Assessment of Wine-Age Based on Colour Parameters and Concentration of diethyl succinate. A Case Study: Red Wined from the Valley of Tulum (San Juan-Argentina).

FABANI, M.P.; RAVERA, M.J.A.; WUNDERLIN, D. A.

Torremolinos- España

Congreso; 4° Meeting TRACE project EU; 2008

TRACE EU CONSORTIA

A large number of changes occur in wines during storage, which can affect their final properties. Colour is one of the most important sensory characteristics of wines, influencing its overall acceptability by consumers. Numerous factors can affect wine colour, such as the grape composition, the vinification method and storage conditions. Wine colour changes with the time, especially during the first few months of storage. Colour stability during aging is closely related to the degree of polymerization between anthocyanins and other phenol compounds. Also, colour influences the perception of other sensory properties such as aroma and flavor. The formation of new aroma compounds together with variations in the amounts of other existing components also take place during storage, affecting the overall quality of the wine. In eded wines diethyl esters of succinic acid are forms during malolactic fermentation, its content increase during wine aging contributing with the bouquet.                We studied the concentration of diethyl succinate and several colour parameters in red wines from Valley of Tulum (Province of San Juan-Argentina), aiming to classify wines in function of its year of elaboration. Our main goal was to assess the age of wine by application of chemometrics to the constructed dataset.                We studied four consecutive vintages (2004–2007) consisting of 100% pure wine varieties. Studied varieties were: Syrah (n= 8), Cabernet Sauvignon (n= 10), Malbec (n= 8) and Bonarda (n= 6), which were provided by the cellar Augusto Pulenta, Finca - "Doña Filomena" (San Juan, Argentina).                Diethyl succinate was determined by HS-SPME, coupled to GC-MS, using a DVB-Carboxen-PDMS fibre. Colour measurements were made in a UV-Vis spectrophotometer. The visible spectrum (400–670 nm) was recorded for each sample. Color intensity was calculated from absorbance measurement at 420, 520 and 620 nm. Total polyphenol index was calculated at 280 nm. Total anthocyanins were analyzed at 520 nm, using a matrix of 1% HCl. The CIELAB parameters L* (lightness); C* (chroma), h* (hue), a* (redness) and b* (yellowness) were determined by using the MSCV software (Ayala, J. F.; Echavarri, J.; Negueruela, A., 2001). Each sample was analyzed by triplicate. The data matrix was build up including the seven analyzed variables and four years analyzed (2004, 2005, 2006 and 2007). We applied  Linear Discriminant Analysis (LDA) to find differences among wine from different vintages.             Stepwise discriminant analysis allows us to differentiate wines from four vintages with 99% accuracy using 4 parameters: diethyl succinate (fruity-melon), chroma, lightness and hue. Box plots show that diethyl succinate and hue allows complete discrimination among wines of different vintages. Considering our present results, we are able to assess the age of red wines from the studied region studied. The evaluation of these parameters could also be used to prevent frauds. The augment in the concentration of diethylsuccinate with the age of wine also allows to confirm that the aroma of wine also change with its age.