La Qualità dei tappi di sughero

The performances of a cork stopper depend from manifold tied up factors both to the characteristics of the product and to the formalities of employment of the same. The success of a corking, therefore, asks for professionalism and realization of good practices of workmanship from numerous subjects. The level of quality of a cork can be valued through the control of some parameters able to furnish an estimate of the performances of the product. National and international standardization organisms are busy in the publication of reference methods. Other methods of test are contained in technical papers (Disciplinare sulla produzione ed utilizzo del tappo di sughero in enologia, Charte des bouchonniers liègeurs, Guide de qualité champagne du bouchon liège, Codiliège, Cork sensory quality control manual) formulated by Associations of producers and inter professional Committees operating in the cork and wine industry and in the food sector. Controls requirement from the industry is evident from the ever-increasing number of tests demanded by cork factories and wine cellars to the laboratories. Referring to the activity of the laboratory of the Stazione Sperimentale del Sughero, the controls able to mostly influence the quality of the wine are analysed. Analysis shows that the controls more frequently demanded on the corks concern the sensory analysis for the determination of migration of mouldy odours, the determination of physical parameters (dimensions, degree of humidity, strength of extraction), the transfer of oxidizing substances and the microbiological tests. The results of the tests show that the measured parameters assume values that commonly respect the approved limits. Since the greatest problem attributed to the employment of the cork stoppers is the migration of mouldy tastes and odours, the connected aspects to determination of 2,4,6-trichloroanisol (TCA) are analysed; TCA, in fact, is the substance mostly implicated in the phenomenon. An ISO TC 87 group is preparing a method of test to determine the quantities of TCA releasable from the cork stoppers under conditions of use.