The fate of cellulose nanocrystal stabilised emulsions after simulated gastrointestinal digestion and exposure to intestinal mucosa

Surface Modification of Okara Cellulose Crystals with Phenolic Acids to Prepare Multifunction Emulsifier with Antioxidant Capacity and Lipolysis Retardation Effect

Emulsion-based foods are widely consumed, and their characteristics involving colloidal and oxidative stabilities should be considered. The fabrication of the interfaces by selecting the emulsifier may improve stability and trigger lipolysis, thereby reducing energy uptake from the emulsified food. The present work aimed to develop Okara cellulose crystals (OCs) as a multifunction emulsifier to preserve the physical and chemical stability of a Pickering emulsion via surface modification with phenolic acids. The modification of OC was performed by grafting with the selected phenolics to produce OC-gallic acid (OC-G) and OC-tannic acid (OC-T) complexes. There was a higher phenolic loading efficiency when the OC reacted with gallic acid (ca. 70%) than with tannic acid (ca. 50%). This trend was concomitant with better antioxidant activity of the OC-G than OC-T. Surface modification based on grafting with phenolic acids improved capability of the OC to enhance both the colloidal and oxidative stability of the emulsion. In addition, the cellulosic materials had a retardation effect on the in vitro lipolysis compared to a protein-stabilized emulsion. Surface modification by grafting with phenolic acids successfully provided OC as an innovative emulsifier to promote physico-chemical stability and lower lipolysis of the emulsion.

Using nanocellulose to improve heat-induced cull cow meat myofibrillar protein gels: effects of particle morphology and content

BACKGROUND

Enhancing protein gel properties is essential to improve the texture of meat products. In this study, the improvement effects of three types of nanocellulose, i.e. rod-like cellulose nanocrystals (CNC), long-chain cellulose nanofibers (CNF) and spherical cellulose nanospheres (CNS) with different concentrations (1, 3, 5, 10, 15 and 20 g kg-1 ), on cull cow meat myofibrillar protein (MP) gel were investigated.

RESULTS

Compared with needle-shaped CNC and spherical CNS, the addition of 10 and 20 g kg-1 long-chain CNF had the most significant improvement effect on gel hardness and water-holding capacity, respectively (P < 0.05), increasing to 160.1 g and 97.8%, respectively. In addition, the incorporation of long-chain CNF shortened the T2 relaxation time and induced the formation of the densest network structure and promoted the phase transition of the gel. However, excessive filling of nanocellulose would destroy the structure of the gel, which was not conducive to the improvement of gel properties. Fourier transform infrared results showed that there was no chemical reaction between the three nanocellulose types and MP, but the addition of nanocellulose was conducive to gel formation.

CONCLUSION

The improvement of MP gel properties by adding nanocellulose mainly depends on its morphology and concentration. Nanocellulose with higher aspect ratio is more beneficial to the improvement of gel properties. For each nanocellulose type, there is an optimal addition amount for MP gel improvement. © 2023 Society of Chemical Industry.

Food gels: principles, interaction mechanisms and its microstructure

Food hydrogels are important materials having great scientific interest due to biocompatibility, safety and environment-friendly characteristics. In the food industry, hydrogels are widely used due to their three-dimensional crosslinked networks. Furthermore, they have attracted great attention due to their wide range of applications in the food industry, such as fat replacers, encapsulating agents, target delivery vehicles, and many more. In addition to basic and recent knowledge on food hydrogels, this review exclusively focuses on sensorial perceptions, nutritional significance, body interactions, network structures, mechanical properties, and potential hydrogel applications in food and food-based matrices. Additionally, this review highlights the structural design of hydrogels, which provide the forward-looking idea for future applications of food hydrogels (e.g., 3D or 4D printing).

