In general, it is desired that product packaging be inert to the product being packaged. However, there are situations where the product and the packaging films interact with each other. In some instances, this is desirable and can be engineered to control a product composition or to add protection to the packaged product. Still, most instances of package/product interactions are not engineered in advance and are only recognized as a result of a package failure or the “modification” of the packaged product.
The situation that first comes to my mind is the extraction of vitamin C and limonene (citrus flavor component) from orange juice by the sealant layer of orange juice containers. In many instances, extra vitamin C and limonene, i.e.: orange flavor, are added to the juice to offset the flavor and vitamin loss to the sealant. The extraction of a product component by the packaging is called “scalping.” For each polymer/product, there will be a partitioning of the packaged product and film components into both parts of the packaged system. This is just like in a chemical extraction with a separatory funnel, where you shake a water solution with an immiscible solvent, to extract organic chemicals from the water into the solvent.
Another situation I know of is the addition of a typical food additive, such as an antioxidant, to a packaging layer so that the antioxidant is extracted into the packaged product to maintain product freshness by inhibiting fat oxidation (rancidity).