Relationship between rheological and morphological characteristics of cellulose nanofibrils in dilute dispersions

Enhanced physicochemical and antifungal properties of starch bionanocomposites reinforced with nanocellulose and functionalized with AgNPs derived from cocoa bean shell

This study explored the synergistic combination of silver nanoparticles (AgNPs), eucalyptus-derived nanofibrillated cellulose (NFC) and cassava starch to develop bionanocomposites with advanced properties suitable for sustainable and antifungal packaging applications. The influence of AgNPs synthesized through a green method using cocoa bean shell combined with varying concentrations of NFC were investigated. Morphological (scanning electron microscopy and atomic force microscopy), optical (L*, C*, °hue, and opacity), chemical (Fourier transform infrared spectroscopy), mechanical (puncture force, tensile strength, and Young's modulus), rheological (flow curve and frequency sweeps, strain, and stress), barrier, and hydrophilicity properties (water vapor permeability, solubility, wettability, and contact angle), as well as the antifungal effect against pathogens (Botrytis cinerea, Penicillium expansum, Colletotrichum musae, and Fusarium semitectum), were analyzed. The morphological analysis indicated excellent interaction between the bionanocomposites constituents. The maximum NFC addition increased the tensile strength of the bionanocomposites by approximately 283.93 % (14.85 MPa) while Young's modulus also showed a significant increase of 303.03 % (417.14 MPa), indicating increased stiffness. Water vapor permeability of the materials decreased by approximately 47.89 %. The materials exhibited hydrophilic properties while maintaining low wettability. Furthermore, the bionanocomposites demonstrated pseudoplastic (Ȳ = 0.59) behavior and an inhibitory effect against fungal pathogens. In conclusion, these innovative materials have the potential to transform packaging technology by serving as sustainable alternatives to petroleum-derived polymers while simultaneously adding value to agro-industrial waste.

Preparation of Soybean Fiber/Sodium Alginate Microgel and Its Application in Low-Fat Yogurt

This study investigates the oral processing characteristics and application of soybean fiber and sodium alginate microgel in enhancing the texture and sensory attributes of low-fat yogurt. By combining soybean fiber with sodium alginate, a stable composite microgel system was developed with a uniform particle-size distribution. Oral lubrication performance was assessed by evaluating particle size, texture, friction coefficient and rheological properties, providing insights into how microgels improve food lubricity. The results showed that adding soybean fiber/sodium alginate microgel to low-fat yogurt significantly enhanced lubrication, texture and sensory quality compared to standard low-fat yogurt. The yogurt sample containing 2 wt% microgel achieved optimal sensory results, improving hardness and adhesiveness. This study suggests that soybean fiber/sodium alginate microgel offer a promising strategy for enhancing the sensory quality in low-fat dairy products, supporting healthier food innovations.

Microwave-Assisted Production of Defibrillated Lignocelluloses from Blackcurrant Pomace via Citric Acid and Acid-Free Conditions

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.

Fabraction of edible bio-nanocomposite coatings from pectin-containing lignocellulosic nanofibers isolated from apple pomace

Minimally processed fruits are increasingly demanded in modern society, but the management of perishable waste pomaces (WPs) and the products' short shelf-life are still big issues. Here, a facile approach of reconstruing apple pomace (AP) into edible bio-nanocomposite coatings of fresh-cutting apple slices was successfully developed through alkaline demethylation followed by high-pressure homogenization. The fibrillation of AP fibers is largely improved by -COO- at a concentration of 1.23 mmol g-1, which is released through alkaline demethylation of pectin, instead of relying on intricated or costly cellulose modifications. The average width of AP nanofibers (AP-NFs) downsizes to 18 nm. By casting, AP-NFs fabricate homogeneous films with comparable transparency (56 % at 600 nm), superior mechanical strength (6.4 GPa of Young modulus and 81.7 MPa of strength) and oxygen barrier properties (79 mL μm m-2 day-1 bar-1), and non-toxicity. Moreover, the AP-NF coatings effectively extend shelf life of apple slices by inhibiting browning and respiration, and retain firmness. This research demonstrates a way to valorize WPs as edible coatings for fruit packaging.