Nanocellulose-stabilized Pickering emulsions: Fabrication, stabilization, and food applications

Pickering emulsions have been widely studied due to their good stability and potential applications. Nanocellulose including cellulose nanocrystals (CNCs), cellulose nanofibrils (CNFs), and bacterial cellulose nanofibrils (BCNFs) has emerged as sustainable stabilizers/emulsifiers in food-related Pickering emulsions due to their favorable properties such as renewability, low toxicity, amphiphilicity, biocompatibility, and high aspect ratio. Nanocellulose can be widely obtained from different sources and extraction methods and can effectively stabilize Pickering emulsions via the irreversible adsorption onto oil-water interface. The synergistic effects of nanocellulose and other substances can further enhance the interfacial networks. The nanocellulose-based Pickering emulsions have potential food-related applications in delivery systems, food packaging materials, and fat substitutes. Nanocellulose-based Pickering emulsions as 3D printing inks exhibit good injectable and gelling properties and are promising to print spatial architectures. In the future, the utilization of biomass waste and the development of "green" and facile extraction methods for nanocellulose production deserve more attention. The stability of nanocellulose-based Pickering emulsions in multi-component food systems and at various conditions is an utmost challenge. Moreover, the case-by-case studies on the potential safety issues of nanocellulose-based Pickering emulsions need to be carried out with the standardized assessment procedures. In this review, we highlight key fundamental work and recent reports on nanocellulose-based Pickering emulsion systems. The sources and extraction of nanocellulose and the fabrication of nanocellulose-based Pickering emulsions are briefly summarized. Furthermore, the synergistic stability and food-related applications of nanocellulose-stabilized Pickering emulsions are spotlighted.

An ex vivo intestinal absorption model is more effective than an in vitro cell model to characterise absorption of dietary carotenoids following simulated gastrointestinal digestion

To get the most accurate food digestion-related data, and how this affects nutrient absorption, it is critical to carefully simulate human digestion systems using model settings. In this study, the uptake and transepithelial transportation of dietary carotenoids was compared using two different models that have previously been used to assess nutrient availability. The permeability of differentiated Caco-2 cells and murine intestinal tissue were tested using all-trans-β-carotene and lutein prepared in artificial mixed micelles and micellar fraction from orange-fleshed sweet potato (OFSP) gastrointestinal digestion. Transepithelial transport and absorption efficiency were then determined using liquid chromatography tandem-mass spectrometry (LCMS-MS). Results showed that the mean uptake for all-trans-β-carotene in the mouse mucosal tissue was 60.2 ± 3.2% compared to 36.7 ± 2.6% in the Caco-2 cells with the mixed micelles as the test sample. Similarly, the mean uptake was higher in OFSP with 49.4 ± 4.1% following mouse tissue uptake compared to 28.9 ± 4.3% using Caco-2 cells for the same concentration. In relation to the uptake efficiency, the mean percentage uptake for all-trans-β-carotene from artificial mixed micelles was 1.8-fold greater in mouse tissue compared to Caco-2 cells (35.4 ± 1.8% against 19.9 ± 2.6%). Carotenoid uptake reached saturation at 5 µM when assessed with the mouse intestinal cells. These results demonstrate the practicality of employing physiologically relevant models simulating human intestinal absorption processes that compares well with published human in vivo data. When used in combination with the Infogest digestion model, the Ussing chamber model, using murine intestinal tissue, may thus be an efficient predictor of carotenoid bioavailability in simulating human postprandial absorption ex vivo.

Review: Harmonised in vitro digestion and the Ussing chamber for investigating the effects of polyphenols on intestinal physiology in monogastrics and ruminants

Because of the relevant effects of plant-derived polyphenols (PPs) on monogastrics and ruminants' nutrition, emissions and performance, an increasing number of in vivo and in vitro studies are being performed to better understand the mechanisms of action of polyphenols at both the ruminal and intestinal levels. The biological properties of these phenolic compounds strongly depend on their degradation, absorption and metabolism. The harmonised in vitro digestion method (INFOGEST) is one of the most reliable in vitro methods used to assess the bioaccessibility and or antioxidant activity of PP contained in different matrixes, as well as the interactions of PP and their degradation products with other feed ingredients. The effects of PP released from their matrix after in vitro digestion on different intestinal physiological parameters, such as epithelium integrity, can be further evaluated by the use of ex vivo models such as the Ussing chamber. This review aims to describe the combination of the INFOGEST method, coupled with the Ussing chamber as a valuable model for the digestion and subsequent effects and absorption of phenolic compounds in monogastrics and potentially in ruminants. The advances, challenges and limits of this approach are also discussed.

