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Determination of iso-alpha-acids, alpha- and beta-acids in isomerised hop pellets by HPLC - Submitted on behalf of the EBC Analysis Committee
Biendl, Virant, M., Varj, P.

For the production of isomerised hop pellets (iso-pellets) hop powder is admixed with a catalyst (e.g. MgO). After pelletisation and packaging under inert gas atmosphere this mixture is heated to approx. 50 C for 8-12 days. During this period alpha-acids are converted into iso-alpha-acids whereas beta-acids are not affected. Small residues of non-isomerised alpha-acids are present in iso-pellets and have to be considered for the application of this hop product in the brewhouse. Thus a method for the simultaneous determination of iso-alpha-, alpha- and beta-acids is necessary. The EBC Analysis Committee decided to test a combination of the methods EBC 7.7 (for sample preparation) and EBC 7.8 (for HPLC analysis). In the summer of 2003 a collaborative trial was carried out using five samples of isomerised hop pellets. Six members of EBC Analysis Committee and two members of AHA (Arbeitsgruppe Hopfenanalyse) participated in this collaborative trial.

BrewingScience - Monatsschrift fr Brauwissenschaft, 57 (July/August 2004), pp. 54-55