Search Results (481)

Marine macrophytes are major components of Mediterranean coastal ecosystems and potential sources of renewable macromolecules, functional extracts, and structural materials. This review critically compares three taxonomically and chemically distinct biomasses: the endemic seagrass Posidonia oceanica, the calcified brown macroalga Padina pavonica, and the filamentous green macroalga Chaetomorpha linum. Their ecological functions and biomass-generation pathways are distinguished because beach-cast seagrass leaves, seasonally detached macroalgae, and biomass removed from eutrophic lagoons cannot be treated as equivalent feedstocks. The review examines green extraction technologies, principal macromolecular and bioactive fractions, biological activities, and application pathways in remediation, agriculture, cosmetics, nutraceuticals, packaging, composites, and construction. Particular attention is given to feedstock heterogeneity, contaminant control, evidence strength, standardization, ecological sourcing, and translational readiness. Comparative analysis identifies P. oceanica primarily as a lignocellulosic and fibrous platform, P. pavonica as a source of brown-algal polysaccharides and phlorotannins, and C. linum as a nutrient-recovery biomass with promising extractive and agronomic applications. The most credible development route is a species-specific cascading biorefinery supported by standardized feedstocks, real-world validation, regulatory planning, and integrated techno-economic and life-cycle assessment. Full article

In this work, five monocarboxylic-acid/Cetyltrimethylammonium Bromide (CTAB) solvent formulations containing formic acid, acetic acid, propionic acid, butyric acid, or lactic acid were systematically compared under identical pretreatment conditions using Phragmites australis straw (PAS) as the feedstock. The lactic acid (LA):CTAB formulation was ultimately selected for further pretreatment of PAS, because it retained substantially more of the initial glucan than formic acid (FA):CTAB, while maintaining a statistically comparable saccharification efficiency. Under the selected conditions (LA:CTAB = 4:1 mol/mol, 170 °C, 60 min), the removal rates of xylan and lignin reached 74.3% and 71.4%, respectively, while an enzymatic hydrolysis efficiency of 72.8% was acquired. In the LA:CTAB-treated liquor, xylooligosaccharides (XOS) and furfural formed in the deep eutectic solvent (DES)-pretreatment liquor contained 4.1 g/L and 1.7 g/L, respectively. Linear fitting between component removal (e.g., xylan removal and delignification) and severity factor (LogR₀) were explored. Molecular analyses of the selected LA system qualitatively indicated attractive interactions around the polar regions of lignocellulosic model compounds and possible dispersive interactions involving the alkyl chain of CTAB. These results illustrate potential noncovalent interaction modes within LA but do not establish a comparative interaction ranking among the five solvent formulations. This study offers theoretical insights into the mechanism of CTAB-based acidic DESs in biomass pretreatment and valorization and suggests a potential direction for the development of efficient and tunable pretreatment solvents for valorization of biomass and co-producing valuable biobased chemicals. Full article

Brewer’s spent grain (BSG) is the primary by-product of the brewing industry and a low-cost lignocellulosic resource rich in phenolics, proteins, and arabinoxylans (AXs). Conventional recovery methods using acids, alkalis, and organic solvents often involve energy-intensive processes, generate hazardous waste, and limit food-grade applications. This review critically examines the evolution of extraction methodologies for BSG bioactives, highlighting the potential of deep eutectic solvents (DES) as sustainable alternatives. Key factors such as solvent chemistry (polarity, pH, and water content) influence bioactives’ recovery and selectivity. Process intensification techniques such as ultrasound, microwave, and pressurised liquid extraction enhance efficiency by reducing extraction time and temperature. The review assesses how various processes modify the structure–function properties of BSG bioactives, including antioxidant activity, protein functionality, and rheological behaviour. A significant finding is that DES research has primarily focused on single compounds, while integrated DES biorefineries for comprehensive valorisation remain underexplored. Future research should therefore prioritise integrated process design that balances recovery, structural preservation, functionality, and sustainability to support scalable, near-zero-waste BSG valorisation for food and nutraceutical applications. Full article

