what is unfermentable

i know lactose and splenda are unfermentable. sugars derived from crystal malt aren't as well. what else will the yeasties not eat?

i got curious about this because just about every brewing software out there i've seen never takes the fermentability of a grain/adjunct into account.

I dont think they will eat Stevia extract

TipsyDragon said:

i got curious about this because just about every brewing software out there i've seen never takes the fermentability of a grain/adjunct into account.

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I'm not sure if I follow you. This seems to be the main thing they do. It's how they estimate the OG and FG of a certain recipe.

ChshreCat said:

I'm not sure if I follow you. This seems to be the main thing they do. It's how they estimate the OG and FG of a certain recipe.

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Not Beersmith, that's for sure! It just estimates the sugar as a whole and estimates your FG NOT taking in to account any unfermentables.

Mashing at a higher temp will yield more unfermentables.

wyzazz said:

Not Beersmith, that's for sure! It just estimates the sugar as a whole and estimates your FG NOT taking in to account any unfermentables.

Mashing at a higher temp will yield more unfermentables.

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Seems to do it for me. I add grains and adjuncts and it changes the estimates. I change my mash temp and it changes again. The one thing it doesn't account for is the attenuation of the yeast. I made my saison and the estimated FG was WAY high.

Hmmm, maybe I'll have to shoot Brad an email to see if he takes this stuff in to account, inquiring minds ya know! I guess it's all just "best guess" either way.

ChshreCat said:

Seems to do it for me. I add grains and adjuncts and it changes the estimates. I change my mash temp and it changes again. The one thing it doesn't account for is the attenuation of the yeast. I made my saison and the estimated FG was WAY high.

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Fascinating, I just checked this out with my version of Beersmith
If I change the grains or adjuncts it re estimates the OG and FG, with the FG estimate being equal to the OG less the yeast attenuation.
If I change the mash temp, it doesn't change the OG or FG
If I change the mash thickness from 1 qt / lb to 2 qt / lb, it makes no difference to the OG or FG.
If I change the yeast to one with a different attenuation, it does change the FG estimate as determined by the attenuation of the yeast
If I adjust the extract yield of crystal to equal that of pale malt, and then replace 5 lbs pale malt with 5 lbs crystal, the OG and FG estimates are unchanged. I would expect this, because there is nothing in the grains and extracts database that indicates how fermentable the item is.

-a.

hmmm... fiddling around with my Beersmith I'm seeing some of the same things. I would have sworn that it changed the FG when I changed the mash temp in the past. Perhaps I should cut back on the peyote mead in the future.

Still, it's accounting for the fermentables in the items. How else does it calculate OG based on the malts you use?

ChshreCat said:

hmmm... fiddling around with my Beersmith I'm seeing some of the same things. I would have sworn that it changed the FG when I changed the mash temp in the past. Perhaps I should cut back on the peyote mead in the future.

Still, it's accounting for the fermentables in the items. How else does it calculate OG based on the malts you use?

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No, it doesn't account for the fermentables. It accounts only for the OG, and guesstimates the FG based on the yeast attenuation, without regard for the mash temperature, mash thickness, or grain characteristics.
I think that most brewing software can calculate the right OG (given the right information, and assuming that the brewer mashes successfully), but I'm not aware of any that can accurately predict the FG which requires knowledge of the mash thickness, mash temperature, and the fermentability of the grains used in the mash

-a.

wow. i seem to of sparked a discussion i didn't intend. i'm sure if you enter 1lb. of lactose per 5 gallons to a recipe the FG wont jump by the 7 points it should. while i always trust a calculated OG given by brewing software the FG is another story. i take it as a best guess.

ChshreCat said:

Seems to do it for me. I add grains and adjuncts and it changes the estimates. I change my mash temp and it changes again. The one thing it doesn't account for is the attenuation of the yeast. I made my saison and the estimated FG was WAY high.

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Alll beersmith does is take your OG, and multiply it by the average attenuation of the yeast selected.