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We study the effect of electrolytes on the stability in aqueous media of spherical lignin particles (LP) and its relevance to Pickering emulsion stabilization. Factors considered included the role of ionic strength on morphology development, LP size distribution, surface charge, interfacial adsorption, colloidal and wetting behaviors. Stable emulsions are formed at salt concentrations as low as 50 mM, with the highest stability observed at a critical concentration (400 mM). We show salt-induced destabilization of LP aqueous dispersions at an ionic strength >400 mM. At this critical concentration LP flocculation takes place and particulate networks are formed. This has a profound consequence on the stability of LP-stabilized Pickering emulsions, affecting rheology and long-term stability. The results along with quartz microgravimetry and confocal microscopy observations suggest a possible mechanism for stabilization that considers the interfacial adsorption of LP at oil/water interfaces. The often-unwanted colloidal LP destabilization in water ensues remarkably stable Pickering emulsions by the effect of network formation., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Mixed Pickering emulsions were prepared by blending anionic nanocellulose-stabilized lipid droplets with cationic nanochitin-stabilized lipid droplets. Changes in the surface potential, particle size, shear viscosity, and morphology of the mixed emulsions were characterized when the droplet mixing ratio was varied. Emulsion properties could be tailored by altering the pH and mixing ratio. Surface potential measurements suggested that the nanochitin-coated lipid droplets adsorbed to the surfaces of the nanocellulose-coated lipid droplets, thereby dominating the overall electrical characteristics of the mixed emulsions. As a result, the mixed emulsions had better stability to coalescence than the single emulsions containing only nanocellulose-coated lipid droplets. Our results suggest that the physicochemical properties, shelf life, and functional performance of Pickering emulsions may be modulated by blending different kinds of particle-stabilized lipid droplets together.

We report on high-internal-phase, oil-in-water Pickering emulsions that are stable against coalescence during storage. Viscous, edible oil (sunflower) was emulsified by combining naturally derived cellulose nanocrystals (CNCs) and a food-grade, biobased cationic surfactant obtained from lauric acid and L-arginine (ethyl lauroyl arginate, LAE). The interactions between CNC and LAE were elucidated by isothermal titration calorimetry (ITC) and supplementary techniques. LAE adsorption on CNC surfaces and its effect on nanoparticle electrostatic stabilization, aggregation state, and emulsifying ability was studied and related to the properties of resultant oil-in-water emulsions. Pickering systems with tunable droplet diameter and stability against oil coalescence during long-term storage were controllably achieved depending on LAE loading. The underlying stabilization mechanism was found to depend on the type of complex formed, the LAE structures adsorbed on the cellulose nanoparticles (as unimer or as adsorbed admicelles), the presence of free LAE in the aqueous phase, and the equivalent alkane number of the oil phase (sunflower and dodecane oils were compared). The results extend the potential of CNC in the formulation of high-quality and edible Pickering emulsions. The functional properties imparted by LAE, a highly effective molecule against food pathogens and spoilage organisms, open new opportunities in food, cosmetics, and pharmaceutical applications, where the presence of CNC plays a critical role in achieving synergistic effects with LAE.

Cellulose nanofibrils (CNF) offer great prospects as a natural stabilizer of colloidal dispersions and complex fluids for application in food, pharma, and cosmetics. In this study, an ionic surfactant (sodium dodecyl sulfate, SDS) was used as emulsifier of oil-in-water and water-in-oil emulsions that were further costabilized by addition of CNF. The adsorption properties of SDS in both, CNF dispersions and emulsions, as well as the influence of composition (CNF and SDS concentration) and formulation (ionic strength, oil, and CNF types) on the phase behavior were elucidated and described in the framework of Windsor systems. At low salinity, the phase transition of emulsions containing CNF and SDS at low concentrations was controlled by molecular transfer in the oil-in-water system. Irregular droplets and "bi-continuous" morphologies were observed at medium and high salinity for systems containing high CNF and SDS concentrations. Water-in-oil emulsions were only possible at high salinity and SDS concentrations in the presence of small amounts of CNF. The results revealed some subtle differences in CNF interfacial activity, depending on the method used for their isolation via fiber deconstruction, either from microfluidization or aqueous counter collision. Overall, we propose that the control of emulsion morphology and stability by addition of CNF opens the possibility of developing environmentally friendly complex systems that display high stability and respond to ionic strength following the expectations of classical emulsion systems.

