AGEING REVEALS THE TERROIR OF AGED RED BORDEAUX WINES REGARDLESS OF THE VINTAGES! TARGETED APPROACH USING ODOROUS COMPOUNDS LEVELS INCLUDING TERPENES AND C13 NORISOPRENOIDS

Abstract

The chemistry of wine is notably complex and is modified by ageing of the bottles. The composition of wines is the result of vine production (under the influence of vintage, climate and soils); yeast production (under the influence of juice composition and fermentation management); lactic bacteria production (under the influence of young wine composition and malolactic fermentation management); and of the ageing process either in vats, barrels or bottles or both. The composition is linked to the quality perceived by consumers but also to their origin, sometimes associated to the “terroir” concept.

Even if the chemical identity of a wine is shaped by a large variety of factors (soil, climate, varieties, microbiology, ageing process), we know now that the terroir and the maturation plays a key role in the sensorial and chemical identity of wines even after ageing (1–4). The aims of that study was to explore the links between terroir, ageing or vintages and the chemical composition. A targeted approach have been tested. It involves the quantification of molecular markers such as esters, terpenes, norisoprenoids or sulphur compounds. It have been applied to a large set of wines composed by 80 samples produced by 7 wineries during a selection of vintages between 1990 to 2007. The statistical analysis of the results permits to highlight similar compositions between wines produced in the same winery despite the variation of berry composition due to the vintage, the variations dues to technical choices and to ageing time. In the current study, the whole volatile composition is essential to the uniqueness of the wines because there are no compounds that are exclusively involved in discrimination of estate. This shows the complex effect of the grape and wine matrix on achieving a typical product. Overall, in the aromatic matrix, there is an existence of a hierarchy in the importance of compounds that permits the unicity of Bordeaux estate. Hence, three families of compounds (terpenes, norisoprenoids and esters) which made it possible to discriminate between the seven Bordeaux estates studied and are therefore influenced by the composition of the grapes. These include TDN, vitispirane, β-damascenone, terpinen-1-ol, α-terpinene, methyl salicylate, cis-linalooxide, ethyl esters of fatty acids (C₄C₂, C₆C₂, C₈C₂) and many others. It’s interesting to note that even after years of bottle ageing, the imprint of the grape is still visible. The personality of each estate through its specific terroir is therefore an indispensable element for the aromatic singularity of each great wine.