Cork-polypropylene composites for food contact: a comprehensive study of morphology, migration, chemical safety, and...

The development of sustainable food contact materials (FCMs) requires not only reduced environmental impact but also demonstrated safety. Cork-polypropylene composites (CPCs), incorporating unmatured cork and waste generated in cork stopper production, represent a promising alternative; however, their safety remains insufficiently addressed. This study provides a comprehensive safety assessment of CPCs containing 15% cork granulates derived from matured and unmatured cork. A multi-analytical approach combining morphological, thermal, and chemical characterisation (SEM, FTIR-ATR, GC-FID, GC-MS, LC-MS, ICP-OES) was integrated with migration testing under repeat-use conditions and sensory evaluation. Genotoxicity was assessed using the Ames bacterial reverse mutation test on migration extracts. Migration results showed low release of both polypropylene-related additives and cork-derived compounds, with furanic substances identified as process-related migrants but decreasing across repeated use cycles and remaining at low levels. No migration of high molecular weight cork constituents (triterpenoids, sterols) was observed in aqueous simulants. All quantified substances complied with regulatory limits. Ames test results demonstrated no mutagenic activity for any migration extract, confirming the absence of DNA-reactive hazards. Overall, CPCs exhibited stable structure, low sensory impact, and favourable chemical and toxicological profiles. This study provides new evidence supporting the safe use of cork-based composites in food-contact applications and advances the integration of bio-based materials within a circular economy framework.