In an article published on May 17, 2017 in the peer-reviewed journal Food Additives & Contaminants: Part A, Van Den Houwe and colleagues from the Scientific Institute of Public Health , Brussels, Belgium, reported on the development of a Tenax® film for use in migration experiments as a simulant for dry foods. Tenax® is a commercial name for poly(2,6-diphenylphenylene oxide) (CAS 24938-68-9), the substance recommended by the European plastics regulation (EU) 10/2011 as the official simulant for dry food to be used in the experiments estimating chemical migration from food contact materials (FCM). Conventionally, Tenax® is brought into contact with an FCM in the form of powder, which is then extracted for quantification of accumulated migrants. For precision, all applied powder needs to be collected at the end of the experiment, which can be challenging.
To offer a more convenient method, the authors proposed using Tenax® film instead of powder. Such film can be constructed by first dissolving Tenax® in a chlorinated solvent (the authors recommend chloroform (CAS 67-66-3)), followed by spreading a known volume on a solid support (e.g. a glass Petri dish), followed by evaporation under air.
To evaluate the performance of Tenax® film compared to conventional Tenax® powder, the authors carried out several migration experiments using both types of recipients. All migrations were carried out for 10 days at 60°C, officially recommended for simulation of long-term storage of dry foodstuffs at room temperature. Tested FCMs were two samples of blank cardboards, rough and smooth, which were spiked with 15 chemicals known to frequently contaminate paper and board FCMs. Especially for the rough cardboard sample, the migration of most contaminants into powder was found to be higher than into film, likely due to the possibility for a more intense direct contact when powder is used.
In 2016, the same group measured the long-term migration of several photo-initiators into dry foods. For example, about 5.4% of the initial content of benzophenone (CAS 119-61-9) was found to migrate from cardboard into cereals after six months at room temperature. In the present study, migration of benzophenone from rough and smooth cardboard into Tenax® film was found to be 14.1% and 26.1%, and into Tenax® powder 38.8% and 36.9%, respectively. Similar relationships were observed for several other compounds.
The authors therefore suggested that, since the transfer of substances via the gas phase plays an important role in real life migration, the simulation by Tenax® film may offer a more realistic estimation of migration into dry foodstuffs, since the use of film reduces the intensity of direct contact, and allows for migration via the gas phase. This new method is also “fast and easy,” and therefore “can open new perspectives” in testing compliance of FCMs intended for dry foodstuffs, the authors concluded.
Van Den Houwe, K., et al. (2017). “The use of Tenax® films to demonstrate the migration of chemical contaminants from cardboard into dry food.” Food Additives & Contaminants: Part A (published May 17, 2017).
Van Den Houwe, K., et al. (2016). “Migration of 17 photoinitiators from printing inks and cardboard into packaged food – results of a Belgian market survey.” Packaging Technology and Science 29: 121-131.