Relations between grape phenolic maturity and red wine phenolic composition.

Phenolic maturity of red Piedmont grape varieties Nebbiolo and Barbera was monitored during the grape harvest in 16 vineyards in 2000 and 2001. The study used the Glories’ method which was modified to avoid some critical parts of the original protocol, mainly regarding the extraction solution used at pH 1. Experimental winemaking processes were performed on a part of the grapes from the vineyards being monitored. The analytical data revealed a correlation between the anthocyanins and flavonoid indexes of grapes and color indexes of wines. The cell maturity index (EA%) is representative of how quickly anthocyanins can be extracted. Moreover, a correlation was found between the seed maturity index (Mp%) and the content of low molecular weight flavanols in the wine. In 2002-2004 this correlation was studied on Nebbiolo, Barbera and Dolcetto grape varieties on an industrial scale. Winemaking carried out using different systems of maceration confirmed the experimental results.