| Autor: |
Wilde, P. J., Husband, F. A., Cooper, D., Ridout, M. J., Muller, R. E., Mills, E. N. C. |
| Zdroj: |
Journal of the American Society of Brewing Chemists; September 2003, Vol. 61 Issue: 4 p196-202, 7p |
| Abstrakt: |
Mechanisms in which fatty acids destabilize beer foam have been studied. Foam stability of a pilot-brewed beer was measured in the presence of a range of concentrations of fatty acids, similar to those found in a range of commercial beers. The foams were sparged with nitrogen and studied using a microconductivity technique. The fatty acid chain length varied from C6to C18, C18:1, and C18:2. While C6to C10fatty acids had no impact on the foam stability over the concentration range studied, the longer-chain fatty acids were more destructive. Thus, C12to C14, C18:1, and C18:2reduced foam stability and the surface elasticity of beer. These data suggest that the fatty acids adsorbed into the protein-stabilized surface weakened the adsorbed film, resulting in an increased probability of coalescence. The saturated fatty acids, C16:0and C18:0, damaged the foam very effectively but did not influence the surface rheology. Light-scattering experiments showed increased numbers of aggregates in these samples, suggesting that these fatty acids destabilized beer foam through a mechanical film-bridging mechanism, similar to that used by particulate antifoam systems. |
| Databáze: |
Supplemental Index |
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