Abstract: The invention provides polymeric films for the storage or packing of plant material, the film being perforate and having a water vapor permeability of not more than 800 g m−2 day−1 and an oxygen permeability of not more than 200000 cm3 m−2 day−1 atmosphere−1, both permeabilities being measured at 25° C. with a relative humidity of 75 percent. Examples of polymers which can be used to make the film are regenerated cellulose, homo and copolymers of polyolefins, e.g. with vinyl acetate or methyl acrylate, polyesters and polyamides. Various plant materials, for example carrots, tomatoes, calabrese and mushrooms heat sealed in packs of films of the invention have shown improved shelf lives compared with similar plant materials packaged for example in polyethylene cling film or polyvinyl chloride stretch wrap.

Abstract: The invention provides methods of packaging plant materials. The plant materials are packaged in a perforate polymeric film, the film being of a polymer having a water vapor transmission rate and an oxygen transmission rate which improve the shelf lives of the packaged materials. The film is selected so that the water vapor transmission rate is substantially that inherent to the film, and the oxygen transmission rate is controlled by the size and/or frequency of perforations in the film. Typically the perforations will have a mean diameter of not more than 100 microns, and preferably from 40 to 60 microns. The frequency of perforations will usually be not more than 1000 per square meter, although at least 10 per square meter will usually be required.