Resolving Multi Layer Packaging Migration Non Conformance Liability in Food Contact Certification
Resolving multi layer migration liability requires linking batch trace numbers to accredited specific migration reports and contract indemnity clauses.
Cold Water Extract En 645
Extraction Method
Laboratory leaching protocols evaluate the transfer of water-soluble substances from paper and board materials intended for direct contact with aqueous foodstuffs. The analytical procedure detailed in cold water extract en 645 immerses fibrous samples in grade three distilled water for twenty-four hours at ambient room temperature. This contact regime simulates brief or ambient contact between moisture-containing food items and porous packaging substrates, measuring hydrophilic constituents that release without thermal acceleration.
Chemical analysts prepare the extract by agitating defined weights of dry paperboard in pure water before vacuum filtering the liquid to remove suspended cellulose fines. The resulting filtrate undergoes analytical characterization for optical brightening agents, formaldehyde content, heavy metals, and dry matter residue.
Analytical Parameter
Aqueous extraction targets polar process aids, water-soluble sizing agents, and biocides retained within the fibre web during paper manufacturing. Testing according to cold water extract en 645 serves food packaging safety by quantifying components that migrate during cold storage or wet packaging conditions. Sizing agents like alkyl ketene dimer and polyvinyl alcohol release measurable fractions into the liquid phase if curing remained incomplete on the paper machine drying section.
Formaldehyde levels in the extract derive from wet-strength resins, including urea-formaldehyde or polyamide-epichlorohydrin chemistries. Limit values established by European regulatory bodies require that aqueous extracts remain neutral in taste, odourless, and free from cytotoxic migrating ions.
Substrate Boundary
Hydrophilic paperboard surfaces interact with liquid water differently than polyolefin coatings or synthetic barriers. Cold water extract en 645 applies specifically to uncoated paper, paperboard, and hydrophilic fibre structures, ceasing to provide meaningful exposure values when testing hydrophobic poly-laminated boards or metallized films. If a carton features an extruded polyethylene layer, migration testing must follow overall migration standards using aqueous simulants rather than paper extraction regimes.
The method quantifies what can dissolve out of the cellulosic substrate itself during moist storage.