Technical Report

Pinot noir Maturity Research: A Comparison of the 1987 and 1988 Harvest Seasons

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  • Our Pinot noir maturity research at OSU has several objectives all related to better understanding the development of varietal character and the compositional changes that occur during ripening. We are trying to develop commercially useful tools to monitor changes in fruit composition and character in order to establish harvest indices better related to wine quality. It is clear that Pinot noir can mature differently in different years and that conventional maturity indices such as Brix, titratable acidity, and pH are not always adequate predictors of "optimal" maturity. Changes in anthocyanin and phenolic content in the skins, organic acid and potassium levels in the juice, berry size and fruit condition, vine condition, and subjective assessments of flavor are all important for evaluating maturity. Some of the questions we hope our research will address are related to Oregon industry experiences in recent years. In 1987, an abnormally hot and early season, was it better to harvest Pinot noir at lower Brix in order to maintain the acid and pH balance and then to add sugar to the desired level, or was it better to harvest at the desired Brix and add acid to bring the acidity and pH back into balance. In 1988, a cool and late season in which Pinot noir matured unevenly due to a poor fruit set, was it better to harvest as soon as the desired Brix was reached, or was wine quality improved by letting the fruit "hang on" the vine longer to achieve more uniform ripening. In our Pinot noir maturity trials we are evaluating the aroma, flavor and compositional differences of wines produced from fruit harvested at different levels of maturity during several harvest seasons. Because the fruit composition at harvest influences winemaking decisions, we are also evaluating how commercial processing practices affect wine composition and quality. Different processing practices may be needed to optimize wine quality of Pinot noir harvested at different levels of maturity. Processing parameters under evaluation include chaptalization (sugar addition), tartaric acid addition to reduce pH, extended maceration, and use of whole clusters during fermentation. In 1987 and 1988 Pinot noir was harvested from our experimental block at the Woodhall III Vineyard in Alpine. Fifty cluster samples were taken at random every 3-5 days and were weighed and analyzed for berry size, Brix, TA, pH, malate, tartrate, potassium, anthocyanin, and phenolic content. Replicated wine lots were produced from fruit harvested every 5-6 days from "early" season to "late" season during each year.
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