Hotmelt adhesives are widely used in the manufacture of multilayer laminates, commonly used as food packaging materials. For this reason, it is very important to determine the composition of the adhesives and to identify which compounds could migrate from the laminate to the food. Twenty four compounds were identified in 2 different hotmelt adhesives, some of them with high toxicity levels according to theoretical model of Cramer, such as 9,10-dihydroanthracene and retene. Some physicochemical properties of these compounds, such as their partition and diffusion coefficients in the different materials used in the laminates, provide useful information for evaluating their potential migration to the food. The determination of the partition and diffusion coefficients was performed with two different laminates made of cardboard or polypropylene cardboard substrates and the adhesive. Partition and diffusion coefficients of the migrants in the adhesives and substrates were calculated from the experimental results. It was found that diffusion was always lower in the adhesive than in the cardboard. All diffusion coefficients determined increased with temperature while the partition coefficients showed the opposite effect. Migration results confirmed that the migration value of a compound was closely related to the calculated partition and diffusion coefficients. None of the migrants exceeded the recommended Cramer exposure values.

A wide variety of adhesives can be used to manufacture multilayer food packaging materials. Since these materials are usually in direct contact with the packed food, compounds from the adhesive may migrate into it. Therefore it is important to determine the composition of the adhesives used. The main aims of this work were to determine the compounds present in the adhesives used in the food packaging, to study their migration to food simulants and finally to use these data to test a mathematical tool designed for predicting migration to food from laminates containing adhesives. For this purpose a total of 45 market samples of multilayer materials (laminates and other glued materials) produced with 29 different adhesives were studied. A total of 55 different compounds were detected in these adhesives, 57% of these compounds migrated into a dry food simulant (Tenax®) through the food contact layer. These data were also used to compare it with the theoretically estimated migration of the adhesive compounds using "upper-bound reference" values for the diffusion and partition coefficients implied in a multilayer migration model. In 93% of the cases the estimated migration results met or exceeded the experimental ones. This is an important requirement for testing the applicability of these theoretical migration estimations for compliance decisions which aim to protect the consumer's health

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Selenium nanoparticles (SeNPs) were incorporated in a flexible multilayer plastic material using a water-base adhesive as vehicle for SeNPs. The antioxidant performance of the original solutions containing spherical SeNPs of 50-60 nm diameter, the adhesive containing these SeNPs, and the final multilayer plastic material to be used as food packaging were quantitatively measured. The radical scavenging capacity due to SeNPs was quantified by a free radical assay developed in the laboratory and by the diphenyl-1-picrylhydrazyl (DPPH) method. DPPH was not efficient to measure the scavenging capacity in the multilayer when the free radical scavenger is not in the surface in contact with it. Several multilayer laminated structures composed by [PET (20 m)-adhesive-LDPE (with variable thickness from 35 to 90 μm)] were prepared and measured, demonstrating for the first time that free radicals derived from oxygen (OH·, O2·, and O2H) cross the PE layer and arrive at the adhesive. SeNPs remain as such after manufacture and the final laminate is stable after 3 months of storage. The antioxidant multilayer is a non-migrating efficient free radical scavenger, able to protect the packaged product versus oxidation and extending the shelf life without being in direct contact with the product. Migration tests of both Se and SeNPs to simulants and hazelnuts demonstrated the non-migrating performance of this new active packaging. Graphical abstract ᅟ.

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