Metalloporphyrin-based electronic tongue: An application for the analysis of Italian white wines

An Electronic Tongue system (ET) composed of "all-solid-state" potentiometric sensors was developed and applied for the identification of white wines. The sensing properties were due to the PVC based membranes doped with several metallo-porphyrins deposited on the surface of glassy carbon working electrodes; potentiometric response towards several ions in a concentration range from 10(-5) M to 10(-1) M were studied and crosssensitivity of sensors was estimated. The sensor array was applied both for the classification and quantitative analysis of "Verdicchio D.O.C." Italian dry white wines produced by nine cantinas. Peculiar parameters of white wines (namely alcoholic degree, volatile acidity, SO2, L-Malic Acid, L-Lactic Acid and Total Polyphenols) individuated by standard analytical methods were compared with the values evaluated by metalloporphyrin-based ET. The system satisfactory discriminates between an artificial wine control and analyzed wines coming from different cantinas and produced in different years. A satisfactory correlation between results of wine analysis performed by certified methods and ET response has been obtained for SO2, L-Malic Acid, and Total Phenols content. The developed procedure allows the monitoring of the acetic acid amount in wines and hence to control wine volatile acidity, so indicating the initial steps of wine spoilage process.