Migration of Printing Ink Constituents from Packaging into Food Simulan

Printing inks contain many substances, the use of which is not allowed in food contact materials. Recently the migration of printing ink constituents from the printed packaging materials into food either through the packaging material or via the set-off phenomenon has been reported. The aim of presented study was to quantify the transfer of selected printing ink plasticisers, i.e. acetyl tributyl citrate (TBAC), bis(2-ethylhexyl) adipate (DEHA), bis(2-ethylhexyl) phthalate (DEHP), 2-ethylhexyl diphenyl phosphate (EHDPP) and tributoxyethyl phosphate (TBEP), from printing of packaging materials into food simulants. Two polymer packaging films, i.e. polyethylene film (LDPE, thickness 50 μm) and laminated polyethylene terephthalate and polyethylene film (PET/LDPE 12 μm/35 μm) were printed with flexography technique to obtained the packaging materials with defined content (0.05 mg/dm2 and 0.5 mg/dm2) of free above mentioned substances in printing layer. The migration of the tested additives through the packaging films into distilled water and 95% ethanol was studied at 6°C and 23°C. The set-off transfer of all plasticisers into LDPE film in contact with printing was tested at 23°C and 40°C. The results confirmed quite easy migration of all tested additives into 95% ethanol through the LDPE film when more than 90% of the total amount of TBAC and DEHP in printing was extracted into the stimulant during 30 day storage at 23°C at both content levels. Lower migration was found for DEHA (i.e. about 86% and 55% for higher and lower content in printing, respectively), TPEC (about 62% and 50%) and EHDPP (69% for lower content in printing). The migration through the laminated PET/PE film was generally about two thirds of that for LDPE film with an exception of DEHA. For DEHA migration through the both tested films were comparable. As expected the plasticiser transfer into distilled water was about 5-10 times slower compared with the migration into 95% ethanol. Surprisingly high levels of the set off transfer from printing into LDPE film at 40°C after 30 days were determined for all tested plasticisers. The found levels of plasticiser transport were as follows: 32%-40% for TBAC, 28% for DEHP, 25% for DEHA, 12% for TBEP and about 2% for EHDPP. The study confirmed the fact that composition of printing inks can significantly influence the safety of food packaging materials and the necessity of acceptation of suitable legislation for the quality control of printing inks for food packages.