A question regarding AA calculation in Beersmith

[mr x]

Does anybody have any idea how Beersmith/Promash calculate AA?

For instance, my grain bill for JZ's Southern English Brown contains 6 lbs of 2 row, and 2.5 lbs of specialty malts. Jam the numbers into Beersmith with my wYeast strain, and it gives me an O.G. and an F.G., with the F.G looking like it's calculated from the Average AA for that yeast strain in the Beersmith database.

Now, if I use 8.5 lbs of 2 row in Beersmith, I get a slightly higher O.G. (.002 in this case), but if I use the same wYeast strain, I get almost the same AA (1% difference).

Shouldn't there be a bigger difference than that? Aren't 2.5 lbs of specialty malts pretty much non-fermentable (crystals, chocolate, etc). Shouldn't Beersmith calculate a significantly lower AA for the 2-row/specialty malt recipe in this example?

I look at the recipe I brewed (from JZ's book), with it's target AA, taste my sample, which I measured at 7% lower AA than the target and Beersmith calculation, find it's pretty good (that's the best I can do descriptively), and wonder, are the given AA numbers right?

[Sent From My iPhone]

I don't think it matters if the sugars are fermentable or not. A beer made with just 10 pounds of Pale Malt and 1 oz of hops will have almost identical IBUs as a beer made with just 10 pounds of Crystal 40 and 1 oz of hops. The first will ferment out drier than the second and have more percieved bitterness. I think...

[mr x]

I'm referring to Alcohol Attenuation, not Alpha Acid.

[Mylo]

I'm not sure if I am following your two examples fully. I also don't have my BeerSmith in front of me at work. That being said - BeerSmith does take into account the apparent attenuation of the yeast that you use. If you start with a 1.060 beer and you put in a yeast with 75% AA, it will estimate your FG at 1.015. If you change the yeast to one with an 80% AA, your estimated FG will be 1.012. If, instead of the yeast change, you added 2.5 pounds of 2 row - your OG would go up to 1.071 (assuming 65% eff) and your FG would be 1.017.


Mylo

[mr x]

Beersmith does take into account the potential S.G. of the various grains, but it does not seem to take into account the fermentability of those grains.

For example:

4.7kg of American 2 row and wYeast 1056 gives an OG/FG of 1.056/1.014

5kg of crystal 80L and wYeast 1056 gives an of 1.056/1.013

From my understanding, crystal malts have very little in the way of fermentable sugars, so how could you possibly get the same (essentially) F.G.?

Which leads me back to the recipe I had brewed (JZ's Southern English Brown). I'm using a wYeast VSS 1469, which looks to have the same attenuation profile as 1968 (69%). Beersmith says I should get the same FG, whether I use 100% 2-row, or a 64/35 ratio of 2row/specialty grain (as per the recipe).
Do you see where I'm going with this?

[Sent From My iPhone]

I'm referring to Alcohol Attenuation, not Alpha Acid.

Dammit, I've been teaching myself speed reading and apparently I suck at it

[mr x]

That's OK. Just work at your speed math and figure out that problem.

[Sent From My iPhone]

Beersmith does take into account the potential S.G. of the various grains, but it does not seem to take into account the fermentability of those grains.


Do you see where I'm going with this?

OK I re-read at normal human speed and you're right, it looks like Beer Smith doesn't take fermentability into consideration. Does Promash?