The increasing global demand for sustainable energy has intensified interest in bioethanol as a renewable alternative to fossil fuels. While first- and second-generation bioethanol technologies have advanced considerably, challenges related to production cost, efficiency, and sustainability remain. Filamentous fungi have emerged as promising biocatalysts due to their ability to produce cellulolytic and hemicellulolytic enzymes that efficiently degrade lignocellulosic biomass into fermentable sugars. Genera including Trichoderma, Aspergillus, Fusarium, Neurospora, and Penicillium play significant roles in enhancing biomass saccharification and improving ethanol production. Co-cultivation strategies involving filamentous fungi and yeasts further enhance substrate utilization, ethanol yield, and process stability, although scalability and culture compatibility remain challenging. Recent advances in metabolic engineering, mutagenesis, and CRISPR-based genome editing have enabled the development of improved fungal strains with enhanced enzymatic performance and substrate conversion efficiency. Beyond bioethanol production, filamentous fungi are increasingly recognized as key components of integrated biorefinery systems through their capacity to utilize diverse feedstocks and generate value-added products, including organic acids, industrial enzymes, and bioactive compounds. Despite limitations such as variable growth rates, substrate heterogeneity, and inhibitory by-products, filamentous fungi represent versatile and sustainable platforms for advancing second-generation bioethanol production and supporting future circular bioeconomy and biorefinery development. Full article

Grape stems (GSs), a key by-product of winemaking, are a rich source of bioactive polyphenols and have potential applications in functional foods, antioxidant additives, and cosmetics. In this study, the production of polyphenol-rich extracts from GS using an ultrasound-assisted, acid-catalyzed organosolv process was explored, using isopropanol as solvent. Sulfuric acid served as an effective catalyst for breaking down lignocellulosic material, and the process conditions were optimized using response surface methodology to maximize efficiency. Following an initial single-factor analysis, sulfuric acid and isopropanol concentrations were selected as the main variables. The optimal conditions—54% isopropanol and 1% sulfuric acid—yielded the highest polyphenol content (50.9 ± 4.4 mg caffeic acid equivalents per gram of dry mass). Further analysis using liquid chromatography–mass spectrometry revealed that acid catalysis significantly altered the polyphenolic composition of the extracts. These changes enhanced antioxidant potency, as expressed by the radical scavenging activity but not by the reducing power, while the exact nature of the newly formed compounds was unclear. Overall, the results provide useful insights into modifying the polyphenolic profile of grape stems to obtain extracts with improved antioxidant capacity, supporting more sustainable and value-added uses of winemaking by-products within biorefinery systems. Full article

Agricultural residues represent an abundant lignocellulosic resource for the production of renewable fuels and value-added products through thermochemical conversion. In this study, the influence of bran and peat as organic and mineral-rich binder components on the pyrolysis behaviour and product distribution of biomass pellets was investigated. Wheat straw, barley straw, and oat husks were pelletized using barley bran or peat as binders and analysed by thermogravimetric analysis coupled with Fourier-transform infrared spectroscopy (TGA-FTIR). The thermal degradation behaviour, product yields, evolution profiles of non-condensable gases, and composition of condensable products were evaluated during pyrolysis at 700 °C. The results indicated that pelletization modified the thermal degradation pathways and product distribution through interactions between biomass and binder components. Bran-bonded pellets promoted the formation of bio-oil and oxygen-containing condensable compounds, with bio-oil yields reaching up to 45.2%, whereas peat-bonded pellets showed increased formation of non-condensable gases and solid residue. CO₂ and CO were the dominant gaseous products, while CH₄ formation mainly occurred at elevated temperatures in the passive pyrolysis region. The results indicate that binder composition plays an important role in controlling pyrolysis pathways and product distribution, providing opportunities for the optimization of agricultural residue-based pellets for bioenergy and circular bioeconomy applications. Full article

Sunflower hulls are an abundant lignocellulosic waste with significant but underexploited potential for the recovery of high-value compounds and production of renewable energy. In this study, an integrated biorefinery approach was developed for the sequential recovery of waxes, free and bound phenolic compounds, and biomethane. Three pretreatment strategies (acid-thermal, mechanically assisted alkaline, and ultrasound-assisted ethanolic) were comparatively evaluated to determine their effects on bound phenolics extraction and biomethane production. Sequential extraction recovered 0.94 g of waxes 100 g⁻¹ d.b. and 145.52 mg GAE 100 g⁻¹ d.b. of free phenolics, with chlorogenic acid as the predominant compound. The different pretreatments exhibited contrasting performances depending on the valorisation criterion considered. Although acid–thermal pretreatment achieved the highest recovery of bound phenolic compounds (99.3 mg GAE 100 g⁻¹ d.b.), ultrasound-assisted ethanolic pretreatment preserved the largest proportion of the original biomass and resulted in the highest overall methane recovery (150% relative to the untreated biomass). Each pretreatment modified the lignocellulosic matrix through hemicellulose solubilization, lignin disruption, and fibre reorganisation, thus explaining the observed differences in phenolic release and biomethane production. The results demonstrate that each pretreatment favours a specific product stream, and that the selection of the most suitable pretreatment depends on the biorefinery’s objective. Full article

