Packaging materials engineered with functions beyond the basic barrier — packaging that actively interacts with the food or its environment to extend shelf life. The toolkit includes ethylene adsorbers that slow fruit ripening, oxygen scavengers that protect fats from rancidity, moisture regulators, carbon dioxide scavengers or emitters, antimicrobial films that release agents such as ethanol to suppress mould, flavour scalpers or emitters, microwave susceptors, and packs with built-in freshness indicators. Regulators treat active components as potential migrants, so safety assessment covers both the packaging material and whatever the active system releases, absorbs or generates.