Caracterización de las vías de transformación oxidativa de los taninos condensados durante el envejecimiento del vino...

The oxidation of condensed tannins via quinone and acetaldehyde pathways critically shapes wine astringency during ageing, yet their individual contributions remain unclear. We developed a pseudo-targeted metabolomics approach with optimized menthofuran depolymerization method, identifying 30 oxidative subunits including new galloylated and trihydroxylated forms. For the first time, both quinone- and acetaldehyde-mediated oxidative units, along with native units of condensed tannins were simultaneously profiled in wines undergoing barrel ageing and different accelerated ageing tests (AATs). Oak barrel ageing significantly reduced native tannins and increased oxidized tannins-a profile unreplicated by AATs. Quantitatively, quinone-oxidized tannins were the predominant oxidized form, exceeding acetaldehyde-derived tannins by 7-9 fold. Structurally, quinone oxidation targeted terminal/extension units, while acetaldehyde units distributed across both free and extension forms. Oxidative susceptibility, EC-type flavanols were most oxidation-prone, whereas trihydroxylated forms exhibited higher stability. This work provides a foundational framework for elucidating tannin transformation during wine ageing.