Food grade PP is not a special polymer. Polypropylene used for food contact and polypropylene used for a garden chair are often the same base resin, and the difference is the additive package and the documentation. This guide explains what the designation actually certifies.
What the designation certifies
Food contact regulation works on substances, not products. A resin grade is cleared when every substance in it, including the antioxidants, slip agents and nucleating agents, appears on a permitted list with conditions of use. The supplier documents this with a letter of guarantee referencing the specific regulation for each substance.
What that means in practice: the certificate belongs to the compound, and the compound is defined by the formulation, not by the label on the bag. Two grades from the same resin manufacturer can differ in whether they are cleared, because they differ in additives.
The conditions of use are part of the certificate
Clearance is granted for defined conditions: the food type, the temperature and the duration. A grade cleared for cold, short-contact use is not cleared for repeated hot filling, and a grade cleared for aqueous foods may not be cleared for fatty foods, because migration behaves differently against fat.
For a moulded part, the conditions of use come from the application, not the material. A bowl used for cold cereal and a container used for hot soup have different migration exposure from the same PP, which is why the part-level test is done under the application's conditions rather than the material's best case.
Migration limits and the part-level test
- Overall migration. The total mass migrating into the simulant is capped, typically at 10 mg per square decimetre in the EU regime.
- Specific migration. Individual restricted substances have their own limits, and the additive package is what is being tested here.
- Sensory. Odour and taste transfer, which catches process problems the chemistry misses.
- Repeated use. A reusable article is tested with successive extractions, because migration is cumulative and a single-contact test understates the exposure.
Why the part fails when the pellets passed
Most food-contact failures on moulded parts are process failures, not material failures:
- Insufficient drying. PP is hygroscopic enough that residual moisture hydrolyses the polymer during moulding, producing low-molecular-weight species that migrate. A part that smells of solvent usually has a drying problem.
- Masterbatch. A pigment or filler that is not itself cleared will contaminate a cleared base resin. The base certificate does not extend to the colourant.
- Regrind. Recycled process scrap is acceptable if it is the same cleared material; recycled post-consumer material is a contamination risk and is not covered by the base certificate.
- Mould release. A release agent that is not food-contact approved migrates directly into the food-contact surface.
What to request
- The compound grade with its food contact clearance and the specific regulation referenced.
- A migration test report on the finished, decorated part, listing the simulants and conditions.
- Confirmation that the colourants, release agent and any coating are covered.
- A re-declaration commitment when any of those change.
Related reading
Our food-grade PP feeding programme supplies migration reports on the decorated parts, and the certification guides cover the FDA and LFGB test conditions in detail.
Related product categories
The materials and part types discussed above are grouped in our sourcing directory:
