Unexpected effect of potassium ions on the copigmentation in red wines

The effect of potassium ions on the Glories color parameters of red wine has been investigated. The results show that temperature dependence of color intensity is high, while no considerable effect of temperature on color hue was obtained. Enhanced color intensity was observed in the presence of potassium ions. Color intensity reaches a maximum, when potassium is added in concentrations of about 0.5 g/dm3. Furthermore, the temperature-dependence of the color intensity was decreased at higher potassium ion concentrations. According to the possible dissociation of phenolic OH, independent measurements validate that changes in pH itself could not be responsible for this unexpected phenomenon.

► High temperature dependence of color intensity was detected. ► No considerable effect of temperature on color hue was obtained. ► The temperature dependence decreased with elevated potassium ion concentrations. ► Enhanced color intensity was observed in the presence of potassium ions. ► Color intensity reaches a maximum at 0.5 g/dm3 added potassium ion concentration.