Studies of functional barriers to migration. 3. Migration of benzophenone and model ink components from cartonboard to food during frozen storage and microwave heating

Studies of the migration of benzophenone from inks and of model ink components incorporated deliberately into cartonboard have been carried out at low temperature and during microwave heating. Benzophenone was found in the packaging of four of seven frozen foods examined and this was attributed to its use as a photoinitiator for UV-cured ink. Benzophenone was found to migrate to the packaged food even from polyethylene-coated board, and this was attributed in part to the fact that polyethylene is rather permeable to low molecular weight substances and is not a good barrier to migration. Additional studies were conducted with two other frozen foods by incorporating model ink components into their cartonboard packaging. The substances were benzophenone, benzylbutyl phthalate, butyl benzoate, chlorodecane and dimethyl phthalate. Migration was readily detected after storing the food at -20°C for 1 week in the impregnated cartonboard. Migration levels in the food increased only slowly thereafter, up to 1 year, except for the most volatile substances used. Subsequent heating of the frozen food using a microwave oven decreased the concentration of some migrants by volatilization, but increased the concentration of other, less volatile substances by heat-accelerated migration. It is concluded that for inks used to print food contact materials, if the content of low molecular weight volatiles is controlled and if transfer of higher molecular weight components via set-off is controlled also, then migration levels could be kept low in these conditions