ECO-SUSTAINABLE PACKAGING MATERIALS FOR THE FOOD INDUSTRY (ECOPACKMAT)
This PhD thesis focused on developing an eco-sustainable packaging material for the food industry, addressing the growing environmental, social, and economic challenges posed by the increased plastic consumption and generation of associated wastes. Aligning with global efforts to transition to a circular economy model, this work explored the use of cellulose as a “backbone” for the generation of biodegradable and high-performance packaging materials. At first, cellulose from underexploited agri-food wastes and plant residues (i.e., giant cane, Posidonia oceanica seagrass, coffee silverskin, and brewer’s spent grain) was obtained using a standardized process reliant on soft chemicals and solvents. Native cellulose was subsequently miniaturized to micro- and nano-forms, namely microfibrillated cellulose (MFC) and cellulose nanocrystals (CNCs), using physical (i.e., high pressure homogenization, HPH) and chemical (i.e., sulfuric acid hydrolysis) methods, respectively. All these products were thoroughly characterized and further tested - both internally (UNIMI) and at the industrial partner’s site (Fedrigoni S.p.a) – in different packaging configurations. Remarkably, a strong correlation between the size of the extracted cellulose and its derivatives, and the functionality of the obtained materials was recorded, demonstrating that it is possible to obtain materials with different functional properties as a function of the miniaturization degree. For instance, the freshly extracted cellulose, that is, in its native macro-form, is suitable for creating both 3D objects through wet molding processing and common paper sheets (Chapter III). The combination of high surface area, UV-shielding behavior, high stiffness, and excellent oxygen barrier performance makes microfibrillated cellulose the ideal substrate for producing eco-friendly stand-alone films for the preservation of oxygen-sensitive foods (Chapter IV). At last, cellulose nanocrystals can be expediently used as nanobuilding blocks for the generation of bionanocomposite films and coatings, again for food packaging applications (Chapter IV). Overall, the basic approach set in this thesis work has a great potential to reduce agricultural wastes and their environmental impact, whilst offering green innovation in the food packaging sector. Nonetheless, room is left for further research activities aimed to i) validate the tested materials through shelf-life and life cycle assessment (LCA) studies, ii) assess the toxicological risk for humans associated with the potential migration to foods of nanoparticles (e.g., cellulose nanocrystals) from packaging materials (such as nanocomposite coatings), and ultimately iii) verify the up-scaling feasibility of the technologies employed in this PhD work through a techno-economic analysis.
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