Home / Summaries / Chemical aspects / hydrophobins-gushing-formation

Beer foam - Gushing

8 important questions on Beer foam - Gushing

An explosive release of carbon dioxide, foam and beer occurs after gentle opening of a beer bottle.

Hydrophobins, a small amphiphilic protein present in fungi

Primary: due to the use of mould-infected grains, likely to impact the entire beer manufacturing batch
Secondary: due to mistakes during processing, or incorrect treatment of the beer, causing the presence of colloidal or solid particles

When barley grains contaminated with fungi (Fusarium or Nigrospora) are used for the brewing process.

Small proteins (10 kDa) containing highly conserved cysteine residues which makes these proteins very stable (like LTP1).
High thermostability --> retain their structure during the brewing process
Amphiphilic molecules, having a distinct hydrophilic and hydrophobic side

hydrophilic side faces water environment
hydrophobic side contains hydrophobic aliphatic amino acid residues, which form a planar patch --> planar patch particularly suitable for binding air-water interfaces

Researchers have developed immunoassays, which can detect the presence of hydrophobins in batches of barley and malt, which are used for brewing.

They will self-associate
Multimers of hydrophobins are formed
Upon multimer formation --> proteins cluster together via their hydrophobic patches and this is energetically favourable
Upon monolayer formation at the air-water interface, multimers dissociate first to less soluble monomers
The monomers then diffuse to the surface and expose their hydrophobic parts to the air phase. This is energetically the most stable situation.

The question on the page originate from the summary of the following study material:

Remember faster, study better. Scientifically proven.