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The relevance of the production process of the corks in their permeability and the influence on the evolution of the wine is determined

Full stop at "Project for the determination of the evolution of oxygen permeability during the different manufacturing conditions of corks and the effect of this parameter on still and sparkling wine" (2017-2022), who has studied several variables in the production and manufacturing process to see how they can affect the permeability of corks and determine their influence on the evolution of still and sparkling wines.

 The antecedents

This new project was created thanks to research generated during the GO-OTR project, funded by Operational Groups of the European Association for Innovation (AEI), which started in 2017 and ended in 2020. The project GO OTR made it possible to identify at the laboratory level certain parameters of the cork production process as important factors in the evolution of cork permeability.

In order to continue the research, the Fundació Institut Català del Suro (ICSuro), as well as all the companies, decided to start a new study based on the knowledge generated. The main objective of this new study was to confirm whether the differences identified at the laboratory level of the oxygen permeability test of corks could be appreciated in wine. Achieving this objective has allowed, on the one hand, to validate the analysis method and, on the other, to acquire knowledge about the process of making corks and its influence on oxygen permeability.

The project has been developed by the Fundació Institut Català del Suro as a research center and coordinator of the partnership of four companies producing corks in Catalonia: J. VIGAS SA and MANUEL SERRA SA, specialized in natural corks, and FRANCISCO OLLER SA and TESA SA, which manufacture agglomerated cork stoppers with two discs for sparkling wine. It has also had the collaboration of the ComitéChampagne and the Instituto de Ciencias de la Vid y el Vino of the Universidad de la Rioja.

The importance of OTR (OxygenTransferRate)

The evolution of the wine is extremely dependent on the amount of oxygen it receives. Oxygen plays a crucial role in the entire oenological process, from the collection of the grapes to the opening of the bottle and the consumption of its contents. Several studies show that the same wine covered with corks with different permeability can evolve differently. For this reason, after bottling, exposure to oxygen depends on the efficiency of the closure. The permeability of each cap is measured as the oxygen transfer rate (OTR) or oxygen entering the bottle over time (mg O2). There is currently no standardized methodology for quantifying the oxygen permeability of a cap. However, the Institut Català del Suro Foundation coordinates the UNE CT56/SC5 working group to implement it. ICSuro started research in this field in 2016.

To make a careful study of how the production process can influence the permeability of corks, several parameters have been studied in their production. In the case of natural corks for still wine, the process and the type of washing, the type of equalization or the surface treatment have been monitored. In the case of sparkling wine corks, the number of discs, the quality and density of the discs, the surface treatment or the quality and compression of the agglomerate have been analyzed.

The conclusions

After five years of study, the following conclusions have been reached:

– Oxoluminescence has been validated as a method for measuring the oxygen permeability of corks, since the conclusions drawn at laboratory level can be extrapolated to wine.

– It has been found that the supply of oxygen after capping with a correctly bottled cork comes from the cork itself and not from the input of external oxygen.

– The bottling process (regularity and control of the oxygen intake) has been reaffirmed as a critical and crucial point to obtain the desired evolution of the wine.

– It has been shown that the position of the bottle after capping is fundamental and the results obtained change depending on whether it is stored vertically or horizontally.

– Participating companies have characterized their production processes in terms of their contribution to oxygen permeability.

– The knowledge acquired during the project should allow the production process to be modulated to increase the homogeneity of the natural cork stoppers.

– The oxygen permeability of the corks and the storage conditions of the wine are key parameters to ensure its correct organoleptic state. These have an influence on the evolution of still wine at an analytical and sensorial level.

– The cap recovery time immediately after capping (one to five minutes) must be respected and the bottles must not be moved or stored in a horizontal position until this time has passed.

– In sparkling wine it has not been possible to verify that the OTR has a definite impact on the organoleptic profile of the wine. New tests will need to be developed in this regard.

Project participants

FRANCISCO OLLER: company founded in 1892, specialists in producing sparkling wine corks exclusively, with 300 million corks produced (2022), sole producer of champagne corks in Champagne (recognized by the French label: Entreprises de Patromoine Vivant).

Worldwide presence, certified company: ISO 9001:2015, ISO 14001:2015, ISO 22000:2018, FSSC22000, FSC, Systecode Excellence and negative carbon footprint.

J. BEAMS: J.Vigas is an independent family company that has been manufacturing natural wine stoppers for wine and cava since 1887. It has three headquarters, one in Extremadura, Vimatap·15, which allows it to be close to the source of the raw material and have full control of the product; and two headquarters in Palafrugell. It is characterized by a tailor-made service, very focused on the customer, and thanks to its versatility it can offer the best caps according to its needs and preferences.

THESIS (Tapones y Especialidades del Corcho SA): Since 1958 specialized in the manufacture of corks with natural cork discs for Sparkling Wines, Caves and Champagnes.
Personal advisor at the winery. It has ISO 9001, ISO 14000, EMAS, SYSTECODE and APPCC certifications.

HIGH SCHOOL CATALAN OF CORK: private non-profit and scientific foundation whose mission is to promote the cork sector. It has three lines of action: research and research on the cork and other applications, quality controls of corks through the Cork Center Laboratory and communication for the dissemination and promotion of the conservation and utilization of corks.

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