Final Gravity and Attenuation

Discussion in 'General Brewing Discussions' started by ChicoBrewer, Nov 22, 2018.

  1. ChicoBrewer

    ChicoBrewer Well-Known Member

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    This is something I have been thinking about for a while. I typically try to "copy" a recipe I find from craft brewer and other sites. It's easy to hit the OG by adding malt however hitting the FG is nigh impossible. Today I was trying to duplicate the SN Resilience recipe. My recipe comes out 5 points lower than the published recipe. This is pretty typical for me. Today I copied Ozarks Resilience recipe while I was creating my own. I was puzzled as to why his recipe was nailing the FG while mine was significantly under. Then I noticed he was using a custom attenuation. My brew sessions typically come out under the recipe editors calculated FG. For instance the Pale Ale recipe I have made five times has a target FG of 1.010. I typically hit 1.008.

    It seems that all of the "push" is to improve attenuation. Adding oxygen and yeast nutrient . . .

    My question is how do you leave more sugar in the final product? I hate to say it but adding a custom attenuation to hit a final gravity looks like cheating unless there is actually a way to decrease it in the real world.

    Wine makers stop fermentation by adding Sulfite. Is there a way to do this in the brewing world?

    What say ye brewers?
     
  2. BOB357

    BOB357 Well-Known Member

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    Mash temp, within reason, can be used to reduce attenuation without making a discernable difference in perceived flavor or body. A more flocculent yeast can do the same if fermented at the lower end of its range.
     
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  3. Trialben

    Trialben Well-Known Member

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    And reverse if you want less attenuation obviously a lower attenuating yeast. 2 points under FG isnt too bad mate! I'd take that as a win:). Maybe you could add carapils or more caramel malt to create less fermentables in the mash coupled with a high alpha amelayse mash using same yeast I recon you'll be Finnishing higher for sure! I've not tried this myself BTW but in theory it sounds correct...:rolleyes:
     
  4. Yooper

    Yooper Administrator
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    Agreed with all the above points!

    I did want to point out that winemakers do NOT use sulfites to stop fermentation- they use sulfites as antioxidants and to inhibit bacteria. Wine yeast is very tolerant of sulfites, that's why winemakers can use them without inhibiting the yeast.
     
  5. White Haus Brews

    White Haus Brews Active Member

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    Yeast attenuation is based on so many different things and even the assumed average number is just an average of many different results. Yes higher mash temp and using less fermentable malts could lead to a higher FG, but I'm not sure that's a good goal in and of itself unless it also helps the flavor of the final product. Once you know how a particular yeast responds to your recipe and brewing process, using a custom attenuation would seem to be the smartest thing to do IMHO. Cheers!
     
  6. sbaclimber

    sbaclimber Well-Known Member

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    #6 sbaclimber, Nov 23, 2018
    Last edited: Nov 23, 2018
    +1
    I have my standard-recipe + process pretty much dialed in and I use custom attenuation. As long as I don't change anything dramatically, it remains pretty spot on.
    Important is consistency....
     
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  7. ChicoBrewer

    ChicoBrewer Well-Known Member

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    Thanks for everyone's reply. Couple of things. As I said before, I have a recipe that I have made several times. I mostly nail the parameters for OG and mash temp. The yeast I am using is US-05. The published "Apparent Attenuation" is 81%. I routinely get 85.7%. If I plug my "custom" (85.7) attenuation the FG is dead on. So the "model" works. My question is - why do I consistently have a higher attenuation than the published one? I am mashing at 152. That seems in the mid to high range.

    @Yooper - I recently made an apple cider that I back sweetened with frozen apple concentrate. I added Campden and potassium sorbate to it. I thought it was to stop the yeast from fermenting the additional sugar. Is that not correct?
     
  8. Yooper

    Yooper Administrator
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    Yes, that's correct. But it's the sorbate that inhibits yeast reproduction. It doesn't kill yeast, but inhibits yeast reproduction so in a cider that has most of the yeast out of it, the sorbate will keep fermentation from restarting. It's not the sulfites that do this.
     
  9. Nosybear

    Nosybear Well-Known Member

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    If you're mashing in a cooler, all you know is the point at which you take your temperature is 152. There will be "hot" and "cold" spots in the mash. So while the "core" of your mash might be 152, the "edges" could be in the low 140's. But it looks like you've found the answer in custom attenuation. If your beer's body and "sweetness" are satisfactory, you've solved the problem.
     
  10. Hawkbox

    Hawkbox Well-Known Member

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    Yeah probably not worth stressing to hard about. My mash cooler holds heat quite well but as said above, there is no way to guarantee consistency.
     
  11. Ozarks Mountain Brew

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    I just use the custom attenuation to reflect what I normally get as a final gravity, most of the yeasts from fermentis are set too high, I always rate it at 78% for my brews and always hit my mark, you really have to know your equipment and set the recipe editor to match, we are making it more customizable for everyone today because of the wide range of brewers we have
     
  12. White Haus Brews

    White Haus Brews Active Member

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    Just out of curiosity have you double checked with another thermometer or calibrated the one you're using?
     
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  13. ChicoBrewer

    ChicoBrewer Well-Known Member

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    Uhhh. I just checked my glass stick thermometer and my digital.

    Stick reads 30F in ice water and 214F in boiling water
    Digital reads 32.3 in ice water and 213.5 in boiling water

    This is in DI water at 200F elevation in Chico.

    Funny thing is I always trusted the stick.

    Anyone have a recommendation for a good mash thermometer?
     
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  14. Head First

    Head First Well-Known Member

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    Sometimes in the glass lab type thermometers some of the liquid gets stuck in the top of the unit. I have one that consistently reads 2 degrees f low. Would not explain boiling temp though. Was that just as it began to boil?
     
  15. ChicoBrewer

    ChicoBrewer Well-Known Member

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    It was boiling for a while. Temp jumps all around on both in boiling water.

    I just bought this one. Looks pretty good and has a long probe which is why I like the stick. I have had the stick for many years. I used it when I had my 125 reef aquarium.
     
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  16. thunderwagn

    thunderwagn Well-Known Member

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    Looks like a good choice. I know the regular digital CDN comes highly recommended and will be my next one if the thermometer I have currently ever dies lol.
     
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  17. BOB357

    BOB357 Well-Known Member

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    Yep. Been using that one for close to a year now with good results. I like the accessories that come with it. Haven't used any of them yet, but they are a nice addition.
     
  18. Ozarks Mountain Brew

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    the only issues with those cheap new products and I've had a few, don't let anything plastic get too hot, even steam, that's the down fall of those cheap china products, the quality of the materials
     
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  19. BOB357

    BOB357 Well-Known Member

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    Yep. This even comes with a 2" round cup like guard that you slip the probe through if it's going to be used over a boiling mass. I have dropped it into strike water a couple of times with no ill results, and am aware that plastic and heat sometimes aren't a good match. Lots of American products are made with Chinese parts, so are suspect as well.

    I worked for a company that advertised, "Made in America, with internationally sourced components". :)
     

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