Compliance testing of food contact materials EU FDA
EU testing Introduction simulants&conditions overall migration specific migration residual content other testing
Overall migration testing
The reason of determining overall migration is that the food contact material may bring about an unacceptable change in the composition of the food (article 3 of the framework Regulation (EC) 1935/2004).
Aqueous simulants
The methods of determining the overall migration into the aqueous simulants (A, B and C) are as follows:
Bring the food contact material in contact with the simulant for a selected time and temperature.
Separate the sample from the simulant and evaporate the simulant.
Determine the weight of the residue and calculate overall migration. As a consequence volatile chemicals, which migrate, are not included in the overall migration value for the aqueous simulants.
Fatty food simulant
Because the fatty food simulant olive oil cannot be simply evaporated, the determination of the overall migration into olive oil is more complicated. The value of overall migration is measured by determining weight loss from the sample. But because the sample might have absorbed components of the fatty simulant during contact, the weight loss of the sample must be corrected for the amount of absorbed fat. The procedure of determining the migration into fat is:
Determine the weight before contact (W1).
Bring the food contact material in contact with the simulant for a specific time and at a defined temperature.
Separate the sample from the simulant and remove as much simulant.
Determine the weight after contact (W2).
Determine the amount of fat absorbed in the sample using a suitable method (F).
Calculate the migration (migration is W1-W2+F).
Migration into fat is a very complicated
factor and errors can be made very easily resulting in higher or lower values.
The following critical issues need to be considered during the determination of
overall migration into fatty foodstuffs:
The weight before and after the contact time is determined. Therefore it is important that in case the material contains moisture, the amount of moisture is identical whilst determining W1 and W2. This could be achieved by conditioning the sample before determining W1 and W2, by means of vacuum drying or using constant relative humidity.
During conditioning volatile components (not being water) are removed resulting in a lower value for overall migration.
In determination of the amount of fat absorbed by the sample (F), not all the fat is extracted, resulting in a value for F, which is too low.
Besides the above there are many more sources of possible error. More detailed information about the determination of the overall migration can be found in CEN methods. The use of olive oil is preferred over the use of alternative simulants, because in most cases 95% ethanol or isooctane is a more stringent simulant resulting in a much higher value of overall migration than the value that would be obtained when olive oil is used.
The EU limit of the overall migration is 10 mg/dm2 or 60 mg/kg. Because olive oil is a severe solvent compared with most fatty foods, a reduction factor ranging from 2-5 may be applied depending on the food. Chocolate has for example a reduction factor of 5, which means that the value obtained for the overall migration into simulant D must be divided by 5 before checking it against the limit (Directive 85/572/EEC).
Furthermore, it should be kept in mind that analytical error in the determination of the overall migration was determined by the EU as 2 mg/dm2 or 12 mg/kg for the aqueous food simulants (A, B and C), whilst the error is 3 mg/dm2 or 20 mg/kg for the fatty food simulant (D).
Methods are described in detail in official CEN methods: