Author Topic: Recipe Design - FG not changing  (Read 6274 times)

Offline roosmur

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Recipe Design - FG not changing
« on: November 17, 2011, 07:56:07 AM »
Hello

I am designing a recipe for a standard bitter. I am using British 2-row pale and some crystal malt as my grain, and have used quantities to get me to the OG I want and colour I want. I have got a decent hop schedule to get me to the bitterness I want, and I have the ABV I want. However, through this all, I am getting a FG of 1.008 (this is the Est Final Gravity field in BeerSmith 2). I want to increase this to around 1.011 by adding an unfermentable adjunct, like dextrin malt or maltodextrin. When I add this ingredient to the recipe, I am expecting to see my OG change, my colour change slightly, and perhaps my ABV% change slightly, but I am expecting to see my FG change for sure. I don't see a change in my FG. (I am trying to anticipate how much of this adjunct to use)

Any ideas?


Offline Myk

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Re: Recipe Design - FG not changing
« Reply #1 on: November 18, 2011, 07:11:15 PM »
It's a very huge failing of all beer programs as far as I know. Nobody allows you to set the fermentability of anything. The programs assume all sugar is fermentable and only rely on attenuation. It would be as simple as adding a box to tell the program to send X% of the gravity from that ingredient to the FG but nobody seems able or willing to do it.

Sure does make it hard to make beers with a lot of crystal or Sweet Stouts and you have to break out a calculator.

Whatever your OG goes up from the unfermentables add that to the FG and ignore what it says about the change in alcohol. So you want it go up 3 points, add enough to increase your OG 3 points and ignore the rest of what it tells you.

Offline BeerSmith

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Re: Recipe Design - FG not changing
« Reply #2 on: November 20, 2011, 08:53:55 PM »
Hi,
  I did improve the FG calculations in BeerSmith quite a bit - it now accounts for average yeast attenuation (per the strain you are using), mash temperature effects as well as high sugar use (which is much more fermentable).  However I've not yet added corrections for unfermentable adjuncts. 

  What I need is really good data on how that affects the FG for a given amount of adjunct - and I have not found that detailed data anywhere yet.

Brad
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Offline Myk

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Re: Recipe Design - FG not changing
« Reply #3 on: November 21, 2011, 09:43:19 AM »
Hi,
  I did improve the FG calculations in BeerSmith quite a bit - it now accounts for average yeast attenuation (per the strain you are using), mash temperature effects as well as high sugar use (which is much more fermentable).  However I've not yet added corrections for unfermentable adjuncts. 

  What I need is really good data on how that affects the FG for a given amount of adjunct - and I have not found that detailed data anywhere yet.

Brad

Not yet? Meaning it's planned? That would be nice, a sweet stout is in my tweaking stage and it's a pain guessing what tweaks to the unfermentables do when everything boosts alcohol too much and doesn't boost FG enough.

How about a box like for the yeast attenuation? That way the user can adjust based on experience. Maybe have it with an advanced setting warning.
If you tweak a recipe using your normal process and the Crystal 50/60 puts 80% of the tweak to the FG you could set that and teach BS how to handle 50/60 with your process.
I think Briess gives the fermentability of their extracts, they used to when I was extract. But even that should be adjustable by the user because when I went to partials I would give the enzymes time to work on the extract before heating it.

Offline dwb

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Re: Recipe Design - FG not changing
« Reply #4 on: February 23, 2012, 10:17:04 AM »
I'm glad I found this thread as this shortcoming has caused me to second guess a couple of recent brews.  I hadn't realized that BeerSmith2 didn't properly adjust for the unfermentability of certain malts and I've been waiting anxiously for a breakfast stout's FG to drop closer to the calculated number to no avail.  It seems that everything went properly, but the program's numbers are off and I can now at least account for this in certain brews.

If there are experiments that we as homebrewers can do to improve these calculations, I'd gladly volunteer to make small test batches and provide you (Brad) with data.

This is a VERY interesting blog post that shows that the math would be quite involved and dependent heavily on other base malts present in the mash.

http://beertech.blogspot.com/2011/03/crystal-malt-experiment-attenuation.html

It's specifically for Crystal, but it shows that something like a Crystal 10 will ferment nearly like a base malt when mashed with one.  I proved this myself with my IIPA recipe which uses a simple grain bill of 10lbs 2 row and 5 lbs Crystal 10.  It finishes out at around 1.011 despite 33% of the grist coming from crystal.

However, my aforementioned breakfast stout is sitting at 1.028 with a makeup of about ~20% specialty grains including crystal, roasted barley, chocolate malt, etc.  BeerSmith thinks it should drop to 1.018 which now seems unreasonable when I do a little more investigation.  Anyhow - cheers!

Offline tom_hampton

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Re: Recipe Design - FG not changing
« Reply #5 on: February 27, 2012, 11:43:04 AM »
That IS a very interesting experiement.  As you say, it highlights the complexity of the problem.  Repeat with alternate yeasts, at alternate fermentation temperatures and alternate base-malts (6-row, maris-otter, etc) and enzymatic availability, and various mash profiles and temperatures.  Then repeat for other specialty malts. 

Then do some pair-wise studies to determine if there are any interdependances between the above variables.  Then, fit it all to an equation of some sort.  Then you get to characterize the sensitivity of the model to error or year-to-year and/or maltster-to-maltster variation. 

Then go back and do it all again to verify the results.  Finally, publish PhD thesis...and go work for Charlie Bamforth.
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Offline Paindoc

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Re: Recipe Design - FG not changing
« Reply #6 on: March 11, 2012, 01:37:18 PM »
When I add maltodextrin to a recipe to add body Beersmith doesn't show a change in the OG either. On a recent weizen I made, just for curiosity I kept hitting the "increase amount" button all the way to 1 lb of maltodextrine (I was actually adding only 4 oz) without any change appearing in the OG or FG. Is there a glitch in my version of the software (2.0.57) that causes the OG to not reflect the maltodextrine addition either?

 

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