Treated closures 3

In a first aspect, the present invention provides a method for producing a coating or diffusion layer on a substrate (e.g. a cork) for use in contact with a food product or beverage, said coating or diffusion layer preventing or inhibiting passage therethrough (e.g. from a cork to an alcoholic beverage) of flavour-active or odour- active compounds (commonly known as cork taint), and said method comprising applying to the surface of said substrate an effective amount of a copolymer comprising a flexible component and a retentive component, said flexible component being sufficiently flexible to allow the coated substrate to undergo compression and recovery (e.g. so as to allow a coated cork according to the present invention to be compressed and then to recover during the bottling process) and said retentive component being able to bind with or otherwise retain flavour-active or odour-active compounds. In a second aspect, the present invention provides a coated substrate, and in particular a coated natural or synthetic cork, produced according to that method.