The researchers claim even though inks are usually placed on the external side of food packaging, it has found migration of ink components on the internal side, mainly due to what it calls a ‘set-off phenomenom’ during the material’s storage.
'Does not behave as a total barrier'
“The application of external lacquers can reduce the ‘set-off phenomenom’ and the migration of these components to food. However, the composition of this lacquer also plays an important role, as it does not behave as a total barrier, but can contribute to an additional migration of components,” said Margarita Aznar, department of Analytical Chemistry, University of Zaragoza.
“Consequently, the composition of these lacquers should be carefully selected to minimize a ‘migration phenomena’ as much as possible.”
The study, called ‘Set-off of non-volatile compounds from printing inks in food packaging materials and the role of lacquers to avoid migration,’ analyses migration from different multilayer materials containing inks to two food simulants (ethanol 95% as a fat simulant and Tenax as a dry food simulant), the effect of ink transference and how it is affected by the presence of lacquers in the material.
A total of 17 migrants coming from inks due to a ‘set-off phenomena’ were found in a migration from multilayer material [ink/PET/aluminium/polyethylene].
According to Aznar, the number of migrants decreased dramatically when a lacquer was added [lacquer/ink/PET/aluminium/polyethylene] and especially when ink was placed under a PET layer [lacquer/PET/ink/aluminium/polyethylene].
Reaction between ink and lacquer
Some new migrants appear by the reaction between ink and lacquer. In material [ink/paper/OPP/Al/PE], when a lacquer was added some migrants decreased but other migrants present both in lacquer and ink increased.
For migration tests, pouches of 0.16 dm2 were manufactured by heat-sealing the materials.
For ethanol experiments, pouches were filled with ethanol 95% according to the rate 6 dm2contact surface/kg of simulant established by the Regulation EU/10/2011  and placed in the oven at 40ºC during 10 days.
Afterwards, ethanolic samples were filtered through 0.20 m PET filters and injected in the UPLC-QTOF-MS system.
For Tenax migration experiments, pouches were filled with 0.64 g of Tenax (4g Tenax per dm2laminate according to UNE-EN 14338 ) and placed in the oven at 40ºC during 10 days. Afterwards, Tenax was extracted two consecutive times with acetone (5g and 3g respectively) in an ultrasonic bath for one hour, following the methodology designed by Vera et al . The recovered acetone was filtered using PTFE filter (0.45 μm), concentrated under a stream of nitrogen up to 200 μL and finally injected in the UPLC-QTOF-MS system.
“Over the total number of migrants found in this work, the combination of ethanol 95% /30V allowed the detection of 87% of compounds, followed by Tenax/30V (70%) and ethanol 95%/70V (60%),” added Aznar.
“For this reason, using ethanol 95% as food simulant and a medium cone voltage of 30V can be considered the best option for a migration screening study.”
All the migration experiments were performed according to the European Regulation for food contact materials EU/10/2011.
SOURCE: ‘Set-off of non-volatile compounds from printing inks in food packaging materials and the role of lacquers to avoid migration’.
DATE: October 27, 2014
AUTHORS: Margarita Aznar, Celia Domeño, Cristina Nerín, Osvaldo Bosetti.
Reference: DYPI 4570