Final gravity & mash temperature

Discussion in 'Recipe Editor' started by Myers, Nov 7, 2013.

  1. Myers

    Myers New Member

    Joined:
    May 20, 2013
    Messages:
    18
    Likes Received:
    3
    Trophy Points:
    3
    On the Editing Recipe page, changing Temp under Mash Guidelines doesn't chage the Final Gravity calculation. Apparently, it is not a dynamic factor for BF's outcomes calculations. My question is, why isn't it, considering that mash temp does have a significant affect on final gravity?
     
  2. LarryBrewer

    LarryBrewer Active Member

    Joined:
    Jun 27, 2012
    Messages:
    1,728
    Likes Received:
    9
    Trophy Points:
    38
    Location:
    Portland, Oregon
    There are many factors that play into FG and attenuation - yeast strain, yeast pitch rate, yeast health, fermentation temperature, grain bill, mash profile, etc etc.

    The way to control the FG in the recipe editor is to change the yeast attenuation. In the yeast section there is a checkbox for 'custom attenuation', and from there you can adjust it. This keeps it simple, and puts the brewer in control.

    Trying to approximate it with an equation would likely lead to a slew of new questions - why is my FG low in case X, why is my FG high in case Y...

    You are encouraged to start a thread in the feature request forum. We'd want to consider all cases and do it comprehensively if we did build it in.
     
  3. bierandbikes

    bierandbikes New Member

    Joined:
    Nov 16, 2012
    Messages:
    2
    Likes Received:
    0
    Trophy Points:
    1
    Location:
    Fredericksburg, VA
    I located this question and answer as I also was curious about FG and how you calculated that number. Using avg attenuation makes sense but does not account for a multitude of other variables. Is there a guideline or graph or complex equation that the brewer could use to estimate the potential attenuation for a specific grain bill, mash temp/time, yeast combo (realizing that many other variables are present with regard to pitching rate, water profiles, yeast nutrients, etc.)? Another helpful bit of information may be how the yeast suppliers calculate the attenuation numbers as many brewers achieve much higher attenuation.

    Thanks for the great resource.
     
  4. Myers

    Myers New Member

    Joined:
    May 20, 2013
    Messages:
    18
    Likes Received:
    3
    Trophy Points:
    3
    From my playing with the various factors presented by BF's Recipe Editor (Fermentables, Pitch Rate, Ferm Temp, Yeast Type), the only factor that seems to affect BF's calculation of FG is Yeast Type, for which BF selects the average attentuation for the yeast type selected.

    The use of different Fermentables (i.e., grain bill) don't seem to affect the BF's calculation of FG; for example, listing a crystal malt instead of a pale malt does not affect FG as long as the two grains' PPG contributions to OG are the same -- in other words, BF for FG calculation purposes seems to treat all types of grains the same and doesn't seem to differentiate among them in terms of their fermentability (i.e., BF apparently assumes all are grains are equally fermentable).

    In his book "How To Brew" (page 86), John Palmer states: "There are three principal factors that determine fermentation activity and results: yeast, wort nutrients, and temperature." He also states (page 63): "Attentuation is not entirely up to the yeast. The fermentability of the wort, as determined by the brewer, sets the limits to which a particular yeast may work."

    In my most recent post (as of now, yet to be posted), I suggested the possibility of BF employing mash temperature as a factor affecting BF's calculation of FG, which, as Mr. Palmer points out in his HTB book (page 149-150), does have a quantifiable affect on FG.
     
  5. LarryBrewer

    LarryBrewer Active Member

    Joined:
    Jun 27, 2012
    Messages:
    1,728
    Likes Received:
    9
    Trophy Points:
    38
    Location:
    Portland, Oregon
    The exception is Maltodextrine and Lactose - these two popular non fermentable sugars add directly to both OG and FG in the recipe editor.
     

Share This Page

arrow_white