The Effect of Microwave and Electron-Beam Treatments on Food and Packaging

A team of researchers based in France has examined the consequences of microwave and electron-beam treatments on food and its packaging using high performance liquid chromatography (HPLC) and gas chromatography (GC) (1).    The packaging of the food we eat poses a huge challenge to the food industry. Consumer demands place extra emphasis on the type of packaging that is produced. It should be compact, microwavable, recyclable, not to mention biodegradable. It must also preserve the food contained within. As a result, manufacturers are turning to more complex polymer materials to meet these demands. These materials need to be examined for their impact on human health and the environment; some polymers can release harmful substances when treated in certain ways.    Polypropylene (PP) films were prepared with a series of additives, and were then treated with electron beam irradiation and microwaves. The PP extracts were separated into six fractions by normal phase HPLC, followed by complete and automated on-line transfer of these to GC (comprehensive two-dimensional analysis, HPLCxGC).   The potential toxicity of the extracts was assessed using three in vitro short-term bioassays and their migrations were performed using a standards-based approach. After the electron-beam treatment some additives decomposed and there was a significant increase in the polyolefin oligomeric saturated hydrocarbons concentration. The electron-beam treatment had a stronger impact on the polymer than the microwave one. It produced degradation products from the additives as well as from the polymer. The additives reduced this degradation of the PP backbone significantly, but also formed degradation products themselves. The microwave treatments (800 or 1100 W) did not lead to structural changes in the PP film. However, the GC–FID–MS analysis indicated the presence of novel degradation products in the film (Irgafos 168 and Irganox 1076).   The team believes that this approach is a big step towards the assessment of the health risks of materials and objects in contact with food. It could also help to comply with the regulations concerning those materials that come into contact with food.   Reference 1. A.M. Riquet et al., Food Chemistry199, 59–69 (2016).