A route for the compatibilization of aqueous dispersions of cellulose nanofibrils (CNFs) with a non-polar polymer matrix is proposed to overcome a major challenge in CNF-based material synthesis. Non-ionic surfactants were used in CNF aqueous dispersions equilibrated with an organic phase (for demonstration, a polystyrene solution, PS, was used). Stable water-in-oil-in-water (W/O/W) double emulsions were produced as a result of the compromise between composition and formulation variables. Most remarkably, the proposed route for CNF integration with hydrophobic polymers removed the need for drying or solvent-exchange of the CNF aqueous dispersion prior to processing. The rheological behavior of the double emulsions showed strong shear thinning behavior and facilitated CNF-PS co-mixing in solid nanofibers upon electrospinning. The morphology and thermal properties of the resultant nanofibers revealed that CNFs were efficiently integrated in the hydrophobic matrix which was consistent with the high interfacial area of the precursor double emulsion. In addition, the morphology and quality of the composite nanofibers can be controlled by the conductivity (ionic strength) of the CNF dispersion. Overall, double emulsion systems are proposed as a novel, efficient and scalable platform for CNF co-processing with non-polar systems and they open up the possibility for the redispersion of CNFs after removal of the organic phase.

Cellulose nanofibrils (CNF) were incorporated in water-in-oil (W/O) microemulsions and emulsions, as well as water-in-oil-in-water (W/O/W) multiple emulsions using soybean oil. The addition of CNF to the aqueous phase expanded the composition range to obtain W/O/W emulsions. CNF also increased the viscosity of the continuous phase and reduced the drop size both of which increased the stability and effective viscosity of the emulsions. The effects of oil type and polarity on the properties of the W/O/W emulsions were tested with limonene and octane, which compared to soybean oil produced a smaller emulsion drop size, and thus a higher emulsion viscosity. Overall, CNF are a feasible alternative to conventional polysaccharides as stability enhancers for normal and multiple emulsions that exhibit strong shear thinning behavior., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Cellulose nanocrystals (CNCs) from ramie fibers are studied as stabilizers of oil-in-water emulsions. The phase behavior of heptane and water systems is studied, and emulsions stabilized by CNCs are analyzed by using drop sizing (light scattering) and optical, scanning, and freeze-fracture electron microscopies. Water-continuous Pickering emulsions are produced with cellulose nanocrystals (0.05-0.5 wt%) grafted with thermo-responsive poly(NIPAM) brushes (poly(NIPAM)-g-CNCs). They are observed to be stable during the time of observation of 4 months. In contrast, unmodified CNCs are unable to stabilize heptane-in-water emulsions. After emulsification, poly(NIPAM)-g-CNCs are observed to form aligned, layered structures at the oil-water interface. The emulsions stabilized by poly(NIPAM)-g-CNCs break after heating at a temperature above the LCST of poly(NIPAM), which is taken as indication of the temperature responsiveness of the brushes installed on the particles and thus the responsiveness of the Pickering emulsions. This phenomenon is further elucidated via rheological measurements, in which viscosities of the Pickering emulsions increase on approach of the low critical solution temperature of poly(NIPAM). The effect of temperature can be counterbalanced with the addition of salt which is explained by the reduction of electrostatic and steric interactions of poly(NIPAM)-g-CNCs at the oil-water interface., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Short-range interactions between surfactant and lipid layers are of great importance in technical applications in complex fluids such as foams, dispersions and emulsions, as well as in the formulation and performance of dispersants, detergents and flocculants. It is also of utmost importance in biological systems where interactions between biomembranes influence a range of processes. The field of short-range interactions has been thoroughly investigated during the past 30 years, following the emergence of a number of techniques to measure interaction forces. Thus, our understanding has increased considerably and it is timely to summarize relevant knowledge accumulated in this area. In this review we focus on the nature of short-range interactions between non-ionic and zwitterionic surfactant and lipid layers exposing their polar groups to the surrounding medium. We discuss the complex interplay of short-range (van der Waals, hydration, steric and other) forces based on recent theoretical and experimental results.

