Wine Oxidation and the Role of Cork

Abstract

The present review aims to show the state of the art of oxidation mechanisms occurring especially in white wines by taking into account knowledge from different fields in relation to the subject. It is therefore divided into three main parts. First, the mechanisms of oxidation relevant to white wine are discussed in the light of recent scientific literature. Next, the phenomenon of oxygen solubility in wine during the winemaking process, and in particular during bottling is stated theoretically as well as practically. Finally, the aspect of wine conservation after bottling is examined with respect to mass transfers which may occur through the closure, with a special emphasis on cork. Currently, specific physico-chemical properties still make cork closures the most important closure type used for the wine market, and especially for high quality wines. This final section will also include a review of studies performed on this subject, which have been analyzed in detail from a theoretical mass transfer point of view, in order to assess the extent to which the proposed scientific tools and the observed tendencies are relevant to progress in the understanding of the impact of this parameter on the behavior of a wine.

Mechanical properties of cork: Effect of hydration

“…Cork is the outer bark of cork oak tree Quercus suber L. This natural polymer has an alveolar cellular structure with an interesting set of properties: low permeability to gas and liquid [1,2], chemical and microbiological stability [3], low conductivity [4] and remarkable elasticity with dimensional recovery [5][6][7]. In view of these features, cork is used in many fields such as insulation [8], shoes insole [9], adsorption of pollutants [10] and obviously as stopper to seal wine bottles [11,12].…”

The cork viewed from the inside

“…The more lenticels there are, the worst cork quality is. The knowledge of the structure is important to better understand the mass transfer properties in its use as a sealing material (Giunchi et al, 2008;Karbowiak et al, 2010;Lequin et al, 2010). Cork is generally sorted visually by hand or by optical analysis (Pereira et al, 1996;Prades et al, 2010) as a function of its overall outside general aspect, considering the defects viewed from the outside are a good estimation of the inside.…”

Sensory Impact of Polyphenolic Composition on the Oxidative Notes of Chardonnay Wines

“…The two kinds of stoppers chosen for this study (synthetic coextruded stoppers and screw cap) presented extreme OTR values to ensure oxidation differences as previously described [3]. Synthetic coextruded stoppers are able to diffuse 10 to 100 times more oxygen that screw caps, and could possibly reveal oxidative deviations earlier in wine compared to more reductive environments when screw caps are used [3,24].…”