Geraniol, a compound closely associated with the aromatics of several favorite American hop varieties. It is essential oil found in some hop cultivars. Geraniol is classified as a monoterpenoid alcohol and is a primary component of rose oil, palmarosa oil, and citronella oil. In hops and beer flavor– related chemistry, it is characterized by rose-like, floral, and citrus fruitlike aroma and flavor. Geraniol is also found in coriander, lavender, lemon, lime, nutmeg, orange, rose, blueberry, and blackberry. When oxidized, geraniol becomes geranial or citral. It is found in Cascade, Citra, Centennial, Chinook, Pacific Hallertau, Southern Cross, Motueka, Aurora, and Styrian Golding hops. It is not found in UK Challenger, U. S. Challenger, Alsace Strisselspalt, Spalt Select, Sterling, Czech Saaz, Millennium, or German Magnum. Interestingly, people have differing abilities to perceive geraniol; this difference is thought to be genetically based. One-third of the population has a perception threshold of about 18 μg/l, whereas the remainder of the population has a threshold of around 350 μg/l. Geraniol is also an effective repellent of mosquitoes and is used in many DEET-free repellent preparations. Victories in that regard may be pyrrhic, however, because geraniol is also an attractant of honeybees.
