New Parameters to Measure Ripeness

Grape samples were collected at two Oakville area vineyards during an 8 week period for analysis of phenolics. Wines were also made from these two vineyards at three different maturity stages. All samples are being analyzed for phenolic content using a relatively new procedure which separates phenols based on size. This year of the project was designed to replicate last year’s effort in order to test for year to year differences, and to expand the use of a new analytical method which is capable of measuring polyphenols from both skins and seeds. At this point, all the samples have been collected and extracted. The chromatographic analysis of the seeds is complete, but the skin and wine analyses are still underway. Preliminary analysis of sensory data on the wines prepared by Mondavi winery for both bitterness and astringency shows increasing astringency with ripeness, the same as last year’s wines, but also shows a trend for increasing bitterness. While these trends are interesting, further statistical analysis will establish the significance of the sensory data. The goals of this year of the project were to: 1) Repeat the measurement of the levels and polymer distribution of phenolic compounds during ripening in vineyards selected in consultation with NCVRG representatives. 2) Compare maturity with specific chemical levels. 3) Prepare, in consultation with NCVRG representatives, wines from the same vineyards at different stages of maturity. 4) Analyze the wines using the same procedure to see if the changes observed in the grapes follow through to the wine.