Chemical migration from paper and board into dry foods

Various contaminants of paper and board have been found to migrate into dry foods, including diisopropylnaphthalenes (DiPN, CAS 24157-81-1), dibutylphthtalate (DiBP, CAS 84-74-2) and other phthalates, trimethyldiphenylmethanes, mineral hydrocarbons, and di(2-ethylhexyl)maleate. In a new study published April 9, 2014 in the peer-reviewed scientific journal Food Additives and Contaminants: Part A, researchers from the UK Food and Environment Research Agency assessed the migration of a variety of contaminants from 4 types of uncoated and untreated paper and board into 4 types of food and the food simulant Tenax^TM (Bradley et al. 2014). The analysis also addressed the changes in food contamination due to the home processing of food, such as peeling, washing and cooking. As uncoated and untreated paper and board is used to package dry food in 50% of cases and food that is to be peeled, washed or cooked in 30% of cases, apples, bananas, potatoes and mushrooms were selected as model food stuffs. Paper samples included corrugated board, a bread bag, fruit board and grey board. Food contact materials used in the study were spiked with model contaminants o-xylene (CAS 95-47-6), acetophenone (CAS 98-86-2), dodecane (CAS 112-40-3), benzophenone (CAS 119-61-9), DiPN and DiBP (levels ranging from 5-20 mg/ml). The 4 food stuffs were packaged in the material, loosely wrapped with aluminum foil to avoid evaporation and simulate stacking during storage, and stored at room temperature for 5 days. Bananas were painted with the spiking solution. After storage food samples were homogenized, extracted and analyzed using GC-MS. The same was done with peeled, washed or cooked samples.

Results. Overall, the researchers found migration to depend on the extent of direct contact with the packaging surface, the extent of indirect contact and surface area of the food and the polarity of the food surface. Highest relative migration was found for DiPN and DiBP from the bread bag into apples (19 and 13% respectively). Benzophenone migrated to the largest extent into potatoes, and acetophenone into mushrooms. Migration of o-xylene and dodecane was mostly below 1%. The researchers cautioned that spiking paper using impregnation results in heterogeneous test materials with a variability of up to 30% among different papers. Migration tests with Tenax^TMshowed that migration levels depend mostly on the nature of the model substance and the food rather than on the detailed characteristics of the paper and board. The tests with Tenax^TM further showed an overestimation of true migration by a factor 9, 21, and 62 for apples, mushrooms and potatoes, respectively. The result that Tenax^TM overestimates true migration confirms previous findings from the European Union BIOSAFEPAPER project which argued that Tenax^TM makes more extensive contact with the FCM surface, is a more aggressive simulant, and storage time is usually more extensive than in reality.

Peeling, washing and cooking showed to have little impact on final contaminant concentrations. Overall the effect of processing was substance dependent, with more polar substances such as benzophenone penetrating deeper into food samples than less polar substances. Peeling apples and potatoes removed most phthalate contamination, but was not effective in removing acetophenone. Only acetophenone and benzophenone migrated into the banana, the other chemicals did not diffuse through the banana peel. Washing only removed the more polar substances such as acetophenone with a rate of 40-50%, whereas it was ineffective at removing the phthalates. Cooking only removed the volatile compound acetophenone, but was ineffective at removing the more non-volatile and non-polar substances DiNP and DiBP. As such, no one processing step was able to reduce contaminant load to a significant extent, as substances either resisted washing, penetrated into the food, or did not evaporate.

Reference

Bradley, E. et al. (2014). “Model studies of migration from paper and board into fruit and vegetables and into Tenax^TM as a food simulant.” Food Additives and Contaminants: Part A (published online April 9, 2014).