Author Topic: Corn Sugar and FG  (Read 5408 times)


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Corn Sugar and FG
« on: November 25, 2008, 09:42:57 AM »
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?

Offline bonjour

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Re: Corn Sugar and FG
« Reply #1 on: November 25, 2008, 10:12:15 AM »
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.



  • Guest
Re: Corn Sugar and FG
« Reply #2 on: November 25, 2008, 10:25:39 AM »
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

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Re: Corn Sugar and FG
« Reply #3 on: November 26, 2008, 07:18:26 AM »
  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...

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  • Guest
Re: Corn Sugar and FG
« Reply #4 on: November 26, 2008, 11:12:24 AM »
Thanks for the reply Brad.



Offline Henway

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Re: Corn Sugar and FG
« Reply #5 on: December 11, 2008, 12:43:42 PM »
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....