Abstract 092
Effect of pH on beer colloidal stability
Cerevisia – Belgian Journal of Brewing & Biotechnology 30 (3): 189-194, 2005
K.J. Siebert
The main source of colloidal material in beer is the result of protein-polyphenol interaction to form insoluble complexes. When these form they also entrain other material. Protein-polyphenol interaction has been shown, both in model systems and in beer, to have a maximum (corresponding to greatest light scattering) at a pH slightly above 4. The precise pH maximum is influenced by the ethanol content. Fining, like haze formation, is based on protein-polyphenol interaction and would be expected to have a similar pH influence. The effectiveness of silica for beer chillproofing has been shown to be greatest at pH 4.2 or 4.6, depending on the silica type. This is very similar to the pH at which protein-polyphenol interaction is greatest and may be due to a similarity of protein-silica binding to protein-polyphenol interaction. Factors that favor higher beer pH, such as higher malt/adjunct ratio and mash acidification, favor formation (and presumably precipitation) of haze material during lagering.
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