Evaluation of the polyphelolic component and sensory characterization of wines produced from grapes with different potential alcohol

Abstract

While a general rise in average temperatures leads to the production of more alcoholic wines, it is difficult to obtain proper phenolic maturity without simultaneously achieving high sugar levels in the grapes. At the same time, the consumer seems to direct his choice, driven by health and problems associated with alcohol, to wines with low alcohol content. With the aim to evaluate the interaction between increasing the potential alcohol degree and the polyphenolic content of musts and wines, a trial was carried out from 2009 to 2011 in the area of Montefalco DOC. The varieties considered were Sangiovese, and Sagrantino, cultivated in two different vineyards belonging to the “Azienda Agricola Arnaldo Caprai.” During the ripening, the technological (sugar, pH, and titratable acidity) and polyphenolical potential (content of extractable polyphenols and anthocyanins) were determined. Grapes from each step of maturation were vinified to obtain six wines with different levels of potential alcohol, from 12° to 17°; these wines were then subjected to sensory analysis. With the progress of maturation, the extractable anthocyanins increase until a maximum value, and then tend to decrease. Sangiovese reached the highest value for this parameter at 14°, while the Sagrantino showed the highest anthocyanins concentration at 15°. In rainy years (2009), the accumulation continues until the last sampling for Sagrantino, while it is stable for other varieties. Extractable polyphenols decrease and then increase again, probably because the extractability of this component tends to increase in full ripe tissues, although it decreases in quantity. The tastings reveal that the favorite wines are those with 14° alcohol for the early variety (Sangiovese), while those with 15° alcohol or more seem to be more appreciated for the Sagrantino. The wines produced from this variety with low alcohol are in fact less colorful, with thin body and astringent tannins, and therefore unpleasant. So, for the production of balanced wines, and reaching the correct polyphenolic maturation, it is necessary to arrive at an alcohol content of about 14 ° for Sangiovese, and must exceed 15 ° for Sagrantino