PREPARATIVE REGIME FOR THE PURIFICATION OF BITTER ACIDS DERIVED FROM HOPS (HUMULUS-LUPULUS L)

The preparation of pure iso-cr-acids from hop-derived extracts is desc ribed. The method relies on the chemical separation of cis- and trans- isomers of the iso-alpha-acids, by the precipitation of the trans-isom ers with dicyclohexylamine (DCHA), followed by C-18 reversed-phase pre parative HPLC using a mobile phase of ethanol-water-glacial acetic aci d (60:40:0.2, v/v). The selectivity of ethanol as an organic modifier allows the purification of more than 500 mg of mixture per day. The ma terials are of high purity and suitable for research in the areas of s ensory analysis, foam behaviour and antibacterial activity.