Recent advance on lignin-containing nanocelluloses: The key role of lignin

Nanocelluloses (NCs) isolated from lignocellulosic resources usually require harsh chemical pretreatments to remove lignin, which face constraints such as high energy consumption and inefficient resource utilization. An alternative strategy involving the partial retention of lignin can be adopted to endow NCs with better versatility and functionality. The resulting lignin-containing nanocelluloses (LNCs) generally possess better mechanical property, thermal stability, barrier property, antioxidant activity, and surface hydrophobicity than lignin-free NCs, which have attracted extensive interest as a promising green nanomaterial for numerous applications. This review provides a comprehensive overview of the recent advances in the preparation, properties, and food application of LNCs. The effect of residual lignin on the preparation and properties of LNCs is discussed. Furthermore, the key roles of lignin in the properties of LNCs, including particle size, crystalline structure, dispersibility, thermal, mechanical, antibacterial, rheological and adhesion properties, are summarized comprehensively. Furthermore, capitalizing on their dietary fiber and nanostructure properties, the food applications of LNCs in the forms of films, gels and emulsions are also discussed. Finally, the challenges and opportunities regarding the development of LNCs are provided.

Palm-based nanofibrillated cellulose (NFC) in carotenoid encapsulation and its incorporation into margarine-like reduced fat spread as fat replacer

Nanofibrillated cellulose (NFC) from plant biomass is becoming popular, attributed to the protective encapsulation of bioactive compounds in Pickering emulsion, preventing degradation and stabilizing the emulsion. NFC, as a natural dietary fiber, is a prominent fat replacer, providing a quality enhancement to reduced-fat products. In this study, NFC Pickering emulsions were prepared at NFC concentrations of 0.2%, 0.4%, 0.6%, 0.8%, and 1% to encapsulate carotenoids. The NFC Pickering emulsions at NFC concentrations of 0.4%, 0.6%, 0.8%, and 1% were incorporated into margarine-like reduced fat (3%) spreads as the aqueous phase. Characterization of both NFC Pickering emulsion and the incorporated NFC Pickering emulsion, margarine-like reduced fat spreads, was conducted with mastersizer, rheometer, spectrophotometer, and texture analyzer. The particle size (73.67 ± 0.35 to 94.73 ± 2.21 nm), viscosity (138.36 ± 3.35 to 10545.00 ± 567.10 mPa s), and creaming stability (25% to 100% stable) of the NFC Pickering emulsions were increased significantly when increasing the NFC concentration, whereas the encapsulation efficiency was highest at NFC 0.4% and 0.6%. Although imitating the viscoelastic solid-like behavior of margarine was difficult, the NFC Pickering emulsion properties were still able to enhance hardness, slip melting point, and color of the reduced fat spreads compared to the full-fat margarine, especially at 0.6% of NFC. Overall, extensive performances of NFC can be seen in encapsulating carotenoids, especially at NFC concentrations of 0.4% and 0.6%, with the enhancement of Pickering emulsion stability while portraying futuristic possibilities as a fat replacer in margarine optimally at 0.6% of NFC concentration. PRACTICAL APPLICATION: Nanocellulose extracted from palm dried long fiber was utilized to encapsulate carotenoids and replace fats in margarine-like reduced fat (3%) spreads. Our study portrayed high encapsulation efficiency and successful fat replacement with promising stability performances. Hence, nanocellulose displayed extensive potential as encapsulating agents and fat replacers while providing quality and sustainability enhancements in reduced-fat food.

Preparation of cellulose nanofibers from potato residues by ultrasonication combined with high-pressure homogenization

In this study, the preparation parameters of cellulose nanofibers from potato residues (PCNFs) by ultrasonication combined with high-pressure homogenization were optimized based on yield, zeta-potential and morphology. The optimal parameters were as follows: ultrasonic power of 125 W for 15 min and homogenization pressure of 40 MPa four times. The yield, zeta potential and diameter range of the obtained PCNFs were 19.81 %, -15.60 mV and 20-60 nm, respectively. Fourier transform infrared spectroscopy, X-ray diffraction and nuclear magnetic resonance spectroscopy results showed that part of the crystalline region of cellulose was destroyed, resulting in a decrease in crystallinity index from 53.01 % to 35.44 %. The maximum thermal degradation temperature increased from 283 °C to 337 °C. PCNFs suspensions were non-Newtonian fluids and exhibited rigid colloidal particle properties. In conclusion, this study provided alternative uses for potato residues generated from starch processing and showed great potential for various industrial applications of PCNFs.

