Researchers in Spain have found that inks commonly used in food packaging materials can transfer to the food inside, even though inks are usually placed on the external side of the packaging.

The scientists from the University of Zaragoza examined migration of ink components from different multilayer materials to two food simulants (ethanol 95%, representing a fat simulant, and Tenax as a dry food simulant). They studied the effect of ink transference and how it was affected by adding external lacquers to the material.

A total of 24 migrants coming from inks were found to transfer from two multi-layer materials. Of these, 17 migrated out of a multilayer material of ink/PET/aluminum/polyethylene due to what the researchers called the "set-off phenomenon" during manufacturing and storage.

The number of migrants decreased dramatically when a lacquer coating was added to the outer layer, and especially when ink was placed under a PET layer (lacquer/PET/ink/aluminum/polyethylene).

But the researchers noted that some new migrants appear as a result of the reaction between ink and lacquer, so the composition of the lacquer material is crucial.

The migration experiments were performed in accordance with European Regulation EU/10/2011 on plastic materials and articles intended to come into contact with food.

The research team's findings have been published in the peer-reviewed journal Dyes and Pigments.