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I've been searching around the net, asking in forums, even writing to Weyermann, trying to figure out what is the correct formula -- using a malt spec sheet -- to calculate the ppg value that I can use in recipes.

According to this article:

http://www.brewersfriend.com/2012/11/30/making-sense-of-efficiency-definitions/

.. I should basically account with moisture content (MC%) and extract fine grind value (DBFG%). However, this gives lower ppg values than is widely referenced for given grains. It feels as if all the other sources do not account for MC%..

For example, I have a spec sheet of Weyermann Pale Ale, where:

  • Moisture content = 4% max
  • Extract dry substance = 79% min

Using formula:

ppg = 0.46214 * DBFG * (1-MC) * 100

.. I calculate:

0.46214 * 77% * (1 - 4.5%) * 100 = 35.049

However, for the reference, there is an add-on feature in BeerSmith that allows to add custom malts and their Weyermann Pale Malt gives ppg as 38.

1) Does anybody know what is the really correct way to calculate the ppg?

2) I've seen all the malt specs give MC% as "max" and DBFG% as "min", but how can I know what is the range (maybe DBFG is in range of 79%..82%, which would make a big difference)?

Thanks in advance!

JB

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I don't think you can calculate this number. They report a max extract using a standardized lab test obviously. But then the rest is subject to too many variables for there actually be something to calculate. Its system and brewer dependent on what the ppg will be. I think your calcs are spot on as far as getting in the ball park. Maybe assume a 5-8% error up and down? But again it'll be dependent on your system, crush and process.

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  • Thanks brewchez. You are definitely correct that it's so much dependent on many variables. Simply already by the fact that people use generic 'Pale Ale' malt in recipes while Pale Ale can be so different depending on maltster. However what bugs me is why I'm getting so low ppg while the whole homebrewing world are using some pre-defined ppg values which are much higher? If I'd not use MC% then I'd get to the same similar result as generic ones, so it seems MC% is not accounted for. Is it right or wrong..
    – jbv
    Commented Apr 28, 2014 at 12:09
  • Also, the numbers can vary based upon the malt batch. You may be able to obtain a spec sheet specific to your grain bag by contacting the distributor or malting company. Otherwise, just use it as ballpark figures.
    – rlshep
    Commented Apr 28, 2014 at 21:05
  • What rate of efficiency are you getting? Do you see big variations across malt varieties? IMHO, crush, mash thickness, and sparge time all affect efficiency a great deal.
    – jalynn2
    Commented Apr 30, 2014 at 17:52
  • jalynn2, I used spec sheets of the exact malts I had and based my calculation as explained in original question. So on brew day, if conversion was complete, I should have got 100% conversion eff. However, in last brew, I got 118%.. If it would be less than 100% then I could try to look if my practice is not efficient, but as it's more than 100% it means the ppg data is not correct.
    – jbv
    Commented May 2, 2014 at 9:27
  • Just an update, the high conversion % was actually caused by the way how our brewing software calculates the efficiencies. The water amount we put in as input to algorithm needed to be tuned down by the change of volume from sugars.
    – jbv
    Commented May 20, 2014 at 8:21

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