Comparison of Different Extraction Methods to Predict Anthocyanin Concentration and Color Characteristics of Red Wines
Stephan Sommer* and Seth Cohen
*Appalachian State University, Fermentation Sciences, 730 Rivers St., Boone, NC 28608 (email@example.com)
Red wines ferment in contact with skins to extract polyphenols and anthocyanins that help build, establish, and stabilize color. The concentration and composition of anthocyanins varies among genera, species, and cultivars. For this study, eleven grapes representing Vitis vinifera (Cabernet Sauvignon, Merlot, Cabernet franc, Barbera, Syrah, Petite Sirah, and Mourvedre), Vitis labrusca (Concord), Musca-dinia rotundifolia (Noble), and French-American hybrids (Marquette, Chambourcin) were selected. All cultivars were fermented on skins and color extraction was monitored daily. Each grape was also extracted using six different methods (microwave, and ultrasound-assisted, Glorie procedure, ITV standard, AWRI method, and solvent extraction of skins) and compared to color characteristics and anthocyanin profiles of the wines produced by fermentation. The extraction pattern varied significantly among cultivars included in this study. This is likely due to differences in extractability caused by variability in ripeness and structural differences among anthocyanins. Maximum color intensity was reached three to 10 days into fermentation, with considerable variation among cultivars. Postfer-mentation maceration, pressing, and sulfur dioxide addition lead to color loss up to 68% of the original maximum, with the highest loss in native American grapes and hybrid varieties. Color loss predominantly occurred in the red hue, followed by blue, with only minor changes in the brown part of the spectrum. Extraction procedures show a tendency to overestimate color in the finished wine, but are more accurate if compared to peak extraction levels during fermentation and are related to average berry and skin weight. Color loss and suitability of different extraction procedures to predict color characteristics of fermented wine strongly depend on the complexity of the anthocyanin spectrum. There is more variability for non-vinifera cultivars, since most extraction methods were developed for V. vinfera. However, ultrasound-assisted extraction shows potential for all cultivars because it is quick, reliable, and environmentally friendly.
Funding Support: N/A