Bacterial cellulose nanofibers improved the emulsifying capacity of soy protein isolate as a stabilizer for pickering high internal-phase emulsions

Microcapsules stabilized by cellulose nanofibrils/whey protein complexes and modified with cinnamaldehyde: Characterization and release properties

This work aims to optimize encapsulation of Zanthoxylum schinifolium essential oil (ZSEO) in microcapsule to enhance its stability and slow-release capability. Herein, the ZSEO microcapsules stabilized by bacterial cellulose nanofibrils/whey protein isolate (BCNFs/WPI) complexes and modified by cinnamaldehyde (CA) were successfully prepared via spray drying. The microcapsules formed by 1.0 wt% BCNFs/WPI complexes at a ratio of 1:7 and fortified with 0.7 wt% CA, exhibited superior physical properties, a smaller powder size and the highest encapsulation efficiency (90.81 %). The spectroscopy analysis and molecular dynamics simulations demonstrated the presence of hydrogen bonding and electrostatic interactions between CA and BCNFs/WPI/ZSEO components, contributing to an increase in the binding energy. The release kinetic modeling revealed that the microcapsules exhibited the delayed release capability in both aqueous and oily model fluids. Moreover, the ZSEO microcapsules modified with CA exhibited enhanced stability during in vitro digestion, offering valuable insights into the microencapsulation of essential oils.

Effects of Astragalus polysaccharide on the physicochemical properties of heat-induced whey protein gels by simultaneous rheology and fourier transform infrared spectroscopy

This study investigated the physicochemical properties of gels induced by heat treatment in the presence of 10% polymerized whey protein (PWP) and different concentrations (1-4%) of Astragalus polysaccharide (AGPS). The results of the particle size, zeta potential, surface hydrophobicity, intrinsic fluorescence, surface free sulfhydryl, rheological and differential scanning calorimetry showed that AGPS improved the tertiary structure stability of PWP. Simultaneous rheology and Fourier transform infrared spectroscopy (SR-IR) traced the breaks of aromatic groups and the formation of PWP-AGPS hydrogels through hydrogen bonding and electrostatic interactions during heat process. The correctness of the experimental results was verified via molecular docking and 2-dimensional correlation spectroscopy (2D-COS). Cryogenic scanning electron microscopy images showed that the interaction between PWP and AGPS caused the denser microstructure of hydrogels. In summary, AGPS could promote gelation and improve the physicochemical properties of PWP-AGPS hydrogels. The findings of this study provided a theoretical basis for the application of protein-polysaccharide hydrogels in the food industry, offering insights for practical use.

Pickering emulsions stabilized by soybean protein-based nanoparticles: A review of formulation, characterization, and food-grade applications

Pickering emulsions (PEs) have attracted considerable interest as platforms for encapsulating and controlling the release of bioactive compounds. Recent studies emphasize the potential of soybean protein nanoparticles to improve PE-based carriers, enhancing the stability and bioavailability of these compounds through unique self-assembly behaviors. This review analyzes recent advancements in the use of soybean protein nanoparticle-stabilized PEs as carriers for bioactive compounds. Various fabrication techniques, including physical, chemical, and biological methods, are explored. The effectiveness of soybean protein nanoparticles, both individually and in combination with polysaccharides or polyphenols, is evaluated, highlighting their roles in stabilizing PEs and enhancing functionality. Findings indicate that soybean protein nanoparticles are effective stabilizers for a wide range of PE structures, including oil-in-water, water-in-oil, high internal phase PEs, and Pickering emulgels. Fabrication methods, properties of Pickering particles, processing parameters, and formulations significantly influence the interfacial behavior, structure, and functionality of PEs. Fabrication methods, properties of Pickering particles, processing parameters, and formulations significantly influence the interfacial behavior, structure, and functionality of PEs. Additionally, innovative applications and future developments of soybean protein-based Pickering nanoparticles are discussed, emphasizing plant-based substitutes and advanced materials. Despite extensive discussions on soybean protein-based PEs in various food forms, research into their techno-functional properties and flavor mechanisms remains limited.

The properties of Pickering emulsions stabilized by bacterial cellulose nanofibrils and its retarding effect on lipid digestion

The rate of lipid digestion can be delayed by the interface modulation of O/W Pickering emulsions. In this study, bacterial cellulose nanofibrils prepared by ball milling synergized with electron beam irradiation (B-IB50) were used as stabilizers to prepare Pickering emulsions. Results showed that B-IB50 formed emulsion systems with good stability. Especially when the content of B-IB50 was >0.6 wt%, emulsions showed excellent storage and environmental stability. Notably, at pH 2.0, the electrostatic repulsion between fibrils was weakened leading to closer cross-linking and giving better protection to the oil droplets. When the content of B-IB50 in emulsions increased from 0.2 wt% to 1.0 wt%, the release of FFA decreased from 66.7 % to 37.8 % during digestion, which indicated that the presence of more B-IB50 inhibited the digestion of lipids. Main mechanisms were proposed for the results: (1) B-IB50 formed a dense interface layer that reduced the binding area of bile salts and lipases; (2) B-IB50 formed the three-dimensional network structure limiting the displacement of bile salts and lipases, thereby reducing the binding to lipids. This study provided theoretical ideas for developing emulsion-based functional foods with lipid-reducing effects.

