Explore the vast range of titles available.

Blackcurrant pomace (BCP) is an example of an annual, high-volume, under-utilized renewable resource with potential to generate chemicals, materials and bioenergy within the context of a zero-waste biorefinery. Herein, the microwave-assisted isolation, characterization and potential application of defibrillated lignocelluloses from depectinated blackcurrant pomace are reported. Depectination was achieved using citric acid (0.2–0.8 M, 80 °C, 2 h, conventional heating) and compared with acid-free hydrothermal microwave-assisted processing (1500 W, 100–160 °C, 30 min). The resultant depectinated residues were subjected to microwave-assisted hydrothermal defibrillation to afford two classes of materials: namely, (i) hydrothermal acid-free microwave-assisted (1500 W, 160 °C, 30 min; DFC-M1-M4), and (ii) hydrothermal citric acid microwave-assisted (1500 W, 160 °C, 30 min; DFC-C1–C4). Thermogravimetric analysis (TGA) revealed that the thermal stability with respect to native BCP (Td = 330 °C) was higher for DFC-M1-M4 (Td = 345–348 °C) and lower for DFC-C1–C4 (322–325 °C). Both classes of material showed good propensity to hold water but failed to form stable hydrogels (5–7.5 wt% in water) unless they underwent bleaching which removed residual lignin and hemicellulosic matter, as evidenced by 13C solid-state NMR spectroscopy. The hydrogels made from bleached DFC-C1–C4 (7.5 wt%) and bleached DFC-M1-M4 (5 wt%) exhibited rheological viscoelastic, shear thinning, and time-dependent behaviour, which highlights the potential opportunity afforded by microwave-assisted defibrillation of BCP for food applications.

The first production of defibrillated celluloses from microalgal biomass using acid-free, TEMPO-free and bleach-free hydrothermal microwave processing is reported. Two routes were explored: i. direct microwave process of native microalgae (“standard”), and ii. scCO2 pre-treatment followed by microwave processing. ScCO2 was investigated as it is commonly used to extract lipids and generates considerable quantities of spent algal biomass. Defibrillation was evidenced in both cases to afford cellulosic strands, which progressively decreased in their width and length as the microwave processing temperature increased from 160 °C to 220 °C. Lower temperatures revealed aspect ratios similar to microfibrillated cellulose whilst at the highest temperature (220 °C), a mixture of microfibrillated cellulose and nanocrystals were evidenced. XRD studies showed similar patterns to cellulose I but also some unresolved peaks. The crystallinity index (CrI), determined by XRD, increased with increasing microwave processing temperature. The water holding capacity (WHC) of all materials was approximately 4.5 g H2O/g sample. The materials were able to form partially stable hydrogels, but only with those processed above 200 °C and at a concentration of 3 wt% in water. This unique work provides a new set of materials with potential applications in the packaging, food, pharmaceutical and cosmetic industries.

Background D-amino acids are far less abundant in nature than L-amino acids. Both L- and D-amino acids enter soil from different sources including plant, animal and microbial biomass, antibiotics, faeces and synthetic insecticides. Moreover, D-amino acids appear in soil due to abiotic or biotic racemization of L-amino acids. Both L- and D-amino acids occur as bound in soil organic matter and as \"free\" amino acids dissolved in soil solution or exchangeably bound to soil colloids. D-amino acids are mineralized at slower rates compared to the corresponding L-enantiomers. Plants have a capacity to directly take up \"free\" D-amino acids by their roots but their ability to utilize them is low and thus D-amino acids inhibit plant growth. Scope The aim of this work is to review current knowledge on D-amino acids in soil and their utilization by soil microorganisms and plants, and to identify critical knowledge gaps and directions for future research. Conclusion Assessment of \"free\" D-amino acids in soils is currently complicated due to the lack of appropriate extraction procedures. This information is necessary for consequent experimental determination of their significance for crop production and growth of plants in different types of managed and unmanaged ecosystems. Hypotheses on occurrence of \"free\" D-amino acids in soil are presented in this review.