The effect of Fenton's reagent (FR) on surface and dispersion properties of black liquor (BL) was investigated. These properties were compared to those of indulin C (IC), a commercial lignin, and egg lecithin (Le). FR was applied at two different bulk concentrations of H2O2 (160 and 320 mM). At pH 8, a minimum in surface tension for the Fenton treated BL was observed. The dispersant ability of BL, IC and Le in oil-in-water (O/W) emulsions was studied by measuring emulsion stability and drop size. It was found that the surface activity and emulsifying capability of BL were higher than those of IC. The emulsifying capability of Le was improved by the FR treatment at low H2O2 concentration.

Nanocellulose is very hydrophilic, preventing interactions with the oil phase in Pickering emulsions. This limitation is herein addressed by incorporating lignin nanoparticles (LNPs) as co-stabilizers of nanocellulose-based Pickering emulsions. LNP addition decreases the oil droplet size and slows creaming at pH 5 and 8 and with increasing LNP content. Emulsification at pH 3 and LNP cationization lead to droplet flocculation and rapid creaming. LNP application for emulsification, prior or simultaneously with nanocellulose, favors stability given the improved interactions with the oil phase. The Pickering emulsions can be freeze–dried, enabling the recovery of a solid macroporous foam that can act as adsorbent for pharmaceutical pollutants. Overall, the properties of nanocellulose-based Pickering emulsions and foams can be tailored by LNP addition. This strategy offers a unique, green approach to stabilize biphasic systems using bio-based nanomaterials without tedious and costly modification procedures. [ABSTRACT FROM AUTHOR]

Despite being non-surface active, nanocelluloses position efficiently at interfaces, already at very low concentration. This behavior has lately triggered a strong interest in the cellulose and colloids communities. This review reports the recent developments on the use of nanocelluloses at interfaces and highlights the fundamental principles governing the high efficiency observed in reinforcing the boundary between two phases. The use of nanocelluloses as emulsifier and emulsion stabilizer is first discussed, and the structural properties of nanocelluloses such as aspect ratio and surface properties are correlated with the high efficiency in forming colloidally-stable multiphase systems. Then, the behavior at the air/water interface is presented and the most recent advances are reviewed with focus on the surface free energy of nanocelluloses and their role in the interfacial self-assembly process. [ABSTRACT FROM AUTHOR]

We take advantage of the amphiphilic properties of technical lignin macromolecules and their inherent high calorific values to formulate oil-in-water (O/W) fuel emulsions with high internal-phase ratios. For the oil phase, we used a combustible hydrocarbon (kerosene) with a measured equivalent alkane carbon number of 12. To adjust the balance of affinity with the oil and water phases and their surface activity, pine kraft lignins were carboxymethylated to different degrees, as quantified by 13C NMR spectroscopy, potentiometric titrations, and zeta potential measurements. Carboxymethylated lignins (CMLs) with a degree of substitution of 30 % displayed a critical aggregation concentration of 3 %. The salinity and pH of the aqueous phase were chosen as formulation variables and adjusted within the Winsor framework. The O/W emulsions were produced by following standard protocols. The drop-size distributions of emulsions with varying pH, degree of substitution, and composition (water-to-oil ratio, WOR) were determined, and the long-term stabilities and rheological behavior of these emulsions were analyzed. Most of the obtained O/W fuel emulsions showed shear-thinning behavior with a drop size of approximately 2.5 μm and were stable for over 30 days. The combustion of the lignins and their respective emulsions was performed, and their higher heating values (HHVs) were quantified. The HHVs of CML and a high-internal-phase (WOR=30:70) O/W emulsion were 20 and 30 MJ kg−1, respectively. Overall, we propose the stabilization of O/W fuel emulsions by lignin as an important avenue in the utilization of this abundant biomacromolecule. [ABSTRACT FROM AUTHOR]

