Willi Mitter (1); (1) Hopsteiner, Mainburg, Germany
Technical Session 6: Hops I
Sunday, August 14 • 3:30–5:15 p.m.
Plaza Building, Concourse Level, Governor’s Square 15
Triggered by the big success of U.S. craft brewers, dry-hopping has
become very popular worldwide. In many brewing trials over the years, we
gained a lot of knowledge in regard to analyses, tastings and
technology. This paper presents an overview of our practical experience
with our standard pale ale (14°P) as the base beer for the tests. After
primary fermentation, we split the basic brew into different storage
tanks, where we used different hop varieties, products and quantities.
By dry-hopping, IBU values clearly increase due to the alpha-acids and
humulinones, which are extracted from the hops during their contact time
in beer. The increase mainly depends on the quantities added and the
varieties used. Dry-hopping causes a loss in iso-alpha-acids; however,
humulinones seem to compensate this iso-alpha loss caused by
dry-hopping. Trials with hop oils and pellets used for dry-hopping
proved the bittering potential of humulinones as well. Numerous sensory
sessions with hundreds of tasters showed that IBUs in dry-hopped beers
do not correlate with the perceived bitterness. An alternative is the
determination of the contents of specific bitter compounds when
considering their bitterness intensity. We further investigated the
storage stability of hop-derived bitter substances in beer, which is
clearly temperature dependent. All bitter compounds degraded during
storage, with iso-alpha-acids being more stable than alpha-acids and
humulinones, respectively.
Willi Mitter was born in 1953. He studied brewing science and
technology of beverages at the Technical University of Weihenstephan,
Germany, and graduated as a Diplom-Ingenieur. From November 1979, he
worked as a technical assistant at the University in Weihenstephan. In
July 1980, he joined the Simon H. Steiner, Hopfen, GmbH company as
manager of the extraction plant in Laupheim. In July 1988 the company
moved to the Hallertau. Since then, Willi has been responsible for the
supervision of Steiner’s production facilities and for technical support
to breweries. In July 1994 he was appointed technical director with
oversight of the Technology Department, including R&D, technical
support to breweries and supervision of production facilities.
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