Search for a more adequate test to predict the long-term migration from the PVC gaskets of metal lids into oily foods in glass jars

Abstract

As shown previously, the conventional testing procedure for simulating long-term migration from the gaskets of metal closures into oily foods does not adequately reflect reality. It appears to be impossible to accelerate migration to the extent that the situation at the end of the shelf life of a product can be anticipated in a few days or weeks. Therefore, we investigated whether long-term migration could be extrapolated from migration rates determined for new lids. Jars were kept in the normal upright position. Since heat treatment may have a strong temporary impact, migration during the initial heating for pasteurization or sterilization and storage at ambient temperature were determined using different lids. Commercial products were recalled from sales points throughout Europe to determine the real migration over extended periods of time and for jars with differing histories. This migration was compared with data from the short-term testing to investigate whether an empirical relationship could be derived. The results show that the short-term test enables the comparison of lids and plasticizers in the initial phase of migration, but that long-term extrapolation presupposes more complex kinetic modeling. The results also demonstrate that the legal relevance of “official” testing methods should be reconsidered to avoid conflict when food contact materials comply with migration limits in the test but not in actual application.

Keywords:

• gaskets
• metal closures
• oily food
• glass jars
• migration testing
• PVC plasticizers
• official methodology

Acknowledgements

This project was partially financed by the Italian Association of Food Product Industries (Associazione Italiana Industrie Prodotti Alimentari, AIIPA) and the Italian Association of Metal Packaging (Associazione nazionale fra i fabbricanti di imballaggi metallici ed affini, ANFIMA).