ESTIMATION OF THE PHENOLIC MATURITY OF RED GRAPES USING THE STANDARD ITV METHOD

For several years, I.T.V. France has been working on a method to estimate the polyphenolic potential of red grape harvests, called the Standard ITV Method. This method could be suitable to provide the viticulturist pertinent and complementary information to that which is currently provided from the following of sugar and total acidity levels during the course of maturation. An in depth study of the different steps of the Standard I.T.V. Method allowed for their optimization and rendered them more reliable. Hence, the sampling, transport and stocking conditions of the samples were specified; the maceration phase of the grapes in the presence of an alcoholic solution was reduced to one hour; in the case of grape varieties with strong colorant potential this step become facultative; the dosage of the anthocyanins makes use of the Puissant-Léon method, which is simple to complete and is rapid, reliable and can be automated (can process up to 60 samples in 6 hours). The repeatability of the method, starting from the sampling of the grape berries up to the anthocyanin measurement, is very good with an average variation coefficient of lower than 5%.