Interfacial Properties and Structure of Emulsions and Foams Co-Stabilized by Span Emulsifiers of Varying Carbon Chain Lengths and Egg Yolk Granules

Interfacial properties significantly influence emulsifying and foaming stability. We here explore the interfacial behavior of egg yolk granules (EYGs) combined with various Span emulsifiers (Span 20, 40, 60, 80) to assess their solution properties, interface dynamics, and effects on emulsifying and foaming stability. The results unveiled that as the Span concentration increased, particle size decreased from 7028 to 1200 nm, absolute zeta potential increased from 4.86 to 9.26 mv, and the structure became increasingly loosened. This loose structure of EYGs-Span complexes resulted in reduced interfacial tension (γ), higher adsorption rate (Kd), and improved interfacial composite modulus (E) compared with native EYGs. These effects were more pronounced with shorter hydrophobic chain Spans but diminished with longer chain lengths. Enhanced interfacial properties contributed to better emulsification and foaming stability, with EYGs-Span complexes displaying increased emulsifying ability and stability compared with natural EYGs. Emulsifying and foaming stability improved in the order of Span 20 > Span 40 > Span 60 > Span 80 as the Span concentration increased. The correlation analysis (p > 0.05) indicated that emulsifying stability was positively associated with interfacial composite modulus and negatively correlated with particle size. Consequently, EYGs-Span composites demonstrate considerable potential for use as effective emulsifiers in food industry applications.

Development and characterisation of a novel bigel based on pea protein hydrogel and rice bran wax oleogel: Enhancement of rheological properties and freeze-thaw stability

In this study, a novel pea protein (PP)-based bigel was developed, featuring a high internal phase emulsion. The impact of gelling agent concentration on the gel properties and freeze-thaw stability of the bigel was investigated. The bigel was comprised of two distinct gel phases: an aqueous-phase gel with a covalent network formed by PP and transglutaminase (TGase), and an oil-phase gel with a crystal network structure of rice bran wax (RBW). Microstructural analysis revealed a bi-continuous network structure in the bigel, with network density increasing as TGase and RBW concentrations rose. Rheological analysis showed that storage modulus (G'), apparent viscosity, and structural recovery of the bigel increased with higher TGase and RBW concentrations. Temperature scanning experiments confirmed that the bigel maintained its elastic solid behavior even at elevated temperatures. Optimal sensory properties and low coefficient of friction were achieved at 0.4 % TGase and 7 % RBW concentrations. Additionally, the bigel exhibited notable freeze-thaw stability at TGase and RBW concentrations exceeding 0.2 % and 5 %, respectively. These findings highlight the excellent gelation properties and stability of the PP-RBW-based bigel, suggesting its potential as a fat substitute in the food industry.

Enhancement of Pickering effect of ovalbumin with bacterial cellulose nanofibers prepared by electron beam irradiation and encapsulation of curcumin

In this study, the enhancement of Pickering effect of ovalbumin (OVA) with bacterial cellulose nanofibers (BCNFs) prepared by electron beam irradiation was investigated and the environmental stability of oil-in-water Pickering emulsions stabilized by OVA/BCNFs complexes was explored by varying ratios of OVA/BCNFS (1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1) and oil phase concentrations (10 %, 20 %, 30 %, 40 %, 50 %, 60 %). Droplet sizes of Pickering emulsions were decreased with the increase of the proportion of BCNFs, while the viscosity and storage modulus (G') of Pickering emulsions were increased. The gel strength of Pickering emulsions was positively correlated with the oil phase content. Pickering emulsions stabilized by OVA/BCNFs complexes were endowed excellent environmental stability under varying pH, ionic strength, and thermal conditions. Moreover, after encapsulating curcumin in Pickering emulsions, the retention rates of curcumin were improved significantly during room temperature, UV light, and thermal treatment. The present study would contribute to the advancement of novel protein/polysaccharide stabilizers and offer novel insight for investigating the stability of Pickering emulsions and delivering lipophilic bioactive compounds.

High internal phase Pickering emulsions stabilized by egg yolk-carboxymethyl cellulose as an age-friendly dysphagia food: Tracking the dynamic transition from co-solubility to coacervates

Although protein-polysaccharide complexes with different phase behaviors all show potential for stabilizing high internal phase Pickering emulsions (HIPPEs), it is not clarified which aggregation state is more stable and age-friendly. In this study, we investigated and compared the stability and age friendliness of HIPPEs stabilized with egg yolk and carboxymethyl cellulose (EYCMC) in different phase behaviors. The results revealed differences in particle size, aggregation state, charge potential, and stability of secondary and tertiary structures of EYCMC. The behavior of EYCMC at the oil-water interface was mainly divided into three phases: rapid diffusion, permeation, and reorganization. The electrostatic interaction, kinetic hindrance, and depletion attraction were the mechanisms primarily involved in stabilizing HIPPEs by EYCMC. Rheological analysis results indicated that HIPPEs had excellent viscoelasticity, structural recovery properties and yield stress. HIPPEs were used in 3D printing, electronic nose testing, IDDSI testing and in vitro digestive simulations for the elderly, demonstrating a fine appearance, safe consumption and bioaccessibility of β-carotene. Soluble complexes showed the best stability and age friendliness compared to other aggregated forms. This study serves as a foundational source of information for developing innovative foods utilizing HIPPEs.

