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