The effect of temperature, pH, and ionic strength on color stability of red wine

Abstract

The temperature and pH dependence of the color stability of a Hungarian red wine (Portugieser variety from Villány, Southern Transdanubia, Hungary) was investigated. Results show that both color intensity and pH were decreased by increasing temperature due to the dissociation of several phenolic OH groups. However, wine color intensity was increased upon addition of HCl even in the presence of additional potassium ions. This leads to the conclusion that added potassium ions change the pH dependence, while the addition of calcium ions resulted in moderated change on the pH dependence of color intensity. Comparing the color changes induced by the temperature or the pH highlights that the change in color intensity is a result of complex processes and its temperature dependence cannot be described solely as the decrease of pH at elevated temperatures.