Enzymatically green-produced bacterial cellulose nanoparticle-stabilized Pickering emulsion for enhancing anthocyanin colorimetric performance of versatile films

To enhance the colorimetric performance of anthocyanin (Ant), a konjac glucomannan (KGM)-based multifunctional pH-responsive indicator film was fabricated by introducing enzymatically prepared bacterial nanocellulose (EBNC) stabilized camellia oil/camellia essential oil Pickering emulsion (BCCE). Specifically, optimized enzymatic hydrolysis time (36 h) was determined based on the particle size and microstructure. Then BCCE (containing 0.4% EBNC) was incorporated into Ant-containing KGM, and the novel active indicator film (KGM-Ant-BCCE) was constructed. Films with varying BCCE concentrations (3%-11%) exhibited enhanced UV shielding, thermal stability, mechanical strength, water vapor and oxygen permeability, hydrophobicity, and antioxidant performance. The pronounced color change of KGM-Ant-BCCE indicated its potential for visually detecting shrimp freshness. Moreover, the biodegradability (25 days) confirmed the environmentally benign property of the film. In summary, incorporating green-produced EBNC nanoparticle-stabilized BCCE offers an innovative pathway to improve the color indication capability of polysaccharide-based smart packaging.

Stability and 3D-printing performance of high-internal-phase emulsions based on ultrafine soybean meal particles

There are numerous studies on the application of soybean whey protein in three-dimensional (3D) printing. In this study, the effects of soybean meal particles (5%, 6%, 7%, 8%, 9%, and 10%) and oil-phase concentrations (70%, 72%, 74%, 76%, and 78%) on the stability and 3D-printing performance of a soybean-meal-based high-internal-phase emulsion were investigated. The results showed that the particle size of the emulsion decreased with increasing soybean meal particle concentration, and that increasing the concentration of the oil phase improved the viscoelasticity of the emulsion. Rheological tests further showed that the higher storage modulus of the emulsion indicated better support and stability. The emulsion with 8% soybean meal-particles and 76% oil-phase concentration exhibited the best printing effect. This study provides an effective solution for the preparation of stabilized high-internal-phase emulsions of soybean meal particles suitable for 3D printing.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat

BACKGROUND

Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken.

RESULTS

The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups.

CONCLUSION

All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Banana peel nanocellulose and soy protein hydrolysate complexed colloidal nanoparticles synthesis using ultrasonic interventions: characterization and stable pickering emulsion formation

Pickering based emulsion system are been gaining interest in active delivery of encapsulated molecules in food system. In the present study, cellulose nanoparticles (CNPs) were isolated from food waste (banana peel) using acid hydrolysis followed by high-intensity ultrasonication. The complex colloidal nanoparticles (CNPSPH) were fabricated using hydrogen bonding and electrostatic interactions between cellulose nanoparticles and soy protein hydrolysates. With 400 W power level for 30 min, size of 53.11 ± 1.45 nm with polydispersity index of 0.21 ± 0.21 and Zeta potential of - 34.33 ± 0.77 were noted for generated CNPs. The three-phase contact angle (o/w) of CNPSPH at a mass ratio of 1:1 CNPs to SPHs (CNPSPH 1:1) was approximately 89.07°, indicating as effective Pickering emulsifiers. Furthermore, the stability of the Pickering emulsion stabilised by CNPSPH complex was investigated under various pH and temperature conditions. The findings will provide solution in development of nanocellulose-soy protein complex particles for a stabilized Pickering emulsion formation.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-023-01477-w.

Preparation and Regulation of Natural Amphiphilic Zein Nanoparticles by Microfluidic Technology

Microfluidic technology, as a continuous and mass preparation method of nanoparticles, has attracted much attention in recent years. In this study, zein nanoparticles (ZNPs) were continuously fabricated in a highly controlled manner by combining a microfluidics platform with the antisolvent method. The impact of ethanol content (60~95%, v/v) and flow rates of inner and outer phases in the microfluidics platform on particle properties were examined. Among all ZNPS, 90%-ZNPs have the highest solubility (32.83%) and the lowest hydrophobicity (90.43), which is the reverse point of the hydrophobicity of ZNPs. Moreover, when the inner phase flow rate was 1.5 mL/h, the particle size decreased significantly from 182.81 nm to 133.13 nm as the outer phase flow rate increased from 10 mL/h to 50 mL/h. The results revealed that ethanol content had significant impacts on hydrophilic-hydrophobic properties of ZNPs. The flow rates of ethanol-water solutions and deionized water (solvent and antisolvent) in the microfluidics platform significantly affected the particle size of ZNPs. These findings demonstrated that the combined application of a microfluidics platform and an antisolvent method could be an effective pathway for precisely controlling the fabrication process of protein nanoparticles and modulating their physicochemical properties.

