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Old 07-09-2008, 03:06 PM   #1
GilaMinumBeer
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Default Estimating Predicted Fermentability?

Of the mash, then combined with the potential attenuation of a chosen yeast to estimate the final outcome of the beer.

How is this done?

I use software but have noticed that regardless of the mash temp I choose, it does not affect the final estimated gravity or alcoholic potential of the brew.

It's common knowledge that mash temperature determines the fermentability of the wort but, how do you calculate the estimated percentage based on gravity and temperature over time?

I assume that, once that figure is determined then it would be a simple matter of calculating the final gravity minus the attenuation potential of the yeast to determine if your brew will be malt forward or Dry.

Anybody know what I am talking about?

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Old 07-09-2008, 03:36 PM   #2
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Yes, and it's quite complicated. Do you have the batch analysis for your primary pale malt? You absolutely need this in order to begin.

Do you know the difference between Real Degree of Fermentation and Apparent Degree of Fermentation? Do you know how your yeast, your brewery's fermentation profile, and brewhouse characteristics impact RDF and ADF?

I can't speak for the software designers, but I suspect that the sheer complication of figuring your desired number has a great effect. Basically, the projected FG is based on a ballpark PPG from the grist, calculated through the average attenuation of the yeast strain chosen. It's hard for the software to know the amounts of unfermentables in your wort without your input, and it's hard for you to figure those numbers without laboratory analysis.

What you're asking for is basically impossible to do on the homebrew level. It requires reduction of variables to an almost ridiculous extent, best done in a well-equipped commercial brewery brewing the same batch over and over.

You dig?

I can try and gin up an approximation, but it's going to be fairly useless, I'm afraid.

Sorry I can't be more helpful!

Bob

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Old 07-09-2008, 03:44 PM   #3
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I pretty much figured this but, wanted to ask.

I assumed that if it was an relatively simple calculation, then the software would calculate for it but, wasn't sure if there was a tool available on-line to estimate degree of fermentability based on mash temp over time.

Thanks for the response anyway.

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