Chemical characterisation and sensory evaluation of Bordeaux wines. Correlation with wine age

Quality evaluation of a red wine is based on wine-tasting. Chemical analyses are performed to understand what compounds influence sensory properties and how they affect them. Quantitative determination of certain chemical compounds is a criterion of wine valuation origin [1] and authenticity [2]. Our study concerning wine quality was carried out with 24 vintages of Cabernet-Sauvignon (CS) and with 7 vintages of Merlot (M) produced by Bordeaux wine-growing areas. Proanthocyanidin monomers and oligomers were identified and quantified by HPLC-UV-Fluo. Galloylation (%G) and prodelphinidins percentage (%P), mean degree of polymerization (mDP) were determined [3]. Total phenolic compounds, total anthocyanins, total tannins, hue, IC′ (color intensity), total acidity, ethanol level and pH were evaluated. Sensory analysis concerning astringency and bitterness intensity was also performed. Total phenolic compounds, anthocyanins, tannins, tannin monomers, hue, IC′,% G,% P, mDP and astringency intensity differentiate both wines according to vintage. Correlation between wine age and: mDP, hue, astringency, phenolic compounds, tannin monomers, total tannin levels are obtained. The qualitative wine tannin characterization is established between astringency and mDP (R 2=0.509, p=0.051, CS; R2=0.780, p=0.000M). mDP is a vintage marker (R 2=0.796, p=0.000; CS and R2=0.946, p=0.000; M). Scale patterns between wine mDP and both ageing and tannin perception are proposed. M wines are characterized by lower levels of total phenolic compounds, tannins, anthocyanins, mDP,% G,% P% levels as well as by lower astringency intensity than CS wines.

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3. Drinkine, J. et al.(2007)J. Agric. Food Chem. 55: 6292–6299.