Direct thermal desorption-gas chromatography and gas chromatography-mass spectrometry profiling of hop (Humulus lupulus L.) essential oils in supportof varietal characterization

The use of direct thermal desorption-gas chromatography-mass spectrometry ( DTD-GC-MS) and DTD-GC-flame ionization detection (DTD-GC-FID) for character ization of hop essential oils is described. Four hop varieties (Nugget, Gal ena, Willamette, and Cluster) from the Yakima valley (Yakima, WA) 1998 harv est were analyzed by DTD-GC-MS and DTD-GC-FID methodology. Approximately 1 g of hops was needed for the analysis. Hop samples were prepared for GC-MS and/or GC-FID profiling in similar to 20 min. More than 100 volatile compou nds have been identified and quantified for each hop variety. The results w ere found to be in good agreement with conventional steam distillation-extr action (SDE) data. A calibration curve for determination of essential oil c ontent in hops by DTD-GC-FID has been generated. Quantitation of hop oil co ntent by DTD-GC-FID was shown to be in good agreement with conventional SDE data. The recovery of key ail components valuable for varietal identificat ion was demonstrated to be highly reproducible and characteristic of each v ariety analyzed when DTD-GC-FID was used for analysis.