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 Maréchal 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 Maréchal 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 Maréchal 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.

中文翻译：

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外源单宁的添加率在杂交红葡萄酒中最佳单宁保留

酿酒师经常添加外源性产品来增加混合红葡萄酒中的单宁含量，但50～400mg/L的推荐用量可能无法有效提高凝聚单宁的终浓度。2013 年，用 Maréchal Foch、Corot noir 和品丽珠酿制了葡萄酒，以比较种间杂交种和葡萄品种中外源单宁的保留情况。通过高效液相色谱固相萃取-间苯三酚分解分析了 12 种商业单宁产品的缩合单宁浓度后，在粉碎后但在酵母之前添加浓度最高的产品（38%），分别为 400、800 和 1200 mg/L接种。每个品种的一批也立即被压下皮，在 1600 毫克/升外源单宁的存在下发酵，然后与对照葡萄酒反混后发酵，最终理论浓度为 400 mg/L 浓缩单宁。在装瓶时，所有处理的单宁浓度都高于它们各自的对照。单宁保留率因品种而异，Maréchal Foch 葡萄酒的单宁保留率从 19% 到 24%，Corot noir 的 25% 到 43% 和品丽珠的 34% 到 48% 不等。回混葡萄酒的单宁保留率与添加 400 mg/L 的 Corot noir 和 Cabernet franc 相似，但 Maréchal Foch 的单宁保留率更高（添加 400 mg/L 时为 75 mg/L，添加 93 mg/L回混的葡萄酒）。尽管所有处理过的葡萄酒中浓缩单宁的浓度都更高，但没有一个超过 50% 的保留。这表明高浓度添加外源性单宁会增加混合红葡萄酒中的凝聚单宁，