Water-insoluble oils, including crude petroleum and a wide variety of refined organic liquids, can cause major problems if spilled or leaked to aqueous environments. Potential environmental damage may be reduced if the spilled oil is promptly and efficiently removed from the water. This article reviews research that sheds light on the use of cellulose-based materials as sorbents to mitigate effects of oil spills. Encouraging results for oil sorption have been reported when using naturally hydrophobic cellulosic fibers such as unprocessed cotton, kapok, or milkweed seed hair. In addition, a wide assortment of cellulosic materials have been shown to be effective sorbents for hydrocarbon oils, especially in the absence of water, and their performance under water-wet conditions can be enhanced by various pretreatments that render them more hydrophobic. More research is needed on environmentally friendly systems to handle oil-contaminated sorbents after their use; promising approaches include their re-use after regeneration, anaerobic digestion, and incineration, among others. Research is also needed to further develop combined response systems in which biosorption is used along with other spill-response measures, including skimming, demulsification, biodegradation, and the use of booms to limit the spreading of oil slicks. [ABSTRACT FROM AUTHOR]

We report for the first time on the use of water-continuous emulsions stabilized by a bio-based macromolecule in a compression-ignition diesel engine and compare their performance, combustion and emissions against the base fuels (diesel, biodiesel, and jet fuel). For this purpose, high internal phase ratio emulsions (70:30 fuel-to-water) were produced by mechanical emulsification using carboxymethylated wood lignin as stabilizer. Combusting experiments were performed with the engine operating at 2000 rpm under three loads (0, 1.26 and 3.26 bar brake mean effective pressure, BMEP). Engine performance, in-cylinder combustion, and exhaust emissions were monitored and compared for the fuels tested. At no load condition and when compared to the respective base (single phase) fuels, an increase in the indicated work was observed for diesel and biodiesel emulsions. Compared to the base fuels, the emulsions resulted in higher engine mechanical efficiency at 1.26 and 3.26 bar BMEP except for jet fuel emulsion at 1.26 bar. Additionally, they displayed a lower brake specific fuel consumption (BSFC), if calculated on the basis of effective fuel content discounting emulsion water, and higher brake thermal efficiency. Compared to the base fuel, the respective emulsions generally presented lower peak in-cylinder pressure, lower heat release rates, and longer ignition delays at 1.26 bar and 3.26 bar BMEP; the opposite effect was observed at no-load conditions. Remarkably, a large reduction of nitrogen oxides (NO x ) emissions was noted in the combustion of the fuel emulsions, which was accompanied with a relatively higher carbon monoxide (CO) release at 1.26 and 3.26 bar (at 0 bar BMEP, the emulsions produced less CO emissions). The effect of emulsions on hydrocarbon emissions and smoke opacity depended on the fuel type and the engine load. Overall, it is concluded that while reports on fuel emulsions involve oil-continuous systems, the proposed water-continuous alternative represents an opportunity for diesel engines, whereby the fuel is dispersed as micrometric droplets for improved combustion and reduced emissions. At the same time, the fuel emulsion formulation takes advantage of the surface activity and high calorific value of widely available, inexpensive lignin stabilizers, making the proposed system a viable option towards cleaner or fully bio-based fuels. [ABSTRACT FROM AUTHOR]

Motivated by the quest for biocompatibility, we report on oil-in-water (O/W), high-internal-phase Pickering emulsions stabilized via complexes of mechanical cellulose nanofibrils (CNF) and food-grade cationic surfactant ethyl lauroyl arginate (LAE). The complexation of oppositely charged CNF and LAE can be held together by electrostatic interaction. Their effect on suspensions electrostatic stabilization, heteroaggregation state, and emulsifying ability was studied and related to properties of resultant interfacial tension between oil and water and 3D printing of emulsions. The Pickering system with adjustable droplet diameter and stability against creaming and oiling-off during storage was achieved resting with LAE loading. Complexes formed by LAE adjustment act as Pickering stabilizers and three-dimensional networks in emulsion system, forming a scaffold with elastoplastic rheological properties that flows above critical stress while, without any additional treatment, exhibiting the required self-standing properties for 3D printing. By understanding the properties of CNF/LAE behavior in bulk and on interfaces, printing edible functional foods of CNF/LAE-based emulgel inks has been demonstrated to enable regulation of oil release. [Display omitted] [ABSTRACT FROM AUTHOR]

