A study into the development of a new migration method for sealing gaskets in twist off closures using solid simulants

Migration testing of sealing gaskets in metal closures for glass jars using oil or alternative solvent simulants leads to exaggerated values compared to low and medium fatty foods because of the strong interaction with the gasket material. In a feasibility study specific migration of epoxidized soybean oil (ESBO) out of a test film made of commercial plasticized PVC gasket material was tested using solid simulants like Tenax (R), LDPE film and two types of solid phase extraction discs (oil & grease, C18) and compared to specific migration into oil, isooctane, 95% ethanol, isooctane-isopropanol (85:15, v/v) and a baby food (risotto with turkey and vegetables, 2.9% fat). Migration was kinetically measured over contact time at 40 degrees C up to 1 month and additionally 1 h at 100 degrees C into oil, baby food and extraction discs and 1 h at 60 degrees C into isooctane to simulate pasteurisation or hoffill conditions. Isooctane-isopropanol caused the highest migration values followed by 95% ethanol, isooctane and olive oil. Into Tenax (R) and LDPE film only very low migration was found. Into extraction discs comparable migration values have been found in relation to the baby food. Pressure between test film and the oil & grease extraction disc had a high impact on the migration value. After solvent cleaning the extraction discs can be re-used. The use of solid phase extraction discs for simulating migration into low-fat foods seem to be promising.