A method for testing the mineral oil barrier properties of packaging materials has been developed as a response for the concerns on contamination of food by mineral oil compounds. The aim was to provide an efficient tool to evaluate packaging materials with respect to this. The method is a modification of the so-called cup test using model compounds comparable with mineral oil components with different length and configuration of the hydrocarbon chain. The model compounds are introduced in the gas phase as penetrants. The absorbed amounts, which have migrated through the barrier, are analysed from a food simulant or powdered sugar. The method has been validated for coated and non-coated boards. Compared with folding boxboard without polymer coating, polyethylene terephthalate-coated board reduces the amount of the C16 compound in food simulant after 7-day tests by a factor of 30. An extended migration model describing sorption mechanisms to both food simulant and fibres in the packing material has been developed. The model simulations for folding boxboard indicate that fibres absorb a significant proportion of the compounds when molecular weight increases. This retards the migration significantly compared with the speed expected by diffusion mechanism only.
- mineral oil
- packaging material