Selective removal of myrcene and improved utilization of alpha-acids by pre-incubation of aroma hops

Hisato Imashuku (1); (1) Asahi Breweries, Ltd., Suita, Osaka, Japan

BCOJ Symposium
Sunday, August 14  •  2:00 – 3:15 p.m.
Plaza Buiding, Concourse Level, Governor's Square  14

Myrcene is one of important aroma substances in hops and produces an undesirable grassy aroma. We have developed new equipment to remove myrcene selectively from hops and applied it to our brewery on a commercial scale. Before dosing at the end of wort boiling, aroma hops are incubated with hot water in a non-boiling state at 90-99°C. During incubation, myrcene is removed more rapidly than linalool. After incubating for 60 min, myrcene was reduced by 80%, but linalool was reduced by 20%. It is thought to be related to the difference in the equilibrium vapor pressure between myrcene and linalool. Therefore, characters of hop aroma can be modified in the final products. In the sensory evaluation, the aroma of the incubated hops was preferred to the control. Moreover, the isomerization of alpha-acids is also improved by incubation. The use of hops was reduced by 10-30% in these trials. The level of removal and isomerization can be regulated by time, temperature and concentration of hops during incubation.

Hisato Imashuku graduated with a degree in agricultural chemistry from the University of Yamaguchi, Japan. He began employment with Asahi Breweries, Ltd. in April 1989 as technical staff in the brewing section. After he had worked at several breweries and in the laboratory, he was transferred to the Production Technology Center in September 2001. He has been the senior technical investigator at Asahi since 2005.