Removal of mineral oil migrated from paperboard packing during cooking of foods in boiling water

The removal of mineral oil migrated from paperboard into food during cooking in boiling water was investigated: noodles, rice, couscous and chocolate drink were cooked as adequate as well as far beyond normal; samples were analyzed for mineral oil before and after cooking. Since direct extraction of cooked noodles with hexane resulted in low yield, water was first extracted with ethanol. During adequate cooking, removal of mineral oil from rice amounted to about 50%, depending on the type, the duration of cooking, and whether or not an excess of water was applied. From couscous, 43% was evaporated when boiled for an excessively long time, but no significant amount when boiling water was added corresponding to the normal procedure. Cooking of noodles did not significantly reduce the mineral oil content. Removal of the mineral oil from dry food is probably hindered by water entering the pores and acting like a barrier: to reach the boiling water, the hydrocarbons would have to diffuse through this water to the surface of the particle, which is impeded by the low solubility of the hydrocarbons.