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Recent years have seen an increased awareness in the importance of diet in the maintainance of health and well being. Phenolic compounds are chemically complex substances widely distributed in plants and food plants and as such are common components of the human diet. Those molecules play an important role in some sensory properties of grapes and wines as color, astringency and bitterness, oxidation reactions and aging. Phenolic compounds, especially flavonoids, have been credited as major contributors to the antioxidant potentials of red wines and this effect has been related to health benefits. The relationship between wine and health has prompted extensive investigations into the associated risk factors, including alcohol consumption. Epidemiological studies have shown that coronary heart diseases are less prevalent in populations consuming moderate and regular amounts of wine.
Our paper reports a study with 25 red Argentine wines from different grape varieties and geographical origins. The total phenol content was determined using well established spectrophotometric methodology and gallic acid as the standard. The concentration of total phenols varied from 13.68 to 20.67 mM gallic acid equivalents (GAE). The highest value corresponded to Merlot (MT), 2002, from Valle de Uco, Mendoza and the minimum to Cabernet Sauvignon (CS), 2001, from Valle de Tulum, San Juan. The wines obtained from the principal grapes in each location had the highest phenol concentration as shown by (CS) in the center ( around 18.22), east (around 16.48) and south (around 18.58) of Mendoza, Malbec (MC) in the center (around 17.73) and Valle de Uco (around 17.89), in Valle de Uco (around 20.67) and Syrah (SY) in the central part of the same province (around 17.90).
The anthocyanin content of wines was determined by using a spectrophotometric method. Total and free anthocyanins as well as polymeric pigments were expressed as mM malvidin-3-glucoside equivalents. Total anthocyanins reach maximal level for MT, 2002 (617.1mM) from Valle de Uco, Mendoza and minimal value for CS, 1997 (222.1 mM) from Valle de Rio Negro. During the aging process the polymeric pigment forms displace the monomeric anthocyanins. The age index, calculated as polymeric anthocyanins/monomeric anthocyanins, increased from 88.1% for CS, 2001 to 161.9% for CS, 2000, both from Valle de Tulum, San Juan.
Antioxidant capacity was assessed by two different procedures. On the one hand it was evaluated using 2,2-diphenyl-picryl hydrazil (DPPH+) and trolox (6-hydroxy-2, 5, 7, 8-tetramethyl-chroman-2-carboxylic acid) as standard. The radical scavenging activity varied from 10.56 to 16.18 mM trolox equivalents (TEAC) corresponding respectively to MC, 2002, from San Rafael and MC, 2001, from Lujan de Cuyo, southern and central regions of Mendoza. On the other hand antioxidant capacity of wines was determined by the analytical procedure based on the color suppression of the radical cation ABTS+ generated by oxidation of the 2,2'-azino-di (3-ethylbenzthiazoline sulfonate) (ABTS) with potassium persulfate. The following wines evidenced maximal antioxidant activity: CS, 2001 (around 27.45 TEAC) and MC, 2001 (around 26.74 TEAC) both from the center of Mendoza, MT, 2002 (around 35.67 TEAC) and SY, 2002 (around 29.73 TEAC) both from Valle de Uco.
Supported by UADE Grants Code PS2021, 2002 and TSH03B, 2003. |