Progress in the Application of Food-Grade Emulsions

The detailed investigation of food-grade emulsions, which possess considerable structural and functional advantages, remains ongoing to enhance our understanding of these dispersion systems and to expand their application scope. This work reviews the applications of food-grade emulsions on the dispersed phase, interface structure, and macroscopic scales; further, it discusses the corresponding factors of influence, the selection and design of food dispersion systems, and the expansion of their application scope. Specifically, applications on the dispersed-phase scale mainly include delivery by soft matter carriers and auxiliary extraction/separation, while applications on the scale of the interface structure involve biphasic systems for enzymatic catalysis and systems that can influence substance digestion/absorption, washing, and disinfection. Future research on these scales should therefore focus on surface-active substances, real interface structure compositions, and the design of interface layers with antioxidant properties. By contrast, applications on the macroscopic scale mainly include the design of soft materials for structured food, in addition to various material applications and other emerging uses. In this case, future research should focus on the interactions between emulsion systems and food ingredients, the effects of food process engineering, safety, nutrition, and metabolism. Considering the ongoing research in this field, we believe that this review will be useful for researchers aiming to explore the applications of food-grade emulsions.

Tracking Bacterial Nanocellulose in Animal Tissues by Fluorescence Microscopy

The potential of nanomaterials in food technology is nowadays well-established. However, their commercial use requires a careful risk assessment, in particular concerning the fate of nanomaterials in the human body. Bacterial nanocellulose (BNC), a nanofibrillar polysaccharide, has been used as a food product for many years in Asia. However, given its nano-character, several toxicological studies must be performed, according to the European Food Safety Agency’s guidance. Those should especially answer the question of whether nanoparticulate cellulose is absorbed in the gastrointestinal tract. This raises the need to develop a screening technique capable of detecting isolated nanosized particles in biological tissues. Herein, the potential of a cellulose-binding module fused to a green fluorescent protein (GFP–CBM) to detect single bacterial cellulose nanocrystals (BCNC) obtained by acid hydrolysis was assessed. Adsorption studies were performed to characterize the interaction of GFP–CBM with BNC and BCNC. Correlative electron light microscopy was used to demonstrate that isolated BCNC may be detected by fluorescence microscopy. The uptake of BCNC by macrophages was also assessed. Finally, an exploratory 21-day repeated-dose study was performed, wherein Wistar rats were fed daily with BNC. The presence of BNC or BCNC throughout the GIT was observed only in the intestinal lumen, suggesting that cellulose particles were not absorbed. While a more comprehensive toxicological study is necessary, these results strengthen the idea that BNC can be considered a safe food additive.

Effects of lipid type and toxicological properties on the digestion of cellulose nanocrystals in simulated gastrointestinal tract

This study aimed to understand the impact of different oil types on the cellulose nanocrystals (CNCs) to modulate lipid digestion and the in vitro gastrointestinal toxicity of CNCs in food systems. We explored the ability of CNCs to modulate lipid digestion in a simulated gastrointestinal system and monitored the gastrointestinal fate of CNC-based emulsions with different oil types. Finally, a small intestine epithelial model was used to evaluate the influence of cytotoxicity. The results suggested that the addition of 0.6 wt% CNCs in the high-fat food model reduced the hydrolysis of free fatty acids (FFAs) from triglycerides by 37.8% after the small intestine phase. CNCs showed the best effect in reducing lipid digestion in emulsions with high unsaturation triglycerides. In addition, the toxicology results suggest that 0.6 wt% CNCs had only a slight effect on reactive oxygen species and cytotoxicity, and no significant change in cell-layer integrity.

