Concentration and Composition of Phenolic Compounds in Grapes and Wine.

In 2003 and 2004 vigor zones were delineated in two commercial vineyard sites based on vine growth variation to assess fruit and wine phenolic chemistry. In 2004, the effects of shading on the accumulation of phenolic compounds were also investigated. Model extractions were done from the shading experiment and the vigor zones in 2004. Wine and extracts were analyzed by HPLC and spectrophotometry. Berry weight, dry skin weight, °Brix, pH and anthocyanin content were higher and titratable acidity and the proportion of malvidin-3-O-glucoside was lower in 2003 compared to 2004. High vigor zones had lower °Brix and higher titratable acidity and a trend for lower anthocyanin content per berry in both years. Site A had proportionally higher peonidin and lower malvidin than site B. While there were minimal differences in seed proanthocyanidin, large increases were found in low vigor zones for skin proanthocyanidin, proportion of (-)-epigallocatechin, and pigmented polymer content in fruit. In 2004, the shade treatment had lower accumulation of flavonols, lower skin proanthocyanidin, minimal differences i