A question regarding AA calculation in Beersmith

[beerocracy]

I'm surprised it would even attempt to guess final gravity due to the number of variables involved. Not just malt composition and yeast selection, but mash schedule, fermentation temperature, oxygenation, etc. That's probably why Wyeast & White Labs list apparent attenuation numbers for their yeasts as a range instead of a single value.

[mr x]

I guess my ultimate comment is that I think the AA% listed in JZ's BCS for Southern English Brown is wrong.

[jamilz]

The number in the book is correct. A couple of things you might consider. First is that you changed to a different yeast. Don't just assume that if the listed attenuation for a yeast is similar it will mean that the results are the same. This is one thing that bugs me. Someone changes the recipe and then says, "Gosh something must be wrong with the recipe." If you change the recipe, then expect different results.

The other thing you might consider is that you're using different ingredients, different equipment, and possibly you're not using the right amount of yeast or O2 or several other factors. What you should do, instead of thinking the number is wrong is look at your process and try to figure out why you're not getting the right amount of attenuation to make the beer turn out right. Adjust until you get the right numbers.

See what you've done now? You've got my panties in a bunch.

[SacoDeToro]

See what you've done now? You've got my panties in a bunch.

Does that mean you need some help getting them off?

[TapItGood]

Holy Crap! You've done it now. You went and got the Pope all riled up!

[mr x]

The number in the book is correct.

Correct as in what Promash calculated, or what you measured? If the AA is correct as to what Promash throws out, then you agree that all the specialty malts have the same fermentability as 2 row?

Ingredients are as close as I can get to yours. The specialty grains were ordered from Morebeer with no subs. One smack pack of yeast with 1 min of O2 should be right on the money, probably excessive for that gravity beer. Mah temp is very well controlled.

The reason I began looking at the software is because I looked at all the other components and they look right. Just trying to understand the nuts and bolts of this process. As opposed to just saying this is fucked up without trying to understand what is in front of me and how this stuff works.

[ziggy]

I think that there is a different way to account for the change in fermentability. If you compare 10 pounds of 2-row to 10 pounds of crystal 40 you have a potential yield of 370 points for 2-row and 340 points for crystal 40. So say your efficiency is 75%. That would give you an OG of 1056 for the 2-row and 1050 for the crystal 40. If you then were to use the same yeast on each batch that attenuated to 75% the batch with 2-row would finish at 1014 and the crystal 40 would finish at 1013.

I think the main factor affecting fermentability is mash temperature. If you were to up the crystal 40 to 11 pounds you would get roughly the same OG as with the 2-row and assuming you magically had the same enzyme action and mash temperature and the exact same fermentation with the exact same yeast that fermented the same i think the final gravities would be pretty darn close.

[mr x]

I think that there is a different way to account for the change in fermentability. If you compare 10 pounds of 2-row to 10 pounds of crystal 40 you have a potential yield of 370 points for 2-row and 340 points for crystal 40. So say your efficiency is 75%. That would give you an OG of 1056 for the 2-row and 1050 for the crystal 40. If you then were to use the same yeast on each batch that attenuated to 75% the batch with 2-row would finish at 1014 and the crystal 40 would finish at 1013.

I think the main factor affecting fermentability is mash temperature. If you were to up the crystal 40 to 11 pounds you would get roughly the same OG as with the 2-row and assuming you magically had the same enzyme action and mash temperature and the exact same fermentation with the exact same yeast that fermented the same i think the final gravities would be pretty darn close.

You think a mash of crystal 40 with the same OG as 2-row will yield the same FG? Everything I have read says the opposite. Maybe I'll enrol at Seibel to find out.