Recent Advances in the Gastrointestinal Fate of Organic and Inorganic Nanoparticles in Foods

Inorganic or organic nanoparticles are often incorporated into foods to enhance their quality, stability, nutrition, or safety. When they pass through the gastrointestinal environment, the properties of these nanoparticles are altered, which impacts their biological effects and potential toxicity. Consequently, there is a need to understand how different kinds of nanoparticles behave within the gastrointestinal tract. In this article, the current understanding of the gastrointestinal fate of nanoparticles in foods is reviewed. Initially, the fundamental physicochemical and structural properties of nanoparticles are discussed, including their compositions, sizes, shapes, and surface chemistries. Then, the impact of food matrix effects and gastrointestinal environments on the fate of ingested nanoparticles is discussed. In particular, the influence of nanoparticle properties on food digestion and nutraceutical bioavailability is highlighted. Finally, future research directions are highlighted that will enable the successful utilization of nanotechnology in foods while also ensuring they are safe.

Elaboration of capsules from Pickering double emulsion polymerization stabilized solely by cellulose nanocrystals

Pickering double oil-in-water-in-oil emulsions O/W/O were stabilized using solely cellulose nanocrystals (CNCs), which were modified by introducing surface brominated functions. The emulsions were formulated using only bio-friendly components, among which isopropyl myristate as oil phase, hydroxyl oligoethylene glycol methacrylate (OEGMA) as macromonomer, tetraethylene glycol diacrylate (TEGDA) as cross-linker, and CNCs as stabilizing particles. Formulation parameters could be tuned easily to modulate the fraction of inner emulsion droplets within the double emulsion drops or change the monomer(s) composition within the aqueous phase. The latter was further polymerized to synthesize matrix capsules. The obtained objects showed good resistance to the vacuum and were efficiently used as promising encapsulation vessels. Both hydrophobic and hydrophilic model dyes were encapsulated, with an encapsulation efficiency of about 90%.

Toxicological studies and some functional properties of carboxymethylated cellulose nanofibrils as potential food ingredient

Carboxymethylated cellulose nanofibrils (CNF) with different carboxyl contents (0, 0.36, 0.72 and 1.24 mmol/g) were prepared and characterized via morphology, diameter distribution, zeta potential, structural features, rheological properties, suspension stability, and thermal properties. The results of toxicological studies of ingested CNF via in vitro and in vivo models were present. In vitro studies used an epithelial-like cell line (Caco-2) to assess the effects of a 24 h incubation with CNF, in which no significant cytotoxicity was observed. In vivo studies were evaluated in mice gavage once per day for 8 weeks with 1% or 3.5% w/w suspension of CNF in water. Blood and serum were collected for analysis. No significant differences in hematology, and serum markers were observed between controls and mice given CNF suspensions. Weight, food intake and feces were recorded for growing development and nutrient retention in feces was measured for investigation of functional properties of CNFs. Mice given CNF suspensions gained a significant increment in fecal fat but a reduction in food intake and weight compared to controls. These findings suggested that CNFs are non-toxic and have potentials in behaving as food additives or supplements to reduce caloric intake.

Zein Colloidal Particles and Cellulose Nanocrystals Synergistic Stabilization of Pickering Emulsions for Delivery of β-Carotene

In this study, we utilized different types of particles to stabilize β-carotene-loaded Pickering emulsions: spherical hydrophobic zein colloidal particles (ZCPs) (517.3 nm) and rod-shaped hydrophilic cellulose nanocrystals (CNCs) (115.2 nm). Either of the particles was incapable of stabilizing Pickering emulsions owing to their inappropriate wettability. When the mass ratio of ZCPs and CNCs was 1:4, the Pickering emulsion showed the best physical and photothermal stability. Compared to the ZCP-stabilized Pickering emulsion (9.29%), the retention rate of β-carotene in the Pickering emulsion costabilized by ZCPs and CNCs was increased to 60.23% after 28 days of storage at 55 °C. Confocal microscopy and cryoscanning electron microscopy confirmed that different types of particles could form a multilayered structure or induce the formation of an interparticle network. Furthermore, the complexation of ZCPs and CNCs delayed the lipolysis of the emulsion during in vitro digestion. The free fatty acid (FFA) release rate of Pickering emulsions in the small intestinal phase was reduced from 19.46 to 8.73%. Accordingly, the bioaccessibility of β-carotene in Pickering emulsions ranged from 9.14 to 27.25% through adjusting the mass ratio and addition sequence of distinct particles at the interface. The Pickering emulsion with the novel particle-particle complex interface was designed in foods and pharmaceuticals for purpose of enhanced stability, delayed lipolysis, or sustained nutrient release.