Oil-in-water Pickering emulsions were successfully prepared via high-energy microfluidization using cellulose nanocrystals (CNC) as interfacial stabilizers. The influence of microfluidization pressure, CNC concentration, and oil type on droplet size and emulsion stability was determined. Under optimized homogenization conditions, CNC formed and stabilized emulsions based on corn, fish, sunflower, flax, orange, and MCT oils. The droplet size decreased with increasing microfluidization pressure from 9 to 17 kpsi, but then increased slightly at 19 kpsi. The creaming stability of the emulsions increased with CNC concentration, which was mainly attributed to the decrease in droplet size (mean particle diameter < 1 μm at CNC-to-oil ratios greater than 1:10) and slightly increased viscosity. The Pickering emulsions were stable to droplet coalescence, presumably due to strong electrostatic and steric repulsions between the lipid droplets carrying adsorbed nanoparticles. The Pickering emulsions had good stability over a range of environmental stresses: pH 3 to 10; NaCl ≤ 100 mM; temperature from 30 to 90 °C. Droplet flocculation was, however, observed under more acidic conditions (pH 2) and at high ionic strength (200–500 mM NaCl), owing to electrostatic screening. Our results indicate that microfluidization is an effective method for forming CNC-stabilized Pickering emulsions suitable for utilization in the food industry. Image 1 • Stable, micron-size oil-in-water emulsions are produced with cellulose nanocrystals (CNC) via high-pressure microfluidization. • Oil droplet size decreases with CNC loading and homogenization pressure. • High stability against coalescence is achieved at low surface coverage. • The emulsions are stable to heating up to 90 °C. • The emulsions are stable in the pH range 3–9 and at low ionic strength. [ABSTRACT FROM AUTHOR]

We introduce a strategy to disintegrate cellulose microfibrils present in the cell walls of plant fibers. The process includes impregnation and mild oxidation followed by ultrasonication, which loosens the hydrophilic planes of crystalline cellulose while preserving the hydrophobic ones. The resultant molecularly-sized cellulose structures (cellulose ribbons, CR) retain a length of the order of a micron (1.47 ± 0.48 μm, AFM). A very high axial aspect ratio is determined (at least 190), considering the CR height (0.62 ± 0.38 nm, AFM), corresponding to 1–2 cellulose chains, and width (7.64 ± 1.82 nm, TEM). The new molecularly-thin cellulose proposes excellent hydrophilicity and flexibility, enabling a remarkable viscosifying effect when dispersed in aqueous media (shear-thinning, zero shear viscosity of 6.3 × 105 mPa·s). As such, CR suspensions readily develop into gel-like Pickering emulsions in the absence of crosslinking, suitable for direct ink writing at ultra-low solids content. [Display omitted] [ABSTRACT FROM AUTHOR]

We introduce Kraft lignin colloids produced by destabilization of a kraft lignin solution by pH shift from 2 to 11. The system includes lignin particles and hydrocolloid aggregates in equilibrium (KLP), which are used to control the emulsifying energy and to stabilize oil-in-water emulsions under high energy at pH 11 and 7, yielding excellent stability (at least three months with no creaming). We investigate emulsify technology (ultrasonication and homogenization), energy input (high energy or low energy), particle desorption, drop size, and rheology on the stability of KLP-based Pickering emulsions according to the system's pH. The ultrasonication leads to fine, stable and homogenous lignin emulsions without observing macroscopic creaming phenomenon, whereas homogenization only limits to alkaline condition. Regarding homogenization process, increasing the energy input helps to reduce the emulsion droplet size and consequently improves emulsion stability. In addition, the emulsion produced at acidic conditions always presented excellent stability, independent of the emulsify parameters. Considering the synergistic effects of emulsification protocol, surface activity, and particle interactions, the results indicate the possibility of extending the applications of kraft lignin as a Pickering stabilizer in neutral and alkaline conditions. It also creates a promising method to control the stability and emulsion microstructure in the industrial KLP based emulsion preparation process. [Display omitted] • Lignin stabilized emulsions were extended from acidic to pH 11. • A synergistic stabilization mechanism at high pH is proposed. • Emulsification process and energy input impact the formation and stability of emulsions. • Emulsions are stable for over three months. • E desorption increases for emulsions stabilized by lignin in the order of pH 11 < 7 < 2. [ABSTRACT FROM AUTHOR]

