Green Technologies for Innovative Materials Production for Active Food Packaging

The Food and Agriculture Organization (FAO) reports that 1.6 billion tons of food are wasted every year in the world, which corresponds to about 1/3 of all food production destined for human consumption. Food waste weighs on a global level as it brings with it a series of problems related to resources such as water, land, energy, labor, capital, the mismanagement of which entails an economic burden of about 680 billion dollars in industrialized countries. The food products most subjected to waste are the fresh ones, with a shelf-life of a few days and the products for which the cold chain is required, such as refrigerated and frozen foods. However, for the latter products, compliance with the cold chain along the entire distribution line cannot unfortunately be guaranteed. These impacts derive both from the unreliable management of transport and marketing, and from the limited thermal insulation capacity of traditional materials such as plastic and cardboard. Furthermore, in parallel with food waste, the second global problem is the increase and accumulation of waste deriving from disposable food packaging of fossil origin. In fact, with increasing industrialization, food and packaging have become a single system whereby if one is wasted, the other is wasted as well. In fact, just think that from the 1950s to 2015, plastics production reached 8.3 billion tons, throwing away about 6.3 billion in nature, of which 79% ended up in landfills and in natural environments, 12% was incinerated and only 9% was recycled. In recent years the situation has improved, in fact, in 2020, according to Eurostat data, 23% of plastic waste produced in Europe ended up in landfills, 42% was incinerated and 35% was recycled. However, these data also show that the objectives set by the European Union, namely the achievement of 50% plastics recycling by 2025 and 55% by 2030 are still far. This demonstrates how the use of biodegradable polymers or biopolymers is increasingly becoming a need rather than a choice. Hence the need to find solutions to minimize if not cancel the effects of these two problems. A potential solution is offered precisely by packaging, conceived not in the traditional sense of the term, i.e., as systems for the containment and generic protection of food from the external environment, but in an innovative way for which packaging has become the protagonist and not a passive part of the food product. With this in mind, the so-called active packaging is designed with the aim of interacting in a controlled way with food in order to preserve its nutritional properties, organoleptic properties and extend its shelf-life, all in a safe way for the consumer and for the manufacturer. To perform this function, active packaging is designed through the incorporation of components capable of releasing or absorbing substances from packaged foods or from the environment surrounding the product and, moreover, systems defined as intelligent packaging allow to monitor the quality of products in real time. Among active packaging, antimicrobial and antioxidant films appear to be the most promising to achieve these goals. While, there is little literature on packaging capable of preserving food from sudden changes in temperature, but a possible approach to control and maintain a desired temperature, for a limited period of time, seems to be represented by the thermal energy storage approach. Therefore, this Ph.D. work was aimed at developing films based on natural polymers, such as the protein zein and the polysaccharide chitosan, and synthetic but biodegradable polymers such as polycaprolactone to investigate the potential of these materials to be used as active packaging. The polymeric matrices obtained were then functionalized by adding natural active ingredients such as vanillin, present in vanilla pods, characterized by antimicrobial activity, spent coffee grounds extract, rich in caffeine and polyphenols, alpha-tocopherol, contained in olive oil with high antioxidant properties and finally, natural phase change materials such as fatty acids to study the feasibility of developing packaging materials with thermal insulation properties. For film production, traditional methods, such as extrusion and molding, are mainly based on the direct loading strategy. However, these techniques have some drawbacks related to the use of toxic and polluting solvents, high temperatures, low penetration of the active agent into the polymeric substrate and reduced loading efficiencies. For this reason, several greener techniques have been investigated, more suitable for the treatment of natural substances, such as electrospinning, solvent casting and spin coating. Only solvents accepted by the Food and Drug Administration were selected for treatment. Furthermore, the use of an indirect loading technique, the impregnation with supercritical fluids, for the loading of the active agents subsequent to the production of the polymeric supports was also studied. The obtained products were characterized mainly in terms of morphology, migration tests in different food simulants, gas barrier properties, mechanical tests and functional activities through the comparison of the materials and techniques used. The results obtained made it possible to identify the strengths and limitations of both the materials and the techniques used. However, it was possible to identify a potential intended use for all the materials optimized and identify possible improvement methods to upgrade these materials. Finally, the economic feasibility of the antimicrobial constructs produced by electrospinning through the production of a business plan was assessed.