Recent Innovations in Emulsion Science and Technology for Food Applications

Emulsion technology has been used for decades in the food industry to create a diverse range of products, including homogenized milk, creams, dips, dressings, sauces, desserts, and toppings. Recently, however, there have been important advances in emulsion science that are leading to new approaches to improving food quality and functionality. This article provides an overview of a number of these advanced emulsion technologies, including Pickering emulsions, high internal phase emulsions (HIPEs), nanoemulsions, and multiple emulsions. Pickering emulsions are stabilized by particle-based emulsifiers, which may be synthetic or natural, rather than conventional molecular emulsifiers. HIPEs are emulsions where the concentration of the disperse phase exceeds the close packing limit (usually >74%), which leads to novel textural properties and high resistance to gravitational separation. Nanoemulsions contain very small droplets (typically d < 200 nm), which leads to useful functional attributes, such as high optical clarity, resistance to gravitational separation and aggregation, rapid digestion, and high bioavailability. Multiple emulsions contain droplets that have smaller immiscible droplets inside them, which can be used for reduced-calorie, encapsulation, and delivery purposes. This new generation of advanced emulsions may lead to food and beverage products with improved quality, health, and sustainability.

Development of curcumin loaded core-shell zein microparticles stabilized by cellulose nanocrystals and whey protein microgels through interparticle interactions

Novel multilayered core-shell microparticles were developed to deliver curcumin using positively charged zein microparticles coated with negatively charged cellulose nanocrystals (CNCs) and positively charged whey protein microgels (WPMs) at pH 4. Different levels of WPMs (0.10%-1.50%, w/v) were utilized to regulate the structure, stability, and in vitro digestion of curcumin loaded zein-CNC core-shell microparticles. The size of zein-CNC-WPM core-shell microparticles ranged from 2087.7 to 2928.2 nm. The electrostatic attraction and hydrogen bonding were mainly involved in the assembly of the core-shell microparticles through particle-particle interactions. The microstructure of the core-shell microparticles was dependent on the level of the WPM. When its appropriate level was adopted (0.50%-1.00%, w/v), the WPM formed a protective shell for zein-CNC-WPM core-shell microparticles. The retention rate of curcumin in the core-shell microparticles increased by 47.56% and 32.79% during light and thermal treatment, respectively. Excess microgels facilitated the bridging aggregation and formation of a network structure on the particle surface, which further reduced their stability and greatly restricted the curcumin release. The potential of nanosized protein microgels was explored to stabilize and modulate the physicochemical properties of multilayered core-shell microparticles through interparticle interactions.

Nanocellulose in Emulsions and Heterogeneous Water-Based Polymer Systems: A Review

Nanocelluloses (i.e., bacterial nanocellulose, cellulose nanocrystals, and cellulose nanofibrils) are cellulose-based materials with at least one dimension in the nanoscale. These materials have unique and useful properties and have been shown to assemble at oil-water interfaces and impart new functionality to emulsion and latex systems. Herein, the use of nanocellulose in both emulsions and heterogeneous water-based polymers is reviewed, including dispersion, suspension, and emulsion polymerization. Comprehensive tables describe past work employing nanocellulose as stabilizers or additives and the properties that can be tailored through the use of nanocellulose are highlighted. Even at low loadings, nanocellulose offers an unprecedented level of control as a property modifier for a range of emulsion and polymer applications, influencing, for example, emulsion type, stability, and stimuli-responsive behavior. Nanocellulose can tune polymer particle properties such as size, surface charge, and morphology, or be used to produce capsules and polymer nanocomposites with enhanced mechanical, thermal, and adhesive properties. The role of nanocellulose is discussed, and a perspective for future direction is presented.

Structural design of zein-cellulose nanocrystals core-shell microparticles for delivery of curcumin

The novel core-shell microparticles were fabricated to deliver curcumin by using hydrophobic zein microparticles as the core and hydrophilic cellulose nanocrystals (CNCs) as the shell. Different concentrations (0.10-1.50%, w/v) of CNCs were utilized to regulate the microstructure, physicochemical stability, and in vitro digestion of the core-shell microparticles. The size of the microparticles ranged from 1017.3 to 3663.7 nm. Electrostatic attraction and hydrophobic interactions were responsible for the assembly of zein-CNCs core-shell microparticles. The microstructure of the microparticles was dependent on the CNCs level. The retention rate of curcumin in the core-shell microparticles was increased by 76.41% after UV radiation. Furthermore, the rise of CNCs level delayed the release of curcumin from the microparticles in gastrointestinal tract and reduced its bioaccessibility. The potential of utilizing hydrophilic nanoparticles was explored to stabilize hydrophobic microparticles through interparticle interactions, which was useful to develop the novel core-shell microparticles for the application in functional foods.

Influence of cellulose nanocrystals (CNC) on permeation through intestinal monolayer and mucus model in vitro

Cellulose nanocrystals (CNC) as a novel ingredient in foods and pharmaceuticals still lacks the safety and functionality information. We aimed to assess the absorption of CNC in small intestine and the effect on cell viability. In the second part, the impact of CNC on substance permeation through mucus layer, including the potential functionality in improving high blood cholesterol, was tested. No noticeable amount of CNC was found to penetrate through differentiated Caco-2 monolayer and in vitro mucus layer, and CNC had low toxicity on Caco-2 cell viability up to 10 mg/mL. CNC at 2 % (w/w) may affect the permeability of the mucus layer and larger molecules are more easily influenced. CNC may also alleviate hypercholesteremia by increasing viscosity of digesta, adsorbing cholesterol, and decreasing bile acids permeation. The results suggest CNC may not penetrate the small intestinal lining and may be used as a functional supplement.

Cellulose Nanocrystals for Skin Barrier Protection by Preparing a Versatile Foundation Liquid

Most of the foundation liquids in the market need makeup removers for cleaning, while the excessive use of makeup removers might lead to skin barrier damage, which would further lead to many kinds of dermatosis, such as skin sensitivity, facial telangiectasia, rosacea, acne, as well as various cosmetic contact dermatitis. Inspired by the protective effect of fiber-rich diet on the intestinal mucosal mechanical barrier, a novel hemp/cellulose nanocrystals (CNCs)-based foundation liquid featuring easy-wiping property has been constructed, which will effectively solve the post-makeup skin cleaning problems. In this experiment, the formula of the foundation liquid can be obtained through hemp/CNCs instead of mineral oil and titanium oxide, which are considered to have undesirable local tolerance, sensitizing potential, and are environmental pollutants, to create a moisture barrier. Industrial hemp is a hot issue in cosmetic research, and a great quantity of discarded industrial hemp stalk is available to be used to produce hemp/CNCs through grinding and acidification. The graft technique is adapted to obtain hemp/CNCs-g-polylactic acid (PLA). By replacing the hydroxyl group on the side of hemp/CNCs, hemp/CNCs-g-PLA reduces the intermolecular hydrogen bonding, resulting in a higher dispersion in the oil phase. The hemp/CNCs-g-PLA has excellent performance in terms of biological compatibility, water resistance, and non-penetration into the skin. With basic features of a foundation liquid to alleviate discoloration, age spots, and skin roughness, the foundation liquid based on hemp/CNCs-g-PLA provides a novel characteristic of easy-wiping, which helps to avoid the damage to the skin barrier caused by excessive cleansing.

