Flavor Activity of Sesquiterpene Oxidation Products, Formed Upon Lab-Scale Boiling of a Hop Essential Oil–Derived Sesquiterpene Hydrocarbon Fraction (cv. Saaz)

The “kettle hop” aroma, a most complicated flavor characteristic of conventionally hopped lager beers, has been associated with hop essential oil–derived oxygenated sesquiterpenoids. In this study, an oxygenated sesquiterpenoid fraction, mainly consisting of sesquiterpene oxidation products, was obtained by lab-scale boiling of a varietal sesquiterpene hydrocarbon fraction (cv. Saaz), and its volatile fingerprint was characterized analytically via headspace solid-phase microextraction GC-MS. Addition of this fraction to nonaromatized iso-α-acid-bittered beer resulted in a shift of the flavor profile in favor of woody, spicy, and hoppy notes. GC-olfactometry analysis of the sensory-relevant oxygenated sesquiterpenoid fraction revealed two zones that were clearly flavor active,the first zone containing humulene epoxide III, humulenol II, and caryophylla-4(12),8(13)-diene-5-ol, and the second zone comprising (3Z)-caryophylla-3,8(13)-diene-5-ol (α and β) and 14-hydroxy-β-caryophyllene. These compounds are candidate key impact compounds for kettle hop aroma. Although the oxygenated sesquiterpenoid fraction was created offline, the fraction shows potential relevance to brewing practice.status: publishe