A food cling film capable of killing bacteria and other pathogens? It is a project that is taking shape, just as the alarm for the killer bacterium re-proposes the theme of food safety. Thanks to ICTP, the Institute of Chemistry and Technology of Polymers of the CNR of Pozzuoli, which has successfully tested a food packaging based on polypropylene – a normal food film – treated with metal oxide microparticles to curb bacterial growth .
“Mind you, the bacterium we are working on is not the killer that the newspapers are talking about, but a harmless colibacter belonging to the same strain, Escherichia Coli DSM498″, explains the research manager, Donatella Duraccio. The first results, however, are very respectable: on the film treated with metal microparticles, bacteria do not take root or die.
The exact mechanism of action of the particles , made with special techniques by a group of researchers of the CNRS – the French national research council – of Toulouse, is not yet known. “The goal was to reach even smaller dimensions, in the order of 100 nanometers – a nanometer is a billionth of a meter – in reality we have only reached 500/600 nanometers”, explains the researcher. “At these dimensions, however, matter changes its properties, for example particles tend to aggregate with each other.”
In addition to the CNRS, the Neapolitan researchers collaborate with the National Food Institute of the University of Denmark DTU, which is working on verifying that the metal molecules do not transfer to the food: “It is not said that these particles are toxic , but the law on the matter requires rigorous experimentation ”, explains Duraccio. “Experiments not on real foods, but on the so-called” food simulants “specially designed to reproduce the worst possible conditions and therefore provide the maximum guarantees”.
Meanwhile, CNR researchers continue to test the treated film on other bacteria and some fungi, to evaluate its effectiveness and understand the mechanism of action: if all goes well – “and if we find an interested company”, observes Duraccio – antibacterial film should be ready within two years. But this is only one step, in a series of projects on the safety of food packaging, as part of the European Cost project on food safety.
“We are following two paths to increase the shelf life , that is the duration, of food products”, explains Duraccio, “that of materials with antibacterial action such as this film, and that of materials capable of blocking oxygen by slowing down the oxidation of foods, especially meat and vegetables’. ANDa film enriched with nano clay particles that form small sheets between which the plastic molecules are inserted, “as if it were the pages of a book or, if you like, the layers of a cake,” says the researcher. “With this type of structure, the oxygen molecules in the air are forced to follow a tortuous, and therefore slower, path to reach the food, which should thus be kept longer”.