Determination of Iso-Alpha-, Alpha- and Beta-Acids in Hop and Isomerized Hop Extracts: A Collaborative Trial

Submitted on behalf of the Analysis Committee of the European Brewery Convention

Abstract

A method, for the determination of iso-alpha-, alpha- and beta-acids in hop and isomerized hop extracts, has been collaboratively tested by members of the European Brewery Convention Analysis Committee and the Arbeitsgruppe Hopfenanalyse. The method, which relies on high performance liquid chromatography with a solvent programme, is recommended for use. It was judged that repeatability (r₉₅) values for alpha- and beta-acids were independent of concentration, whereas the value for iso-alpha-acids and reproducibility (R₉₅) values for alpha-, beta- and iso-alpha-acids were dependent on concentration. Values of r₉₅ and R₉₅ respectively were for: alpha-acids, 0.91 and -0.41 + 0.057 m, over the range 29.4 to 62.7% m/m; beta-acids, 0.67 and -0.20 + 0.119 m, over the range 8.5 to 20.9% m/m and iso-alpha-acids, 0.15 + 0.024 m and 0.39 + 0.073 m, over the range 3.3 to 81% m/m.