[Analytical characterization of varietal wines and aging phenomena]

We have studied some wines issued from pure varieties (Gamay, Pinot, Syrah, Malbec, Merlot, Tannat, Jurançon) and from country wines where they are predominant (Cahors: Malbec; Corbieres: Carignan). We have analysed the most important classes of compounds: volatile components, free amino acids, mineral elements, phenolic components, organic acids. In regard of the large variation of "oligoconstituants" and "macroconstituants" concentrations (ratio: I to 30 000), we examine the proportions between the minimum and the maximum of the variation range. We define an abundance degree from 0 to 100 p. 100 for every compound. With this unique scale, it is possible to include all parameters on the same graph and to determine the general profile of a wine from the relative abundance of its components. The wine profiles from same country wine or same variety have approximately the same shape and their curves are well superposed. On the other hand, when we compare the profiles of wines issued from two different varieties, we rapidly visualise the most important differences. We have for instance grouped on a graph the parameters which differentiate Gamay from Pinot and Merlot from Jurançon. Then we show on a precise example the resemblance between a country wine profile (Cahors) and that one of its predominant variety (Malbec). The differences we have observed are well explained by secondary varieties (Jurançon, Merlot, Tannat). The same procedure is applied to study the aging of wines. A graphic representation shows the variations during seven years (1970 to 1976). Five parameters are found to characterise with good precision the age of wine: isobutanol, methyl-3 butanol-1, ethyl acetate, ethyl lactate, ethyl succinate. With a detailed analysis of the components of wines, it is possible to differentiate varieties, age and perhaps many other aspects.