The increasing demand for clean energy to mitigate air pollutant emissions, together with the need for sustainable carbon-based materials under the circular economy, has driven the exploration of renewable carbon materials derived from lignocellulosic biomass as a renewable bioresource. Due to its abundance, high carbon content, and favorable thermochemical properties, coconut shell was used as a feedstock for producing biocoke at higher pyrolysis temperatures (i.e., 700, 750, 800, and 850 °C) for comparison with commercial coal coke. The pore properties (i.e., surface area and pore volume) and chemical characteristics of commercial coal coke and the resulting biocoke products were characterized. The chemical characterization primarily involved energy-dispersive X-ray spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FTIR). The findings showed that the pore properties of the biocoke exhibited an upward trend as the pyrolysis temperature increased and were significantly higher than those of commercial coal coke (i.e., 294.37–467.05 m²/g vs. 6.33 m²/g based on the BET surface area). In contrast to the commercial coal coke, the proximate analysis results revealed that the resulting biocoke products possessed higher fixed carbon contents (i.e., 76.94–84.56 wt% vs. 78.40 wt%) and calorific values (i.e., 26.90–33.06 MJ/kg vs. 25.39 MJ/kg). Although the pore properties of Biocoke-700 (produced at 700 °C) were not significantly different from those of the other biocoke products, it appeared to be the optimal sample based on its lower energy consumption, low ash content (i.e., 2.25 wt%), and high fixed carbon content (i.e., 84.56 wt%). Based on the EDS and FTIR analyses, the resulting biocoke products retained moderate oxygen contents (14–18 wt%), implying the presence of oxygen-containing functional groups on the surface. In addition, the biocoke ash mainly contained inorganic compounds such as iron oxides, whereas the coal coke ash primarily consisted of silica and alumina. Full article

Background: γ-Valerolactone (GVL), a green volatile platform compound derived from lignocellulosic biomass, has recently been identified as one volatile organic compound produced by the plant growth-promoting rhizobacterium Stutzerimonas stutzeri NRCB010. Although our previous transcriptomic and phenotypic studies have verified that exogenous GVL can promote the growth of tomato seedlings, the global metabolic reprogramming behind this promoting effect remains unclear. Methods: Tomato seedlings were subjected to exogenous GVL treatments at three concentrations (0, 0.25, 0.5 g/L) for 24 h and 48 h separately. Combined with physiological growth measurements, ultra-high-performance liquid chromatography–tandem mass spectrometry-based widely targeted metabolomics was applied to systematically characterize GVL-mediated metabolic reprogramming. Results: GVL remarkably improved seedling height, biomass and root development, with 0.25 g/L GVL showing the strongest promoting effect. A total of 703 metabolites including lipids, flavonoids and alkaloids were identified. Principal component analysis and orthogonal partial least squares discriminant analysis revealed distinct metabolic separation between control and treated groups, verifying time and concentration dependent metabolic shifts. After 24 h, GVL activated primary pathways (the tricarboxylic acid cycle, amino acid and purine metabolism) to supply growth energy; after 48 h, central carbon and secondary biosynthetic pathways were enriched, and 0.5 g/L GVL specifically triggered defensive isoquinoline and indole alkaloid biosynthesis. Conclusions: GVL coordinately remodels primary and secondary metabolic networks to accelerate tomato seedling growth, which provides sufficient metabolomic evidence for developing GVL as a novel bio-based plant biostimulant. Full article

