## 1 Introduction  
A sparkling wine is characterized as a product in which the carbon dioxide is generated exclusively by fermentation [1]. The production of sparkling wine can follow the traditional method (Champenoise), which consists of two fermentation phases. Initially, the grape must is fermented into a base wine. Then, a second fermentation takes place inside the bottle, where the wine undergoes an aging process in contact with the lees. This second fermentation, known as \"prise de mousse\", occurs after the addition of a \"tirage solution\" or a mix that includes yeast, sucrose, nutrients and, sometimes, bentonite [2; 3; 4]. Then, the product is closured hermetically, with a screw cap or a cork stopper. The second fermentation takes between two and three months, or when the sugar concentration is less than 1.5 g L\({}^{-1}\)[1], and the product subsequently rests in the bottle with lees for at least nine months of aging. An autolysis process takes place when the base wine remains in contact with the yeast lees [1]. The lees release nitrogenous and volatile compounds, polysaccharides, and phenolic compounds [5], which provides the complexity characteristic of cava. The result is a significant change in wine composition and foam formation that has a very important role in the sparkling wine \"bouquet\" [6]. The final step of this traditional method to obtain sparkling wine is the riddling, with the aim of removing the yeast lees from the bottle, followed by the disgorging process. This last process is performed manually in the case of bottles closured with cork stoppers or mechanically in the case of the use of screw caps. The final product must have a minimum pressure of four atmospheres, measured at 20 \({}^{\circ}\)C.  
The second fermentation of base wine, as well as the aging stage in the bottle, is carried out in closed bottles. Traditionally agglomerated cork stoppers with two natural disks held in place with a metal staple are used, but nowadays, a screw cap is the most common closure, because it allows for automation on the bottling and disgorgement line. However, some producers continued using cork stoppers in all production or in premium products due to the favorable outcome of sensory attributes [7]. A screw cap is made up of a metal cap that screws onto the threads on the bottle neck. It typically has an inner lining composed of multiple layers: a polyvinylidene chloride (PVDC) film, a tin-foil layer serving as a gas barrier, and a polyethylene (PE) wad to maintain compression [8]. Saranex is one of the most common screw caps and consists of a PE core coated on both sides with PVDC [9]. Another screw cap is Daraforum, or a non-polyvinylidene (PVC) compound based on polyolefinic raw materials. As previously mentioned by [10], the components of screw caps have distinct functions: PVDC provides an effective barrier against oxygen, while PE acts as a barrier to water vapor. Although screw-cap closures are easy to remove from the wine bottle, the metal cap, usually aluminum, can lead to the releasing of metal ions into the wine during bottle aging [11; 12]. On the other hand, cork is the outer bark of _Quercus super_ L. a western Mediterranean evergreen oak tree. Cork is a very suitable material for wine stoppers due to its peculiar properties, such as its impermeability to liquid and air, elasticity, resilience, compressibility and chemical inertness [12; 13; 14; 15]. Although the production of different types of cork stoppers is by far the most important application of cork, it also has applications in construction, design, cosmetics, and clothing, among others [16; 17]. The type of closure has an effect on the aroma composition of wines during aging due to several factors, including the oxygen ingress through the bottles, the desorption of volatile compounds from the closures into the wine, and the scalping of volatile compounds present in wine by the closures [8; 18]. Cork has been used for centuries as a closure material for the conservation of both still and sparkling wines.