J Agric Food Chem. 2018 Sep 5;66(35):9259-9268. doi: 10.1021/acs.jafc.8b01996. Epub 2018 Jun 8.
Numerous monomeric and oligomeric flavanol sulfonation products were observed in 10 wines. Levels of 0.85-20.06 and 0-14.72 mg/L were quantified for two monomeric sulfonated flavan-3-ols and, surprisingly, were generally higher than the well-known native flavan-3-ol monomers. Increasing SO levels during wine aging increased the sulfonate-modified flavan-3-ol monomers and dimers along with higher concentrations of native monomers. The results indicate that >10% of SO is reacting with the C-4 carbocation, formed from acid cleavage of the interflavan bond, perhaps by a bimolecular S2-type reaction, and as a reducing agent. In addition, the high SO wine had the lowest protein-binding tannin levels, tannin activity, and mean degree of polymerization (mDP), and acidic SO treatment of condensed tannin abolishes protein binding. Thus, SO changes tannin composition during wine aging, and the substantial formation of sulfonate-modified flavan-3-ols may provide an additional explanation for the reduction in astringency of aged red wines.
在 10 种葡萄酒中观察到了许多单体和寡聚黄烷醇磺酸化产物。两种单体磺酸化黄烷-3-醇的含量为 0.85-20.06 和 0-14.72mg/L，这令人惊讶的是，其含量通常高于众所周知的天然黄烷-3-醇单体。在葡萄酒陈酿过程中 SO 水平的增加会增加磺酸化修饰的黄烷-3-醇单体和二聚体，同时也会增加天然单体的浓度。结果表明，超过 10%的 SO 与 C-4 碳正离子反应，碳正离子由间位键酸裂解形成，可能通过双分子 S2 型反应，并作为还原剂。此外，高 SO 葡萄酒的蛋白质结合单宁含量、单宁活性和平均聚合度（mDP）最低，且缩合单宁的酸性 SO 处理会破坏蛋白质结合。因此，SO 在葡萄酒陈酿过程中改变了单宁的组成，磺酸化修饰的黄烷-3-醇的大量形成可能为陈酿红葡萄酒涩味减轻提供了另一种解释。
