Technical Session 11: Brewhouse Operations Session
Sebastian Kappler, Technische Universität München, Institute for brewing and beverage technology
Co-author(s): Martin Zarnkow and Thomas Becker, Technische
Universität München, Institute for Brewing and Beverage Technology,
Germany
ABSTRACT: Iso-alpha-acids are the main contributors to
bitterness perception in beer. In the brewing process, however, only
about 30% of the alpha-acids present in hops are isomerized and
transferred into the finished beer. To reduce costs for hopping of beer
by an increase in utilization rate, several solutions have been
suggested over the past few years. Mostly either the use of
pre-isomerized hop products or a pre-treatment of hops prior to dosage
has been described. Formerly presented results showed a highly
significant decrease in bitterness quality and aging stability with the
increase in utilization rate achieved by isomerization of hops prior to
dosage. Probably due to a high amount of degradation products of alpha-,
beta-, and iso-alpha-acids, a harsh bitterness was created. Also, aging
stability was reduced due to polymerization reactions of hop and malt
polyphenols during thermal treatment of hop pellets together with common
lauter wort. It was obvious that further studies to increase the
quality of the resulting beer while using pre-isomerization technology
was necessary. In this work the influence of various technologies and
varying parameters for treatment of hop products was evaluated.
Pilot-scale trials, as well as industrial-scale trials, were done to
evaluate the influence of various technologies on sensorial and
analytical attributes, as well as behavior during aging of beer.
Particular attention was paid to the bitterness profiles of fresh and
forced-aged beers. All brews were analyzed in comparison to common
brewed beers. This paper presents solutions to increase utilization rate
while maintaining the quality of bitterness as well as aging stability.
Pre-treatment of hops can be enhanced by optimizing the time and
temperature of treatment while reactions are minimized, for example, by
optimizing the composition of the medium. The influence of the use of
different catalysts and lauter fractions, as well as variations in pH
value, is shown. Finally, the influence of variations in point of dosage
to the boiling wort is exposed. Suitable approaches toward an improved
yield of bitter acids together with an acceptable bitter quality are
shown!
Sebastian Kappler received a Dipl.-Ing. degree in
brewing and beverage technology from Technische Universität München in
2008. He began his employment with the Augustiner-Wagner Brewery in
Munich as an apprentice to a brewer and maltster in 2000. After becoming
an assistant he started his studies on brewing science at the
Technische Universität München. Since May 2008 he has been working as a
scientific employee at the Institute 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.
