Gelatin molecular structures affect behaviors of fish oil-loaded traditional and Pickering emulsions

The Preparation, Properties, and Characterization of Octenyl Succinic Anhydride-Modified Turmeric Starches and Their Emulsification for Pickering Emulsions

Turmeric has extensive applications in various fields, including food and medicine. However, research on turmeric starch remains relatively scarce. There is a significant lack of in-depth studies on its processing properties and starch modification abilities. In this context, octenyl succinic anhydride (OSA)-modified turmeric starches (O-MTSs) were synthesized. Subsequently, a comprehensive investigation was carried out, including property analysis, characterization, and evaluation of the emulsifying capacity. The alterations in solubility, swelling degree, syneresis, and transparency of turmeric starches before and after modification were systematically studied. The characterization of O-MTSs was conducted using a scanning electron microscope (SEM), particle size analysis, X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis. The possibility of using O-MTS as an emulsifier to prepare Pickering emulsions was explored. The results show that O-MTS had better solubility, swelling degree, syneresis, and transparency compared to turmeric starches (TSs). The O-MTS retained a relatively intact morphology, but its particle size slightly increased, and the characteristic peak at 995 cm-1 shifted to some extent. The relative crystallinity decreased from 32.59% to 18.39%, and the water-binding capacity of O-MTSs improved accordingly. O-MTSs could better stabilize Pickering emulsions as an emulsifier compared to TSs. With the increase in the degree of substitution (DS) and concentration of the O-MTS, its emulsification index (EI) demonstrated an upward trend.

Tripolyphosphate-chitosan-pea protein interactions confers long-term stability to 3D printed high internal phase Pickering emulsions

This research explores the interactions of tripolyphosphate-chitosan-pea protein (TPP-CS-PP) in improving the stability and storage of 3D printing food inks. Chitosan (CS) and pea protein (PP) were complexed at various concentrations with 80 % palm olein to produce high internal phase Pickering emulsions (HIPPEs) 3D printing food inks. The resulting CSPP HIPPEs exhibited shear-thinning behaviour and the flexibility to switch between solid and liquid states, ideal for 3D printing. CSPP1:150 achieved the best 3D printing resolution and shape fidelity due to electrostatic attraction of CS-PP and excess PP enhancing adhesion at the oil/water interface. After spraying tripolyphosphate (TPP), crosslinking with CS and phosphorylation of PP further improved HIPPE resistance to deformation and oiling off for 2 days post-printing. This is a significant improvement over the control. Thus, further investigation on the interaction of TPP with CS and PP is warranted to further improve the storage stability of 3D printed food inks.

Stable Pickering emulsions of cinnamaldehyde were formulated using tannic acid-assisted cellulose nanofibers and applied for mango preservation

Recent explorations into cinnamaldehyde (CIN) have identified its potential as a natural preservative, particularly when incorporated into active packaging to enhance the shelf-life of fruits and vegetables. This study explores the use of cellulose nanofiber (CNF)-stabilized Pickering emulsions as a novel delivery system for essential oils, demonstrating broad applicability in food preservation strategies. We employ CNF as Pickering stabilizers to effectively emulsify and encapsulate CIN, investigating the influence of tannic acid (TA) concentrations on the stability of these emulsions. Results reveal that a TA concentration of 0.05 % significantly improves emulsion stability against centrifugation, freeze-thaw cycles, and thermal stresses. This enhanced stability is attributed to hydrogen bonding between TA and CNF, which fosters a uniform and robust network structure. Moreover, the incorporation of TA markedly boosts both the antioxidant properties and the bacteriostatic effectiveness of the CIN Pickering emulsion. Notably, DPPH radical scavenging efficacy escalated from 31.96 % to 93.82 %, and ABTS radical scavenging increased from 22.0 % to 86.31 %. We developed a functional coating by integrating carboxymethyl chitosan (CMCS) with the CIN Pickering emulsions. Application of this coating on mangoes under ambient conditions proved effective in minimizing weight loss, retarding senescence, inhibiting enzymatic activities, and consequently extending the fruit's shelf life.

