DEVELOPMENT OF GREEN INDUSTRIAL TECHNOLOGIES FOR THE AGRI-FOOD CHAIN

This three-year PhD Thesis research project focused on the development and optimization of sustainable industrial protocols for the agri-food sector. The main objective was to integrate enabling technologies, in specific microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), subcritical water extraction (SWE), and pulsed electric fields (PEF), alone or in combined protocol hybridization, into novel processing strategies aimed at both process intensification and the valorisation of agro-industrial by-products. Initial investigations were carried out at the laboratory scale to assess the potential of various biomasses and consecutively, thanks to a collaboration with Tropical Food Machinery (Busseto, PM, Italy), industrial prototypes were designed and tested for scalability studies. The Thesis presents six case studies on selected biomasses chosen for their relevance in the agri-food sector and potential to yield high-value compounds, highlighting both their technical viability and sustainable processing at various scales. Pomegranate peels were subjected to polyphenol extraction using MAE and microwave-assisted subcritical water extraction (MASWE) techniques, coupled with downstream purification via membrane filtration. Blueberry pomace was fractionated using water-based sequential extraction approaches to isolate bioactive pigments and polyphenols. Hazelnut skins were also treated with MASWE, and the process was subsequently scaled up to a semi-industrial level using a 250-liter pilot plant reactor. Ultrasound-assisted protein recovery was applied to grape seeds, with an upscale UAE prototype processing 5 kg of biomass. A significant opportunity was the involvement in the commissioning and optimization of prickly pear juice extraction, alongside a valorisation study of the resulting by-product, specifically prickly pear peels. Furthermore, ultrasound and pulsed electric field technologies were applied at an industrial scale as alternatives to traditional malaxation in extra virgin olive oil production. All recovered extracts were analysed for their chemical composition and assessed for antioxidant, antimicrobial, and antitumoral activities through dedicated bioassays specific to each protocol. In addition to the technological performance, the sustainability of each process was critically evaluated together with the achieved Technology Readiness Level (TRL). As a final step, a tailored green extraction metric was developed, incorporating both productivity indicators and environmental criteria such as chemical safety and energy consumption. This sustainability impact-metric, named Sustainability Impact for eXtraction Score (SIX Score) enabled a comparative analysis of proposed alternative technology to conventional technique, highlighting both the improvements achieved and the methodological limitations in a standardized framework. This research wants to contribute to the advancement of green processing strategies in the agri-food sector by demonstrating scalable, sustainable, and bioactive compound-rich valorisation pathways for diverse agri-food residues.