Monitoring grape ripeness using a voltammetric electronic tongue

Abstract

The use of a voltammetric electronic tongue as a tool to monitor grape ripeness is proposed herein. The electronic tongue consists of eight metallic electrodes housed inside a stainless steel cylinder. The study was carried out over a period of ca. 1 month (August 2012) on different grape varieties (Macabeo, Chardonnay, Pinot Noir, Cabernet Sauvignon, Shyrah, Merlot and Bobal) from various vineyards near Requena and Utiel (Valencia, Spain). Apart from the electrochemical studies, the physico-chemical parameters, such as, Total Acidity, pH and °Brix, were also determined in grapes. The PCA models, obtained using the physico-chemical or electrochemical data, showed variation of ripenesswith time.Moreover the studywas completed by using partial least squares (PLS) regression in an attempt to establish a correlation between the data collected from the electronic tongue and Total Acidity, pH and °Brix values. A good predictive modelwas obtained for the prediction of Total Acidity and °Brix. These results suggest the possibility of employing electronic tongues to monitor grape ripeness and of, therefore, evaluating the right time for harvesting.