Fish oil-loaded silver carp scale gelatin-stabilized emulsions with vitamins for the delivery of curcumin

The encapsulation of curcumin in the emulsions has attracted much attention in functional food development. Herein, the fish oil-loaded silver carp scale gelatin-stabilized emulsions with vitamins were explored for the delivery of curcumin. The curcumin encapsulation had no obvious effect on the formation, storage stability, lipid oxidation, and in vitro droplet digestion behaviors of the emulsions. Both vitamin C (VC) and vitamin E (VE) additions had obvious effects on the peroxidation values of the emulsions: VC + VE < VC < VE < Control < fish oil. The accumulative free fatty acid release percentages were dependent on the vitamins: VC (89.6 ± 1.1%) > Control (86.1 ± 1.0%) > VC + VE (80.5 ± 0.8%) > VE (76.4 ± 1.2%). The emulsions' curcumin retention at room temperature and in vitro digestion behaviors (transformation, bioaccessibility, and bioaccessibility index) depended on vitamin additions: VC + VE ≈ VC > VE ≈ Control. This work was beneficial for the development of fish gelatin-stabilized emulsions to deliver curcumin.

Preparation of 1,2-benzenedialdehyde-crosslinked oligo-gelatin conjugates and poly-gelatin nanoparticles to stabilize traditional and Pickering emulsions, respectively

This research aimed to develop a desolvation and 1,2-benzenedialdehyde crosslinking method to prepare crosslinked gelatin substances for emulsion stabilization. The oligo-gelatin conjugates and poly-gelatin nanoparticles could be formed at the 1,2-benzenedialdehyde concentration of 50 g/L and ≥ 150 g/L, respectively. The formation mechanism involved intra/inter-molecular amine-benzenedialdehyde-thiol and amine-benzenedialdehyde-amine crosslinking reactions. With increasing 1,2-benzenedialdehyde preparation concentrations (50-450 g/L), the crosslinked gelatin substance sizes increased from 81.5 ± 20.1 nm to 105.5 ± 20.8 nm in the dried state, and increased (from 35 ± 8 nm to 220 ± 36 nm) then decreased to 115 ± 28 nm in the water. Furthermore, the fish oil emulsions stabilized by the crosslinked gelatin substances showed different creaming stability: 250 g/L (43.5 ± 1.5 %) > 350 g/L (41.4 ± 1.0 %) > 450 g/L (37.5 ± 2.2 %) > 150 g/L (11.2 ± 0.4 %) > 50 g/L (0.0 ± 0.0 %). The results suggested this method was useful for preparing oligo-gelatin conjugates and poly-gelatin nanoparticles to stabilize traditional and Pickering emulsions, respectively.

Enhanced stability of curcumin encapsulated in fish gelatin emulsions combined with γ-Polyglutamic acid

This study examined the rheological properties, interfacial characteristics, particle size, zeta potential, Turbiscan stability index (TSI), morphology, and encapsulation efficiency of curcumin (Cur) loaded fish gelatin (FG) emulsions modified with γ-polyglutamic acid (γ-PGA). The results showed that adding γ-PGA significantly increased curcumin encapsulation efficiency. At 0.3 mg/mL, FG emulsions had an encapsulation efficiency of 80.14 %, while FG-γ-PGA emulsions reached 90.35 %. The FG-γ-PGA emulsions also showed enhanced stability and resistance to phase separation, remaining stable for seven days, compared to three days for FG emulsions. After 24 h, the TSI of FG emulsions with 0.6 mg/mL Cur was 2.46, significantly higher than the 0.55 TSI for FG-γ-PGA emulsions at the same concentration. FG-γ-PGA emulsions had smaller droplet sizes, and analysis of interfacial characteristics, particle size, and zeta potential indicated better system stability than FG emulsions. These improved properties of FG-γ-PGA emulsions highlight their potential as efficient carriers for curcumin. Overall, the favorable characteristics of FG-γ-PGA emulsions suggest promising applications in the food industry, especially for developing functional foods with extended shelf life and enhanced nutritional benefits.

Benzenedialdehyde-crosslinked gelatin nanoparticles for Pickering emulsion stabilization

