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L 25
Isothermal and non-isothermal
decomposition kinetics of s-methylmethionin
L 26
Fermentable and non-fermentable
carbohydrates addition during
brewing - effects on palate fullness,
oxidative processes and formation
of specific aging compounds
L 27
Control of cereal flavor of beer by
changing the pH and amino acid
and reducing sugar composition in
wort during boiling
Yarong Huang 1 , Johannes Tippmann 1 ,
Thomas Becker 1
1Technische Universität München, Lehrstuhl für Brau- und
Getränketechnologie, Freising, Germany
Niklas Ole Brandt 1 , Thomas Kunz 1 ,
Frank-Jürgen Methner 1
1Technische Universität Berlin, Lab of Brewing Science,
Berlin, Germany
Shoko Inaba 1 , Minoru Kobayashi 2 ,
Kazuhiko Uemura 1 , Masayuki Aizawa 1
1Asahi Breweries Ltd., Department of Brewing Technology,
Moriya-Shi Ibaraki, Japan, 2 Asahi Breweries Ltd., Department
of Flavor and Chemical Analysis, Moriya-Shi Ibaraki, Japan
DESCRIPTION OF TOPIC:
Dimethylsulfid, which has a characteristic
taste and aroma of cooked celery, is one of
the most studied off-flavors in wort and beer.
Although there have been many kinetic studies
conducted with different wort boiling
systems under isothermal conditions, the
results are difficult to apply to the heatingup
process, in which the decomposition of s-
methylmethionin (SMM) also take place. And
it is not easy to define t=0 under isothermal
conditions. In this study the kinetics of thermal
decomposition of SMM was studied using
multiple dynamic measurements under isothermal
and non-isothermal conditions. For
both methods, the reaction mechanism (g(x))
follows first-order kinetics. The kinetic triple
(Ea, A, g(x)) obtained from the non-isothermal
method is compared with the results from
isothermal method. In order to predict the
formation of DMS and provide a better control
during brewing process, a kinetic model was
developed, which is applied to the heating-up
process and boiling process.
DESCRIPTION OF TOPIC:
Prior researches have shown unexpected reducing
potentials of different carbohydrates
at low pH of wort and beer. Additional investigations
were carried out to get a deeper inside
in the behaviour of sugars on oxidative
processes during brewing and beer storage.
In correlation to the reduction potentials,
sugars show an opposite effect on oxidative
processes in wort and beer. In dependence
to the sugar type an acceleration of radical
generation and formation of specific aging
compounds is detectable. The mechanisms
based on the generation of specific intermediate
Maillard products with reductone/endiol
structure and their strong reduction capacity
against metallic ions resulting in an acceleration
of oxidative processes caused by Fenton
reaction.
In case of commonly used unfermentable sugars
to get palate fullness heat stress during
wort boiling is disadvantageous. To avoid heat
effects and to use the positive effect on SO2
formation the addition prior fermentation is
suggested.
DESCRIPTION OF TOPIC:
An overabundance of cereal flavor can reduce
the drinkability of high-malt beer. In contrast,
the quality of low-malt beer is often reduced
by an insufficiency of cereal flavor. How ever,
other than changing the quantity of malt
used in the brewing, there is little knowledge
about the factors controlling the cereal flavor.
We found that cereal flavor is controlled by
changing the wort boiling condition affecting
Maillard reaction. Beer produced using wort
boiled at pH 4.0 had less cereal flavor than
that of beer produced by boiling the wort at
pH 5.2. More cereal flavor and higher levels of
flavor-active aldehydes were present in the finished
beer boiled at a higher pH. We also demonstrated
that the characteristic cereal-like
flavor of beer was affected by changing the
composition of amino acids or reducing sugars,
the Maillard reaction substrate, in wort.
We conclude that the cereal flavor in beer can
be controlled by altering the pH and the composition
of the wort during boiling.
Yarong Huang
Niklas Ole Brandt
Shoko Inaba
She studied Brewing Science and Beverage
Technology and graduated with a Dipl.-Eng.
Degree in brewing and beverage technology
from the Technical University Munich (TUM) in
the year 2009. Since December 2009 she has
been employed as a PhD student in the field
of brewing research to investigate the chemical
reactions of important process markers
during wort boiling processes at the TUM in
Freising-Weihenstephan, chair of Brewing
and Beverage Technology (Prof. Dr. Thomas
Becker).
Niklas Brandt has started his brewing career
with an internship in a craft brewery. In 2007
he began an apprenticeship as a brewer and
maltster at the Brauerei Beck & Co. Bremen
which he successfully completed in December
2009. Since October 2009, Niklas Brandt
studies Brewing and Beverage Technology at
the Technische Universität Berlin, which he
will finish in spring of 2013. Beside the study
he works as a student research assistant
at the Department of Biotechnology, Lab of
Brewing Science.
Received a MS degree in Agricultural Science
from Tohoku University, Japan, in 2006, where
she majored in Animal Microbiology. She joined
Asahi Breweries, Ltd. in April 2006. Since
January 2009, she has been working at department
of Brewing Technology, Reserch Laboratories
for Brewing.
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