Endoglucanase pretreatment aids in isolating tailored-cellulose nanofibrils combining energy saving and high-performance packaging

Cellulose nanofibrils (CNFs) have emerged as a potential alternative to synthetic polymers in packaging applications owing to their oxygen and grease barrier performance and mechanical properties. However, the performance of CNF films is dependent on the intrinsic characteristics of fibers, which are changed during CNF isolation. Understanding the variations in these characteristics during CNF isolation is crucial for tailoring CNF film properties to achieve optimum performance in packaging applications. In this study, CNFs were isolated by endoglucanase-assisted mechanical ultra-refining. The changes in the intrinsic characteristics of CNFs and their impact on CNF films were systematically investigated as functions of the degree of defibrillation, enzyme loading, and reaction time using the design of experiments. Enzyme loading had a significant effect on the crystallinity index, crystallite size, surface area, and viscosity. Meanwhile, the degree of defibrillation greatly influenced the aspect ratio, degree of polymerization, and particle size. CNF films prepared from CNFs isolated under two optimized scenarios (casting and coating applications) exhibited high thermal stability (approximately 300 °C), high tensile strength (104-113 MPa), high oil resistance (kit n°12), and low oxygen transmission rate (1.00-3.17 cc·m^-2.day^-1). Therefore, endoglucanase pretreatment can obtain CNFs at lower energy consumption, resulting in films with higher transmittance, higher barrier performance, and lower surface wettability than the control samples without enzymatic pretreatment and other unmodified net CNF films reported in the literature without intensive loss of mechanical and thermal performance.

3D Printable Hybrid Gel Made of Polymer Surface-Modified Cellulose Nanofibrils Prepared by Surface-Initiated Controlled Radical Polymerization (SI-SET-LRP) and Upconversion Luminescent Nanoparticles

A cellulose nanofibril-based hybrid gel material was developed by grafting the polymerized stearyl acrylate (PSA) and upconversion nanoparticles (UCNPs) onto cellulose nanofibrils (CNFs) via Cu⁰-mediated radical polymerization (SET-LRP) to create a highly cross-linked CNF system. A two-step strategy was exploited to surface-exchange the ligand of the UCNPs from a hydrophobic ligand (oleic acid) to a hydrophilic small-molecule ligand (2-acrylamido-2-methyl-1-propanesulfonic acid, AMPS) and therefore be suitable for SET-LRP. The characteristics and properties of the hybrid material (UCNP-PSA-CNF) were monitored by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), rheology, X-ray diffraction (XRD), and microscopic analysis. Those characterization techniques prove the efficient modification of the CNF, with the presence of 1.8% UCNPs. The luminescence measurement was carried out using a homebuilt confocal microscope with a 980 nm laser source. The nanostructure of UCNPs and their incorporated CNF species were measured by small-angle X-ray scattering (SAXS). In addition, this CNF-based hybrid gel has decisive rheological properties, such as good viscoelasticity (loss tangent was below 0.35 for the UCNP-PSA-CNF gel, while the PSA-CNF gel reached the highest value of 0.42), shear-thinning behavior, and shape retention, and was successfully applied to three-dimensional (3D) gel printing throughout various 3D print models.

