Studies have shown that the wine phenolic compounds originate mainly from grape extraction during vinification [1] and to a less extent from the wood barrel during maturation or even from yeast metabolism [2] [3] or other microbial sources [4] [5] .

It is well known that phenolic compounds are important ingredients of wine and affect several sensory attributes, such as color and astringency [6] [7] . With regard to the influence of phenolic compounds upon wine color, it has been shown that anthocyanins have the stronger effect on the color of young red wines. The concentration of anthocyanins in young red wines ranges between 200 and 500 mg/L, while decreases to 10 to 20 mg/L during aging [7] . Red wines contain 1500 to 2500 mg/L of total phenolic compounds [8] . In general, the color of aged red wines, as well as the chemical and sensory profile results from different combinations of the phenolic compounds [9] - [12] .

On the other hand, the development of the astringent taste of red wines is due to the concentrated tannins (catechins), which are very important for the long term stabilization of color [13] - [15] . The astringent taste of red wines results from the reaction of saliva proteins (proline rich) with the wine tannins [16] .

Antioxidant and antibacterial activity of phenolics has been well established [7] . Flavonoids act as antioxidants and protect plant DNA damage from ultraviolet irradiation. Regarding human health, it is shown that polyphenols protect from cardiovascular diseases. Polyphenols of wines are more biologically available because they exist in a diluted form whereas, in plants, they are either polymerized or insoluble or even strongly bound to other matrices. Moderate wine consumption is associated with decreased cardiovascular diseases even in nations that are well known to follow a high fat consumption diet (French paradox) [17] - [19] . On the other hand, moderate wine consumption is shown to reduce the incidents of senile dementia and Alzheimer disease [20] .

Phenolic acids present antibiotic and antiseptic attributes thus are used for food preservation. It is likely that these acids play some role in the microbiological stability of wine, mainly towards bacteria. Those phenolic acids that posses two phenolic hydroxyls (-OH) in ortho-position, such as gallic acid, have the attribute to easily oxidise in quinones, affecting the color of white wines [7] . One of the most important phenolic acids is p-coum- aric acid, provided that it is an important metabolite in the formation of phenylalanine lyase, an enzyme that is involved in the formation of flavonoids and stilbenes. It has been found that coumaric acid concentrations increase during stress periods of vine [21] . Furthermore, hydroxycinnamic acids, where p-coumaric acid belongs, form complexes with anthocyanins (pyranoanthocyanins), which contribute to the color stabilization of wine during aging [9] [22] .

The purpose of this study is to assess and compare several color markers and phenolic acid concentrations of wine made from different grape varieties, as well as wines vinified with different techniques or aged under diverse conditions.