Araújo Paula, Fernandes Ana, de Freitas Victor, Oliveira Joana
Laboratório Associado para a Química Verde, Departamento de Química e Bioquímica, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, 687, 4169-007 Porto, Portugal.
Int J Mol Sci. 2017 Apr 4;18(4):762. doi: 10.3390/ijms18040762.
A new chemical pathway yielding A-type vitisins in red wines is proposed herein from the reaction between anthocyanins and oxaloacetic acid (OAA). This new chemical path is thought to occur in the first stages of the wine production even during the fermentation process. This is due to the revealed high reactivity of OAA with anthocyanins compared with the already known precursor (pyruvic acid, PA). In model solutions at wine pH (3.5), when malvidin-3--glucoside (mv-3-glc) is in contact with OAA and PA a decrease in the OAA concentration is observed along with the formation of A-type vitisin. Moreover, part of the OAA is also chemically converted into PA in model solutions. The reaction yields were also determined for OAA and PA using different mv-3-glc:organic acid molar ratios (1:0.5, 1:1, 1:5, 1:10; 1:50, and 1:100) and these values were always higher for OAA when compared to PA, even at the lowest molar ratio (1:0.5). The reaction yields were higher at pH 2.6 in comparison to pH 1.5 and 3.5, being less affected at pH 3.5 for OAA. These results support the idea that OAA can be at the origin of A-type vitisins in the first stages of wine production and PA in the subsequent ageing process.
本文提出了一种在红葡萄酒中由花青素与草酰乙酸（OAA）反应生成A型葡萄素的新化学途径。这种新的化学途径被认为发生在葡萄酒生产的最初阶段，甚至在发酵过程中。这是因为与已知的前体（丙酮酸，PA）相比，OAA与花青素显示出更高的反应活性。在葡萄酒pH值（3.5）的模型溶液中，当矢车菊素-3-葡萄糖苷（mv-3-glc）与OAA和PA接触时，会观察到OAA浓度降低，同时形成A型葡萄素。此外，在模型溶液中，部分OAA也会化学转化为PA。还使用不同的mv-3-glc:有机酸摩尔比（1:0.5、1:1、1:5、1:10、1:50和1:100）测定了OAA和PA的反应产率，即使在最低摩尔比（1:0.5）下，OAA的反应产率与PA相比也总是更高。与pH值1.5和3.5相比，pH值2.6时反应产率更高，OAA在pH值3.5时受影响较小。这些结果支持了这样一种观点，即OAA可能是葡萄酒生产最初阶段A型葡萄素的来源，而PA是后续陈酿过程中A型葡萄素的来源。
