22. Bitterness assessment in dry-hopped beers based on sensory and analytical analysis

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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