In this work, three types of benzenedialdehydes (1,2-, 1,3-, and 1,4-BDAs) were used to prepare BDA-crosslinked gelatin nanoparticles and the 1,2-BDA-crosslinked gelatin nanoparticle was explored to stabilize fish oil-loaded Pickering emulsions. The nanoparticle preparation was dependent on both pH and crosslinker types. 1,2-BDA and preparation pH of 12.0 induced the most nanoparticle amounts among the three BDAs and a pH range of 3.0-12.0. The crosslinked gelatin nanoparticles (10-nm scale) could aggregate to form larger nanoparticles (hundred-nanometer scale) in the water. The BDA crosslinking induced lower emulsifying properties (EAI: 10.2 ± 0.3 m2/g; ESI: 69.7 ± 3.6 min) for gelatin nanoparticles than gelatin (EAI: 30.9 ± 0.6 m2/g; ESI: 267.8 ± 2.0 min). With the increase of the gelatin nanoparticle concentrations (5-40 g/L), the emulsion viscosity increased (163 ± 9-422 ± 3 mPa s at the rotary speed of 60 rpm), the interfacial tension decreased (10.3 ± 0.2-7.2 ± 0.2 mN/m), and the creaming indexes decreased (42.1% ± 0.7%-13.3% ± 0.8% at day 21). The higher sodium chloride concentration (0.0-0.8 mol/L) induced the lower emulsion stability, even obvious phase separation (0.8 mol/L of NaCl). Therefore, the sodium chloride addition should be carefully considered for the development of emulsion-based foods. This work provided useful information for the development and application of protein nanoparticles.

Complex coacervation of low methoxy pectin with three types of gelatins for the encapsulation of fish oil

Herein, the complex coacervation of low methoxy pectin (LMP) with three types of gelatins was explored to encapsulate fish oil. The fish oil@gelatin-LMP complex coacervates with good precipitation separation could be obtained at low gelatin concentrations (Fish gelatin, FG: 10-80 mg/mL; porcine skin gelatin, PSG: 10-40 mg/mL; bovine skin gelatin, BSG: 10-80 mg/mL), high gelatin: fish oil mass ratios (4:1-1:1), appropriate gelatin: LMP mass ratios (3:1-12:1 for FG and PSG, 6:1 for BSG), and appropriate pH (FG: 4.90-5.50; PSG: 4.80-5.40; BSG: 4.10-4.50). FG induced similar loading ability, lower encapsulation ability, and comparable peroxide values to the mammalian gelatins. FG induced higher or similar free fatty acid released percentages to mammalian gelatins in the in vitro gastrointestinal model at low gelatin concentrations (10-40 mg/mL). These results provided useful information to understand the protein-polysaccharide complex coacervation to encapsulate oil-based bioactive substances.

Preparation and characterization of high-methoxyl pectin/glycerides emulsion for pH-responsive, targeting, and sustained release of fat-soluble substances

In this study, a pH-responsive emulsion system was prepared, combining high-methoxyl pectin (HMP) with camellia oil glycerides (CG). The emulsion was characterized as O/W type, with HMP serving as the wall material and CG as the oil phase. The physicochemical properties, pH responsiveness, digestion stability, and encapsulated delivery capabilities of the HMP-CG emulsion were investigated. The emulsion showed an average droplet size of 480.47 ± 76.19 nm, possessing a negative charge and a pronounced core-shell structure. HMP package CG enhanced hydrophilic ability and enabled targeted release within the small intestine through the structural changes of HMP. The presence of HMP and CG increased droplet dispersion and target digestibility of the emulsion system, leading to sustainable small intestine-specific release. Overall, HMP-CG emulsion system, composed of natural materials, exhibited the ability to achieve targeted and controllable release via pH-responsive mechanisms, offering an alternative for developing gel materials incorporating fat-soluble substances.

Characteristics and stabilization of Pickering emulsions constructed using myosin from bighead carp (Aristichthys nobilis)

Myosin from bighead carp (Aristichthys nobilis) as a main type of fish protein possesses a good emulsifying ability. However, whether bighead carp myosin (BCM) could construct stable Pickering emulsions is still unclear. Therefore, myosin particles and Pickering emulsions stabilized by bighead carp myosin (BCMPEs) were analyzed. The surface structure of BCM particles at 0.6 mol/L NaCl treatment was uniform and compact with a contact angle of 86.4 ± 2.7°, exhibiting the potential ability to construct O/W Pickering emulsions. The size and flocculation index (FI) of BCMPEs decreased with the increase in BCM concentrations of 1%-4% (w/v). Reversely, the size of BCMPEs increased with the increase in oil-water ratios. BCM particles could uniformly distribute at the oil-water interface to stabilize BCMPEs at a BCM concentration of 4% (w/v) and an oil-water ratio of 6:4 (v/v). This study could help explore fish proteins to construct Pickering emulsions for the deep processing of fish products.

