problems with estimated FG/ABV

I've noticed two seperate problems with estimated final gravity.

1. If you have a recipe and you add your first yeast, it ignores attenuation of subsequent yeasts.  For example you add a lower attenuation yeast like WLP002 first and then add WLP001 it only uses the WLP002 to estimate FG.  It should be using the highest attenuating yeast for this calculation.

2. If you select a mash profile such as 'BIAB- Pilsner step mash' it seems to show that you will have the good attenuation expected in the estimated final graviy.  The problem is if you have 2 temperatures in the step mash that are both in the saccharification range, the estimated final gravity and estimated abv ignore the lower temperature part of the mash.  For example you have one step at 145F for 60 minutes and another step at 155F for 10 minutes, it bases the FG estimate only on the 155F step.

Thanks,
  I'll make note of item (1) and try to correct that.  Item (2) I actually did correct for an upcoming version of BeerSmith which should be out this fall.

Brad

Oh man, please do fix this.  It has bugged me for the last year.  I've just been using the 'measured OG/FG' fields to at least have some way to estimate the ABV prior to fermentation while trying to design a beer.

I do a lot of temperature raising in mashes for my lagers from 133, to mid 140s and midtoupper 150s... beer smith doesn't seem to be able to handle it.  I also like to do Hochkurz decoctions, but again I don't know if Beersmith is able to estimate the efficiency/FG when I have all of these crazy raises in place.

However just to temper the above feedback, I REALLY love this software and all it has done for me and everyone else out there.  Please keep up the great work!

Hi,
I sent a support request via your website earlier today. This is a follow up. I?m using BeerSmith 2.3.7.

Using my hochkurz profile, I cannot get predicted FG below 1.020. As you can see in attached screen grabs, the current profile estimate is FG 1.020 and therefore the ABV is only 5.9%. This appears to be a bug, since using the same temp and time with a single infusion profile (145*F, not 148*F) yields FG of 1.009 and ABV of 7.3%. IMO, these values should be quite close to each other. Please advise.

Regards,
Tom

BeerSmith said:

Thanks,
I'll make note of item (1) and try to correct that. Item (2) I actually did correct for an upcoming version of BeerSmith which should be out this fall.

Brad

Click to expand...

Replying to this old thread because it is the closest to what I'm looking for.

Using BeerSmith 3 and find that it underestimates FG significantly for the following full-bodied mashing profile.
60oC for 10min (mashing in)
70oC for 50min (infusion)
78oC for 5min (mashing out)
Calculates FG to be ~1.007, while it measures at ~1.016 (have 3 different datasets for this). OG is calculated accurately at BHE of 68%.
If I delete the 60oC step in the profile it calculates the correct 1.016 FG. It therefore overestimates the effect of the initial 60oC step.
I use 60oC mash-ins for all my profiles (dry, balanced & full) to improve non-enzymatic gelatinization and maximize initial B-amylase activity.

Anything I can adjust on my side to keep the correct mashing profile and get an accurate FG?

Thank you in advance.

Calculating the final gravity is always a hit-or-miss situation. Like all programs I have looked at, the equation for the fermentability of the wort used does not take into account rest time nor the effect of subsequent rests. It uses the first rest temperature within the saccharification range of the starches as the basis for the FG calculation.

I have not found a way around it, so I just don't worry about it and brew how I want. I know approximately where I want to be at the end of the fermentation for final gravity and go by that as my target.

Bioengineer said:

Anything I can adjust on my side to keep the correct mashing profile and get an accurate FG?

Click to expand...

You can eliminate your 60 C mash step. With most malts that is not necessary, so unless you are using some oddball malt you can just skip that step. Mashing in the normal range of 64 C - 69 C will give BeerSmith a better chance at estimating your fermentability. For my normal mash temperatures of 64 - 67 C I find that BeerSmith predicts my final gravity within a couple of points, which is close enough for me.

--GF

Thank you Oginme & GigaFemto for your responses. In the meantime, I saw that only the full-body profile with the high mashing temp (70oC) gives this aberration. I'll just omit the 60oC step in the software when I use it.