Acetylated Kraft lignins were evaluated for their ability of structuring vegetable oils into oleogels. Microwave-assisted acetylation was used to adjust lignin's degree of substitution according to reaction temperature (130 to 160 °C), and its effect in improving the viscoelasticity of the oleogels, which was related to the hydroxyl group content. The results were compared with those obtained by Kraft lignins acetylated using conventional methods at room temperature. A higher microwave temperature resulted in gel-like oil dispersions with improved viscoelastic properties, and stronger shear-thinning character, along with enhanced long-term stability. Lignin nanoparticles structured castor oil by enhancing hydrogen bonding between the hydroxyl groups of the oil and the nanoparticles. The oil structuring capacity of the modified lignins enhanced the stability of water-in-oil Pickering emulsions that resulted from low-energy mixing. • Acetylation and nanosize reduction are able to compatibilize lignin with castor oil. • Acetylation tune could be obtained through microwave temperature modification. • Acetylation provided enhanced rheological characteristics of oleogels. • Both systems stabilize water-in-oil emulsions with up to 30 wt% water content. [ABSTRACT FROM AUTHOR]

We report on high-internal-phase, oil-in-water Pickering emulsions that are stable against coalescence during storage. Viscous, edible oil (sunflower) was emulsified by combining naturally derived cellulose nanocrystals (CNCs) and a food-grade, biobased cationic surfactant obtained from lauric acid and L-arginine (ethyl lauroyl arginate, LAE). The interactions between CNC and LAE were elucidated by isothermal titration calorimetry (ITC) and supplementary techniques. LAE adsorption on CNC surfaces and its effect on nanoparticle electrostatic stabilization, aggregation state, and emulsifying ability was studied and related to the properties of resultant oil-in-water emulsions. Pickering systems with tunable droplet diameter and stability against oil coalescence during long-term storage were controllably achieved depending on LAE loading. The underlying stabilization mechanism was found to depend on the type of complex formed, the LAE structures adsorbed on the cellulose nanoparticles (as unimer or as adsorbed admicelles), the presence of free LAE in the aqueous phase, and the equivalent alkane number of the oil phase (sunflower and dodecane oils were compared). The results extend the potential of CNC in the formulation of high-quality and edible Pickering emulsions. The functional properties imparted by LAE, a highly effective molecule against food pathogens and spoilage organisms, open new opportunities in food, cosmetics, and pharmaceutical applications, where the presence of CNC plays a critical role in achieving synergistic effects with LAE. [ABSTRACT FROM AUTHOR]

Cellulose nanofibrils (CNF) offer great prospects as a natural stabilizer of colloidal dispersions and complex fluids for application in food, pharma, and cosmetics. In this study, an ionic surfactant (sodium dodecyl sulfate, SDS) was used as emulsifier of oil-in-water and water-in-oil emulsions that were further costabilized by addition of CNF. The adsorption properties of SDS in both, CNF dispersions and emulsions, as well as the influence of composition (CNF and SDS concentration) and formulation (ionic strength, oil, and CNF types) on the phase behavior were elucidated and described in the framework of Windsor systems. At low salinity, the phase transition of emulsions containing CNF and SDS at low concentrations was controlled by molecular transfer in the oil-in-water system. Irregular droplets and "bi-continuous" morphologies were observed at medium and high salinity for systems containing high CNF and SDS concentrations. Water-in-oil emulsions were only possible at high salinity and SDS concentrations in the presence of small amounts of CNF. The results revealed some subtle differences in CNF interfacial activity, depending on the method used for their isolation via fiber deconstruction, either from microfluidization or aqueous counter collision. Overall, we propose that the control of emulsion morphology and stability by addition of CNF opens the possibility of developing environmentally friendly complex systems that display high stability and respond to ionic strength following the expectations of classical emulsion systems. [ABSTRACT FROM AUTHOR]

