There are three ways in which this can happen. The first relates to the production process where, after printing, the unprinted side of the stock comes into contact – either in the stack or on the reel – with the printed side below, with the possibility of transferring visibly-undetectable ink constituents. In the case of visible set-off of ink, printed articles are scrapped, but material affected by invisible set-off is still converted. This explains why these substances are able to transfer or ‘migrate’ from printed packaging to the food.
The second form of interaction occurs where substances of low molecular weight can migrate through the board or paper.
Thirdly, volatile substances can transfer from the packaging via the gas phase and negatively affect food.
Folding cartons are primarily printed using sheet-fed offset and, generally speaking, standard sheet-fed offset inks contain migration-capable substances (such as mineral oil) for which board and paper pose no barrier, and it’s possible for substances to migrate through the substrate.
In addition to high migration potential on paper and board, many ink constituents also demonstrate a propensity to migrate through polyolefin coatings and bags. This means that PE and PP coatings or inner bags made of paper, OPP or PE film don’t act as a barrier to these substances. It’s not possible, therefore, to rule out substances from ink constituents transferring from cartonboard printed on an offset press to package contents even if the contents are additionally packaged in a paper, OPP or PE bag. In this case, organoleptically-sensitive foodstuffs may suffer a change in taste.
Legislators demand state-of-the-art technology
Fundamental guidelines for food packaging are laid down by EU Regulations (EC) Nos 1935/2004 and 2023/2006. Definitive in this respect is Article 3 of Regulation (EC) No 1935/2004, which states that food packages are to be manufactured such that no substances that endanger human health, change the composition of the food, or change the organoleptic properties of the food can transfer from the packaging to the food.
This requirement relates to the final product packaging, and not to its constituent components such as substrates, printing inks and coatings. For this reason, it’s the manufacturers and marketers of such packaging who bear responsibility in accordance with European law.
On the safe side with MGA
To solve the problem of migration, the hubergroup developed the MGA inks and coatings system that guarantees the highest possible degree of safety for the consumer. This product series, which has been on the market for a few years, reduces the level of ink- and coating-related migration from primary and secondary packaging. In addition to the printing ink, the water-based coating essential when printing food packaging and the fount solution required for the offset process must also be taken into account.
With its Corona-MGA sheet-fed offset inks, Acrylac- MGA water-based coatings and MGA fount concentrates, the hubergroup offers a complete system of low-migration products for the sheet-fed offset segment.
Outstanding results are achieved through the exclusive use of components with a minimal migration potential. In addition, all raw materials with a potential to migrate have been evaluated by the European Food Safety Authority (EFSA) with respect to food contact and confirmed to be harmless. Solvents used are special fatty acid esters that are scarcely capable of migrating through cartonboard.
The purity of raw materials used also plays an important role; and this is specified in agreements with the hubergroup’s suppliers. Additionally, special software checks all formulae in order to ensure that only approved components have been used.
These inks and coatings are produced in completely separate production facilities in order to fulfil GMP requirements for ink manufacture and to prevent contamination with components from conventional inks. These facilities are used to produce only low-migration products and nothing else. And thanks to the comprehensive batch tracking system installed in all hubergroup’s plants, each component that goes into any of these inks can be traced right back to its origin.
Entire production process optimised
Of course, inks and coatings are just one part of the system; other raw materials and the entire production process (printing, carton manufacture, etc) must meet the requirements.
MGA stands for the maximum degree of safety possible from inks used in the production of food packaging. As such, MGA assumes some of the responsibility printers bear with respect to folding food cartons.