In an article published on April 30, 2019, scientists from the European Commission Joint Research Centre studied the effects of pre-heating polypropylene cups prior to migration testing. National Reference Laboratories were discovered to have been applying pre-heating in order to reach the required testing temperatures more rapidly. In its role as the European Union Reference Laboratory for Food Contact Materials (EURL-FCM), the Centre conducted a study to determine if this pre-heating could have an effect on testing results for regulatory compliance.
Published results from the study show that heat-treated cups can have changes in crystallinity and that physical changes were observed on the surface of the material using microscopy. These changes were found “to have impact on the migrating amounts of additives under certain pre-heating conditions.” Consequently, the EURL-FCM recommends that National Reference Laboratories and control laboratories “avoid pre-heating FCM articles prior to migration testing.”
JRC (April 30, 2019). “Guiding laboratories in migration testing of polypropylene cups.”
Lopes et. al. (2019). “Influence of pre-heating of food contact polypropylene cups on its physical structure and on the migration of additives.” Food Packaging and Shelf Life (published March 14, 2019).