Recent Advances in Food Emulsions and Engineering Foodstuffs Using Plant-Based Nanocelluloses

In this article, the application of nanocelluloses, especially cellulose nanofibrils and cellulose nanocrystals, as functional ingredients in foods is reviewed. These ingredients offer a sustainable and economic source of natural plant-based nanoparticles. Nanocelluloses are particularly suitable for altering the physicochemical, sensory, and nutritional properties of foods because of their ability to create novel structures. For instance, they can adsorb to air-water or oil-water interfaces and stabilize foams or emulsions, self-assemble in aqueous solutions to form gel networks, and act as fillers or fat replacers. The functionality of nanocelluloses can be extended by chemical functionalization of their surfaces or by using them in combination with other natural food ingredients, such as biosurfactants or biopolymers. As a result, it is possible to create stimuli-responsive, tailorable, and/or active functional biomaterials suitable for a range of foodapplications. In this article, we describe the chemistry, structure, and physicochemical properties of cellulose as well as their relevance for the application of nanocelluloses as functional ingredients in foods. Special emphasis is given to their use as particle stabilizers in Pickering emulsions, but we also discuss their potential application for creating innovative biomaterials with novel functional attributes, such as edible films and packaging. Finally, some of the challenges associated with using nanocelluloses in foods are critically evaluated, including their potential safety and consumer acceptance.

Cellulose and cellulose derivatives: Different colloidal states and food-related applications

Development of new sources and isolation processes has recently enhanced the production of cellulose in many different colloidal states. Even though cellulose is widely used as a functional ingredient in the food industry, the relationship between the colloidal states of cellulose and its applications is mostly unknown. This review covers the recent progress on illustrating various colloidal states of cellulose and the influencing factors with special emphasis on the correlation between the colloidal states of cellulose and its applications in food industry. The associated unique colloidal states of cellulose like high aspect ratio, crystalline structure, surface charge, and wettability not only promote the stability of colloidal systems, but also help improve the nutritional aspects of cellulose by facilitating its interactions with digestive system. Further studies are required for the rational control and improvement of the colloidal states of cellulose and producing food systems with enhanced functional and nutritional properties.

Nanocellulose: From Fundamentals to Advanced Applications

Over the past few years, nanocellulose (NC), cellulose in the form of nanostructures, has been proved to be one of the most prominent green materials of modern times. NC materials have gained growing interests owing to their attractive and excellent characteristics such as abundance, high aspect ratio, better mechanical properties, renewability, and biocompatibility. The abundant hydroxyl functional groups allow a wide range of functionalizations via chemical reactions, leading to developing various materials with tunable features. In this review, recent advances in the preparation, modification, and emerging application of nanocellulose, especially cellulose nanocrystals (CNCs), are described and discussed based on the analysis of the latest investigations (particularly for the reports of the past 3 years). We start with a concise background of cellulose, its structural organization as well as the nomenclature of cellulose nanomaterials for beginners in this field. Then, different experimental procedures for the production of nanocelluloses, their properties, and functionalization approaches were elaborated. Furthermore, a number of recent and emerging uses of nanocellulose in nanocomposites, Pickering emulsifiers, wood adhesives, wastewater treatment, as well as in new evolving biomedical applications are presented. Finally, the challenges and opportunities of NC-based emerging materials are discussed.

Recent advances of characterization techniques for the formation, physical properties and stability of Pickering emulsion

Recently, there have been increasing demand for the application of Pickering emulsions in various industries due to its combined advantage in terms of cost, quality and sustainability. This review aims to provide a complete overview of the available methodology for the physical characterization of emulsions that are stabilized by solid particles (known as Pickering emulsion). Current approaches and techniques for the analysis of the formation and properties of the Pickering emulsion were outlined along with the expected results of these methods on the emulsions. Besides, the application of modelling techniques has also been elaborated for the effective characterization of Pickering emulsions. Additionally, approaches to assess the stability of Pickering emulsions against physical deformation such as coalescence and gravitational separation were reviewed. Potential future developments of these characterization techniques were also briefly discussed. This review can act as a guide to researchers to better understand the standard procedures of Pickering emulsion assessment and the advanced methods available to date to study these emulsions, down to the minute details.

Simulating human digestion: developing our knowledge to create healthier and more sustainable foods

The gold standard for nutrition studies is clinical trials but they are expensive and variable, and do not always provide the mechanistic information required, hence the increased use ofin vitroand increasinglyin silicosimulations of digestion.

