Influence of vine vigor on Pinot noir fruit composition, wine chemical analysis, and wine sensory attributes

The relationships among grapevine (Vitis vinifera) vigor variation and resulting fruit composition, fruit chemical analyses, wine chemical analyses, and sensory attributes were investigated. The study was conducted in a commercial vineyard consisting of the same clone, rootstock, age, and vineyard management practices. In 2003, vine vigor parameters were used to designate vigor zones within two vineyard sites to produce research wines. Similar winemaking practices were used. Descriptive sensory analysis and partial least squares (PLS) modeling was done on two-year-old wines. Wines and model extracts were analyzed by HPLC. Significant sensory attributes included earthy, chemical, heat, sweet, sour, bitter, and astringent. Astringency was the most important attribute used to differentiate the wines. Low vigor wines had much higher astringency than high vigor wines. Positively correlated variables included number of seeds per berry, fruit total tannin (mg/kg), and skin tannin (mg/kg), while total flavan-3-ol monomers per seed, total flavan-3-ol monomers per berry, fruit TA, and berry weight were negatively correlated with the sensory attributes. Interestingly, seed tannin was not an important variable in the model. There was a strong relationship between fruit total tannin and wine astringency, which was related to differences in skin rather than seed-derived tannin. There was a strong relationship between measured and predicted astringency.