Behavior of Hop-Derived Volatile Thiols in European and American Flavor Hop Varieties over a Late Harvest Period

In this study, we applied the late harvest trial, previously tested on several hops harvested in Japan, to European and American flavor hop varieties harvested in Germany and the U.S., respectively. Hallertau Blanc from Germany is a 3S4MP-rich variety; Citra and Mosaic from the U.S. as 4MSP-rich varieties. The trials were conducted with samples from the standard harvest date (STD) and the days after the standard harvest date (+DAS). Hallertau Blanc was harvested at STD, +DAS 14, +DAS 20, and + DAS 30 in the year 2017. Citra and Mosaic were harvested at STD and + DAS 14 in 2017. As a result, in Hallertau Blanc, the level of 3S4MP increased both in the hop cones and in the test beer brewed with late harvest sample. In the sensory evaluation of the Hallertau Blanc trial, the “green” characteristic increased significantly in the hop water extraction by boiling (HWEB) sample of the late harvest hop cones and also in the test beer brewed with this hop sample. On the other hand, the changes of 3S4MP in the Citra and Mosaic hop trials were small and the late harvest method had little effect on the level of 3S4MP and the sensory impression of the HWEB samples and the test-brewed beers. These results suggest that late harvest is useful for 3S4MP-rich hops because of its increasing effect on the 3S4MP content in hop cones.