Default Attenuation in Recipe Calculator

Discussion in 'General Brewing Discussions' started by burgerearl, Aug 17, 2014.

  1. burgerearl

    burgerearl New Member

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    Hi,

    I've put in a couple of recipes that use Safale US-05. The default attenuation is 72%, but the data sheet at Safale (http://www.fermentis.com/wp-content/upl ... A_US05.pdf) says 81%.

    Is there a reason for the lower number or is this a mistake? I'm a brand new brewer, but both batches I've done so far (both with US-05) have been much closer to 81% than 72%.
     
  2. Ozarks Mountain Brew

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    the default attenuation is just a safe estimate basted on all brewers, if you know your getting more you can change it in the custom attenuation check box by adding your percent
     
  3. sbaclimber

    sbaclimber Well-Known Member

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    What OMB said.
    Based on the differences in listed default attenuations (both here and from the manufacturers), I expected to have a reduced attenuation when I recently switched from WLP007 to US-05. *knock-on-wood* so far it has still been pretty high with US-05, and quite a bit higher than the listed default. (w/ 007 I was getting 87%+, w/ 05 still 85%+)
     
  4. burgerearl

    burgerearl New Member

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    Ah, I was missing this detail. Would populating the database with attenuations from the manufacturer's data sheets be a reasonable feature request?
     
  5. Ozarks Mountain Brew

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    also don't get Attenuation confused with efficiency just for fun here's a good start on what it really means

    quoting From Wikipedia, the free encyclopedia

    Attenuation (brewing)

    In brewing, attenuation is the percentage that measures the conversion of sugars into alcohol and carbon dioxide by the fermentation process. The percentage is calculated by comparing weight or specific gravity of the extract before and after fermentation.
    Attenuation = 100 % * (starting extract - current extract) / (starting extract)
    This formula works with extract given in weight percentages or degree Plato. Extract refers to all the non water substances (sugars, dextrins, proteins, vitamins, minerals, etc.) that are present in the wort. The percent extract or Plato scale is a measure in percent of how much of the wort’s weight is extract. Since, at least in the wort and beer gravities that most brewers work with, an almost linear relationship between (specific gravity - 1) and extract percentages exists, the above formula can also be expressed as:
    Attenuation = 100 % * (starting gravity - current gravity) / (starting gravity - 1)
    for brewers who prefer to work with specific gravity.[1]
    Real vs. apparent attenuation[edit]
    Because fermentation produces ethanol, which has a lower density than water (gravity of 0.787 at 25°C [2]), using the formula given above will give a higher value than the actual percentage of sugars consumed.[3] Brewers are generally referring to apparent attenuation when using the word without qualification,[4] though commercial breweries do concern themselves with the real attenuation—the actual percentage of sugar consumed by the yeast.
    Measurement of this value is important in brewing because it is an indicator of yeast health and because specific attenuation levels are important for certain styles of beer. A beer which does not attenuate to the expected level in fermentation will have more residual sugar and will thus be sweeter and heavier-bodied than planned.[5]
     

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