The specific extinction values for the most important bitter acids are determined.

No abstract

Simplified counter‐current distribution procedures are described which allow correct analysis of the α acids and iso α acids content of hop extracts.

A High Performance Liquid Chromatography (HPLC) method for automated routine analysis of the hop bitter acids is described. It allows the simultaneous determination of a-acids, /3-acids, cohumulone and colupulone. This analysis based on two chromatographic runs takes less than i h.With this new method as reference, the defects of existing conductometric titration techniques were studied and a new improved conductometric method based on toluene-buffer extraction was developed. The new methods are applicable to all forms of hop products containing a-and /3-acids.Analysis for a-acids with ether-acid aqueous msthanol extraction gives results which are too high because of several basic defects.

The results of new investigations on hop extract anal/sis are presented. The main findings are:(1) The specific extinction (257) of a-acids at 276 nm in iso-octane used at present in CCD and paper strip analyses is 3-5% too high: analytical results have therefore been too low. The new extinction value to be used is 248.(2) "the result of paper strip analysis depends very much on the amount of