INTEGRAZIONE DELLA CHIMICA E DELLA BIOTECNOLOGIA PER LA VALORIZZAZIONE SOSTENIBILE DELLA BIOMASSA

This PhD work is part of a national project CARDIGAN (CARDoon valorisation by InteGrAted biorefinery), which was focused on the valorization of cardoons. a typical biomass of Mediterranean area. The first activity was the optimization of supercritical CO2 extraction (scCO2) applied on the cardoon leaves. Extracts (CLEs) were analysed by means of NMR and GC-MS to identify the most important bioactive molecules and to compare the composition of extracts obtained by different technologies by other partners in the project. The characterization indicated that scCO2 method extracts preferentially hydrophobic components whereas the Naviglio® technology allows to obtain extracts rich in cynaropicrin, a bioactive molecule with hepato-protectant activity. A first manuscript was published in collaboration with the Univ. of Naples and CNR-IPCB dealing with the formulation of bio-based polymeric films enriched with CLEs, which demonstrated increased the mechanical and barrier properties. The biological properties of CLEs were also investigated in collaboration with the neurobiology research group at the University of Trieste. The biological tests indicated that the CLE obtained by scCO2 from plants harvested in spring was able to induce a significant rescue of neuronal atrophy in an in vitro model of Rett syndrome neurons. RTT neurons whereas the more hydrophilic extracts, rich in cynaropicrin, exerted a toxic effect. The second part of the project was focused on the valorization of cardoon seed oil to obtain epoxidized fatty acids as precursors in the synthesis of biolubricants and bioplasticizers. After the characterization of the cardoon seed oil, two lipases were used for its hydrolysis, up to 2L scale. The chemoenzymatic epoxidation was then carried out on oleic, linoleic and linolenic acids in solvent-less conditions at 50°C. To improve the sustainability of the enzymatic process, the covalent immobilization of lipases on a renewable bio-composite material, rice husk, was investigated. The cellulosic fraction of rice husk was oxidized using laccase enzymes in the presence of TEMPO radical. The process leads to the oxidation of the primary hydroxyl groups of the glucose units of cellulose to aldehyde groups, which were exploited for the direct anchoring of the enzymes via formation of imine bonds with the superficial lysin residues of the proteins. These sustainable formulations were tested in various reaction media and under mechanical stress. The last part of this research was focused on the delignification of rice husk with the objective of improving its accessibility to oxidizing reagents and enzymes, while decreasing the hydrophobicity of this composite material.