VIEW ARTICLE    DOI: 10.1094/ASBCJ-46-0014

Composition of Male Hop Oil. Gail B. Nickerson, Peggy A. Williams, and Alfred Haunold, Oregon State University and USDA-ARS, Corvallis, OR 97331. J. Am. Soc. Brew. Chem. 46:0014, 1988.

Although the male hop flower is of no economic importance, information about its quality characteristics is useful in breeding new hop varieties. The lupulin glands of male genotypes like those of female hops contain volatile oils. The terpenes myrcene and farnesene are not present in the oil of males. The sesquiterpenes caryophyllene and humulene are present, and the proportion of humulene/caryophyllene is a varietal characteristic in male hops. Cadinene, selinene, calacorene, and calamenene were also detected in male hop oil by gas chromatography/mass spectroscopy. Composition of the oil in lupulin glands was determined by direct injection of a pentane extract and compared with the steam-distilled oil of female hops cones. The oil composition of male genotypes from the U.S. Department of Agriculture hop germ plasm collection at Oregon State University showed a wide range in the proportion of humulene and caryophyllene. The male parent's humulene/caryophyllene ratio was shown to have an effect on the humulene/caryophyllene ratio of the female progeny of a cross.

Keywords: Humulus lupulus L., Male hops, Essential oil composition, Lupulin, Humulene, Caryophyllene