Migration of mineral oil, photoinitiators and plasticisers from recycled paperboard into dry foods: a study under controlled conditions

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.