Low-cost lignocellulosic residues offer a sustainable route to fungal pigment production. In this study, six biomass residues were evaluated as culture-medium supplements for Arthrinium phaeospermum, and their chemical constituents that may be associated with enhanced red pigment production were investigated. Fungal growth, pigment production, and pigment productivity were measured on biomass-amended potato dextrose agar. Following initial screening, Paulownia powder and sugarcane bagasse were selected, and their concentrations were optimized in mixed media. Ethanolic extracts of both materials were characterized using Fourier-transform infrared spectroscopy and ultra-performance liquid chromatography–mass spectrometry, and four major Paulownia-derived compounds were individually evaluated. The optimal medium, containing 4 mg/mL Paulownia powder and 3 mg/mL sugarcane bagasse, produced 3.09 g/L red pigment, representing a 2.02-fold increase over the control. Sugarcane bagasse primarily promoted fungal growth, whereas paulownia enhanced pigment productivity. Among the tested compounds, 0.2 mg/mL 4-methylumbelliferone (4M) showed the strongest stimulatory effect, increasing pigment production 3.01-fold over the control. These findings demonstrate that combining forestry and agro-industrial residues can simultaneously support fungal growth and pigment production. Paulownia-derived coumarins, particularly 4-methylumbelliferone, may contribute to this stimulatory effect and warrant further mechanistic investigation. Full article

Wood vinegar (WV), also known as pyroligneous acid, is the aqueous condensate produced during lignocellulosic biomass pyrolysis, generated alongside biochar and non-condensable gases. In forest biorefineries, it represents a promising value-added coproduct capable of transforming forestry and agroforestry residues into a multifunctional bioproduct. Its composition, dominated by water, organic acids, phenolic compounds, aldehydes, and ketones, confers antimicrobial, antioxidant, biostimulant, herbicidal, and preservative properties. This review critically examines WV production, chemical composition, purification strategies, mechanisms of action, and applications, explicitly distinguishing evidence-based uses from prospective ones. Current evidence supports applications in agriculture, wood preservation, environmental management, and forestry, including forest nursery production and clonal propagation of Eucalyptus and Pinus. However, the literature remains fragmented by compositional variability, non-standardized terminology, limited mechanistic understanding, and scarce long-term toxicological and techno-economic assessments. WV holds significant potential for sustainable biomass valorization and circular bioeconomy strategies. Realizing this potential requires harmonized analytical protocols, standardized formulations, rigorous mechanistic studies, life-cycle assessments, and regulatory frameworks that support the transition of this heterogeneous pyrolysis byproduct into a reliable commodity within integrated forest biorefineries. Full article

Corn stover (CS), as a major agricultural residue in Northeast China, suffers from inefficient anaerobic digestion (AD) due to its rigid lignocellulosic structure and the generation of inhibitory phenolic compounds during pretreatment. Alkaline hydrogen peroxide (AHP) disrupts lignocellulosic structures while generating methanogenesis-inhibiting phenolic compounds. Current pretreatments only resolve either lignocellulosic rigidity or phenolic toxicity, with no integrated method to mitigate both simultaneously. This work investigated a combined strategy of AHP pretreatment coupled with MnO₂ amendment to improve methane production from CS using laboratory-scale batch AD. Results demonstrated that 3% AHP pretreatment induced structural modifications and altered lignin-related functional groups, while the subsequent addition of 1.0 g MnO₂ significantly (p < 0.05) removed up to 28.4% of the generated total phenolic equivalents and alleviated volatile fatty acid (VFA) accumulation. The Mn-AHP group achieved the highest cumulative methane production of 449.28 ± 13.25 mL/g VS, representing a 14.6% increase compared to the control and a 3.24% improvement over the AHP-only group. Microbial analysis revealed increased relative abundance of acidogenic bacteria (e.g., Synergistota) and a compositional shift in the archaeal community toward a structure dominated by Methanobacterium and Methanothrix. These findings indicate that coupling AHP with MnO₂ is a promising approach to address the dual challenges of lignocellulosic recalcitrance and phenolic inhibition, providing a feasible pathway for agricultural waste valorization. Full article

