Wines & Vines

February 2018 WINES&VINES 29 VIEWPOINT influences of geography, topogra- phy, soil and underlying geology. 3 However, some varieties are im- pacted more than others with regard to warmer temperatures and seasonal variations. Tight- cluster grapes are much more prone to fungal diseases, as are thin-skinned varieties compared to thick-skinned varieties. Variet- ies such as Viognier, Petit Man- seng and Tannat have proven to do well in the warm, humid envi- ronment of Virginia. Vintage-to-vintage variations are likely to become much greater, as seen throughout the world. It is not climate change, per se, that will affect some, but the erratic nature of the unpredictable weather that may be a greater problem. Increased seasonal vari- ations may influence fruit set and will affect maturity and maturity evaluations. We can expect the asynchrony among primary (such as Brix) and secondary metabo- lites (aroma, flavor and phenols) will likely increase. Additionally, as a function of changing environ- mental conditions during fruit set, fruit variation within otherwise uniform blocks may increase. Even in the most uniform vineyard, the coefficient of varia- tion for various components is broad at best: Brix 4%-5%, TA 10%-12%, berry weight 6%-20% and color 13%-18%. 9 These ranges will certainly increase in some areas and will require great sampling precision. Ripeness assessment In 2016, Boris Champy reported that harvest dates for his Pinot Noir at Louis Latour in Beaune, France, had moved from mid- October to approximately Sept. 20. 4 D. Frederick Frank reports that his New York vineyard has experienced a 10% increase in growing degree-days (GDD) in the past 10 years. 7 One obvious contribution of global climate change is the tendency in some regions to pick grapes at slightly earlier ripeness. Optimally, this should occur following the loss of green tannins in the fruit. Animals, insects and plants have moved to higher elevations and more northerly climates to adjust to warmer temperatures. It is likely that viticulture will follow a similar pattern in the future. 3 Some grapegrowers have chosen to plant vines at higher altitudes to find cooler ripening climates. This can impact heat and, likely, ultraviolet interception. Tannin and color Red wine cap management strate- gies and skin contact time must be reviewed in the context of changes in seasonal variability and fruit chemistry. (See "Climate Can Impact Phenol Concentra- tions at Harvest" on page 28.) Differences in phenols are both qualitative and quantitative. The major quantitative differences due to climate lie in the ratio of anthocyanin to skin tannins at harvest. This ratio is important due to the influences on color, color stability, mouthfeel and aroma integration. During fermentation, oxidative condensation reactions occur, re- sulting in tannin polymerization. This continues until a terminal polymer end reacts with an antho- cyanin molecule, stopping the pro- cess. Thus, anthocyanins act as bookends, limiting chain elonga- tion. As such, the more anthocya- nins there are relative to tannins, the shorter the resulting polymers and the "finer" the tannins. Thus, seasonal variations that impact this ratio also impact the resultant polymer length. Tannin-anthocyanin polymers help stabilize color. Small poly- mers have relatively fewer protein- binding sites, thus producing less astringency. These small colloids provide a surface area that allows for integration of aroma compo- nents. Additionally, climate change can impact the concentration and type of color cofactors, compo- nents that bind with anthocyanins providing additional spectral color. Longevity/reductive strength Small pigmented polymers help provide red wine reductive strength. Reductive strength is es- sentially a measure of the uptake of oxygen, providing longevity, or the ability of a wine to age. This is an important quality attribute, analogous to a wine's chi (qi), or life force. Reductive strength is Custom made - Handcrafted Barrels

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