Pickering emulsions are stabilized using complexes of cellulose nanocrystals (CNC) and nanochitin (NCh). The colloidal behavior and heteroaggregation in aqueous media are studied in relation to complex formation and net charge. The complexes are remarkably effective in stabilizing oil-in-water Pickering emulsions under conditions of slightly net positive or negative charges, as determined by the CNC/NCh mass ratio. Close to charge neutrality (CNC/NCh ~5), large heteroaggregates form, resulting in unstable emulsions. By contrast, under net cationic conditions, interfacial arrest of the complexes leads to non-deformable emulsion droplets with high stability (no creaming for 9 months). At given CNC/NCh concentrations, emulsions with up to 50% oil fraction are produced. This study shows how to control emulsion properties beyond consideration of the typical formulation variables, for instance, through adjusting CNC/NCh ratio or charge stoichiometry. We highlight the possibilities that are available for emulsion stabilization by using a combination of polysaccharide nanoparticles. • Colloidal behavior of heteroaggregated cellulose nanocrystal/nanochitin is tunable. • Pickering stabilization is tailorable via changing the mass ratio of CNC/NCh. • High stability of emulsions against coalescence is achieved for at least 9 months. • High-oil-loaded emulsions (up to 50%) are obtained at low CNC/NCh level. [ABSTRACT FROM AUTHOR]

In this review, we discuss the application of cellulose nanoparticles as a sustainable and cost-effective source of green stabilizers for formulation of foodstuff. Fibrillar cellulose nanocrystal and nanofibril stabilize Pickering systems because of their ability to adsorb at the oil/water interfaces, forming protective layers. They also form associative structures in the continuous phase, increasing their viscoelastic properties and preventing flocculation. We describe the chemical and structural features of nanocelluloses and discuss the principles that support their utilization as stabilizers, especially in the context of recent prospects in food and health domains, given safety and regulatory advances. In addition, we describe the benefits of combining nanocelluloses with other food ingredients to extend their functional attributes. Particularly, nanocellulose-based Pickering emulsions are used to create edible soft materials with multiple functionalities. This article is expected to stimulate the use of nanocelluloses as functional ingredients to create food products with improved performance and novel properties. [Display omitted] • Plant-based nanocellulosic particles are sustainable and economic natural nanoparticles. • Cellulose nanocrystals and nanofibrils are effective stabilizers in Pickering emulsions. • Novel food emulsions are being created from cellulose nanoparticles and composites. • Nanocellulose-stabilized emulsions provide new or improved functionalities in foods. [ABSTRACT FROM AUTHOR]

Abstract: A new approach based on microemulsions formulated with at least 85% water and minority components consisting of oil (limonene) and surfactant (anionic and nonionic) is demonstrated for the first time to be effective for flooding wood’s complex capillary structure. The formulation of the microemulsion was based on phase behavior scans of Surfactant–Oil–Water systems (SOWs) and the construction of pseudo-ternary diagrams to localize thermodynamically stable one-phase emulsion systems with different composition, salinity and water-to-oil ratios. Wicking and fluid penetration isotherms followed different kinetic regimes and indicated enhanced performance relative to that of the base fluids (water, oil or surfactant solutions). The key properties of microemulsions to effectively penetrate the solid structure are discussed; microemulsion formulation and resultant viscosity are found to have a determining effect in the extent of fluid uptake. The solubilization of cell wall components is observed after microemulsion impregnation. Thus, the microemulsion can be tuned not only to effectively penetrate the void spaces but also to solubilize hydrophobic and hydrophilic components. The concept proposed in this research is expected to open opportunities in fluid sorption in fiber systems for biomass pretreatment, and delivery of hydrophilic or lipophilic moieties in porous, lignocellulosics. [Copyright &y& Elsevier]

There is increasing interest in the food industry to develop plant-based emulsifiers for sustainability, ethical, and health reasons. In this study, we showed that stable Pickering emulsions could be fabricated using either cellulose or and chitin nanofibrils, as well as their physical mixtures. These emulsions were highly stable to droplet coalescence during storage, which we attributed to the ability of the nanofibers to adsorb to the oil droplet surfaces and form a thick particulate layer that protected them from coalescence. Moreover, the nanofibers formed a 3D-network in the aqueous phase that prevented the oil droplets from moving, thereby improving their creaming stability. We identified the optimum nanoparticle concentration and nanochitin-to-nanocellulose ratio required to formulate these emulsions. These nanofibers may be useful as edible particle-based emulsifiers for forming more sustainable plant-based food emulsions. Image 1 • Pickering emulsions were formed from plant-based nanoparticles. • Cationic nanochitin and/or anionic nanocellulose were used. • The optimum nanoparticle concentration and ratio was identified. • The Pickering emulsions had good stability against coalescence during storage. [ABSTRACT FROM AUTHOR]