Soy protein isolate-sodium alginate colloidal particles for improving the stability of high internal phase Pickering emulsions: Effects of mass ratios

The potential of sodium alginate (SA) at different mass ratios to improve the emulsifying ability of soy protein isolate (SPI) in high internal phase Pickering emulsions (HIPPEs) was evaluated in this work. SPI-SA particles were used as a natural particle stabilizer of HIPPEs with 80 % oil phase. The properties of particles with varying SPI to SA ratios (10:0, 10:1, 10:3, 10:5, 10:10, and 10:15 w/w) were evaluated. HIPPEs with a 10:10 SPI to SA ratio exhibited the smallest droplet sizes. Both the storage modulus and loss modulus of the HIPPEs increased with increasing SA addition ratios, implying that HIPPEs with higher SA addition have stronger gel characteristics. In addition, super-resolution microscopy and cryogenic scanning electron microscopy indicated that SA addition strengthened the compactness of the interface film and increased the distribution uniformity of HIPPEs. In conclusion, the combination of SPI and SA is beneficial for improving the performance of HIPPEs.

Tannic acid-enriched nanocellulose hydrogels improve physical and oxidative stability of high-internal-phase Pickering emulsions

A cellulose suspension and tannic acid (TA) were co-sonicated to prepare TA-incorporated nanocellulose hydrogels with the aim of improving the physical and oxidative stability of high-internal-phase emulsions (HIPEs). Cellulose nanocrystal (CNC) hydrogels were used to stabilize HIPEs, relying on the interfacial adsorption behavior of CNCs and the reversible gelation properties of hydrogels. TA was incorporated due to its ability to improve emulsification performance and antioxidant properties. Introducing TA enhanced the gel strength of hydrogels by decreasing the interfibrillar distance. The utilization of CNC-TA hydrogels effectively improved physical properties of HIPEs. This improvement included a reduction in droplet size from the initial 103.41 μm to 39.66 μm, an enhancement of the gel structure, and an improvement in storage stability. A denser and orderly interfacial structure was formed in CNCs-TA hydrogel stabilized HIPEs due to anchoring TA at the interface driven by the hydrogen-bonding interaction between CNCs and TA. This densely interfacial layer with good antioxidant activity markedly enhanced the oxidative stability of emulsions, as evidenced by the low level of oxidation products in HIPEs. This study has the potential to extend the utilization of CNC-stabilized emulsions to new applications in the food, cosmetic, and pharmaceutical industries.

Development of high internal phase Pickering emulsions stabilized by egg yolk and carboxymethylcellulose complexes to improve β-carotene bioaccessibility for the elderly

The work aimed to develop the multi-protein mixture of egg yolk as natural particles to stabilize high internal phase Pickering emulsions (HIPPEs) to improve the bioaccessibility of β-carotene in the elderly. The results showed that the depletion attraction drove the adsorption of egg yolk protein particles at the oil-water interface and the formation of osmotic droplet clusters due to the attachment of particle-coated droplets in the dispersed phase, leading to kinetic blocking and stable gelation of HIPPEs. Rheological measurements showed that HIPPEs had shear thinning, low shear stress, viscoelastic properties, and structural recovery properties, which facilitated easy consumption for the elderly. The stability of HIPPEs was verified by ionic and centrifugal stability tests, demonstrating their potential for application to complex gastric environments. HIPPEs have been applied to the International Dysphagia Dietary Standardization Initiative (IDDSI) test and simulated in vitro digestion in older adults, demonstrating their safe swallowability and high β-carotene bioaccessibility. Our findings suggest solutions for food practitioners facing the aging problem and provide new insights for preparing age-friendly foods.

Freeze-thaw stability of Pickering emulsion stabilized by modified soy protein particles and its application in plant-based ice cream

Pickering emulsions are of great interest to the food industry and their freeze-thaw stability important when used in frozen foods. Particles of soybean isolate (SPI) were heat treated and then crosslinked with transglutaminase (TG) enzyme to produce Pickering emulsions. The protein particles produced using unheated and uncrosslinked SPI (NSPI) was used as the benchmark. The mean particle size, absolute zeta potential, and surface hydrophobicity of protein particles produced using heat treatment and TG crosslinking (at 40 U/g) SPI (HSPI-TG-40) were the highest and substantially higher than those produced using NSPI. The thermal treatment of protein particles followed by crosslinking with TG enzyme improved the freeze-thaw stability of Pickering emulsions stabilized by them. The Pickering emulsions produced using HSPI-TG-40 had the lowest temperature for ice crystal formation and they had better freeze-thaw stability. The plant-based ice cream prepared by HSPI-TG-40 particle-stabilized Pickering emulsions had suitable texture and freeze-thaw stability compared to the ice cream produced using NSPI. The Pickering particles produced using heat treatment of SPI followed by crosslinking with TG (at 40 U/g) produced the most freeze-thaw stable Pickering emulsions. These Pickering particles and Pickering emulsions could be used in frozen foods such as ice cream.

