Sulfur Substances Of Hop Oils And Identification Of Hop Varieties - Advantages And Limitations

Sulfur compounds of hop oils are important components of hop oils although their share is relatively very small, approximately 1 %. A collection of 30 sulfur-containing volatiles was detected by gas chromatographic analysis of hop oils which were isolated from the hops by steam distillation. Thioesters S-methylthio-hexanoate, S-methylthio-isovalerate, S-methylthio-butyrate have been identified as the dominant components. It was found out that the composition of sulfur compounds of hop oils, examined on a set of 14 Czech hop cultivars, is varietally characteristic. Statistical evaluation using multivariate statistical methods has shown that the spectrum of sulfur substances can be used to determine the variety authenticity for only a few cultivars (Boomerang, Kazbek, Gaia, Vital). For other varieties it is not sufficient to distinguish them reliably. The analysis of sulfur compounds of hop oils must therefore be considered as an auxiliary chemotaxonomic tool. To determine the identity of the variety with greater reliability, it is necessary to use other chemotaxonomic tools (terpenic and oxygenated substances of hop essential oils, bitter substances, prenylfavononoids and polyphenols). Genetic methods are also an important approach at determining and identifying the purity of hop varieties.