Department of Agricultural and Food Sciences, University of Bologna, Piazza Goidanich 60, 47521 Cesena (FC), Italy.
RUFFINO S.r.l.-a Constellation Brands Company-Winemaker, P.le Ruffino 1, 50065 Pontassieve (FI), Italy.
Molecules. 2020 Mar 8;25(5):1215. doi: 10.3390/molecules25051215.
One property of oenological tannins, oxygen reactivity, is commonly exploited in winemaking. The reactivity is mediated by the presence of catalysts (i.e., transition metals and sulfur dioxide) and protects wine against oxidation. This work compares the oxygen consumption rate (OCR) of four commercial oenological tannins (two procyanidins from grape skin and seed, an ellagitannin from oak wood and a gallotannin from gallnut) in a model wine solution and Chianti red wine. All samples were subjected to consecutive cycles of air saturation at 20 °C to increase the total level of oxygen provided. After each cycle, the oxygen level was measured by means of a non-invasive luminescent sensor glued to a transparent surface (sensor dots) until there was no further change in substrate reactivity. The OCR followed first-order kinetics, regardless of the tannin. As expected, the ellagitannin showed the fastest OCR, followed by the two from grape seeds and skins and finally the gallotannin. The total O consumption in the red wine was almost double that of the model solution, due to the oxidation of wine substrates. The measurement of OCR is helpful for setting up an advanced winemaking protocol that makes use of tannins to reduce the use of sulfur dioxide.
葡萄酒单宁的一个特性是氧气反应性，这在酿酒过程中经常被利用。这种反应性是由催化剂（即过渡金属和二氧化硫）的存在介导的，可保护葡萄酒免受氧化。这项工作比较了四种商业葡萄酒单宁（两种来自葡萄皮和种子的原花青素、一种来自橡木的鞣花单宁和一种来自五倍子的没食子单宁）在模型酒溶液和基安蒂红葡萄酒中的耗氧率（OCR）。所有样品都在 20°C 下进行连续的空气饱和循环，以增加提供的总氧量。在每个循环之后，通过将发光传感器粘贴在透明表面上（传感器点）来测量氧水平，直到底物反应性不再发生变化。OCR 遵循一级动力学，与单宁无关。不出所料，鞣花单宁的 OCR 最快，其次是来自葡萄种子和果皮的两种单宁，最后是没食子单宁。由于葡萄酒基质的氧化，红葡萄酒中的总 O 消耗几乎是模型溶液的两倍。OCR 的测量有助于建立一个先进的酿酒方案，该方案利用单宁来减少二氧化硫的使用。