Lima bean (Phaseolus lunatus Linn.) protein isolate as a promising plant protein mixed with xanthan gum for stabilizing oil-in-water emulsions

BACKGROUND

Lima bean protein isolate (LPI) is an underutilized plant protein. Similar to other plant proteins, it may display poor emulsification properties. In order to improve its emulsifying properties, one effective approach is using protein and polysaccharide mixtures. This work investigated the structural and emulsifying properties of LPI as well as the development of an LPI/xanthan gum (XG)-stabilized oil-in-water emulsion.

RESULTS

The highest protein solubility (84.14%) of LPI was observed and the molecular weights (Mw ) of most LPI subunits were less than 35 kDa. The enhanced emulsifying activity index (15.97 m2  g-1 ) of LPI might be associated with its relatively high protein solubility and more low-Mw subunits (Mw  < 35 kDa). The effects of oil volume fraction (ϕ) on droplet size, microstructure, rheological behavior and stability of emulsions were investigated. As ϕ increased from 0.2 to 0.8, the emulsion was arranged from spherical and dispersed oil droplets to polyhedral packing of oil droplets adjacent to each other, while the LPI/XG mixtures changed from particles (in the uncrowded interfacial layer) to lamellae (in the crowded interfacial layer). When ϕ was 0.6, the emulsion was in a transitional state with the coexistence of particles and lamellar structures on the oil droplet surface. The LPI/XG-stabilized emulsions with ϕ values of 0.6-0.8 showed the highest stability during a 14-day storage period.

CONCLUSION

This study developed a promising plant-based protein resource, LPI, and demonstrates potential application of LPI/XG as an emulsifying stabilizer in foods. © 2023 Society of Chemical Industry.

Soy protein isolate/carboxymethyl cellulose sodium complexes system stabilized high internal phase Pickering emulsions: Stabilization mechanism based on noncovalent interaction

The interactions between carboxymethyl cellulose sodium and proteins can regulate the interfacial and rheological properties of HIPEs, which plays a leading role in the stabilities of HIPEs. This article prepared various ratios of soluble soy protein isolate/carboxymethyl cellulose sodium (SPI/CMC) complexes in different proportions and examined the impact of various ratios of complexes on the structure and interface properties of complexes systems. Additionally, it explored the co-emulsification mechanism of HIPEs using SPI and CMC. At appropriate ratios of SPI/CMC, SPI and CMC mainly combine through non covalent binding and form complexes with smaller particle sizes and stronger electrostatic repulsion. The interfacial properties indicated that adding appropriate CMC increased the pliability and reduced the interfacial tension, while also enhancing the wettability of SPI/CMC complexes. At the ratio of 2:1, the SPI/CMC complexes-stabilized HIPPEs exhibited smaller oil droplets size, tighter droplet packing, and thicker interfacial film through the bridging of droplets and the generation of stronger gel-like network structures to prevent the coalescence/flocculation of droplets. These results suggested that the appropriate ratios of SPI/CMC can improve the physical stability of HIPEs by changing the structure and interface characteristics of the SPI/CMC complexes. This work provided theoretical support for stable HIPEs formed with protein-polysaccharide complexes.

Nanocellulose from Cocoa Shell in Pickering Emulsions of Cocoa Butter in Water: Effect of Isolation and Concentration on Its Stability and Rheological Properties

There is a growing interest in developing new strategies to completely or partially replace cocoa butter in food and cosmetic products due to its cost and health effects. One of these alternatives is to develop stable emulsions of cocoa butter in water. However, incorporating cocoa butter is challenging as it solidifies and forms crystals, destabilizing the emulsion through arrested coalescence. Prevention against this destabilization mechanism is significantly lower than against coalescence. In this research, the rheological properties of nanocellulose from cocoa shell, a by-product of the chocolate industry, were controlled through isolation treatments to produce nanocellulose with a higher degree of polymerization (DP) and a stronger three-dimensional network. This nanocellulose was used at concentrations of 0.7 and 1.0 wt %, to develop cocoa butter in-water Pickering emulsion using a high shear mixing technique. The emulsions remained stable for more than 15 days. Nanocellulose was characterized using attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), hot water and organic extractives, atomic force microscopy (AFM), degree of polymerization (DP), and rheological analysis. Subsequently, the emulsions were characterized on days 1 and 15 after their preparation through photographs to assess their physical stability. Fluorescent and electronic microscopy, as well as rheological analysis, were used to understand the physical properties of emulsions.

