Influence of metal ions on beer properties, with special reference to foam
article
Nickel ions have a pronounced effect on the surface viscosity of beer foam; the effect, which is closely correlated with foam duration, is ascribed to a metal‐faohumulone complex in the beer. Extraction of isohumulone with isooctanefrom beer containing metal ions gives variable results; from acidified beer nearly all the isohumulone is recovered, except in presence of copper and iron (“redox metals”), but when the beer is not acidified less isohumulone is extracted, the quantity recovered being smallest when the beer contains nickel. With iron and copper present the absorption spectra of extracts differ from the normal, giving further indication of the formation of metal‐isohumulone complexes. All metals do not have the same effect, and distinction can be made between the redox metals which easily pass into another state of oxidation and metals such as nickel and cobalt which cannot do this. A study has been made of the influence of nickel ions (5 p.p.m.) on isohumulone content, brilliance, taste and gushing (overfoaming) when beer is stored; during 6 weeks the isohumulone content gradually diminished and the brilliance also decreased slightly but only during the last week was there some difference in taste, the treated beer being adjudged slightly less bitter. Cobalt can induce gushing, though it is less effective in this respect than nickel. 1960 The Institute of Brewing & Distilling
Topics
TNO Identifier
358538
DOI
https://dx.doi.org/10.1002/j.2050-0416.1960.tb01732.x
Source
Journal of the Institute of brewing, 66(5), pp. 399-407.
Pages
399-407
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