Effects of five tissue sources of silver carp by-products on the structure, physicochemical and emulsifying properties of gelatin

The effects of tissue sources on gelatin's physicochemical and functional properties remain unclear. This work aimed to analyze the effects of five tissue sources on the properties of fish gelatins. Five gelatins were extracted from different silver carp by-products (skin, scale, fin, head, and bone) and the effects of tissue sources on the gelatin's properties were studied. The gelatin's β-sheet percentages and total sodium dodecyl sulfate-polyacrylamide gel electrophoresis band intensities (β, α1, and α2 chains) showed similar dependence to the tissue sources: skin ≈ scale > fin ≈ head > bone. Bone-related gelatins (from head and bone) showed lower water-holding capacity and fat-binding capacity values than the other gelatins. Tissue sources significantly affected the gelatin's gel strength values: skin ≈ fin > scale > bone ≈ head. Scale and bone gelatin solutions had significantly lower rheological apparent viscosities than other by-product gelatin solutions. The interfacial tension and rheological apparent viscosity values of the fish oil-loaded gelatin-stabilized emulsions depended on the gelatin tissue sources and gelatin concentrations. In particular, skin, scale, and fin gelatins induced no obvious emulsion creaming at the gelatin concentration of 10 g/L during the emulsion storage. Bone-related gelatins induced higher emulsion creaming index values for the emulsions with 10 g/L of gelatins during the emulsion storage. This work confirmed tissue sources could significantly affect the properties of gelatins. Five tissue sources had different effects on the structural, physicochemical, and emulsifying properties of silver carp by-product gelatins. Especially, the gelatins from different silver carp by-products showed different water-holding and fat-binding capacities, gel strengths, interfacial tension, rheological apparent viscosities, and emulsion stabilization abilities. These properties are important considerations for the application of silver carp by-product gelatins in food and other industries.

A novel Pickering emulsion gels stabilized by cellulose nanofiber/dihydromyricetin composite particles: Microstructure, rheological behavior and oxidative stability

Particle concentrations (w) and oil content (Φ) are crucial factors influencing the gel stability of Pickering emulsions. To understand the stabilization mechanism comprehensively, we prepared emulsion gels stabilized by CNF/DMY composite particles at various w (0.5-1.5 wt%) and Φ (0.2-0.6, v/v). The microstructure revealed the adsorption of these particles at the oil-water interface, with excess particles forming a three-dimensional network structure in the continuous phase. Rheological studies showed that the network structure of Pickering emulsions was significantly influenced by w and Φ, resulting in improved emulsion gel strength that hindered the movement of oil droplets and oxygen in the continuous phase, thereby enhancing emulsion stability. Three scenarios for the critical strain (γco) were observed: at Φ = 0.2, γco decreased with increasing w, while at Φ = 0.4, γco increased with increasing w. At Φ = 0.6, γco remained relatively constant regardless of w. In conclusion, adjusting particle concentration and oil content enabled the control of microstructure, rheological properties, and antioxidant capacity of emulsion gels. These findings could be a valuable resource for formulating and ensuring the quality of emulsion gel-based products in the food industry.

Developing fish oil emulsion gel enriched with Lentinula edodes single cell protein and its effect on controlling the growth of Acinetobacter baumannii

In this study, the characterization of fish oil (FO) emulsion gel (EGEL) containing single cell protein (SCP) produced from Lentinula edodes (L. edodes) and its potential inhibition against Acinetobacter baumannii (A. baumannii) were investigated. Oil extracted from the fish liver was emulsified with tween 80 and water, and then gelled using gelatin with the assistance of an ultrasonic homogenizer. The characteristics and surface analysis of SCP-EGEL were examined using FTIR (Fourier-transform infrared spectroscopy) and SEM (Scanning electron microscope). The particle size distribution and zeta potential of SCP-EGEL were measured using a Malvern Zetasizer. When SCP-EGEL was applied to the surface of the medium inoculated with A. baumannii, the inhibition zone (IZ) was 8.2 mm. An expansion of the IZ was observed (10.2 mm) when SCP-EGEL was applied to a fish skin (FS) surface prepared in the shape of a 6-mm diameter disc. In the SEM images, when SCP was added to lipo gel, the gel structure appeared flattened or swollen in some areas. The appearance of SCP cells being covered with gel gave the impression that they have a secondary wall. Therefore, the resulting complex can potentially be used as an additive in animal and human nutrition, in functional food coatings to suppress A. baumannii, and in fish feed to enrich it with protein.