Carbotrace 480 is a commercially available fluorescent optotracer that specifically binds to cellulose’s glycosidic linkages. Herein, the use of Carbotrace 480 is reported as an analytical tool for linking cellulose content to hydrogel formation capability in defibrillated celluloses obtained from proprietary microalgae. Defibrillated celluloses obtained from acid-free hydrothermal microwave processing at low temperature (160 °C) showed poor hydrogel formation attributed to a low cellulose concentration as evidenced through the lack of Carbotrace fluorescence. High temperature (220 °C) processing afforded reasonable gels commensurate with a higher cellulose loading and stronger response to Carbotrace.

The exploitation of unavoidable food supply chain wastes resulting from primary and secondary processing for chemicals, materials, and bioenergy is an important concept in the drive towards circular-based, resource-efficient biorefineries rather than petroleum refineries. The potential production of hydrogels (materials) from unavoidable food supply chain wastes, which are naturally rich in biopolymers such as cellulose, hemicellulose, pectin, and lignin, represents an interesting opportunity. However, these intertwined and interconnected biopolymers require separation and deconstruction prior to any useful application. Thus, this study aims to explore the formation of hydrogels from defibrillated celluloses (MW-DFCs) produced via acid-free stepwise microwave hydrothermal processing of blackcurrant pomace residues. Initially, pectin was removed from blackcurrant pomace residues (MW, 100–160 °C), and the resultant depectinated residues were reprocessed at 160 °C. The pectin yield increased from 2.36 wt.% (MW, 100 °C) to 3.07 wt.% (MW, 140 °C) and then decreased to 2.05 wt.% (MW, 160 °C). The isolated pectins were characterized by attenuated total reflectance infrared spectroscopy (ATR-IR), thermogravimetric analysis (TGA), and 13C NMR (D2O). The cellulosic-rich residues were reprocessed (MW, 160 °C) and further characterized by ATR-IR, TGA, and Klason lignin analysis. All the MW-DFCs contained significant lignin content, which prevented hydrogel formation. However, subsequent bleaching (H2O2/OH−) afforded off-white samples with improved gelling ability at the concentration of 5% w/v. Confocal laser microscopy (CLSM) revealed the removal of lignin and a more pronounced cellulosic-rich material. In conclusion, the microwave-assisted defibrillation of blackcurrant pomace, an exploitable unavoidable food supply chain waste, affords cellulosic-rich materials with the propensity to form hydrogels which may serve useful applications when put back into food products, pharmaceuticals, cosmetics, and home and personal care products.

Deep eutectic solvents (DES) are one of the most promising green technologies to emerge in recent years given their combination of environmentally friendly credentials and useful functionalities. Considering the continued search for new DES – especially those that exemplify the aforementioned characteristics, we report the preparation of DES based on natural analogues of l‐ascorbic acid for the first time. The onset of eutectic melting occurred at temperatures far below the melting point of the individual components and resulted in the generation of glass forming fluids with glass transition temperatures, viscosities and flow behavior that are comparable to similar systems. This work expands the current array of DES that can be produced using naturally occurring components, which given their potential to be bio‐derived, interesting physicochemical properties (e. g. propensity to supercool and vitrify) and apparent antibacterial nature, may provide utility within a range of applications. Vitamin boost! Unheralded, naturally‐occurring l‐ascorbic acid (Vitamin C) analogues have been used to form novel DES for the first time. Displaying comparable physicochemical properties to similar state‐of‐the‐art systems, it is hypothesized that these DES may have application as cryoprotectants or antibacterials.

The availability of chemically rich food supply chain waste (FSCW) gives it considerable potential as a resource for the manufacture of chemicals including materials and fuels. By applying clean chemical technologies to the extraction and conversion of molecules from FSCW, we can aim to produce genuinely green and sustainable products to help meet the legislative and consumer-oriented demands of a sustainable society. Low-temperature microwave (MW) processing is a particularly powerful technology to achieve this aim and is shown to be effective for several different high-volume, geographically diverse biomass types.

