In the present work, brewers’ spent grain (BSG), which represents the major by-product of the brewing industry, was recovered from a regional brewery and fractionated in order to obtain a complete valorization. In particular, the whole process was divided in two main parts. A first pretreatment with hot water in an autoclave allowed the separation of a solution containing the soluble proteins and sugars, which accounted for 25% of the total starting biomass. This first step allowed the preparation of a medium that was successfully employed as a valuable growing medium for different microbial fermentations, leading to valuable fungal biomass as well as triglycerides with a high content of linear or branched fatty acids, depending on the microorganism used. The solid water-insoluble residue was then submitted to a lignocellulose deep eutectic solvent-mediated fractionation, which allowed the recovery of two important main fractions: BSG cellulose and BSG lignin. The latter product was tested as potential precursor for the development of cement water reducers with encouraging results. This combination of treatments of the waste biomass appeared to be a promising sustainable strategy for the development of the full exploitation of BSG from a circular economy perspective.

In the present work, rice husks (RHs), which, worldwide, represent one of the most abundant agricultural wastes in terms of their quantity, have been treated and fractionated in order to allow for their complete valorization. RHs coming from the raw and parboiled rice production have been submitted at first to a hydrothermal pretreatment followed by a deep eutectic solvent fractionation, allowing for the separation of the different components by means of an environmentally friendly process. The lignins obtained from raw and parboiled RHs have been thoroughly characterized and showed similar physico-chemical characteristics, indicating that the parboiling process does not introduce obvious lignin alterations. In addition, a preliminary evaluation of the potentiality of such lignin fractions as precursors of cement water reducers has provided encouraging results. A fermentation-based optional preprocess has also been investigated. However, both raw and parboiled RHs demonstrated a poor performance as a microbiological growth substrate, even in submerged fermentation using cellulose-degrading fungi. The described methodology appears to be a promising strategy for the valorization of these important waste biomasses coming from the rice industry towards a circular economy perspective.

Lignin nanoparticles (LNPs) are promising components for various materials, given their controllable particle size and spherical shape. However, their origin from supramolecular aggregation has limited the applicability of LNPs as recoverable templates for immobilization of enzymes. In this study, we show that stabilized LNPs are highly promising for the immobilization of phospholipase D (PLD), the enzyme involved in the biocatalytic production of high‐value polar head modified phospholipids of commercial interest, phosphatidylglycerol, phosphatidylserine and phosphatidylethanolamine. Starting from hydroxymethylated lignin, LNPs were prepared and successively hydrothermally treated to obtain c‐HLNPs with high resistance to organic solvents and a wide range of pH values, covering the conditions for enzymatic reactions and enzyme recovery. The immobilization of PLD on c‐HLNPs (PLD‐c‐HLNPs) was achieved through direct adsorption. We then successfully exploited this new enzymatic preparation in the preparation of pure polar head modified phospholipids with high yields (60–90 %). Furthermore, the high stability of PLD‐c‐HLNPs allows recycling for a number of reactions with appreciable maintenance of its catalytic activity. Thus, PLD‐c‐HLNPs can be regarded as a new, chemically stable, recyclable and user‐friendly biocatalyst, based on a biobased inexpensive scaffold, to be employed in sustainable chemical processes for synthesis of value‐added phospholipids.

Cutin, one of the main structural components of tomato peels, is a waxy biopolymer rich in hydroxylated fatty acids. In this study, 10,16-dihydroxyhexadecanoic acid (10,16-diHHDA) was extracted and isolated from tomato peels and exploited to develop fully crosslinked polyesters as potential candidates for replacing fossil-based metal protective coatings. A preliminary screening was conducted to select the base formulation, and then a design of experiments (DoE) was used as a methodology to identify the optimal composition to develop a suitable coating material. Different formulations containing 10,16-diHHDA and other biorefinery monomers, including 2,5-furandicarboxylic acid, were considered. To this end, all polyesters were characterized through differential scanning calorimetry (DSC) and gel content measurements to determine their T_g value and crosslinking efficiency. Compositions exhibiting the best trade-off between T_g value, chemical resistance, and sufficiently high 10,16-diHHDA content between 39 and 48 wt.% were used to prepare model coatings that were characterized for assessing their wettability, scratch hardness, chemical resistance, and adhesion to metal substrates. These polyester coatings showed a T_g in the range of 45–55 °C, a hydrophobic behavior with a water contact angle of around 100°, a good solvent resistance (>100 MEK double rubs), and an adhesion strength to steel higher than 2 MPa. The results obtained confirmed the potential of cutin-based resins as coatings for metal protection, meeting the requirements for ensuring physicochemical properties of the final product, as well as for optimizing the valorization of such an abundant agri-food waste as tomato peels.

In this work, a Design-of-Experiments (DoE) methodology was adopted to study and optimize the ultrasonication process of lignin in water to obtain lignin nanoparticles (LNPs) so as to establish qualitative and quantitative cause–effect relationships between the operating variables (i.e., lignin concentration, processing time, and sonication amplitude) and the distinctive features of the so-obtained nanostructured materials. Monitoring the evolution of the chemical, physical, morphological, and thermal characteristics of lignin upon ultrasonic irradiation enabled the identification of the most relevant process parameters (viz., factors) affecting the average particle size and shape, concentration of hydroxyl/carboxyl groups, and suspended fraction of particles, which were taken as the target materials characteristics (viz., systems responses). Interestingly, the selection of suitable process conditions allowed to obtain exclusively spherical LNPs with perfectly circular shape profile, thus providing the first demonstration of the formation of lignin nanospheres through a size-reduction method not relying on the use of solvents or other chemicals. Furthermore, highly predictive fitting models were generated and validated to accurately and reliably estimate the system responses at any experimental point within the investigation range. As a validation of such process optimization, poly­(vinyl alcohol) (PVA) films incorporating up to 20% (w/w) of either pristine or ultrasound-treated lignin were prepared so as to evaluate the effect of tailored lignin (nano)­particle characteristics on the chemical, morphological, thermal, and mechanical properties of the resulting (nano)­composite systems. The nanometric size of LNPs, together with their spherical morphology and lower molecular weight vs pristine systems was found to foster stronger matrix–filler interactions and improved distributive mixing within the PVA matrix, ultimately leading to higher-performance nanocomposite materials. This work provides new insights into the production of LNPs via ultrasonication, demonstrating that precise control over their size, morphology, and chemical functionalities can be predictively attained by the optimal tuning of relevant process parameters.

The growing demand for sustainable biorefinery approaches calls for efficient, environmentally benign strategies to valorize agricultural residues and ensure their complete utilization. This study explores the combination of deep eutectic solvents (DESs) and microwave heating technology as a greener process for the selective fractionation of agri-food waste residues in a zero-waste perspective. Within this framework, five representative biomasses were thoroughly investigated, namely brewer’s spent grain, raw and parboiled rice husks, rapeseed cakes, and hemp hurds. DES formulation was selected for its ability to solubilize and separate lignocellulosic components, enabling the recovery of a polysaccharide-rich fraction, lignin, and bioactive compounds. DES extraction was performed using both microwave heating and conventional batch heating, enabling a direct comparison of the two methods, the optimization of a more sustainable fractionation process, and the maximization of yields while preserving the functional integrity of the recovered fractions. A comprehensive characterization of the separated fractions was carried out, revealing that the two fractionation methods do not yield significant differences in the composition of the primary components. Moreover, a ¹³C CP-MAS NMR analysis of the recovered lignins demonstrates how this analytical technique is a real fingerprint for the biomass source. The results demonstrate the great potential of microwave DES-mediated fractionation as a mild, tunable, and sustainable alternative to conventional methods, aligning with green chemistry principles and opening new approaches for the full valorization of waste byproducts