Volatile composition of oak wood from different customised oxygenation wine barrels: Effect on red wine

The compounds that the wood releases to the wine and the oxygen transmission rate (OTR) of the barrel define the final wine. The new possibility of choosing the OTR of the barrel allows the winemaker to globally control the ageing process. The aim of this work was to study the volatile composition of woods classified according to their OTR, which are used to build barrels for wine ageing. The results showed that volatile composition differs depending on wood OTR and the temperature reached during toasting. On the toasted side of the stave in contact with the wine, low OTR wood had a statistically higher content in furan compounds (5-hydroxymethylfurfural, furfural and 5-methylfurfural), acetovanillone and phenolic aldehydes (vanillin and syringaldehyde), while 4-ethylguaiacol and trans-β-methyl-γ-octalactone were significantly higher in staves with a high OTR. The same red wine aged first for three months in high and low oxygenation barrels presents different characteristics.

Evaluation of oxygen exposure levels and polyphenolic content of red wines using an electronic panel formed by an electronic nose and an electronic tongue

An electronic panel formed by an electronic nose and an electronic tongue has been used to analyse red wines showing high and low phenolic contents, obtained by flash release and traditional soaking, respectively, and processed with or without micro-oxygenation. Four oxygen transfer rate conditions (0.8, 1.9, 8.0, and 11.9 μl oxygen/bottle/day) were ensured by using synthetic closures with controlled oxygen permeability and storage under controlled atmosphere. Twenty-five chemical parameters associated with the polyphenolic composition, the colour indices and the levels of oxygen were measured in triplicate and correlated with the signals registered (seven replicas) by means of the electronic nose and the electronic tongue using partial least squares regression analysis. The electronic nose and the electronic tongue showed particularly good correlations with those parameters associated with the oxygen levels and, in particular, with the influence of the porosity of the closure to oxygen exposure. In turn, the electronic tongue was particularly sensitive to redox species including oxygen and phenolic compounds. It has been demonstrated that a combined system formed from the electronic nose and the electronic tongue provides information about the chemical composition of both the gas and the liquid phase of red wines. This complementary information improves the capacity to predict values of oxygen-related parameters, phenolic content and colour parameters.

Analysis of the influence of the type of closure in the organoleptic characteristics of a red wine by using an electronic panel

An electronic panel formed by an electronic nose, an electronic tongue and an electronic eye has been successfully used to evaluate the organoleptic characteristics of red wines vinified using different extraction techniques and micro-oxygenation methods and bottled using closures of different oxygen transmission rates (OTR). The three systems have demonstrated a good capability of discrimination by means of Principal Component Analysis (PCA). Partial Least Squares Discriminant Analysis (PLS-DA) has permitted to establish prediction models based on the type of closure, the polyphenol content or the effect of micro-oxygenation. The best correlations found using the e-eye and the e-nose are related to the OTR of the closure. In contrast, the electronic tongue is more sensitive to the polyphenol content. The discrimination and prediction capabilities of the system are significantly improved when signals from each module are combined. The electronic panel can be a useful tool for the characterisation and control of oxygen and antioxidant capability of red wines.