This research explores the production of activated carbon from a lignocellulosic precursor, corn cobs, as a potential method for the removal and adsorption of phenolic and nitrophenolic compounds. Colombia is a major corn producer, with a national production of 1,559,194 tons in 2024. Currently, approximately 0.5 to 3.2 kg of corn residue per kg of product is not commercially utilized. The objective is to focus on the removal of phenol, 2-nitrophenol, 4-nitrophenol, and 2,4-dinitrophenol from simulated solutions to evaluate the adsorption capacity under optimal conditions. Phenolic and nitrophenolic compounds are considered highly toxic molecules for the environment, especially in the plastics and agrochemical production sectors. These compounds are pollutants in wastewater due to their impact on aquatic life and human health. This not only contributes to the utilization of residual biomass but also to the circular economy by promoting its valorization in environmental remediation processes. The diameter and average volume of the pores are large enough to promote rapid diffusion kinetics of the phenolic compounds within the pore structure, which varies from 0.207 to 0.544 cm³ g⁻¹, and their adsorption capacity. The most adsorbed phenol was found to be 4-nitrophenol, with up to 97 mg of contaminant (4-nitrophenol) adsorbed per gram of activated carbon (sample designated AC-TK), at initial concentrations ranging from 0.0 ppm to 3.0 ppm. Furthermore, magnetite plays a crucial role in the adsorption of 2-nitrophenol. With this compound, up to 86 mg of 2-nitrophenol per gram of activated carbon was adsorbed at a concentration of 14 ppm, whereas without magnetite, a smaller amount was adsorbed at lower initial concentrations (ppm) for the same compound. Full article

Anaerobic digestion (AD) plays a key role in the circular bioeconomy by converting organic waste into renewable energy and facilitating the sustainable utilisation of waste materials. Agricultural and agro-industrial by-products are increasingly recognised as valuable AD feedstocks due to their widespread availability and significant bioenergy potential. However, many of these substrates contain plant-derived bioactive compounds, such as polyphenols, tannins, flavonoids and terpenes, which can influence microbial communities and process performance. Depending on their concentration and chemical characteristics, these compounds may inhibit microbial activity, impair process stability, and ultimately decrease methane production. This review critically synthesises current knowledge on the occurrence, bioavailability and biological activity of plant-derived bioactive compounds in agricultural feedstocks used for anaerobic digestion, with particular emphasis on their implications for process performance and reactor stability. The principal mechanisms through which phytochemicals influence anaerobic digestion include enzyme inhibition, membrane disruption, interference with syntrophic interactions and trace metal chelation. The available evidence demonstrates a pronounced dose-dependent response, whereby low concentrations may exert neutral or selective modulatory effects. In contrast, elevated concentrations disrupt microbial activity, leading to volatile fatty acid accumulation, prolonged lag phases and reduced methane production. Current mitigation strategies include substrate pretreatment, co-digestion, microbial adaptation, adsorbent-assisted detoxification and the use of DIET-promoting materials. An integrated evidence matrix is proposed to link phytochemical composition with reactor configuration, operational parameters and mitigation strategies, thereby providing a practical framework for feedstock-specific process optimisation. Overall, the available evidence demonstrates that reliable evaluation of agricultural feedstocks should extend beyond conventional biochemical methane potential assessment to incorporate phytochemical composition, microbial functional responses and key operational parameters. Such an integrated approach can improve the prediction of methane recovery and support evidence-based optimisation of anaerobic digestion within circular bioeconomy systems. Full article

The agri-food sector generates significant quantities of by-products and waste biomass, representing both an environmental challenge and an opportunity for resource recovery within a circular bioeconomy. This study developed a decision-support framework for the sustainable valorization of major residues from the Italian agri-food sector. Following a Material Flow Analysis (MFA) of multiple Italian agri-food supply chains, tomato and grape supply chains were selected as representative case studies because they generated the largest quantities of valorizable by-products among the agri-food sectors evaluated, namely tomato pomace and grape marc. MFA based on FAOSTAT and PRODCOM data (2019–2023) was combined with a literature review to assess biomass availability and physicochemical characteristics. The analysis identified tomato pomace and grape marc as the predominant residues. Tomato pomace showed high moisture content (63.34%), balanced organic composition, and a favorable C/N ratio, supporting its suitability for anaerobic digestion with an average biomethane potential (BMP) of 0.143 m³ CH₄/kg TVS. Conversely, grape marc exhibited a carbon-rich lignocellulosic structure, with a carbon content of 47.67%, C/N ratio of 24.73, and BMP of 0.195 m³ CH₄/kg TVS, favoring thermochemical conversion pathways, particularly pyrolysis. The framework also highlights the importance of cascading strategies, prioritizing the recovery of high-value compounds, and pretreatment approaches to improve biomass conversion efficiency. Overall, this approach supports optimized resource recovery and sustainable agri-food waste management. Full article