Lignocellulose based nanomaterials are emerging green biosolids commonly obtained from wood pulp. Alternative feedstocks, such as as unavoidable food waste, are interesting resources for nano/microfibers. This research reports the production and characterization of microfibrillated lignocellulose (MFLC) from cassava peel (CP) and almond hull (AH) via acid-free microwave-assisted hydrothermal treatment (MHT) at different temperatures (120–220 °C). During processing, the structural changes were tracked by ATR-IR, TGA, XRD, 13C CPMAS NMR, zeta potential, HPLC, elemental analysis (CHN; carbon, hydrogen and nitrogen), TEM and SEM analyses. The microwave processing temperature and nature of feedstock exerted a significant influence on the yields and properties of the MFLCs produced. The MFLC yields from CP and AH shifted by 15–49% and 31–73%, respectively. Increasing the MHT temperature substantially affected the crystallinity index (13–66% for CP and 36–62% for AH) and thermal stability (300–374 °C for CP and 300–364 °C for AH) of the MFLCs produced. This suggested that the MFLC from CP is more fragile and brittle than that produced from AH. These phenomena influenced the gelation capabilities of the fibers. AH MFLC pretreated with ethanol at low temperature gave better film-forming capabilities, while untreated and heptane pretreated materials formed stable hydrogels at solid concentration (2% w/v). At high processing temperatures, the microfibrils were separated into elementary fibers, regardless of pretreatment or feedstock type. Given these data, this work demonstrates that the acid-free MHT processing of CP and AH is a facile method for producing MFLC with potential applications, including adsorption, packaging and the production of nanocomposites and personal care rheology modifiers.Graphic abstract

Antibiotic Microbial Resistance (AMR) is a major global challenge as it constitutes a severe threat to global public health if not addressed. To fight against AMR bacteria, new antimicrobial agents are continually needed, and their efficacy must be tested. Historically, many transition metals have been employed, but their cytotoxicity is an issue and hence must be reduced, typically by combination with organic polymers. Cellulose of natural origin, especially those derived from unavoidable residues in the food supply chain, appears to be a good capping agent for the green synthesis of silver nanoparticles. Herein, we describe a green synthesis method to produce a novel biocomposite, using ascorbic acid as reducing agent and microfibrillated cellulose as a capping agent and demonstrate this material to be an efficient antimicrobial agent. Silver nanoparticles were obtained in the cellulose matrix with an average size of 140 nm and with antimicrobial activity against both sensitive and resistant Gram positive (using 1500 ppm) as well as sensitive and resistant Gram negative (using 125 ppm) bacteria. Also, an inverted disk-diffusion methodology was applied to overcome the low-solubility of cellulose compounds. This novel silver nanoparticle-cellulose biocomposite synthesized by a green methodology shows the potential to be applied in the future development of biomedical instruments and therapeutics.

The exploration of cucumber waste as a potential biorefinery feedstock is reported. Initially, extractives (essential oils) were isolated from cucumber waste via vacuum microwave hydro-distillation (VMHD). The yield and quality of the extractive were compared with respect to traditional hydro-distillation (HD). The essential oils were obtained over a range of microwave power (500, 750, 1000 W) and vacuum pressures (100, 200, 300 mbar). The highest quality (0.49 wt %) was obtained at a microwave irradiation power of 500 W and a vacuum of 300 mbar. VMHD is much quicker and more energy-efficient than HD. Within the context of a zero-waste biorefinery, the extractive-free residues were the solid residues from two different extraction methods were compared and characterized by ATR-IR, 13C solid-state NMR spectroscopy, SEM, TGA, and CHN elemental analysis. The resultant residues are cellulosic-rich, and no significant changes were observed with VMHD and HD treatment. The results indicated that the utilization of these residues can provide an efficient, inexpensive, and environment-friendly platform for the production of cellulosic materials.