• Lignocellulosic nanofibrils (LCNF) are prepared from wood using recyclable p -TsOH. • The residual lignin content in LCNF can be easily tailored by the hydrolysis temperature. • LCNF behavior at the oil-water interface depends on residual lignin concentration. • A higher residual lignin in LCNF results in Pickering emulsions with superior properties. Lignocellulose nanofibrils (LCNF) were used to prepare oil-in-water Pickering emulsions and to assess the role residual lignin in interfacial stabilization. Two LCNF fractions of similar morphology (length ∼700 nm and width ∼8 nm) and structure (polymorphism and crystallinity) were obtained by microfluidization of fibers obtained by hydrothermal treatment of wood with a recyclable organic acid. The LCNF with higher residual lignin was less hydrophilic and, correspondingly, performed better as Pickering stabilizer, producing emulsions of smaller droplet size and higher resistance to creaming. Long-term emulsion stabilization (over 40 days) was achieved with LCNF at concentrations as low as 0.24 (w/v)% based on emulsion volume. We conclude that LCNF-stabilized Pickering emulsions can be finely tuned by varying the residual lignin content, providing a rationale for LCNF selection according to lignin type and concentration as variables affecting stabilization. Complementary considerations include the possible benefits of the residual lignin in LCNF, including antioxidant and UV absorption properties. [ABSTRACT FROM AUTHOR]

Nature-derived nanoparticles are increasingly being explored for their potential to regulate the digestion of ingested lipids. In this study, we examined the impact of emulsifier format (molecular versus particle) on the gastrointestinal fate of vitamin D 3 -fortified emulsions by measuring their physicochemical properties, microstructure, digestibility, and bioaccessibility using an in vitro human gastrointestinal tract (GIT) model. Nanochitin (NCh) was used as an example of a particle-based (Pickering) emulsifier, whereas Tween 80 (T80) was used as an example of a small molecule surfactant. A series of 2 wt% oil-in-water emulsions containing different initial levels and locations of nanochitin and Tween 80 were prepared: (i) nanochitin-emulsions (0.02 wt% NCh); (ii) Tween 80-emulsions (0.02 wt% T80); (iii) nanochitin-emulsions (0.02 wt% NCh) plus Tween 80 (0.02 wt% T80); and (iv) Tween 80-emulsions (0.02 wt% T80) plus nanochitin (0.02 wt% NCh). The nanochitin-emulsions were much more prone to droplet aggregation within the simulated GIT than the T80-stabilized ones. Lipid digestion was 30% less and vitamin bioaccessibility was 45% less for the nanochitin-emulsions than for the T80-stabilized ones. Adding T80 to the nanochitin-emulsions, increased the rate of lipid digestion, whereas adding nanochitin to the Tween 80-stabilized ones, decreased the rate. The reduction in lipid digestion and bioaccessibility in the emulsions containing nanochitin may have been for a number of reasons: the adsorbed nanochitin layer hindered the ability of lipase to reach the lipid phase; the nanochitin-coated droplets were highly aggregated in the GIT, which reduced the area of lipids accessible to the lipase; and, the cationic nanochitin bound to anionic bile acids, fatty acids, or lipase. Our results suggest that nanochitin slows down lipid digestion, which may be advantageous for developing high-satiety foods, but that it also reduces vitamin bioaccessibility, which would be undesirable from a nutritional perspective. Image 1 • Pickering emulsions stabilized by either nanochitin or Tween 80 were prepared. • Lipid digestion and vitamin D 3 bioaccessibility of these emulsions were monitored. • Nanochitin-coated lipid droplets behaved differently to surfactant-coated ones. • Nanochitin reduced lipid digestion and vitamin bioaccessibility. [ABSTRACT FROM AUTHOR]