Lactose to beer, is there FG correction?

[70Cuda383]

just trying to do some calculations on a porter/stout that I'm trying out. I went big, and am shooting for around 9-10% ABV. trying to run some numbers to see my potential, but I added 1 lb of lactose to the wort during boil. since this is unfermentable sugar, I assume it's going to drive up the gravity readings, and mess with calculations.

is there an equation on how to "predict" what the final alcohol will be with lactose sugar in the mix?

 

[builderguy]

I'd like to know this too

 

[mccann51]

So you're wondering what the lactose contribution to the SG is, right?

 

[Yooper]

A pound of lactose in a 5 gallon batch adds .007 to the OG. And since it's unfermentable, it would add .007 to the FG as well.

 

[JLem]

The alcohol content will be the same as if you hadn't added the lactose - it doesn't ferment so doesn't add any alcohol.

 

[70Cuda383]

Right, but I don't know my FG, I can estimate it knowing the attenuation of the yeast, but not all of my OG will ferment out.

 

[Yooper]

Right, but I don't know my FG, I can estimate it knowing the attenuation of the yeast, but not all of my OG will ferment out.

But it the OG is seven points higher due to the lactose, and the FG is 7 points higher than the FG, it is easily estimated.

Say your actual OG is 1.070. But it would have been 1.063 without the lactose. The FG should be, say, 1.010. You'd add 7 points to that to account for the unfermentable lactose, for 1.017. ABV would not change as you'd still use the (OG-FG) x 131 = ABV formula.