New ways to determine bitter substances in beer and wort

The simultaneous HPLC determination of iso-alpha acids, tetrahydro-iso-alph a acids, alpha-acids and beta-acids is a valuable and reliable tool for the analysis of substances contained in beer. The content of unmodified and re duced bitter hop substances can be determined by means of just one single a nalysis. The used base-activated, cross-linked C18 separating column with a citrate-buffered (pH7) acetonitril methanol gradients as mobile phase make s complete separation possible within 60 minutes. An additionally developed isocratic method to determine iso-alpha-acids and isoxanthohumol in beer s amples permits working at more favourable costs and easy handling. The spec imens were prepared with a C8 fixed phase cartridge (SPE). Various beers an d hop extracts could be successfully analysed by this method. This method m akes identification of various beer and hop characteristics in respect of t heir acids and the corresponding isomers possible.