FDA has jurisdiction over food-contact materials, including cellulosic and hardened-protein casings, and may require compliance with food additive or food-contact substance regulations. If protein casings are derived from animal hides or connective tissue, USDA APHIS may also require documentation confirming the source country's animal-health status. Importers should consult a licensed customs broker or regulatory specialist to confirm the applicable entry requirements for their specific casing type and country of origin.

Collagen casings are edible or inedible depending on thickness and are co-extruded or stuffed with the meat product; they remain on the finished sausage. Cellulose casings are non-edible and are stripped before retail sale, making them standard for skinless frankfurter production. This functional distinction affects not only classification but also the food-safety documentation required at entry, since edible collagen casings may face additional scrutiny as a food ingredient.