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Migration testing of polyethylene terephthalate: Comparison of regulated test conditions with migration into real food at the end of shelf life

: Gehring, Carina; Welle, Frank


Packaging Technology and Science 31 (2018), No.12, pp.771-780
ISSN: 0894-3214
ISSN: 1099-1522
Journal Article
Fraunhofer IVV ()

Polyethylene terephthalate (PET) in contact with food must comply with the requirements laid down in the European Regulation (EU) 10/2011, which specifies conditions for migration tests. For real contact times longer than 30 days, accelerated migration tests are performed at elevated temperatures for a maximum of 10 days at 60°C. These conditions should represent the end of the shelf life (e.g. 365 days at 23°C) and are calculated using the Arrhenius equation on the basis of a default activation energy of 80 kJ/mol. However, for PET, it is well known that the activation energy is strongly dependent on the molecular size of the migrant. Small molecules like acetaldehyde have activation energies in PET of ~80 kJ/mol. For larger molecules like 2-aminobenzamide with a predicted activation energy of diffusion of 134.4 kJ/mol, the storage times at 60°C and 40°C equivalent to the migration after 1 year at 23°C are 0.85 and 18.9 days, respectively. These findings were confirmed by experimental migration tests. For 2-aminobenzamide, migration for 10 days at 60°C corresponded to a storage time at 23°C of 11.7 years, which is significantly higher than the long-term storage of more than 6 months as foreseen in Regulation (EU) 10/2011. For larger molecules, the corresponding storage times at 23°C would even be longer, thus overestimating by far the migration at the end of shelf life. Contact conditions of 10 days at 60°C are too severe for PET. Migrant-specific and polymer-specific diffusion parameters should therefore be considered when designing accelerated migration tests for long-term applications.