Bacterial cellulose nanofibers used as nanofillers improved the fresh-keeping performance of gelatin-based edible coating for fresh-cut apples

In this study, bacterial cellulose nanofibers (BCNs) (0%, 1%, 2%, and 3%) were used as nanofillers to prepare gelatin-based edible films, and their physical properties and fresh-keeping performance were investigated. The microstructure observation showed that the BCNs were well dispersed in the gelatin-based edible films and the surface roughness of the films increased with the increase of BCNs content. X-ray diffraction and thermogravimetric analysis showed that the crystallinity and thermal stability of the film were significantly increased with the increase of BCNs. Fourier-transform infrared spectroscopy analysis suggested that hydrogen bond interactions occurred between BCNs and gelatin polymers, leading to improved mechanical properties with the increase of BCNs content. Furthermore, the barrier performance was also improved with the increase of BCNs content, where gelatin-based edible films with 2% BCNs showed the best mechanical property. Meanwhile, the gelatin-based film-forming solutions (FFSs) containing different BCNs were coated on the fresh-cut apples and the corresponding fresh-keeping performance was investigated. The results showed that the fresh-keeping parameters of fresh-cut apples coated with FFSs containing BCNs were better as compared with those of pure gelatin FFSs. Moreover, the fresh-keeping parameters were improved with the increase of BCNs, especially the FFSs containing 2% BCNs that showed the best fresh-keeping parameters. Therefore, BCNs, used as nanofillers, are an excellent enhancer to improve the fresh-keeping performance of the gelatin-based edible coating, showing a promising potential application in the food preservation field.

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.

Understanding the structure, interfacial properties, and digestion fate of high internal phase Pickering emulsions stabilized by food-grade coacervates: Tracing the dynamic transition from coacervates to complexes

Although protein-polysaccharide complexes have shown tremendous potential in stabilizing high internal phase Pickering emulsions (HIPPEs), it is unclear whether coacervates have the same potential to be used as effective Pickering stabilizers. In this study, HIPPEs were prepared by ovalbumin (OVA)-pectin (PE) coacervates during the transition from coacervates to complexes. The results showed that enhanced OVA-PE interactions significantly affected the wettability and surface-tension reduction ability of the OVA-PE coacervates. At pH 2, the coacervate-stabilized HIPPEs exhibited smaller oil droplet sizes (21.3±2.3 μm), tighter droplet packing, and finer solid-like structures through the bridging of droplets and the generation of stronger gel-like network structures to prevent coalescence and lipid oxidation. The gastrointestinal digestion results proved that the OVA-PE coacervates promoted lipid hydrolysis and improved the bioaccessibility (from 19.7±0.7% to 36.5±2%) of curcumin-loaded HIPPEs. Our work provides new ideas for the development of biopolymer particles as effective Pickering stabilizers in the food industry.

Nanocellulose: An amazing nanomaterial with diverse applications in food science

Recently, nanocellulose has gained growing interests in food science due to its many advantages including its broad resource of raw materials, renewability, interface stability, high surface area, mechanical strength, prebiotic characteristics, surface chemistry versatility and easy modification. Since then, this review summarized the sources, morphology, and structure characteristics of nanocellulose. Meanwhile, the mechanical, chemical, and combined treatment methods for the preparation of nanocellulose with desired properties were elaborated. Furthermore, the application of nanocellulose in Pickering emulsions, reinforced food packaging, functional food ingredient, food-grade hydrogels, and biosensors were emphasized. Finally, the safety, challenges, and future perspectives of nanocellulose were discussed. This work provided key developments and effective benefits of nanocellulose for future research opportunities in food.

Conformational changes and physicochemical attributes of texturized pea protein isolate-konjac gum: With a new perspective of residence time during extrusion

The present study aimed to investigate the effects of different extrusion temperatures (110, 130 and 150 °C) and konjac gum addition (0.1 %, 0.2 %, and 0.3 %) on the flow behavior, physicochemical properties and microstructure of extruded pea protein isolate (PPI). The results showed that the textured protein could be improved by enhancing the extrusion temperature and adding konjac gum during extrusion. The water/oil holding capacity of PPI decreased and the SH content increased after extrusion. With temperature and konjac gum content increased, the β-sheet of extruded proteins transformed to other secondary structural components, and Trp residue transformed to a more polar environment, illustrating the changes in protein conformation. All extruded samples presented as yellow hue with little green and higher lightness, while excessive extrusion process reduced the brightness and promoted more formation of browning pigments. Extruded protein showed more associated layered with some air pores, and its hardness and chewiness increased with the increase of temperature and konjac gum concentration. Cluster analysis showed that the addition of konjac gum could effectively improve the quality characteristics of pea protein under low temperature extrusion, and the effect was similar to that of high temperature extrusion product. With the increase of konjac gum concentration, the flow pattern of protein extrusion gradually converted from plug flow to mixing flow, and the disorder degree of polysaccharide protein mixing system was enhanced. Moreover, Yeh-jaw model showed better fitting effect in F(θ) curves compared to Wolf-white.

Biopolymer-based pickering high internal phase emulsions: Intrinsic composition of matrix components, fundamental characteristics and perspective

Pickering HIPEs have received tremendous attention in recent years due to their superior stability and unique solid-like and rheological properties. Biopolymer-based colloidal particles derived from proteins, polysaccharides and polyphenols have been demonstrated to be safety stabilizers for the construction of Pickering HIPEs, which can meet the demands of consumers for "all-natural" products and provide "clean-label" foods. Furthermore, the functionality of these biopolymers can be further extended by forming composite, conjugated and multi-component colloidal particles, which can be used to modulate the properties of the interfacial layer, thereby adjusting the performance and stability of Pickering HIPEs. In this review, the factors affecting the interfacial behavior and adsorption characteristics of colloidal particles are discussed. The intrinsic composition of matrix components and fundamental characteristics of Pickering HIPEs are emphatically summarized, and the emerging applications of Pickering HIPEs in the food industry are reviewed. Inspired by these findings, future perspectives concerning this field are also put forward, including (1) the exploration of the interactions between biopolymers used to produce Pickering HIPEs and target food ingredients, and the influence of the added biopolymers on the flavor and mouthfeel of the products, (2) the investigation of the digestion properties of Pickering HIPEs under oral administration, and (3) the fabrication of stimulus-responsive or transparent Pickering HIPEs. This review will give a reference for exploring more natural biopolymers for Pickering HIPEs application development.

