Valorization of side-streams from the food industry through the use of green technologies

This paper summarizes my three-year doctoral thesis project at the Food and Dietary Products Laboratory of the Department of Pharmacy (DIFAR) of the University of Genoa (Italy) with the collaboration of the Sustainability & Circular Economy Team of ANFACO-CECOPESCA (Vigo Spain), the Synthesis Team of AIMPLAS (Valencia, Spain), the Department of Marine Biotechnology of NOFIMA (Tromsø, Norway), Environmental and Molecular Microbiology Team of MICAMO Lab (Genoa, Italy), the Food Chemistry Group of the Magna Graecia University (Catanzaro, Italy), and with other research groups at the University of Genoa (Italy). As discussed in the Introduction, the growing production of side streams generated by the food industry is causing serious environmental, economic, and social issues, necessitating swift and effective solutions. Embracing a "zero waste" economy and the principles of "circular economy" and "green chemistry," innovative and eco-friendly extraction techniques like EAE (Enzymatic-assisted extraction), UAE (Ultrasound-assisted extraction), MAE (Microwave-assisted extraction), and SFE are proposed to upcycle food by-products. What is usually seen as side stream/ by-product can be considered a valuable source of bioactives with significant economic potential and interest across various markets, possibly including food, cosmetics, pharmaceuticals, and plastics. The main project of this PhD is EcoeFISHent, Horizon 2020 Program–Green Deal (G.A. ID 101036428), aiming to upcycle discarded or underutilized biomass from the fish supply chain to achieve the goals of the 2030 Agenda for Sustainable Development, which include promoting responsible production and consumption and safeguarding water resources. All the work within EcoeFISHent is discussed in chapters 1, 2, and 3. In Chapter 1, it is reported a study, supported by the EcoeFISHent project, that emphasizes the importance of exploiting dehydrated unsorted mixed side streams from the tuna canning industry with a focus on raw tuna leftovers from Generale Conserve (ASdoMAR®), an Italian tuna canning company. A key innovation highlighted in this study is the simultaneous recovery of non-collagenous proteins (hydrolysates NCs, ALKs) from connective tissue and collagenous compounds (gelatin G and Hydrolyzed Gelatin Peptides, HGPs) from bones and scales, all within a single cascade flowchart with good prospects in terms of industrial scalability, supporting a zero-waste economy. The findings reveal new possibilities for utilizing these substances in biodegradable packaging, nutritional supplements, and skincare products. The study described in Chapter 2 is expanded to include the potential valorization of both solid and liquid side streams obtained from the steaming process of tuna fillets, always following dehydration. The protein hydrolysates isolated from the solid mixed dehydrated fish powder were extracted using two different protocols with and without the inclusion of an exogenous enzyme (Enzymatic-Assisted Extraction, EAE). The extracts were characterized, with a focus on the protein hydrolysates to assess their potential use as nutraceuticals. In Chapter 3, it is discussed the lipid extraction from Ligurian aquaculture side streams from Aqua de Mâ (Lavagna, Italy), making a comparison between different green extraction methods (conventional solid/liquid cold extraction with green solvents, microwave-assisted extraction -MAE with green solvents, and enzymatic-assisted extraction -EAE). In Chapter 4, it is presented the chemical-bromatological analysis of Round Calabrian Hazelnut (Nocciola di Cardinale), together with the exploitation of some by-products and their potential antioxidant activity. In conclusion, this thesis aimed to propose effective upcycling of food side streams, seeking to pave the way for the adoption of sustainable extraction technologies that turn both animal and vegetable leftovers into potentially high-added-value products.