Varietal Discrimination of Hop Pellets by Essential Oil Analysis I. Comparison of Fresh Samples

The aim of this study was to differentiate hop pellets by essential oil analysis. Volatile compounds of five aromatic cultivars (Styrie, Saaz, Lublin, Mount Hood, and Hallertau) and seven bitter cultivars (Northern Brewer, Nugget, Pride of Ringwood, Northdown, Galena, Target, and Challenger) were extracted with a Likens-Nickerson simultaneous solvent extractor. The extracts had a strong hop aroma that varied according to the type of hop. Approximately 100 compounds were separated by gas chromatography (GC) and identified by GC-mass spectrometry. An identification flowchart including seven terpenic compounds, four esters, and one methyl ketone was established to discriminate between fresh samples of the 12 investigated cultivars. High amounts of bergamotene and farnesene were found only in Saaz, Lublin, and Styrie samples. Quantification of 4-decenoic acid methyl ester and 3-methyl butyl isobutyrate proved a quick means of distinguishing non-European and European bitter hops from aromatic cultivars.

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