Presenter: Niklas O. Brandt, Technische Universität Berlin,
Institute of Food Technology and Food Chemistry, Chair of
Brewing Science, Berlin, Germany
Coauthors: Thomas Kunz and Frank-Jürgen Methner,
Technische Universität Berlin, Institute of Food Technology
and Food Chemistry, Chair of Brewing Science, Berlin,
Germany
Carbohydrates are very important in human nutrition since they
are used in the food and beverage industries. In this study the
influence of fermentable and commonly used non-fermentable
sugars on oxidative processes and the formation of specific
aging compounds during beer production were evaluated.
In previous investigations, the reducing potentials against
Fe3+ of different sugars at low pH were determined using an
optimized Chapon method. These results were in conflict with
widely accepted general classifications of sugars into reducing
and non-reducing species. The properties of carbohydrates
at alkaline pH are well known, but in pH areas of wort and
beer the properties of carbohydrates change depending on
the type of sugar. For example, the so-called reducing sugar
glucose loses its reducing potential, whereby the reducing
capacity of sucrose rises because of an acidic hydrolysis
splitting and the strong reducing capacity of the generated
fructose at low pH ranges. The aim of these investigations
was to gain better insight into the influences of different
carbohydrates during brewing, with a focus on oxidative wort
and beer stability. Thereby, the influence of sugar additions
on aging compounds (oxygen indicator: 3-/2-methylbutanal)
were evaluated in wort and beer by GC-MS and compared to
the antioxidative potential measured via EPR spectroscopy
(EAP and T values), as well as reducing potentials against Fe3+
(optimized Chapon method) and SO2 contents. In correlation
with the measured reduction potential, the sugars show the
opposite effect on oxidative processes during wort boiling
by the formation of specific intermediate Maillard reaction
products with a reductone/endiol structure. An acceleration
of radical generation by the Fenton-Haber-Weiss reaction
mechanism and the formation of specific aging compounds
follows. On the other side, sugars raise the osmotic pressure
on yeast during fermentation, leading to higher sulfur dioxide
production, which could act as an antioxidant by scavenging
ROS and binding aldehydes in carbonyl complexes. The results
show that sugars influence the pro- and antioxidative system
of beer directly and lead to the suggestion for improvement of
beer’s shelf life by adding non-fermentable sugars just before
fermentation, so the negative effect on radical generation during
wort boiling can be avoided and the positive influence on SO2
formation during fermentation is utilized.
Niklas Brandt started his brewing career with an internship
in a craft brewery in Lower Saxony, Germany. Afterward,
he began an apprenticeship as a brewer and maltster at the
Brauerei Beck & Co. in Bremen (AB InBev Germany), which
he successfully completed (2007–2009). Since October 2009
Niklas has been studying brewing and beverage technology at
the Technische Universität Berlin. His bachelor degree study
was finished in April 2013, and he is currently working on his
master’s degree studies. In addition to these studies, Niklas
began research work in January 2011 as a student assistant at
the Technische Universität Berlin, Institute of Food Technology
and Food Chemistry, Chair of Brewing Science. It was here
that his bachelor degree thesis work, dealing with research on
sugars during brewing, was done. Niklas also works on the
EPR spectrometer and assists with different projects in the
laboratory and pilot brewery.
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