Wrong FG

Discussion in 'Recipe Editor' started by gokcenami, Feb 12, 2019.

  1. gokcenami

    gokcenami New Member

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    According to my recipe, the final gravity should've been 1015, but I measured 1010 on bottling day.
    I rechecked ingredients and yeast but everything is correct. No need to mention that there are no sugar additions.

    How is this possible?
    Fermentis/Safale Us-05 is a very common, popular yeast strain so the recipe should be correct.

    I added the full package because my recipe was a little high on original gravity, could this be the reason?
     
  2. Yooper

    Yooper Administrator
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    Attenuation depends on many things- simple sugars are more fermentable for example, and the software takes the average attenuation of the yeast strain chosen. If you are getting better attenuation than the average, you can add your attenuation in the box under "custom attenuation" and you should then get an accurate FG in the recipe builder.
     
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  3. Nosybear

    Nosybear Well-Known Member

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    It's likely either a) measurement error or b) you somehow got a highly fermentable wort. The calculations on this site are based on assumptions and standard equations - likely the assumption was off (estimated attenuation). It's not a problem with the recipe builder or its calculations. Brew a few more times, maybe the same batch, then see if your process is biased, that is, produces results off by similar amounts each time.
     
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  4. gokcenami

    gokcenami New Member

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    OK I entered a new attenuation value but it's %10 higher than normal. Difference seemed very high to me.

    OK but if I had more fermentable sugars out of my grain billl, wouldn't it give a denser OG?
     
  5. Nosybear

    Nosybear Well-Known Member

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    There's only so much potential sugar in the grain. A "more fermentable" wort simply means you converted more of the starches in the grain to fermentable sugars. OG remains the same, you have just balanced your wort more toward maltose than dextrines.
     
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  6. ChicoBrewer

    ChicoBrewer Well-Known Member

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    I experienced this phenomenon with my house Pale ale. It also uses Chico yeast. I adjusted the attenuation to match fg. Later I adjusted my mash temp up from 152 to 155. That put me back in the average attenuation ballpark. I also discovered that my thermometer was off by a couple of degrees and bought a new one. My mash was probably lower than 152 by a couple of degrees.
     
  7. Yooper

    Yooper Administrator
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    Exactly- a lower mash temperature means a more fermentable wort, while a higher mash temperature favors alpha amylase and will create a less fermentable wort. Neither is good nor bad- it's what you as the brewer decide your beer should be.

    Some ingredients are more fermentable than others as well.

    The calculator does a good job overall of estimating the FG, but since the attenuation range can vary quite a bit, even an average is an estimate and not necessarily highly accurate.

    The S05 strain has a pretty large attenuation range- from something like 71-81%, with the middle being the average so yours may be higher or lower depending on your mash and your ingredients.
     
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  8. ChicoBrewer

    ChicoBrewer Well-Known Member

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    It prolly goes without saying but don't adjust mash Temps to hit targets adjust them to make good beer. It just so happens that 155 makes my pale ale better IMO (and my opinion is all that counts in this case) :p
     
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  9. dmtaylor

    dmtaylor New Member

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    Did you ask the yeast why they fermented too far? What did they say?

    Seriously, though... Yeast is a living organism. They're going to do whatever they want, which might not always be what we want or expect.

    FWIW, US-05 gives me an average 83-84% attenuation. Not sure what your recipe assumed (I can't get the link to work) but my guess is that's the real problem.
     

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