Sensory Characterisation of Dried Hop Cones for Specific Aroma Traits

Hops (Humulus lupulus) impart many of the specific flavours and aromas that define the style of beer. To develop hop selections that confer intense, desired or novel sensory characteristics to beer is a key objective of hop breeding research. This prompted investigations on the use of sensory evaluation of hop raw material, i.e. dried cones, as a tool for identifying promising cultivars early in the breeding and development process. In the first approach, dried hop cones from a large number of cultivars were evaluated by trained sensory panels for the intensity of citrus aroma. Data collected across two years showed a very large variation in intensity of that aroma across hop cultivars. While dried cones from most breeding cultivars exhibited relatively weak citrus aroma intensities, some attained higher scores than commercial selections included for comparison purposes. Overall, the sensory method provided robust information for selection of breeding plants with appropriate citrus-like aroma properties. In the second approach, dried cones from 41 hop cultivars were evaluated for the presence/absence of nine aroma traits (grapefruit, passionfruit, feijoa, banana, hay, ginger, onion/garlic, sweaty, and piney). The purpose was to identify cultivars with salient, specific aroma nuances that could be of interest to the brewing industry. Significant differences were established between hop cultivars in citation frequencies for grapefruit, passionfruit, hay, ginger, onion/garlic and sweaty aroma notes. Overall, the most salient aroma traits exhibited by each of the cultivars evaluated provided information for decision making regarding whether to pursue their development.