Abstract 077
The effect of pH on protein-polyphenol particle size
Proc. Eur. Brew. Conv. 28th Congress – Buapest 2001 pp. 791-800
K.J. Siebert and P.Y. Lynn
It is known that variations in haze particle size affect human and instrumental perceptions of turbidity, as well as filtration and sedimentation behavior. Haze intensity was known to be influenced by pH, but this had not been studied in detail. The haze-active (HA) protein gliadin and the HA polyphenol tannic acid were combined in various proportions in buffer model systems at several different pH’s. Haze intensity and particle size distribution were observed under each condition. There were large changes in haze intensity with pH, with the largest particle sizes and haze intensities near pH 5 and much lower hazes at higher and lower pHs. Only a limited number of particle sizes were observed under each condition, and the patterns varied with the protein/polyphenol ratio.
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