Measuring and modelling Syrah red wines evolution: Ageing tests, color and new molecular indices

A Syrah red wine ageing experiment was set up during 24 months to measure the influence of different micro-agglomerated corks on wine composition and color. Two new wine ageing indices based on targeting phenolic composition (I_ox, oxidation index and I_su, sulfonation index) or colorimetric one (Hue) are proposed. The results showed that the slopes of evolution of these indices varied according to the wine as well as the index studied, and that the initial composition played a predominant role in these evolutions. In addition, the oxygen transfer rate (OTR) of the cork modulates the rate of evolution of the oxidation index and color, but had no impact on the sulfonation index. Partial least squares (PLS) regressions were used in order to establish some models that can predict the ageing index slope based on accelerated ageing tests (AATs), voltammetric parameters and phenolic composition measured before bottling. The models involved different explaining variables for each test and showed good predictive capacities with correlation coefficients (R²) > 0.79.