SEBASTIAN KAPPLER (1), Matthias Kern (1), Martin Krottenthaler (1), Thomas Becker (1)
(1) Technische Universität München-Weihenstephan, Lehrstuhl für Brau- und Getränketechnologie, Freising, Germany
Iso-α-acids are the major contributor to the bitter perception in
beer. They contribute to over 85% to the overall bitterness of
traditional beers. In the brewing process, however, only about 30% of
the α-acids present in hops are isomerized and transferred into the
finished beer. Although hop products cause only relatively little costs
for breweries, many of them try to reduce costs and economic
imponderability by saving in hopping technology. Several researchers
suggested a pre-isomerization of hop prior to wort boiling. Although
overall utilization rate could get increased by such technologies, the
negative influence to beer quality and the need of plant-specific
modifications has to be mentioned. In this paper, the influence of
several techniques, namely a subdivided hop dosage, grinding of hop
pellets prior to dosage, an increase in the pH value of wort, dosage of
CaSO4 or MgO, gassing of wort with CO2, hopping of
first wort, and dosage of silica gel, on utilization rate and beer
quality is shown. All of these technologies are possible nearly without
any reconstruction. It could be shown that an increase in hop
utilization can lead to an improvement or at least a maintenance of beer
quality. Pilot-scale trials were done to evaluate the influence of
various treatment technologies to sensorial and analytical attributes.
Particular attention is directed towards bitterness profiles of fresh
and forced aged beers. All trials were done with reference to common
brewed beers. The results presented in this paper provide a better
understanding of the conversions during the brewing process and its
influence on beer quality. Suitable approaches toward an improved yield
of bitter acids and an improved bitter quality are shown.
Sebastian Kappler received a Dipl.-Ing. degree in brewing and
beverage technology from Technische Universitaet Muenchen in 2008. He
began his employment with the Augustiner-Wagner brewery in Munich,
Germany, as an apprentice to a brewer and maltster in 2000. After
achieving the level of assistant, he started his studies on brewing
science at the Technische Universitaet Muenchen. Since 2008 he has been
working as a scientific employee at the Chair for Brewing and Beverage
Technology in Weihenstephan. The topic for his doctoral thesis is the
evaluation of the factors affecting the yield of isohumulones during
preparation of wort.
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