Biopolymers have recently been receiving a lot of attention for food packaging because they offer several advantages that make them viable alternatives to synthetic plastics: they are biodegradable, renewable, non-toxic and readily available in nature.

Biopolymers are a large family of materials, including natural materials (polysaccharides, proteins, lipids, etc.), chemically synthesised materials (polylactic acid, polyvinyl alcohol, etc.) and materials of microbial origin (polyhydroxyalkanoates, polyhydroxybutyrate, etc.).

While these materials are interesting for certain properties, they have poor mechanical and barrier properties, as well as inadequate thermal stability compared to conventional synthetic plastics, and therefore have not yet become widespread in the food packaging sector. In addition, biopolymers are more expensive to produce and scale-up remains a problem.

However, integrating nanotechnology with the world of biopolymer materials can mitigate these disadvantages and open up new possibilities. Nanomaterials consist of particles smaller than 100 nanometres (nm), where 1 nm is equivalent to 1 millionth of a millimetre. Their small size means that the properties of nanomaterials are very different from those of “traditional” materials; specifically, they are characterised by:

⦁ high reactivity, because their small size results in a high surface area/volume ratio, meaning that a high percentage of atoms are on the surface of the solid and more available for reactions;

⦁ excellent optical properties, resulting in transparent materials capable of shielding UV rays;

⦁ excellent mechanical and thermal properties, due to the fact that their small size allows for the uniform distribution of stress and heat in reinforced polymer matrices;

⦁ good barrier properties against gases (oxygen, carbon dioxide, etc.) and moisture;

⦁ in some cases, good antimicrobial and antioxidant properties, the latter being particularly important for the packaging of fatty foods, oils and vitamin-rich products, as they protect them from oxidative damage that can lead to oxidative rancidity and nutrient loss.

Therefore, nanomaterials can modulate the properties (mechanical, barrier, thermal and optical) of the materials in which they are incorporated, thus meeting specific requirements for food storage and packaging.

A review by Indian and Swedish researchers has shown that the incorporation of different nanofillers into biopolymers can significantly improve all of the above properties.