Effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax® and modelling hereof
The aim of this study was to investigate the effect of relative humidity on the migration of benzophenone from paperboard into the food simulant Tenax®. Kinetic migration investigations were carried out with three relative humidities in the interval between 39% and >73%. All investigations were carried out at a constant temperature of 34°C. It was found that the migration of benzophenone after more than 30 days was 4.8 times higher at a relative humidity of 64%–71%, and 7.3 times higher at a relative humidity of >73%, compared with that at a relative humidity of 39%–49%. Diffusion and partition coefficients were derived from the results by using a software for modelling migration in multilayer materials. Both the diffusion coefficient and the partition coefficient, between paperboard and Tenax®, decrease with increasing relative humidity. The experimental results were correctly modelled only when the paperboard was regarded as a one-layer system as compared with a two-layer system: where the main part of the paperboard (B1) has a high diffusion rate and a thin part of the paperboard (B2) in contact with the foodstuff has a lower diffusion rate.
Supercritical fluid extraction of potential migrants from paper and board intended for use as food packaging materials.
The optimization of supercritical fluid extraction using CO2 for the extraction of contaminants in 15 samples of recycled paper and board (P&B) has been studied. An experimental design was used for simultaneous optimization of the variables involved in both the extraction step and the collection of the extract. Methanol was used as modifier. Several plastisizers such as diethyl phthalate, diisobutyl phthalate, di-n-butyl phthalate, dioctyl adipate, and diethylhexyl phthalate (from 2 to 100 microg/g of paper) were found in the recycled P&B samples. A discriminate analysis applied to all results obtained allow us to classify the samples in three different groups according to the content of recycled pulp (0, 10-30, and > 80% of recycled pulp), the sample thickness (from <300 to >600 microm), and the surface treatment of the paper. The analytical behavior and the results are discussed.
Studies on 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.