Determination and verification of hop varieties by analysis of essential oils

The composition of essential oil in hops depends mainly on hop variety and less on growing, processing and storage conditions. Therefore the data on the composition can be used to distinguish between hop varieties. During the years 1998–2000, 78 samples of the commonly grown varieties in Slovenia were analyzed by gas chromatography. Research was focused on the selection of suitable components characteristic of the varieties in question. Since the changes in essential oil composition due to ageing are the most important interferences for determination of the varieties, these influences were successfully suppressed using the so-called indexes. Sixteen representative peaks were selected, indexes were calculated and processed by cluster analysis and principal component analysis. The developed method was shown to be effective on all hop varieties important in Slovenia and gave excellent results in daily laboratory practice.