Ciriaco, Lidia (2025) ENHANCEMENT OF WASTE DERIVED FROM AGRO-INDUSTRIAL ORIGIN. [Tesi di dottorato]

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Abstract

Triticum vulgare, or aestivum, is an annual herbaceous plant belonging to the genus Triticum, family Poaceae. The aqueous extract of Triticum vulgare (TVE) is obtained from the whole germinated plants, and it is involved in tissue repair processes, stimulating chemotaxis and fibroblast maturation. During the production process of this aqueous extract, a significant quantity of solid and liquid waste is produced, and to date, no purpose has been found for these wastes. Waste management is an emerging challenge, and agro-industrial residues offer opportunities beyond traditional disposal. My PhD project focused on the analysis and characterization of wastes from TVE production (Damor Farmaceutici, Italy), with the aim to vlorize them according to circular economy principles (Reduce, Reuse, Recycle). In the first part of the project, I analysed and characterised, from a chemical-physical and biological point of view, the solid waste (SW) and liquid waste (LW), to assess their biocompatibility and possible reuse with a view to sustainable valorisation. Advanced techniques, including ultra-high performance liquid chromatography coupled with high-resolution mass spectrometry (UHPLC-Q-Orbitrap HRMS), revealed that ferulic acid was the predominant phenolic compound in SW (89.782 mg/kg), while dihydroferulic acid prevailed in LW (6.24 mg/L). These compounds represented 55.87% and 84.39% of the total bioactive compounds detected in the solid and liquid fractions, respectively. Antioxidant activity was higher in SW (8.598 mmol Trolox/kg in ABTS; 7.262 mmol Trolox/kg in FRAP), consistent with its higher phenolic content (TPC). Finally, cytotoxicity assessment was conducted using in vitro preclinical models of human skin (HaCaT and HDFa lines) by exposing cells to the samples for 24, 48 and 72 hours. No cytotoxic effects were observed even at the highest concentration tested (100 μg/mL) at 72 h. Based on these promising results, during the second part of the PhD project, I focused more attention on the solid waste. Although traditional extraction techniques, such as organic solvent extraction, are widely used for their efficiency, they present different disadvantages such as long extraction times, high solvent consumption and environmental drawbacks. In order to overcome these limitations and to reduce environmental impact, new-generation solvents such as natural deep eutectic solvents (NADES) have recently emerged. Eight different NADES formulations with varying physicochemical properties (pH, polarity, and viscosity) were investigated. The extraction efficiency was assessed through ferulic acid recovery analysis by UHPLC-Q-ToF-HRMS. The highest recovery of ferulic acid was achieved with the NADES composed of betaine:1,3-butanediol:water (1:3:10.6, molar ratio), attributed to its moderate pH, low viscosity, and water content. The extraction process parameters were optimized through Response Surface Methodology (RSM). Results showed that the extraction yield was comparable to that obtained using a conventional hydroalcoholic mixture. Non-targeted analysis revealed the presence of different bioactive compounds, depending on the extraction method used. Overall, this work highlights the potential of wheat-based pharmaceutical waste as a source of bioactive compounds. Solid waste, rich in ferulic acid and antioxidants and free of cytotoxic effects, shows the most promising characteristics, while liquid waste, although less concentrated, remains a source of valuable molecules. The study also demonstrates the feasibility of NADES as a sustainable and effective alternative to traditional solvents, enabling the production of ready-to-use extracts for food and nutraceutical applications. In conclusion, the results of my PhD thesis underline the possibility and importance of valorising waste by exploiting its bioactive compounds to reduce environmental impact and promote health benefits. The thesis is structured as follows. Chapter 1, organized into six sections and related subsections, introduces the general framework of waste management and by-product valorization, with a focus on bioactive compounds, wheat-derived wastes, and extraction/characterization techniques. Chapter 2 outlines the research objectives, while Chapters 3 and 4 present the experimental results for the specific aims. Chapters 5 and 6 provide reflections and conclusions, respectively. Finally, Chapter 7 serves as the Appendix. A complete list of abbreviations is provided at the end of the thesis.

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