Determination of total charge content of whiskey by polyelectrolyte titration: Alteration of polyphenols

Whiskeys with maturation periods of 1 to 26 y were analyzed by polyelectrolyte titration at various pH levels. The amounts of charge (polyelectrolyte concentration), which were mainly attributable to polyphenols which were extracted from wood casks during the maturation, were determined. The amounts of charge, namely polyphenols, increased with increasing periods of maturation. On the other hand, the ratio of amounts of charge in the alkaline region compared to those in the neutral region became smaller with longer storage. It was found that polyphenols were extracted over time from the wood cask by whiskey, but they were oxidized to alter the polyphenol compositions, which stabilized clusters (molecular association) between alcohol and water to make whiskeys mellow.