Assay to sensorially reveal “hidden” oxidation defects in non-volatile complexes

Oxidation is one of the most critical challenges in winemaking, yet some of its most damaging effects remain invisible — at least until it is too late. Research has shown that a significant proportion of commercial wines contain aldehydes at levels high enough to cause typical oxidation aromas during ageing. The problem is that these compounds are often present in odourless, reversible forms, bound to amino acids, alcohols or SO2, making them undetectable by conventional sensory evaluation at the time of bottling.
In this presentation, Mónica Bueno of the LAAE-University of Zaragoza introduces an innovative winery-level assay designed to sensorially reveal these hidden oxidation compounds before they become a problem. The approach uses a reagent capable of displacing aldehydes from their odourless complexes, effectively anticipating the sensory deterioration that may occur during ageing — and giving winemakers a practical tool to act before it is too late.
The presentation walks through the experimental design in detail: the selection of temperature and reaction time conditions, the preparation of wine samples at different aldehyde concentrations, and the sensory methodology applied, including a classification test carried out by a trained panel. Chemical analyses of the main aldehyde fractions complement the sensory results, providing a robust and multi-dimensional picture of each wine’s oxidative status.
The study also includes a decision-point application tested on red wines in the run-up to bottling, with results that demonstrate the real-world potential of this approach for guiding critical winemaking decisions.
A highly relevant contribution for enologists and quality control teams working on wine stability and shelf-life management.

The lecture reproduced in this video was presented at the 24th edition of Enoforum (Zaragoza, 15–16 May 2024)