8.10.1 - Free Amino Nitrogen in Wort by Spectrophotometry - Manual Method (IM)
The determination of the free amino nitrogen content of wort using colorimetry with ninhydrin. The method gives an estimate of amino acids, ammonia and, in addition, the terminal α-amino nitrogen groups of peptides and proteins. Proline is partially estimated at the wavelength used. The method is not specific for α-amino nitrogen since γ-butyric acid which is present in wort gives a colour reaction with ninhydrin.