3: Calculation of Free Amino Nitrogen Contents of Wort and Malt
Calculation of nitrogen contents of worts of different gravities.
1 Measure the free ammo nitrogen level in the Institute of Brewing
2 Ascertain from tables (reference 1 below) the appropriate concentration
of soluble extract in gm per 100 ml at 20° C for the Institute of
Brewing wort and for the defined wort.
If A = free amino nitrogen (mgs per litre) in Institute of Brewing
C1 = soluble extract in gms per 100 ml at 20° C for Institute of
C2 =soluble extract in gms per 100 ml at 20° C for the defined wort
Free amino nitrogen (mgs per litre) at the defined gravity
• The calculation can be simplified by taking C1 and C2 = excess
gravity of the Institute of Brewing wort and defined wort respectively.
• The same equation can be used to calculate total soluble nitrogen
Calculation of free amino nitrogen content as dry basis in malt
A x 0·5065 = mgs free amino nitrogen in 50 gms malt as is
mgs free amino nitrogen in
gms malt dry basis
where M = moisture content %
% free amino nitrogen in dry malt
Calculation of free amino nitrogen in total soluble nitrogen
% free amino nitrogen in total soluble nitrogen
where T = total soluble nitrogen in malt, dry basis.
The factor 0·5065 has been derived assuming that the volume of spent
grains in a 515 mls mash is 8·5 mls. Currently, when calculating
total soluble nitrogen the volume of spent grain is taken to be
15 mls. The error involved is not considered to be significant.
This anomoly has been brought to the attention of The Institute
of Brewing Analysis Committee.
Goldiner, F., Klemann, H., and Kampf, W. Rohrzucker, Alcohol, Stammewurke
and Korrektionstafel, 1966 Institute for Garungsgewerbe, Seestrasse
13, D-l, Berlin N65, Germany.
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