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The bioabsorption of aromas in cork, an opportunity for the sector

The cork is a high quality product and about 7 out of 10 bottles that are corked in the world are corked. Acceptance and recognition of its quality by consumers is widespread in the main countries; even so, the cork sector continues to work to mitigate one of the weak points of corks that is inherent to its natural origin and its particular internal structure. Alternative caps or non-cork caps (both synthetic and screw) have historically strengthened their position in the capping market by appealing to their absence of TCA.

Trichloroanisole (TCA) is a harmless molecule in terms of health but has the disadvantage that it is detectable by the human nose at a very low concentration (of the order of 3 parts per trillion in white wine and 8 parts per trillion in red wine or, what would be the same, the volume of TCA in a spoonful of coffee in an Olympic swimming pool) and which affect the bouquet end of wine This fact has led the cork sector to promote research and innovation for the development of new technologies for the detection and/or elimination of these aromatic compounds.

Most of the companies in the cork sector have systems for the extraction and reduction/elimination of aromas present in the products obtained from the different stages of production of cork stoppers. Although the application of these new technologies has succeeded in considerably reducing the presence of sensory deviations associated with cork stoppers, the cork industry continues to bet on the continuous improvement of its technologies, in particular, due to the persistence of some of these compounds, as would be the case of TCA. In addition, it should be borne in mind that it is not possible to apply intense treatments since the properties of cork depend largely on its cellular structure, which at the same time can be affected depending on the conditions to which it is exposed submit this material.

It is for this reason that an operational group formed by five cork manufacturing companies from the Catalan cork sector, -Costa Quer SA, DE MARIA TAPS SL, J. VIGAS SA, TESA SA and FRANCISCO OLLER SA- is being set up to promote the project "Development of a TCA removal system in corks based on the use of adsorbents and biosorbents" with the aim of developing an innovative system for removing aromas in corks that is based on the combination of different adsorbent and biosorbent materials. These materials will be applied in the reduction systems that companies already have with the aim of increasing their efficiency without having to increase the values of the factors responsible for the reduction (temperature, pressure...).

Throughout the project, eight adsorbents/biosorbents have been evaluated in order to determine their reduction potential by haloanisoles (TCA, TeCA, TBA, PCA) and four have been selected, two suitable for application in systems of cleaning and extraction of aromas that use water and, both suitable for application in the environment. The selected materials are active carbons obtained from vegetable by-products such as coconut shell. On a laboratory scale, the selected materials have presented a percentage reduction of haloanisoles from 69.5% to 88.4% in the case of adsorbents applied in a liquid medium and from 40 to 96% in the case of adsorbents applied in a gaseous medium.

The next step was the design of two versatile prototypes that contain the materials and can be installed in the different reduction systems present in companies. Currently, its efficiency in reducing these aromas is being validated based on the analysis of cork samples before and after passing through the system and the environment where they are applied. Finally, the adsorbents/biosorbents used must be analyzed in order to determine the useful life of this material.

With the present project it is intended have two prototypes intended to increase the efficiency of the systems for reducing organoleptic deviations that companies already have in order to give an impetus and increase the competitiveness of their products with respect to alternative caps, given that these are the ones that defend their use against the natural cap, ensuring the absence of deviations. The cork industry, however, is where more resources are being allocated, especially in innovation, and is reaching a very different reality.

It is a project co-financed by the European fund FEDER and the Department of Agriculture, Livestock, Fisheries and Food of the Generalitat of Catalonia through Operation 16.01.01 (cooperation for innovation) of the PDR of Catalonia 2014-2020.