Enhancing the prebiotic effect of cellulose biopolymer in the gut by physical structuring via particle size manipulation

Cellulose is generally recognised as dietary fibre with no limit of permissible quantity in food, and its consumption may modulate digesta content and impact positively on the gastrointestinal physiology and gut microflora. However, cellulose in its native form possessed inherent undesirable physical properties, making it unattractive for food applications. Here, we postulate that by changing cellulose size to nanometric scale, its prebiotic effect would be altered and fermented differently in contrast with micro size cellulose by the gut microbiome and promote the yield of metabolites such as short chain fatty acids (SCFAs). Using faecal matter from three healthy human donors as microbial source, in vitro fermentation of variable size fractions of cellulose from the same were fermented under anaerobic conditions, and SCFAs as well Bifidobacterium selectively isolated and analysed. The increase in production of acetate (194%), butyrate (224%) and propionate (211%) after 24 h of fermentation was significantly promoted by the size reduction and revealed size-dependent relationship as exemplified R² values >0.83. Consequently, gavaging rats with nanometric size cellulose (125 nm) significantly (p < 0.05) increased these SCFAs yields as well Bifidobacterium counts in contrast with both control and the micro scale size cellulose. Therefore, engineered nanocellulose might have beneficial physiological impact on the gut with improved prebiotic effect.

Permeability of the small intestinal mucus for physiologically relevant studies: Impact of mucus location and ex vivo treatment

The small intestinal mucus is a complex colloidal system that coats the intestinal mucosa. It allows passage on nutrients/pharmaceuticals from the gut lumen towards the epithelium, whilst preventing it from direct contact with luminal microorganisms. Mucus collected from intestinal tissue is often used in studies looking at inter-mucosal transport of food particulates, drug carriers, etc. However, detaching the highly hydrated native mucus from the tissue and storing it frozen prior to use may disrupt its physiological microstructure, and thus selective barrier properties. Multiple-particle tracking experiments showed that microstructural organisation of native, jejunal mucus depends on its spatial location in the intestinal mucosa. The inter-villus mucus was less heterogeneous than the mucus covering villi tips in the pig model used. Collecting mucus from tissue and subjecting it to freezing and thawing did not significantly affect (P > 0.05) its permeability to model, sub-micron sized particles, and the microviscosity profile of the mucus reflected the overall profiles recorded for the native mucus in the tissue. This implies the method of collecting and storing mucus is a reliable ex vivo treatment for the convenient planning and performing of mucus-permeability studies that aim to mimic physiological conditions of the transport of molecules/particles in native mucus.

Inhibition of H1N1 influenza virus infection by zinc oxide nanoparticles: another emerging application of nanomedicine

BACKGROUND

Currently available anti-influenza drugs are often associated with limitations such as toxicity and the appearance of drug-resistant strains. Therefore, there is a pressing need for the development of novel, safe and more efficient antiviral agents. In this study, we evaluated the antiviral activity of zinc oxide nanoparticles (ZnO-NPs) and PEGylated zinc oxide nanoparticles against H1N1 influenza virus.

METHODS

The nanoparticles were characterized using the inductively coupled plasma mass spectrometry, x-ray diffraction analysis, and electron microscopy. MTT assay was applied to assess the cytotoxicity of the nanoparticles, and anti-influenza activity was determined by TCID50 and quantitative Real-Time PCR assays. To study the inhibitory impact of nanoparticles on the expression of viral antigens, an indirect immunofluorescence assay was also performed.

RESULTS

Post-exposure of influenza virus with PEGylated ZnO-NPs and bare ZnO-NPs at the highest non-toxic concentrations could be led to 2.8 and 1.2 log10 TCID50 reduction in virus titer when compared to the virus control, respectively (P < 0.0001). At the highest non-toxic concentrations, the PEGylated and unPEGylated ZnO-NPs led to inhibition rates of 94.6 and 52.2%, respectively, which were calculated based on the viral loads. There was a substantial decrease in fluorescence emission intensity in viral-infected cell treated with PEGylated ZnO-NPs compared to the positive control.

CONCLUSIONS

Taken together, our study indicated that PEGylated ZnO-NPs could be a novel, effective, and promising antiviral agent against H1N1 influenza virus infection, and future studies can be designed to explore the exact antiviral mechanism of these nanoparticles.