Determination of amino acids in beer and wort
Free forms of amino acids in beer originate mostly from malt. The following method enables fast quantitative determination in beer and wort of the following free amino acids: arginine, lysine, tyrosine, phenylalanine, histidine, leucine and iso-leucine (total), methionine, valine, proline, alanine, glycine, cystine, tryptophan, aspartic and glutamic acids. Total content of amino acids is fdetermined after hydrolysis of proteins.
Free amino acids are transformed to phenylthiocarbamyl derivatives (PTC derivatives) by means of phenyl-isothiocyanate and their ionic forms are separated in the quartz capillary under the action of an electric field. The PTC derivatives are determined by measuring their own absorbance at 254 nm wavelength in a buffer solution.