Changes in the proton exchange rate in commercial spirits (whiskies ag
ed 5-25 years and brandies aged 5-45 years) during aging were calculat
ed from the relationship between the line width (full width at half-ma
ximum intensity) of O-17 nuclear magnetic resonance signals and the pH
at 298 K. The exchange rate of water protons in the spirits was accel
erated with age.