Wednesday, April 11, 2012

Calculating Nitrogen/YAN/FAN in a batch of Mead/Beer/Wine

Okay, so as an extension to calculating PPM (my explanation of calculating PPM, Read it first if you don't already know about PPM) I wanted to explain how to calculate nitrogen additions to your brew.

I only talk about the Lallemand products here because they are just about the only guys out there who will tell us what's in their shit!  Seriously people, if they won't tell us what's in there we are going on FAITH and that's just as bad as grabbing a handful, walking 10 feet away then throwing it at the fermenter.  Whatever goes in is how much you add.  Does that sound right?  NO!




First some constants...
  • Fermaid-K = 13% YAN (Yeast Available Nitrogen)
  • DAP (Diammonium phosphate) = 21% YAN  (Yeast Available Nitrogen)
  • 1 teaspoon of Fermaid-K is roughly equivalent to 4 grams
  • 1 teaspoon of DAP is roughly equivalent to 3.9 grams
  • 1 Gallon = 3.785 Liters

So if you want to add 200ppm of YAN to your 5 gallon batch of mead do the following... Its just like in the PPM calculation article.  Go READ IT! 
  • YAN(mg)=200ppm * 18.93Liters = 3,786mg = 3.786g of YAN
  • What are you using to get there?  DAP/Fermaid-K?  For the sake of this example let's assume you want to use both at a 70/30 ration of Fermaid-K to DAP.  Fermaid-K=70% of 3.786g = 2.65g YAN from Fermaid-K.  DAP = 30% of the same 3.786g = 1.136g YAN from DAP.
  • Here's the rub.  You know how much YAN you need to add but that doesn't correlate to how much total you need to put in.  See?  Fermaid-K is only 13% YAN!  The solution is easy. More math...
    • 2.65g YAN from Fermaid-K which is 13% YAN. 2.65g YAN/ 13% = 20.39g Fermaid-K
    • 1.136g YAN from DAP which is 21% YAN.  1.135g YAN/ 21% = 5.4g DAP
  • So there you have it.  To get 200ppm of YAN in a 5 gallon batch using a 70/30 ratio of Fermaid-K to DAP you need to add 20.39g of Fermaid-K and 5.4g of DAP.
Notice I didn't even mention how I got to that 70/30 split?  Or how I didn't talk about why 200ppm was chosen?  Or when the additions should come, or how they may or may not be split up?  Yep, I noticed it too!

I'll write up more on that later.  In the meantime here are some links that you may want to read...





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