Conflicting info on sugar content of beer

[TrappistBeerFan]

Hi can anybody tell me how much sugar per litre a beer with a gravity of 1010 has got please?

A chart that my local brew shop gave me says it has 12 grams per litre but my hydrometer says 30. Other charts that I have seen online also differ from both of those figures so could anyone give me an exact amount of sugar per litre for a beer that has a gravity of 1010 and also 1006.

Thanks


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[GilaMinumBeer]

Are you asking about adjunct sugar? That depends on how much of the gravity is made up from grain.

Or are you trying to make a sugar water with gravity of 1.010 or 1.006?

 

[TrappistBeerFan]

Sorry I should of said how much sugar is in a litre of beer with an fg of 1010 and 1006.


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[feinbera]

...or are you talking about residual sugar?

This will vary based on the original gravity – because alcohol is less dense than water, a beer that started with a higher OG will have more residual sugar than a beer with a lower OG and the same final gravity, because the greater amount of less-dense-than-water alcohol "cancels out" some of the denser-than-water residual sugar. I don't have a formula to give you, but, if you look around for "real attenuation" formulas, which tell you what percent of the sugar was converted to alcohol based on the original and final gravities, you should be able to use that as a starting point – if you know how much sugar you started with, and what percentage was converted, it's easy to figure out how much is left unconverted.

 

[TrappistBeerFan]

What about say westmalle tripel? Apparently it starts at 1100 and finishes at 1008.

Thanks


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[TrappistBeerFan]

Or to put the question a different way, how many grams of sugar are there in a litre of liquid that has a reading of 1010?


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[Talgrath]

Unfortunately, the only way to really know is to lab test your beer. I found this: https://winemakermag.com/501-measuring-residual-sugar-techniques that has some techniques that apply to home brewed wine for determining residual sugars, but the two techniques mentioned are for wine and are only a very rough approximation. If you're looking for sugar to the gram, you'll need a lab test kit and some spare cash, such as White Labs' test kits. http://www.whitelabs.com/other-products/tk2300-beer-analysis-sample-kit You'll have to pay them extra to figure out sugar content. Why do you need to be so exact? Are you trying to get information for a diabetic?

 

[TrappistBeerFan]

Yes a friend is diabetic so I'm just trying to gather info on certain beers that he likes.

I don't need to be scientifically exact, it's just that as I said the chart that I got from the shop says that a litre of beer with a reading of 1010 has 20 grams of sugar less than some of the charts online for the same reading. Obviously that's a big difference and I would like to know which one is correct.


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[hlm123]

http://www.howtobrew.com/section2/chapter12-4-1.html

If sugar yields 46 gravity points per pound per gallon, and there are 3.785 liters in a gallon, then 10 gravity points in 1 liter would mean (1 pound)*(10/46)/3.785 = 26 grams of sugar.

 

[TrappistBeerFan]

Thanks


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[dyqik]

http://www.howtobrew.com/section2/chapter12-4-1.html

If sugar yields 46 gravity points per pound per gallon, and there are 3.785 liters in a gallon, then 10 gravity points in 1 liter would mean (1 pound)*(10/46)/3.785 = 26 grams of sugar.

However, if there's alcohol in the liquid, as there is in beer, then that lowers the gravity well below that of just sugar dissolved in water. Alcohol has a gravity of 0.787.

You need the ABV (or OG and FG to calculate ABV) as well to make this calculation - if the final gravity is 1.010 and it's a 5% ABV beer, then the liquid is 5% ethanol, 95% water, plus the sugar (which to first order doesn't change the volume). The gravity of beer minus the sugars is 0.95*1.0 + 0.05*0.787 = 0.989, so that you have 1010-989 = 21 gravity points from unfermentables which is equivalent to 55g/l of sugars, not 10 points and 26g/l of sugars.

This could then be complicated by the fact that some of the unfermentables might not be sugars, and/or you might care about the type of sugars - e.g. lactose in a milk stout. Yeast will preferentially eat simple sugars over more complex kinds.

Doing that calculation for Westmalle Tripel, with an FG of 1.010 and an ABV of 9.5%, the water+alcohol gravity is 0.980, giving 30 gravity points of unfermentables remaining, for 78g/l if that's all sugars.

 

[TrappistBeerFan]

Wow 78 grams per litre. I would have never have thought westmalle tripel had that much sugar in it?


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[dyqik]

Wow 78 grams per litre. I would have never have thought westmalle tripel had that much sugar in it?

That's a maximum, as not all unfermentables will be sugar, and in any case, not all sugars are created equal. Some sugars are much sweeter tasting than others (e.g. lactose, as used in milk stouts, isn't very sweet at all, but it doesn't get eaten by the yeast). They also differ in their effect on diabetics.

 

[Talgrath]

That's a maximum, as not all unfermentables will be sugar, and in any case, not all sugars are created equal. Some sugars are much sweeter tasting than others (e.g. lactose, as used in milk stouts, isn't very sweet at all, but it doesn't get eaten by the yeast). They also differ in their effect on diabetics.

Yep, that's why I'd say, if you're trying to serve your beer to a diabetic who really needs to watch sugar that closely, you're probably going to need professional testing. Approximations are okay, but they won't be very accurate.