Gushing, also known as fobbing, is a problem that has been linked to multiple sources, including Fusarium infection in grain used in the production of beer. After comprehensive research on raw materials spanning many years, no single substance has yet been identified in a measurable quantity in malt infected with Fusarium, which can clearly be linked to gushing behavior in the finished beer.
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Current research is exploring different groups of substances (proteins and hydrophobins) that are present in greater quantities in kernels infected with
Fusarium [1].
In reproducible laboratory tests as well as in commercial beers, it has been proven that porous or sharp-edged particles (approx. 1–10 µm in diameter) such as calcium oxalate, calcium carbonate, crystallized dextrins as well as filter aids (diatomaceous earth/kieselguhr, perlite, activated charcoal) can cause gushing if present in certain concentrations [2]. Additionally, poor glass quality (rough interior) can also bring about gushing. Furthermore, the carbon dioxide concentration and the size of the gas bubbles also influence gushing behavior [3].
Research has shown that the reproducibility of the results varies over a wide range [4], so that no data for r and R can be given.
References
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L. Winkelmann, BWelt 25, 749–751, 2004
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M. Zarnkow, W. Back, BWelt 9/10, 363–370, 2001
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S. Fischer, Schlussbericht für das Forschungsvorhaben R 314 der Wissenschaftsförderung der Deutschen Brauwirtschaft e. V., 9–11, 2000
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A. Haikara, T. Sarlin, S. Home, J. Inst. Brew. 111, 247, 2005
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A sample is collected of the cereal to be tested and a hot water extraction is carried out. After cold break separation, the sample is carbonated and bottled. After shaking and then opening the bottle, the volume of liquid that fobs over and out of the bottle is measured. This value is used to determine the gushing potential for the malt or adjunct.