Michael Huber München GmbH

Interaction

What types of interaction can take place between packaging and contents?


More than 95% of all foodstuffs traded in West European retail is packaged. Consumer protection demands that packages do not in any way contaminate the packaged food. Some sheet-fed offset inks in use for printing folding boxes for food packaging can fulfil this demand only to a limited degree.

Interaction between packaging and the contents inside, can occur in three different ways:


Due to the nature of the production process, the side of the stock that will face the package content in the finished article, comes into contact with the printed side while on the press (in the stack or on the reel). This possible transfer of invisible ink constituents, such as solvents or plasticisers, is known as "invisible setoff". These substances can also come into contact and migrate into the package content.





Low molecular substances originating from a layer of ink or varnish can migrate through the substrate to the food. Likewise, substances from the substrate can migrate into the food.





Furthermore, volatile substances in a closed inner containment of a packaging can migrate via gas phase deposition, in all likelihood affecting flavour and odour of the foodstuffs.


Until now, mainly avoiding flavor and odour transfer via gas phase has been investigated. Detection and minimisation of substance transfer by "invisible set-off" and migration is relatively new.

In Europe, folding boxes and paper wrappers are mainly printed in sheet-fed offset. The employed printing inks usually contain vegetable oils, mineral oils and fatty acid esters of low molecular weight as "solvents". Board and paper provide absolutely no barrier to these substances. This means that invisible set-off is not the only possibility of substance transfer, because mentioned solvents are also able to migrate through the substrate.    

In addition to a high migration potential on paper and board, these substances also demonstrate a strong propensity to migrate through polyolefin layers or inner bags. This means that PE and PP laminate layers or inner bags made of paper, OPP or PE film do not act as a barrier to these substances. Also PET films or aluminium foils that are too thin are inadequate barriers.
Even if the contents are additionally packaged in a paper, OPP or PE bag, it is therefore not possible to rule out substance transfer from folding boxboard to the package content. In this case, organoleptically sensitive foodstuffs may suffer a change in taste.

For more information on the "Conformity of foodstuff packages", see

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