Emulsions stabilised by casein and hyaluronic acid: Effects of high intensity ultrasound on the stability and vitamin E digestive characteristics

This study aimed to prepare an emulsion stabilised by an ultrasound-treated casein (CAS)-hyaluronic acid (HA) complex and to protect vitamin E during in vitro digestion. It was found that high-intensity ultrasound (HIU) treatment significantly changed the hydrogen bonding, electrostatic interaction and hydrophobic interaction between CAS and HA, reduced the particle size of the CAS-HA complex, increased the intermolecular electrostatic repulsion, and thus significantly improved the emulsifying properties of the CAS-HA complex. Meanwhile, the creaming index (CI) and confocal laser scanning microscopy images showed that the stability of the CAS-HA-stabilised emulsion was the best when treated at 150 W for 10 min, which could be attributed to the enhanced adsorption capacity of the CAS-HA complex at the oil-water interface and the viscosity of the formed emulsion. In vitro digestion experiments revealed that the emulsion stabilised by the ultrasound-treated CAS-HA complex had a good protective effect on vitamin E. This study is significant for the development of emulsions for the delivery of lipophilic nutrients.

Formulation and stabilization of high internal phase emulsions: Stabilization by cellulose nanocrystals and gelatinized soluble starch

In this work, high internal phase emulsions (HIPEs) stabilized by naturally derived cellulose nanocrystals (CNC) and gelatinized soluble starch (GSS) were fabricated to stabilize oregano essential oil (OEO) in the absence of surfactant. The physical properties, microstructures, rheological properties, and storage stability of HIPEs were investigated by adjusting CNC contents (0.2, 0.3, 0.4 and 0.5 wt%) and starch concentration (4.5 wt%). The results revealed that CNC-GSS stabilized HIPEs exhibited good storage stability within one month and the smallest droplets size at a CNC concentration of 0.4 wt%. The emulsion volume fractions of 0.2, 0.3, 0.4 and 0.5 wt% CNC-GSS stabilized HIPEs after centrifugation reached 77.58, 82.05, 94.22, and 91.41 %, respectively. The effect of native CNC and GSS were analyzed to understand the stability mechanisms of HIPEs. The results revealed that CNC could be used as an effective stabilizer and emulsifier to fabricate the stable and gel-like HIPEs with tunable microstructure and rheological properties.

Characterization of bacterial cellulose nanofibers/soy protein isolate complex particles for Pickering emulsion gels: The effect of protein structure changes induced by pH

In this work, the influence of soy protein isolated at different pH values (1-9) on the self-assembly behaviors of bacterial cellulose nanofibers/soy protein isolate (BCNs/SPI) colloidal particles via anti-solvent precipitation were investigated. The results showed that the formation of BCNs/SPI at pH values of 1-5 was mainly driven by electrostatic interaction, while the formation of those at pH values of 5-9 was driven by weak molecular interactions including hydrogen bonding and steric-hindrance effect. The FTIR demonstrated that the conformation of protein involved a transition from order to disorder at the level of secondary structure as pH values were away from the isoelectric point. The fluorescence spectroscopy and UV-vis adsorption spectroscopy indicated that hydrophobic region of SPI at pH value of 5 displayed more exposed as compared with that at pH values away from the isoelectric point. The changes in structure conformation of SPI induced by pH values led to the changes in properties of the BCNs/SPI colloidal particles including particle size, microstructure, crystallinity, hydrophily, thermal stability, and rheological properties. Furthermore, the structures of BCNs/SPI colloidal particles at different pH values significantly affected the stability of Pickering emulsion gels stabilized by the corresponding complex colloidal particles. This study provided a theoretical basis for the design of food-grade Pickering emulsion gels stabilized by BCNs/SPI complex colloidal particles.

Protein-Based High Internal Phase Pickering Emulsions: A Review of Their Fabrication, Composition and Future Perspectives in the Food Industry

Protein-based high internal phase Pickering emulsions (HIPEs) are emulsions using protein particles as a stabilizer in which the volume fraction of the dispersed phase exceeds 74%. Stabilizers are irreversibly adsorbed at the interface of the oil phase and water phase to maintain the droplet structure. Protein-based HIPEs have shown great potential for a variety of fields, including foods, due to the wide range of materials, simple preparation, and good biocompatibility. This review introduces the preparation routes of protein-based HIPEs and summarizes and classifies the preparation methods of protein stabilizers according to their formation mechanism. Further outlined are the types and properties of protein stabilizers used in the present studies, the composition of the oil phase, the encapsulating substances, and the properties of the constituted protein-based HIPEs. Finally, future development of protein-based HIPEs was explored, such as the development of protein-based stabilizers, the improvement of emulsification technology, and the quality control of stabilizers and protein-based HIPEs.

