Influence of grape variety, vine system and enological treatments on the colour stability of young red wines

The short shelf life of wines from the Northwest of the Iberian Peninsula requires careful control of their colour characteristics. In this work, we studied such characteristics in wines made from three different Vitis vinifera red grape varieties grown in northwestern Spain (viz. Sousón, Mencía and Brancellao, in sequence of decreasing colour intensity). The colour of the resulting wines was found to be influenced by the particular grape variety, the vine pruning and training system and the use of enological treatments such as the addition of yeasts, enzymes or tannins, or cold maceration. Wine colour was measured in terms of the PVPP index and UV–vis parameters such as colour intensity, tint, the total polyphenol index (TPI), total anthocyans and tannins. In addition, individual and free anthocyanins were determined by HPLC in some samples. The effects of these variables were studied with a view to establishing the most appropriate conditions for ensuring colour stability during the shelf life of the resulting wine. Based on the results, the wines from Sousón and Mencía grapes contain appropriate amounts of anthocyans, TPI and tannins to retain an acceptable colour during their storage in bottles. The pruning and training system used with the vines was found to affect the colour characteristics of the wine; thus, cordon systems increased the proportion of anthocyanins by 10%, 20% and 70% in the Sousón, Mencía and Brancellao variety, respectively. On the other hand, the addition of yeasts and enzymes favoured colour development in the Mencía variety.