Wine absorption by cork stoppers

Abstract

Cork is used in enology due to the unique physicalmechanical and chemical properties of the material including impermeability and mechanical behavior. These properties guarantee the maintenance of liquid tightness for prolonged periods of time, as well as a minimal cork-wine interaction (Maga and Puech, 2005;Silva et al., 2005). Despite its low intensity, the influence of this interaction on the evolution of bottled wine is outstanding, as shown by the numerous studies published on the transfer and absorption of volatile compounds by cork stoppers and the effect of the stopper system on wine micro-oxygenation (Juanola et al., 2005;Lopes et al., 2005;Skouroumounis et al., 2005).This work is focused on a less studied aspect: absorption of liquids by the cork stopper. The interest in the absorption phenomenon is due to the fact that it notably AbstractTo evaluate the magnitude of wine absorption by cork under conditions as close to reality as possible and its evolution in time, ready-to-use natural cork stoppers and "1+1" cork stoppers were used to close bottles filled with red wine. Stoppers were removed after 3, 6, 12 and 24 months of contact to determine absorption of liquid and liquid progression along the lateral surface of the cork stopper. Variation of absorption with contact time was studied by adjusting the model Absorption = a t (R 2 : 82.19 -93.63%). A scheme of the evolution of wine absorption with time is proposed, differentiating liquid flow along cork-glass interface, diffusion in cell walls and liquid flow through the cell lumens. In conditions of use, a value of 4.48·10 -13 m 2 s -1 was obtained for non-radial diffusion coefficient (D).Additional key words: cork-wine interaction, diffusion, natural cork stopper, technical cork stopper. Resumen Absorción de vino por los tapones de corchoEl objetivo del presente trabajo fue evaluar la magnitud de la absorción de vino por el corcho en condiciones reales y su evolución con el tiempo. Para ello, se utilizaron tapones de corcho acabados, naturales y "1+1" para cerrar botellas de vino tinto. Los tapones fueron extraídos después de 3, 6, 12 y 24 meses de contacto con el vino y se determinó la absorción y la progresión del líquido por la superficie lateral del tapón. Para estudiar la variación de la absorción con el tiempo, se ajustaron modelos del tipo Absorción = a t (R 2 : 82,19 -93,63%). Se presenta un esquema de esta evolución, diferenciando el flujo de líquido a lo largo de la superficie corcho-vidrio, la difusión en las paredes celulares y el flujo de líquido a través del lumen de las células de corcho, obteniéndose un valor de 4,48·10 -13 m 2 s -1 para el coeficiente de difusión en dirección no radial para el corcho en condiciones de uso.Palabras clave adicionales: difusión, interacción corcho-vino, tapón de corcho natural, tapón de corcho técnico.Abbreviations used: CETIE (Centre Technique International de l'Embouteillage et du Conditionnement), RH (relative humidity), SE

Permeability of Cork for Water and Ethanol

“…Once cork becomes soaked, oxygen ingress could be reduced by a factor of 10 as we measured for He in this work. It is also possible that the huge variability of permeation measured before for He (3 orders of magnitude) is significantly reduced for wet cork, in line with the results of other authors who tested cork closures under real conditions. ,, From this work it may be recommended that bottles should be placed horizontally for long-term storage of wine, assuring minimum oxygen ingress in the bottle, as is already common practice. As future work, the effect of a mixture of ethanol and water as well as wine will be used to assess the permeation and selectivity of cork to the main components of wine.…”

Non-Destructive Measurement of Water Diffusion in Natural Cork Enclosures Using Terahertz Spectroscopy and Imaging

“…The presence of these potentially highly anisotropic features in the cork implies a highly variable local diffusion rate. The extraction and migration of volatile chemicals from the cork [16] will depend on the local diffusion rates and the presence of volatiles in the area of contact between the wine and the cork.…”

Cork and Cork Stoppers: Quality and Performance

“…On the other hand, a cork stopper absorbs water/wine, and this liquid penetration through the cork is governed by the diffusion of the liquid in contact with the surface of the stopper [3]. González-Adrados et al [38] evaluated the magnitude and evolution in time of absorption phenomena under conditions as close to reality as possible and described the transport of liquid as a combination of liquid progression by the cork-glass interface and diffusion through cell walls. [3]).…”