High-performance Liquid Chromatography Solid-phase Research Articles

Winemakers often add exogenous products to increase the tannin content in red hybrid wines, but the recommended dosage of 50 to 400 mg/L may not increase the final concentration of condensed tannins effectively. In 2013, wines were made from Marechal Foch, Corot noir, and Cabernet franc to compare retention of exogenous tannins in interspecific hybrids and Vitis vinifera. After analyzing 12 commercial tannin products for condensed tannin concentration via high-performance liquid chromatography solid phase extraction-phloroglucinolysis, the product with the highest concentration (38%) was added at 400, 800, and 1200 mg/L after crush but prior to yeast inoculation. One lot of each cultivar was also pressed off the skins immediately, fermented in the presence of 1600 mg/L exogenous tannin, then back-blended postfermentation with a control wine for a final theoretical concentration of 400 mg/L condensed tannin. At bottling, tannin concentrations in all treatments were greater than their respective controls. Tannin retention rates varied by cultivar, ranging from 19 to 24% in Marechal Foch wines, 25 to 43% in Corot noir, and 34 to 48% in Cabernet franc. The back-blended wines had similar tannin retention rates to those with 400 mg/L additions in Corot noir and Cabernet franc, but greater tannin retention in Marechal Foch (75 mg/L with a 400 mg/L addition and 93 mg/L in the back-blended wines). Though concentrations of condensed tannins were greater in all treated wines, none exceeded 50% retention. This suggests that high concentration additions of exogenous tannin increase the condensed tannins in hybrid red wines, but retention rates vary by cultivar.

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