Issue link: http://winesandvines.uberflip.com/i/1031957
70 WINES&VINES October 2018 WINEMAKING PRACTICAL WINERY & VINEYARD F ormation of polymeric pigments is important for suc- cessful cellaring of red wine as they help soften wine's astringency and provide long-lasting color. Research supported by the Washington State Wine Commission has identified factors that can maximize polymeric-pigment formation to help improve red-wine quality. During fermentation and while red wine ages, polymeric pigments form from the reaction of anthocyanins and tannins, phenolic compounds that come mainly from the skin and seeds of the fruit. Anthocyanins contribute to the red color of grapes and wine; tannins are astringent but add flavor complexity and structure to a wine. A study by Washington State University scientists examined the effects of fruit maturity, alcohol and wine aging on the con- centration of anthocyanins, tannins and polymeric pigments in Cabernet Sauvignon and Syrah. The goal was to determine the most important factors involved in forming polymeric pigments and provide winemakers with practical guidelines to keep poly- meric pigments stable in a wine environment over time. This article summarizes the research that answers the following questions: 1) What drives polymeric pigment formation—the con- centration of anthocyanins or tannins? 2) Is there a critical antho- cyanin-to-tannin ratio in the fruit or wine that winemakers should target to maximize the formation of polymeric pigments? Constant vineyard conditions Syrah and Cabernet Sauvignon grapes were used to obtain dif- ferent anthocyanin and tannin concentrations and ratios between the two compounds. Cabernet Sauvignon generally produces grapes with darker color and high levels of tannins. Syrah grapes are typically dark but lower in tannins than Cabernet Sauvignon. The two cultivars are prevalent in Washington State. The trial was conducted in a commercial vineyard in the Columbia Valley AVA during the 2015 growing season. Fruit (1.5 tons) was harvested at three different maturity levels: 20 o , 24 o and 28 o Brix. Harvest dates were separated by approxi- mately three weeks between each pick. Initial fruit-soluble solids concentration (Brix) was manipu- lated in the winery by removing juice (saignée) and then either sugar adjustment or water-back prior to fermentation to have three alcohol concentrations (low 11-12%, medium 14-15% and high 17%) represented at each grape maturity. (See Figure 1, Three Harvest Dates, Nine Wines.) Saignée occurred immediately after the crush to minimize anthocyanin loss while maintaining the juice-to-solids ratio across all treatments. Improving Red Wine Color and Mouthfeel Over Time Maximizing polymeric pigments can help winemakers improve red-wine quality By Caroline Merrell and Melissa Hansen BOTTOM LINE If you want more polymeric pigments in your wine, make sure your fruit is fully ripe for development of anthocyanins. If you are in a region where long hang time is problematic, for high-tannin varieties, maximize color through vineyard-management techniques that encourage open canopies and good sun exposure to the fruit zone. These include open canopy, deficit irrigation, leaf removal and low-vigor vines. For low- tannin varieties such as Syrah and Pinot Noir, maximize color development in vineyard and winery techniques to increase tannin levels (minimum of 20 days of skins -on extended maceration); ferment at higher tempera- tures or make higher-alcohol wines (2%-3% higher than your normal concentration). THREE HARVEST DATES, NINE WINES Experiment was designed to achieve varied tannin and anthocyanin concentrations within the same vineyard. FRUIT MATURITY WINERY SUGAR TREATMENT 20 Brix 20 Brix 24 Brix 28 Brix 24 Brix 20 Brix 24 Brix 28 Brix 28 Brix 20 Brix 24 Brix 28 Brix