Migration from recycled paperboard was monitored after 2, 4 and 9 months of storage for six test foods industrially packed in five configurations, four with internal plastic films. After 9 months, the migration of mineral oil saturated hydrocarbons into foods directly packed in the paperboard amounted to 30-52 mg/kg, which corresponded to 65%-80% of those of a volatility up to that of the n-alkane C₂₄ in the paperboard. The concentration of the migrated aromatic hydrocarbons in the foods ranged from 5.5 to 9.4 mg/kg. More than half of this migration occurred in the first 2 months. Differences between the foods amounted to mostly less than a factor of 2 and seemed to be related to porosity or permeability more than fat content. Nine photoinitiators were detected in the paperboard, of which eight migrated into the packed food at up to 24%. Several plasticisers were present in the recycled paperboard, but only butyl phthalates showed significant migration. After 9 months, up to 40% of diisobutyl phthalate and 20% of dibutyl phthalate migrated into the food with direct contact. The internal polyethylene film hardly slowed migration, but the film and the tray absorbed approximately three times more mineral oil than the food, despite constituting merely 4% of the mass of the pack. Oriented polypropylene strongly slowed migration: The highest migration of saturated hydrocarbons measured after 9 months (2.3 mg/kg) corresponded to only 3% of the content in the paperboard and included migrated polyolefin oligomeric saturated hydrocarbons. Coating of polypropylene with an acrylate further slowed the migration, but the migration from the paperboard was still detectable in four of the six samples. Polyethylene terephthalate was a tight barrier.

Conventional migration testing for long-term storage at ambient temperature with Tenax® was applied to a recycled paperboard as well as to the same paperboard with a polyethylene or polypropylene film in between. Test conditions were from the European Union plastic Regulation 10/2011, that is, 10 days at 60°C, but previous standard conditions of 10 days at 40°C were also applied. The results were compared with the migration into real packs made of the same packaging material containing six test foods and stored over 9 months. For the direct contact, simulation at 60°C overestimated the maximum migration of the saturated hydrocarbons in the real packs by 73%. Simulation reflected hardly any effect by the plastic films and resulted in an overestimation of the maximum migration into the real packs by a factor of 5.1 and 27 for the polyethylene and the polypropylene film, respectively. Analogous simulation was performed with polenta (corn semolina) instead of Tenax®. Three main causes for this deviation were identified: (i) at 60°C, migration reached beyond n-C₃₅, whereas it ends at about n-C₂₄ in reality. (ii) Tenax® is a far stronger adsorbent than foods, resulting in almost complete extraction. (iii) The significant barrier effect of polypropylene films at ambient temperature is lost at increased temperature. The suitability of such simulation for the prediction of long-term migration is questioned.

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The results of a

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