Cellulose Nanofibers from Schinus molle: Preparation and Characterization

Schinus molle (SM) was investigated as a primary source of cellulose with the aim of discovering resources to generate cellulose nanofibers (CNF). The SM was put through a soda pulping process to purify the cellulose, and then, the fiber was treated with an enzymatic treatment. Then, a twin-screw extruder and/or masuko were utilized to help with fiber delamination during the nanofibrillation process. After the enzymatic treatment, the twin-screw extruder and masuko treatment give a yield of 49.6 and 50.2%, respectively. The optical and atomic force microscopy, morfi, and polymerization degrees of prepared cellulosic materials were established. The pulp fibers, collected following each treatment stage, demonstrated that fiber characteristics such as length and crystallinity varied according to the used treatment (mechanical or enzymatic treatment). Obviously, the enzymic treatment resulted in shorter fibers and an increased degree of polymerization. However, the CNF obtained after enzymatic and extrusion treatment was achieved, and it gave 19 nm as the arithmetic width and a Young's modulus of 8.63 GPa.

Relationships between Size Distribution, Morphological Characteristics, and Viscosity of Cellulose Nanofibril Dispersions

Rheological parameters of cellulose nanofibril dispersions (CNF) are relevant and commonly used as quality control for producing of this type of material. These parameters are affected by morphological features and size distribution of the nanofibrils. Understanding the effect of size distribution is essential for analyzing the rheological properties, viscosity control, performance of CNFs, and potential dispersion applications. This study aims at comprehending how the morphological characteristics of the CNFs and their size distribution affect the rheological behavior of dispersions. The CNF dispersions were fractionated by size, obtaining six fractions of each, which were analyzed for their morphology and rheology (viscosity, intrinsic viscosity). In the dilute region, the viscosity and intrinsic viscosity behavior of CNF dispersions are linear concerning the size distribution present in the dispersion. In the semi-dilute region, the size of the fibrils and the fiber aggregates have a relevant effect on the viscosity behavior of CNF dispersions, which are satisfactorily related (R² = 0.997) using the rule of logarithmic additivity of the dispersion viscosities of size fractions.

Effect of Oxalic Acid Concentration and Different Mechanical Pre-Treatments on the Production of Cellulose Micro/Nanofibers

The present work analyzes the effect of process variables and the method of characterization of cellulose micro/nanofibers (CMNFs) obtained by different treatments. A chemical pre-treatment was performed using oxalic acid at 25 wt.% and 50 wt.%. Moreover, for mechanical pre-treatments, a rotary homogenizer or a PFI mill refiner were considered. For the mechanical fibrillation to obtain CMNFs, 5 and 15 passes through a pressurized homogenization were considered. The best results of nanofibrillation yield (76.5%), transmittance (72.1%) and surface charges (71.0 µeq/g CMNF) were obtained using the PFI mill refiner, 50 wt.% oxalic acid and 15 passes. Nevertheless, the highest aspect ratio (length/diameter) determined by Transmission Electron Microscopy (TEM) was found using the PFI mill refiner and 25 wt.% oxalic acid treatment. The aspect ratio was related to the gel point and intrinsic viscosity of CMNF suspensions. The values estimated for gel point agree with those determined by TEM. Moreover, a strong relationship between the intrinsic viscosity [η] of the CMNF dispersions and the corresponding aspect ratio (p) was found (ρ[η] = 0.014 p^2.3, R² = 0.99). Finally, the tensile strength of films obtained from CMNF suspensions was more influenced by the nanofibrillation yield than their aspect ratio.

Impact of the Enzyme Charge on the Production and Morphological Features of Cellulose Nanofibrils

The available research does not allow specific relationships to be established between the applied enzymatic-mechanical treatment, the degree of polymerization, and the characteristics of the cellulose nanofibrils (CNFs) produced. This work aims to establish specific relationships between the intensity of enzymatic treatment, the degree of polymerization of the cellulose, the morphology of CNFs, and the tensile strength of the CNF films. It is determined that the decrease in the degree of polymerization plays an essential role in the fibrillation processes of the cell wall to produce CNFs and that there is a linear relationship between the degree of polymerization and the length of CNFs, which is independent of the type of enzyme, enzyme charge, and intensity of the applied mechanical treatment. In addition, it is determined that the percentage of the decrease in the degree of polymerization of CNFs due to mechanical treatment is irrespective of the applied enzyme charge. Finally, it is shown that the aspect ratio is a good indicator of the efficiency of the fibrillation process, and is directly related to the mechanical properties of CNF films.