Hop Utilization in the Brewery-An Interbrewery Comparison. Tove Jacobsen and Tore Hage, Brewing Industry Research Institute, Oslo, Norway, and Rune Kristensen and Karl E. Malterud, Department of Pharmacy, University of Oslo, Oslo, Norway. J. Am. Soc. Brew. Chem. 47:0062, 1989.

High-performance liquid chromatographic analysis of α-acids in hops and iso-α-acids in wort samples from six breweries showed that between 30 and 75% of the α-acids originally added to the kettle can be found as iso acids in the finished wort. The variations are mainly due to differences in equipment but are also influenced by the hop product used. In the range 10.5-13.5° P, no relationship between hop utilization and original gravity was found. Cluster analysis of samples from 14 breweries showed that wort or beer samples (three types of beer) could be divided into three groups with varied ratios of isocohumulone to other isohumulones. The chemical composition of the groups remained relatively constant from wort to beer. Classification of the samples did not correspond to the level of hop utilization in the respective breweries.

Keywords: α-Acids, Cohumulone, Hops, Humulone, Isomerization