Migration of mineral oil from printed paperboard into dry foods: Survey of the German market. Part II: Advancement of migration during storage.

In April 2010, 119 samples of dry foods packed in paperboard boxes and stored at ambient temperature were collected from the German market. The migration of mineral oil from the recycled paperboard and printing ink was analyzed for the first time immediately after collection and reported in Vollmer et al. (Eur Food Res Technol 232:175-182, 2011). It frequently exceeded 10-100 times the 0. 6 mg/kg limit for mineral oil saturated hydrocarbons (MOSH) derived from the WHO/JECFA evaluation published in 2002. As most samples were far from the end of the shelf life, analyses were repeated 4 months later and a third time either at the expiry date or after 16 months. The average MOSH concentration in the foods increased from 8. 9 to 14. 3 mg/kg (by 60 %), which indicates a rapid migration during the first months of storage, but also a further increase up to the end of the shelf life. The maximum migration reached 101 mg/kg. In the third measurement, the average concentration of the migrated mineral oil aromatic hydrocarbons was 2. 2 mg/kg, with a maximum at 13. 2 mg/kg. Most types of food behaved similarly, differences mostly reflecting the types of packaging rather than the food properties. Exceptions were table salt (hardly any migration) and noodles (low migration). Internal bags with an aluminum foil or PET layer were complete barriers. Migration through plastic with vapor-deposited aluminum or acrylate-coated polypropylene was reduced, but still sometimes exceeded 0. 6 mg/kg. Internal bags of polyethylene had a weak effect on slowing migration, but acted as a sink for mineral oil: Although on average they only constituted 1. 1 % of the total mass of the packs, they absorbed nearly 40 % of the migrating hydrocarbons. Polypropylene was a similar sink. In addition, it strongly slowed migration, but at the third measurement the 0. 6 mg/kg limit was nevertheless exceeded in 11 of 16 samples. Polyolefin oligomeric saturated hydrocarbons (POSH) from the plastic or heat-sealable layer, largely branched hydrocarbons similar to MOSH, often migrated in the range of 1-5 mg/kg.