed method. I always compared the answers to what I got using the more conventional SG methods used by home brewers and smaller breweries. The errors were usually more than a few tenths. In those methods we start with the OG. What is that? Certainly we can make (with narrow range hydrometers) an accurate measurement of the SG of the liquid in the fermenter but how much water is carried off with the escaping CO2 during the fermentation? Next we measure the apparent extract and make an assumption about how much alcohol comes from a unit loss of apparent extract. How many of us are aware that the loss depends on the OG and use the Balling factor in our calculations. Note that when I said above that I compared measured (per ASBC) ABV to calculated ABV I was using the Balling factor and still got errors of a few tenths. I finally started estimating the apparent effective OG by running the Balling calculation in reverse and recording that rather than the original hydrometer reading as the OG.Today a moderately sized brewery can afford an Alcolometer - a device which estimates ABV from IR absorption and density measurements. It too back calculates OG.
Without one of those I'd say ±0.5% is a pretty reasonable error bandwidth.

 

[cactusgarrett]

What HE said.

 

[bucketnative]

Without one of those I'd say ±0.5% is a pretty reasonable error bandwidth.

That's good to know. I did some reading on the spectroscopic methods, and they seem to have greatly improved in the last 5 or so years, to the point that little to no sample prep is required.

I hadn't considered loss of water during fermentation, nor the loss of some mass due to yeast propagation. All sources of potential error in a purely gravimetric measurement.