A sharper characterization of the geographical origin of Lebanese wines by a new interpretation of the hydrogen isotope ratios of ethanol.

The hydrogen isotope ratios of the methyl [(D/H)I] and methylene [(D/H)II] groups in ethanol can be used as geographical origin tracers of wines. These ratios reflect not only the deuterium content of sugars but also that of water in the grape medium, and hence are influenced by the irrigation, the degree of ripeness at harvest, and other viticultural and enological practices. Thus, the isotopic redistribution coefficients between water in the grape must and the methyl and methylene sites of ethanol were determined and then used to compute an isotopic ratio [(D/H)Is] representing the contribution of the fermentable sugars to (D/H)I.