Presenter: Jan O. Schneidereit, Technische Universität Berlin,
Berlin, Germany
Coauthors: Thomas Kunz and Frank-Jürgen Methner,
Technische Universität Berlin, Berlin, Germany
The spontaneous overfoaming of carbonated beverages upon
opening a bottle without agitation is a problem that is wellknown
in the beverage industry. Although the decoding of the
occasion and mechanism of the “gushing effect” has been part
of several research activities, a complete explanation has not
been found yet. Numerous factors causing and contributing to
gushing have been discussed. A first step toward solving this
problem has been research to distinguish two types of gushing
based on the origin of the gushing inducer. On the one hand
there is malt-related gushing, known as primary gushing, which
is caused by fungal metabolites. On the other hand secondary
gushing is a consequence of technological faults during production.
An important role in the formation of primary gushing
is assigned to low molecular weight proteins, especially to
fungus-specific hydrophobins. These proteins are secreted by
various filamentous fungi. An important characteristic feature is
the presence of eight conserved cysteine residues that build four
intramolecular disulfide bridges. Furthermore, metallic ions
like iron could be identified as an important influencing factor
on gushing effect. Our previous investigations have shown that
these kinds of metallic ions are involved in haze-active protein-
polyphenol complexes and support or initiate the formation
of equivalent complexes with protein-polyphenol compounds.
The agglomeration of the described low molecular weight
hydrophobin proteins that are co-complexed with these kinds
of metallic ions are able to integrate and stabilize CO2 bubbles
because of their high hydrophobin surface activity. Upon
the release of pressure, the stabilized microbubbles, and in
consequence the absorbed oversaturated CO2, expand and rise.
Thereby, the bubbles entrain the surrounding liquid, resulting in
overfoaming of the beverage. For the prevention of this process
the responsible complexes of low molecular weight hydrophobin
proteins, including metallic ions, need to be reduced or
removed. An promising approach is reaction and complexation
with gallotannins, which belong to the group of hydrolyzable
tannins. Due to their chemical structure, gallotannins react
primarily with SH-group containing proteins like cysteine by
adsorption and precipitation. Thereby, the emerging complexes,
including the important gushing acting factors, can be removed
nearly completely during the clarification steps. The gallotannin-
protein complexes containing hydrophobin proteins and
metallic ions are removed completely by whirl pooling, maturation,
and filtration. Our studies have shown that the application
of specific gallotannins in the right quantity and dosing point
during the production or brewing process can be used to significantly
reduce or avoid the gushing effect in beverages.
Jan Ole Schneidereit started his brewing career with an apprenticeship
as a brewer and maltster at the Brauerei Beck and
Co. in Bremen (AB InBev Germany), which he successful completed.
Since October 2009, Jan Ole has been studying brewing
and beverage technology at the Technical University Berlin. His
bachelor degree studies were completed in June 2013, and he is
currently working on his master’s degree. In addition to these
studies, Jan Ole began research work in November 2011 at the
Technical University Berlin, Institute of Food Technology and
Food Chemistry, Lab of Brewing Science. It was here that his
bachelor’s degree thesis work, dealing with the application of
gallotannins to avoid gushing, was done. Jan Ole also works as
a student assistant at the Technical University Berlin, Institute
of Biotechnology, Laboratory of Microbiology.
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