P-58. Application of gallotannins to prevent gushing in beer and carbonated beverages

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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