Metal oxide nanoparticles for active, intelligent and safe food packaging

The food industry is under constant pressure to provide safe and appetizing food products. To meet consumer demands, it regularly improves both food quality and packaging technology.

Food packaging is essential for maintaining the safety and quality of products, from processing and manufacturing, through handling and storage, to the consumer. Petroleum-based plastics (such as polyethylene terephthalate, polypropylene and polystyrene) have been widely used to wrap foods to protect their contents from microbial contamination and spoilage. However, plastics do not fully protect food from the environment and, consequently, cannot fully guarantee product quality and safety. What's more, plastic undergoes continuous fragmentation and can create micro- and nanoplastics that have harmful effects on the environment and human health. New biodegradable biomaterials are being developed as alternatives to plastics to meet the demands of consumers and the food industry. However, these "green", environmentally-friendly biopolymers often suffer from inadequate mechanical properties for wrapping food, degrade easily and fail to provide a barrier to gases. By incorporating nanoparticles into biopolymers, we can obtain bionanocomposites with improved mechanical properties. Bionanocomposites meet food packaging specifications to effectively protect products from light, UV, moisture, oxygen and bacterial contamination, while remaining environmentally friendly and low-cost. However, requirements concerning the biocompatibility, stability and non-toxicity of materials in contact with food condition the marketing of bionanocomposites for food packaging.

Among nanomaterials, metal oxide nanoparticles (NPs) such as zinc oxide (ZnO) and titanium oxide (TiO ₂ ) are the most widely used inorganic particles for food packaging development. In the present review, advances since the 2010s in strategies for incorporating metal oxide NPs into food packaging films and their applications are presented, along with their modes of action. In addition, risk assessment methods for NP release from films and their potential cytotoxicity for human cells, intestinal microbiota and the gastrointestinal tract are outlined. Finally, European legislation on the safety of nanomaterials for packaging is presented. The aim of this article is to present how nanotechnology can meet some of the needs of the food industry, which faces many challenges in guaranteeing fresh, tasty food with extended shelf life. At the same time, consumers are demanding sustainable packaging materials that will reduce the environmental problems associated with plastic waste, and expect the food industry to reduce its use of preservatives.