Identification of Phenolic Compounds in the Phenolic Fraction of Young and Aged Wines from Argentina
Maria Gilda Stivala, Margarita Beatriz Villecco,
and Pedro Adrián Aredes Fernández*
*Facultad de Bioquímica, Química y Farmacia – Universidad
Nacional de Tucumán – CONICET, Ayacucho 471, San Miguel de
Tucumán/Tucumán/4000, Argentina (pedroaredes@conicet.gov.ar)
The wine industry is an important sector of the Argentine economy. Phenolic compounds (PCs) are important wine compounds due to their biological activities. The aim of this study was to obtain qualitative and quantitative characterization of the PCs in the low-molecular weight phenolic fractions (LMF) of young (Y) and aged (A) Tannat red wines produced in Colalao del Valle, Tucumán, Argentina. Both LMF were obtained from 750 mL dealcoholized wine (pH 2.0) by successive extractions with ethyl acetate. Total PC concentrations in wine were determined using the Folin reagent and expressed in mg/L GAE. The LMF was characterized using a liquid/liquid extraction method coupling diode-array and fluorescence detectors (LC-DAD-FLD) to quantify PCs. The presence of PCs in both fractions was confirmed by thin-layer chromatographic profiles, comparing the similar Rf to pure PCs used as standard. The total PC content in the wine was 3320.38 and 3094.66 mg/L GAE for Y and A wines, respectively. Twenty PCs were quantified in the LMF by LC-DAD-FLD. PC concentrations detected were higher in the LMF-Y (26938.80 μg/g dry extract) than in the LMF-A (17400 μg/g dry extract). Gallic acid, epigallocatechin gallate, and caffeic acid were the most abundant compounds, with concentrations between 9363.9 and 2003 μg/g dry extract in LMF-Y and 6956.60 and 1606.70 μg/g dry extract in LMF-A, followed by (+)-catechin and p-coumaric acid. The decrease of low molecular weight PCs evidenced in this work after aging of Tannat wine could be explained by complexing and condensation reactions between anthocyanins and the PCs, as demonstrated previously in the scientific literature. These results constitute an important contribution to the knowledge of the effects of wine maturation on low molecular weight phenolic composition.
Funding Support: CONICET
