MEASUREMENT OF THE REDOX POTENTIAL OF WINE

A reproducible method for measuring the redox potential of wines using platinum electrodes was developed involving a consistent electrode pr etreatment and carefully controlled experimental conditions. Reproduci bility favoured platinized electrodes (+/- 3mV), over unplatinized ele ctrodes (+/- 6 mV), while poisoning was found to have a greater effect on platinized electrodes. However, the dependence of the potential up on the degree of platinization indicated that both platinized and unpl atinized electrodes should be used to maximize the information obtaine d about the redox state of a wine. A linear relationship was observed between the potential and pH of 26 wines tested, particularly on plati nized electrodes. The measured potentials are discussed in terms of mi xed potential theory and the influence of adsorbates.