Liquor in Beer, calculating and adjusting ABV and FG

[Irrefragable]

I have been collaborating with a fellow home brewer about adding different liquors to a couple of beers, but haven't been able to find much information about how much we can get away with adding on this or any other forum.

Adding a liquor such as whiskey will of course reduce the FG (whiskey is ~0.92), but it seems like this could be adjusted for by adding additional maltodextrine or lactose. By doing this it seems like one could get away with adding fairly substantial amounts of liquor.

As an extreme example, I have an imperial stout fermenting that should hit an FG of ~1.018 and have an ABV of ~7.9%. The math shows that addition of 1lb Maltodextrine and 45oz of Whiskey (ABV 43%, Gravity 0.92) should leave a beer with an FG of 1.021 and an ABV of 10%.
{All calculated in MS Excell}

While this example is abit extreme, it is a good illustration of the concept. I want the beer to have the extra ABV and the strong peaty flavor of the scotch I will be adding to it.

Does this reasoning seem reasonable, or is there something I am missing? I am aware that the volume of whiskey may overpower some of the other flavors of the beer. I am also aware that some recipes call for the addition of up to 16oz of different liquors, but have never seen anything as high as what my numbers propose.

 

[nebben]

I have done something like this with a fortified wine before. I first calculated what my adjusted original gravity would have been (I did syrup feedings during the fermentation process to allow the yeast to acclimate to high amounts of sugar/alcohol), and then measured the "final" gravity. By knowing the OG and FG, I calculated the approximate ABV % then plugged them into a Pearson's square calculator (http://winemaking.jackkeller.net/blending.asp). It will allow you to determine how much of any percentage of fortifying alcohol to add to reach a desired final blended ABV.

 

[dcp27]

Adding a liquor such as whiskey will of course reduce the FG (whiskey is ~0.92), but it seems like this could be adjusted for by adding additional maltodextrine or lactose. By doing this it seems like one could get away with adding fairly substantial amounts of liquor.

I wouldn't do anything to adjust for it. I'd just take my FG reading before adding the alcohol and then calculate your ABV based on the volumes, i.e. (19L * 8% + 0.5L *40%) / 19.5L = 8.82%

 

[BSBrewer]

+1 for dcp27's method...thats the same way I do it.

 

[Irrefragable]

Thanks for the quick replies.

Ideally I wouldn't need to worry about raising the FG with non-fermentables but this beer's OG was lower than optimal and depending on how much attenuation I get the FG may be near the bottom of the BCJP guidelines for the style (Russian Imperial Stout FG 1.03-1.018), even before the addition of the Scotch.

In the future I'll try to get a higher OG so I don't need to worry about adjusting the FG up.

 

[Irrefragable]

Duplicate post

 

[Calder]

Thanks for the quick replies.

Ideally I wouldn't need to worry about raising the FG with non-fermentables but this beer's OG was lower than optimal and depending on how much attenuation I get the FG may be near the bottom of the BCJP guidelines for the style (Russian Imperial Stout FG 1.03-1.018), even before the addition of the Scotch.

In the future I'll try to get a higher OG so I don't need to worry about adjusting the FG up.

How does it taste? I wouldn't worry about BJCP guidelines. You brewed it. you should be proud of it. Personally I prefer it dryer. I would be concerned about how the lactose would affect the final taste of the beer.

Just add the whiskey and not be concerned about the gravity.