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Corn Sugar and FG

G

gxm

When I add Corn Sugar to a recipe, the FG goes up.  My understanding is that Corn Sugar is 100% fermentable, and since it ferments into alcohol, the FG estimate should actually go down.

As an example, create a recipe with 7 pounds Pale Liquid Extract.
The OG is 1.050 & the FG 1.013.

Add a pound of corn sugar, and the OG goes 1.059, and the FG increases to 1.015.
Since the pound of corn sugar adds about 1% alcohol, I would expect it to decrease the FG by 2 points.

Am I missing something?
 

bonjour

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Adding sugar should not change the FG, either up or down, since it is 100% fermentable.  Technically it may go down slightly since alcohol is lighter than water, but not up.


Fred
 
G

gxm

Perhaps I was not clear in my initial post.  My complaint is with Beersmith, not my beer.

According to my calculations, adding 1% by volume of 100% alcohol (SG 0.080) will decrease the FG by a measurable amount.
Say you have an FG of 1.010, so

(100 * 1.010 + 0.080) / 101 = 1.008
 

BeerSmith

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Hi,
  The FG estimate calculation is primarily a function of original gravity (estimate) and the average attenuation of the yeast.  It does not do an ingredient-by-ingredient analysis of fermentability.  I'm sorry to dissappoint...

Cheers,
Brad
 

Henway

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Sorry for hijack, but this is closely related.

Is there a way to have the corn sugar added to the ferment rather than the boil in BeerSmith?  It will obviously affect OG but hopefully not FG.  It also seems to ONLY allow addition at the beginning of the boil for the full boil duration.

Just a thought....
 
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