Enhancing the stability of oil-in-water emulsions by non-covalent interaction between whey protein isolate and hyaluronic acid

This study aimed to investigate the effect of non-covalent interactions between different concentrations (0.1-1.2 %, w/v) of hyaluronic acid (HA) and 3 % (w/v) whey protein isolate (WPI) on the stability of oil-in-water emulsions. Non-covalent interactions between WPI and HA were detected using Fourier-transform infrared spectroscopy. The addition of HA increased the electrostatic repulsion between molecules and reduced the particle size of WPI. Circular dichroism spectroscopy results indicated that the addition of HA caused an increase in β-sheet content and a decrease in α-helix and random coil content in WPI. Moreover, HA increased the emulsion viscosity and strength of the interfacial network structure. Micrographs obtained using confocal laser scanning microscopy indicated that the emulsion with 0.8 % (w/v) HA exhibited good dispersion and homogeneity after storage for 14 d. Complexation with HA significantly altered the rheological and emulsifying properties of WPI, providing an emulsion with excellent stability under heating treatment, freeze-thawing treatment and centrifugation. The results provide a potential for HA application in emulsified foods.

Natural Amphiphilic Shellac Nanoparticle-Stabilized Novel Pickering Emulsions with Droplets and Bi-continuous Structures

Shellac is a natural amphiphilic substance, and its nanoparticles can be used to stabilize Pickering emulsions with droplets and bi-continuous structures. In this study, shellac nanoparticles (SNPs) were produced through the anti-solvent method, and these SNPs were used to produce a series of Pickering emulsions. Fourier transform infrared results showed that SNPs were generated through hydrogen bonding and hydrophobic effects. The contact angle of SNPs was 122.3°, indicating that hydrophobicity was their dominant characteristic. According to the results of confocal laser scanning microscopy, the Pickering emulsions stabilized by SNPs showed oil-in-water, bi-continuous structure, and water-in-oil characteristics, which were dependent on the oil-phase content. The resistance value of the emulsified part of these Pickering emulsion systems significantly increased at an oil-phase ratio of 80-90% (more than 10⁵ MΩ), as compared with the 10-70% oil-phase content (around 1 MΩ). The viscosity of SNP-stabilized Pickering emulsions with bi-continuous structures was highest at 40% oil-phase content. The porous material prepared by using Pickering emulsions with bi-continuous structures as a template had an interconnected structure and was able to absorb both water and oil. This study indicated that these amphiphilic SNPs readily form bi-continuous structures and effectively stabilize Pickering emulsions with droplets. These SNPs are expected to have increased application in food and pharmaceutical industries.

Bacterial Cellulose Nanofibril-Based Pickering Emulsions: Recent Trends and Applications in the Food Industry

The Pickering emulsion stabilized by food-grade colloidal particles has developed rapidly in recent decades and attracts extensive attention for potential applications in the food industry. Bacterial cellulose nanofibrils (BCNFs), as green and sustainable colloidal nanoparticles derived from bacterial cellulose, have various advantages for Pickering emulsion stabilization and applications due to their unique properties, such as good amphiphilicity, a nanoscale fibrous network, a high aspect ratio, low toxicity, excellent biocompatibility, and sustainability. This review provides a comprehensive overview of the recent advances in the Pickering emulsion stabilized by BCNF particles, including the classification, preparation method, and physicochemical properties of diverse BCNF-based particles as Pickering stabilizers, as well as surface modifications with other substances to improve their emulsifying performance and functionality. Additionally, this paper highlights the stabilization mechanisms and provides potential food applications of BCNF-based Pickering emulsions, such as nutrient encapsulation and delivery, edible coatings and films, fat substitutes, etc. Furthermore, the safety issues and future challenges for the development and food-related applications of BCNFs-based Pickering emulsions are also outlined. This work will provide new insights and more ideas on the development and application of nanofibril-based Pickering emulsions for researchers.

Janus particles: A review of their applications in food and medicine

In contrast to conventional particles that have isotropic surfaces, Janus ("two-faced") particles have anisotropic surfaces, which leads to novel physicochemical properties and functional attributes. Janus particles with differing compositions, structures, and functional attributes have been prepared using a variety of fabrication methods. Depending on their composition, Janus particles have been classified as inorganic, polymeric, or polymeric/inorganic types. Recently, there has been growing interest in preparing Janus particles from biological macromolecules to meet the demand for a more sustainable and environmentally friendly food and pharmaceutical supply. At interfaces, Janus particles exhibit the characteristics of both surfactants and Pickering stabilizers, and so their behavior can be described using adsorption theories developed to describe these surface-active substances. Research has highlighted several potential applications of Janus particles in food and medicine, including emulsion formation and stabilization, toxin detection, antimicrobial activity, drug delivery, and medical imaging. Nevertheless, further research is needed to design and fabricate Janus particles that are suitable as functional ingredients in the food and biomedicine industries.