Adding corn sugar to dry out a beer post fermentation

Do you guys do this? If you do, how do you approach is mathematically? I've on occasion added malto-dextrine to add body, but that math is pretty simple because it doesn't ferment.

Say I have 2.5 gallons of extract based beer that finishes @ 1.018 and I wanted it more like 1.010 would it be worthwhile to add some corn or table sugar to dry it up a little?

While I've never tried this, it could probably be done. However, going from 1.018 to 1.010 is going to take quite the addition of corn sugar... a quick calculation suggests you would need to add about 0.75 lb of pure ethanol to reach 1.010. I'm not sure how much corn sugar that would take, but I'm guessing at least a pound.

What was the OG of this beer? Recipe?

You could also consider adding amalyse powder or beano to make more fermentable sugars out of the unfermentable sugar in the beer. However this is difficult to control and it would be easy to end up with bitter booze-water instead of beer.

petep1980 said:

Do you guys do this? If you do, how do you approach is mathematically? I've on occasion added malto-dextrine to add body, but that math is pretty simple because it doesn't ferment.

Say I have 2.5 gallons of extract based beer that finishes @ 1.018 and I wanted it more like 1.010 would it be worthwhile to add some corn or table sugar to dry it up a little?

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No. Adding sugar will increase your ABV, not reduce your FG. If you wanted to dry it out you would of needed to sub the sugar for some of the extract in the recipe.

I know adding sugar will not lower the FG, chance are it could be increased.

skeezerpleezer said:

No. Adding sugar will increase your ABV, not reduce your FG. If you wanted to dry it out you would of needed to sub the sugar for some of the extract in the recipe.

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Can you explain your reasoning?

Are you assuming the sugar doesn't ferment out completely? Because if it does, you've essentially just added a mixture of water & alcohol, so SG < 1.000, which would bring down the FG. (and boost the ABV)

skeezerpleezer said:

No. Adding sugar will increase your ABV, not reduce your FG. If you wanted to dry it out you would of needed to sub the sugar for some of the extract in the recipe.

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Yeah adding sugar water is basically like adding some .997 gravity liquid

TyTanium said:

Can you explain your reasoning?

Are you assuming the sugar doesn't ferment out completely? Because if it does, you've essentially just added a mixture of water & alcohol, so SG < 1.000, which would bring down the FG. (and boost the ABV)

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Adding sugar does not remove the remaining sugars in the 1.018 wort. It will ferment out, leaving a 1.018 gravity with more alcohol. I was basing this off of his question of adding sugar. I didn't see anything about increasing the volume.

skeezerpleezer said:

Adding sugar does not remove the remaining sugars in the 1.018 wort. It will ferment out, leaving a 1.018 gravity with more alcohol.

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But it will dilute it. Add straight water to a 1.018 beer...it will no longer be 1.018

If increasing the volume, you would need to add 2g of liquid. The amount of sugar needed would depend on where you want to end up alcohol wise.
2.5*.018=.045 gravity points
.045/.010= 4.5 gallons

TyTanium said:

But it will dilute it. Add straight water to a 1.018 beer...it will no longer be 1.018

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Not by adding just sugar. The question was adding sugar, not sugar water.

Good point, but aren't you still diluting? Assuming it ferments 100%, you're essentially diluting with straight alcohol.

I guess, I don't see how you can boost ABV without reducing your FG, aside from adding something with a higher residual FG.

...maybe I'm not understanding the math, ..add anything with an FG lower than 1.018, and you'll end up with something lower than 1.018. Only way not to change the FG is to add something with a 1.018 FG, right?

TyTanium said:

Good point, but aren't you still diluting? Assuming it ferments 100%, you're essentially diluting with straight alcohol.

I guess, I don't see how you can boost ABV without reducing your FG, aside from adding something with a higher residual FG.

...maybe I'm not understanding the math, ..add anything with an FG lower than 1.018, and you'll end up with something lower than 1.018. Only way not to change the FG is to add something with a 1.018 FG, right?

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You're correct. You're not changing the amount of residual sugars much, but the gravity will still be lower, since the liquid will be less dense.

TyTanium said:

Good point, but aren't you still diluting? Assuming it ferments 100%, you're essentially diluting with straight alcohol.

I guess, I don't see how you can boost ABV without reducing your FG, aside from adding something with a higher residual FG.

...maybe I'm not understanding the math, ..add anything with an FG lower than 1.018, and you'll end up with something lower than 1.018. Only way not to change the FG is to add something with a 1.018 FG, right?

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Strictly looking at the math:

You would only be diluting it with the volume that the sugar addition takes up. So if you add a pound of sugar dissolved in a quart of water, you can assume that you are essentially diluting 5 gallons of 1.018 liquid by adding a quart of 0.997 liquid (assumes that the sugar water will be completely fermented out) to so your new FG would be:

((5 gal x 1.018 SG) + (¼ gal x 0.997 SG)) / (5 gal + 1/4 gal) = 1.017.

You would have to add 3 gallons of 0.997 liquid in order to get to a FG of 1.010 (Note that you now would have 8 gallons of beer now). You can add the total amount of sugar to the original amounts, calculate the OG based on the final volume of 8 gallons, and figure out your ABV that way.

But you shouldn’t just look at the math. There are many variables that will make a beer taste ‘dry’ or ‘sweet’, including water profile, IBUs, flavor/aroma hops, etc.

The math is kind of funny though. Say I have a beer that finishes at 1.004 (which has happened) and I wanted it to come out around 1.012 for whatever reason, I never add enough malto dextrine to get all the way to 1.012. I usually add enough to go up .02 or .04 and it comes out nicely.

This is why I'm looking for someone with experience with this circumstance.

Yepp, I agree that you cant just look at the math. I don&#8217;t have any experience adding sugar to dry a beer out, but I have diluted a 4 gallon batch with about ½ gallon to make a slightly lighter beer. It turned out ok, but the beer had fermentation temperature problems to begin with so it definitely wasn&#8217;t an ideal beer.

I say you add about ¾ to 1 lb of sugar and see what happens (and report back here!)

I would advise substituting 10-15% of the extract with sugar. You won't reach 1.010, but it won't be as high as 1.018.

Let the yeast eat the maltose first, then during high krausen, pitch the sugar.

Petep1980, I have a couple of questions:

1. What was the expected FG range, based on your OG and yeast attenuation range?

2. Have you tried re-starting fermentation by adding yeast nutrient and shaking your fermentor to stir up the yeast?