Insert for crown or screw caps for the closure of bottles.

An insert for a mechanical clamping cap of a screw and crown type, for closure of bottles, said cap comprising a body and said insert being designed to be fixed to said body facing a surface of said body facing an interior of the bottle when said cap is closed over said bottle,

• said insert comprising a sealing element capable of being compressed in one part between said body and a portion of said bottle when said cap is closed over said bottle, and comprising a permeating element connected to said sealing element, said permeating element being impermeable to liquids and having a permeability to oxygen measured at 20° C. of between 10−6 and 10−10 (Ncm3*cm/cm2*cmHg*s), said permeating element being designed to close a passage made in said cap between an inside and outside of the bottle, and having a thickness and surface such as to control the flow of oxygen between the inside and outside of the bottle, with the cap fitted, between 0.1 and 5 milligrams per month.