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Est Attenuation vs Yeast Max Attenuation

ryancanderson

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Hello. I have been following my brew with a tilt hydrometer (that I believe is within 1 or 2 pts). I am using dried Lutra kveik and it seems to have "stalled" at 1.010 FG. According to Beersmith 3, it expected to reach 1.005. Digging a little deeper, I noticed that the Lutra attenuation is supposed to be between 75 and 82%, meaning my 77.6% isn't out of the ordinary. This reassures me, but my concern is that Beersmith 3 used an estimated attenuation of 88.8% for a yeast that is max 82% according to the manufacturer. Is this working as intended? I read a note in the updated features that you modified how the attenuation calculated depending on our mash schedule, but does it not also take the max for the yeast into account? Thanks!

Cheers,

Ryan

P.S. I manually tweaked the max attenuation for the yeast in my recipe and it did change. It is taken into account in some way, but the estimated attenuation was still higher than the max.
 

BOB357

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BeerSmith relies heavily on user inputs in order to calculate values. Estimated values are only as accurate as the numbers you enter. Before entering your first recipe it's imperative that you create an accurate equipment profile and check to be sure that your measuring devices are accurate and/or calibrated. This includes double checking markings on vessels you use to measure volumes.

You can go into the database and check to be sure various values for individual ingredients are correct and change anything you find to be in error. In this case, select Ingredients/yeast to view all of the yeast listings. Enter the yeast in question into the search box and then double click on the entry to view details. Many of the ingredient entries come from other users and there is always a possibility of error. If you find an error, simply correct it.

Just to clarify your understanding of modifying estimated attenuation; every degree Fahrenheit can change the final gravity by ~.00125. Changes within a recipe don't carry over to the data base. There are other factors that affect attenuation as well, so don't be too quick to hang your hat on a single value.

There is quite a learning curve but, once you get the hang of it, you'll find BeerSmith to be the absolute best brewing software available. For specific information go to http://beersmith.com/support/ .
 

Oginme

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Ryan,

Adding some insight to Bob357's response, if you have any simple sugars in your recipe then the program will consider those inputs as 100% fermentable regardless of the yeast attenuation.  Attentuation ranges published by the yeast companies are performed on a standard, all-malt wort and process variables such as the fermentability of the grist, mash temperature, number and viability of the yeast cells, and fermentation conditions will change the actual apparent attenuation which the yeast exhibits.

Due to the impossibility of the program to account for every variable, I view the final gravity target as nothing more than an informed guess.


 

Kevin58

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Also consider that Krausen can build up on top of the Tilt hydrometer throwing off your readings. I never use mine to determine final gravity but just as an indication of when fermentation is complete.
 

ryancanderson

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Oginme said:
Ryan,

Adding some insight to Bob357's response, if you have any simple sugars in your recipe then the program will consider those inputs as 100% fermentable regardless of the yeast attenuation.  Attentuation ranges published by the yeast companies are performed on a standard, all-malt wort and process variables such as the fermentability of the grist, mash temperature, number and viability of the yeast cells, and fermentation conditions will change the actual apparent attenuation which the yeast exhibits.

Due to the impossibility of the program to account for every variable, I view the final gravity target as nothing more than an informed guess.

Thanks for the insight. I have a significant amount of flaked corn in the recipe and maybe that is skewing the number higher. I'll keep that in mind. I decided to pitch some champagne yeast to see if I can shave a few points off and dry it out even more.
 

ryancanderson

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Kevin58 said:
Also consider that Krausen can build up on top of the Tilt hydrometer throwing off your readings. I never use mine to determine final gravity but just as an indication of when fermentation is complete.

Thanks for the comment. I am aware of the krausen potentially affecting the reading of a tilt hydrometer and I haven't drawn off a sample to confirm yet. I did pitch some champagne yeast earlier today to try and dry it out even more and did notice little lumps of yeast floating on the surface everywhere, so it could just be a wrong reading.
 

Kevin58

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I would like to hear back to see what the champagne yeast has done. It is a pretty common story, even among some commercial brewers, that champagne yeast can be used to fix a "stuck" fermentation. But that has not been the case in my experience and those in my club. Our belief now is that all the simple sugars have already been consumed by the ale yeast and that the champagne yeast will have no better luck with the complex sugars that are left. Unless the FG difference is way off we don't even bother trying to "fix" it. It's beer and it will be what it wants to be. If it doesn't match our expectations then it is probably our expectations/calculations that were wrong to begin with.
 

jomebrew

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A friend dropped off a keg of DIPA that stalled around 1.040 from 1.092 starting.  He re-oxygenated the beer (yeah, really) and pitched more US-05. That helped a bit but stalled again around 1.032. He pitched Champagne yeast, I think it was Premier Blanc, which fermented down to 1.024.

The beer is rather dark and had some Belgian quad character and a noticeable sweetness.  Not a terrible beer but nowhere near a Double IPA. And, well, I wouldn't drink it.

I learned from the sour beer world, creating a starter from the target environment acclimates the yeast and gives a better chance of fermenting the beer to target final gravity.  So, I suggested next time he pitch an acclimated starter, made using some of the stalled beer and a little oxygen, into the stalled beer around 65F and let it go another week or monitor the gravity for changes. 

The Dogfish Head story of dumping stalled 120 minute IPA stuck with me. Sometimes you can't fix it and best to dump it and move on.

If you are going to try to fix it, understanding the science and biology will help you get further down the path. For example, while Champagne yeast can dry out a beer, putting it in a oxygen free stalled beer in an toxic alcohol environment will create off flavors and severely impact the yeasts viability.
 
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