Electrochemical tomato (Solanum lycopersicum L.) characterisation using contact probe in situ voltammetry

An in situ electrochemical contact probe methodology for characterising tomato samples is proposed. It is based on the record of the voltammetric response of antioxidant compounds when glassy carbon electrodes are inserted into the pericarp of fresh tomato specimens cut in half. The absence of pretreatment and in situ sampling avoid sample contamination and the oxidation of air-sensitive compounds thus increasing the representativity of the analytical data relative to conventional electrochemical analysis. Characteristic voltammetric responses recorded for such compounds, including rutin, chlorogenic acid, naringenin, naringenin chalcone and ascorbic acid have been obtained. A positive correlation between the (total phenolic compounds)/(ascorbic acid) ratio and peak intensity ratios has been found when analysing the voltammograms. This fact led us to differentiate between diverse tomato varieties and also tomatoes sample growth under different agronomic conditions and harvested at two ripeness stages.