The Influence of Hop Harvest Date on Hop Aroma in Dry-Hopped Beers

The aim of this work was to investigate the influence of hop harvest date on the sensory properties of a dry-hopped lager. The selected harvest dates encompassed a period of 24 days, from a very early (date 1) to a very late (date 5) harvesting date. Analysis of the hop samples confirmed an increase in hop oil and alpha-acids over the harvest season. On average, the alpha-acids contents of hop samples from date 5 were 28% higher than those from date 1. The hop oil contents of hops harvested on date 5 were on average 30% higher than those harvested on date 1. This increase over the harvest season is not only of importance for brewing and dry hopping but is also an economic factor for breweries. Not only were the late-harvested hops rated better in aroma quality, the beers brewed there from were also rated better when late-harvested hops were used. Profiling of the beers showed that some hop characters developed with later harvest dates, while other characters decreased with later harvest dates. The beers containing hops harvested at later dates were also rated better when using a modified version of the DLG tasting scheme, which did not focus on hop characters but on the fulfillment of general beer parameters, including aroma, taste, body, and bitterness. Triangle tests of the beers revealed that not only the harvest date was a significant influence on sensory distinguishability but also the crop location. This was proven for all four crop locations, although the distance among the locations was only 1.2�24 km. These findings reveal the sensitivity of dry-hopped beers, as many of the characteristics of the raw hops used were transferred to the finished beers.