https://phys.org/news/2019-01-craft-beer-cool-consume-fresh.html

Craft beer is not only popular in the US

Craft beer plays a big role in the U.S. beer market, but is also becoming increasingly popular in Germany. A strong hop aroma distinguishes many craft beers from mainstream beers. Brewmasters achieve the latter by an additional, late addition of hops to the young beer. This so-called "dry hopping" confers a substance with the complicated name 4-mercapto-4-methylpentan-2-one. Its odor is reminiscent of black currant berries. Just a few nanograms (ng) of the odorant per liter significantly influence the beer aroma. As previous analyses of the two scientists show, some new American hop varieties in particular contain larger amounts of this substance. These include varieties such as Citra, Eureka, Simcoe and Apollo.