Tilapia head gelatins to stabilize fish oil emulsions and the effect of extraction methods

The preparation and use of gelatins from fish by-products have attracted much attention in the field of food science. Herein, four types of tilapia head gelatins were extracted and characterized: hot water-pretreated gelatin (HWG), acetic acid-pretreated gelatin (AAG), sodium hydroxide-pretreated gelatin (SHG), and pepsin enzyme-pretreated gelatin (PEG). The gel strength values followed the order: PEG (74 ± 1 Bloom) > AAG (66 ± 1) > HWG (59 ± 1) > SHG (34 ± 1). The foaming properties, fish oil emulsion viscosity, emulsion activity, and emulsion stabilization ability followed this order: PEG > HWG ≥ AAG > SHG. The effect mechanisms of extraction methods and gelatin concentrations on the emulsion stability involved the interfacial tension, emulsion viscosity, and fat-binding capacity. This work provided important knowledge for analyzing the relations between the structure and function of gelatin. It also provided a high-value application method of fish wastes.

O1/W/O2 double emulsion gels based on nanoemulsions and Pickering particles for co-encapsulating quercetin and cyanidin: A functional fat substitute

An O1/W/O2 double emulsion gel, as a functional fat substitute and based on nanoemulsions and hydrophobic Pickering particles, is prepared by two-step emulsification to co-encapsulate hydrophilic cyanidin and hydrophobic quercetin. Nanoemulsions loading quercetin are fabricated by Tween-80 and combining high-speed and high-pressure emulsification. Phytosterol nanoparticles stabilize the W-O2 interface of the secondary emulsion to load cyanidin in the W phase. The concentration of Tween-80 is optimized as 0.3% by the droplet size and viscosity of nanoemulsions. The structural stability of double emulsion gels will be weakened along with the increase of nanoemulsions, showing lower modulus and encapsulation efficiency (EE) and bigger droplets. In double emulsion gels, the EE of quercetin and cyanidin reaches 93% and 85.6%, respectively. Analysis of molecular interaction indicates that Tween-80 would decrease the in-situ hydrophobicity of phytosterol nanoparticles by hydrogen bonding adsorption, thereby weakening the emulsification. The pH-chromic 3D printing of double emulsion gels is designed according to the pH sensitivity of cyanidin. Texture profile analysis is performed to test the textural properties of 3D-printed objects. The simulated digestion is conducted on double emulsion gels. The double emulsion gel with fewer nanoemulsions is beneficial for protecting quercetin and improving the delivery due to the higher structural stability, while that with more nanoemulsions is conducive to the digestion of cyanidin and camellia oil due to weakened semi-solid properties. This double emulsion gel further simulates fat tissues by co-encapsulating hydrophilic and hydrophobic substances, promoting the application of fat substitutes in the food industry.

Molecular modification of low-dissolution soy protein isolates by anionic xanthan gum, neutral guar gum, or neutral konjac glucomannan to improve the protein dissolution and stabilize fish oil emulsion

Herein, the effects of anionic xanthan gum (XG), neutral guar gum (GG), and neutral konjac glucomannan (KGM) on the dissolution, physicochemical properties, and emulsion stabilization ability of soy protein isolate (SPI)-polysaccharide conjugates were studied. The SPI-polysaccharide conjugates had better water dissolution than the insoluble SPI. Compared with SPI, SPI-polysaccharide conjugates had lower β-sheet (39.6 %-56.4 % vs. 47.3 %) and α-helix (13.0 %-13.2 % vs. 22.6 %) percentages, and higher β-turn (23.8 %-26.5 % vs. 11.0 %) percentages. The creaming stability of SPI-polysaccharide conjugate-stabilized fish oil-loaded emulsions mainly depended on polysaccharide type: SPI-XG (Creaming index: 0) > SPI-GG (Creaming index: 8.1 %-21.2 %) > SPI-KGM (18.1 %-40.4 %). In addition, it also depended on the SPI preparation concentrations, glycation times, and glycation pH. The modification by anionic XG induced no obvious emulsion creaming even after 14-day storage, which suggested that anionic polysaccharide might be the best polysaccharide to modify SPI for emulsion stabilization. This work provided useful information to modify insoluble proteins by polysaccharides for potential application.

Inhibition performance of almond shell hydrochar-based fish oil emulsion gel on Klebsiella pneumonia inoculated fish skin and its characteristics

In this study, the inhibition potential against Klebsiella pneumoniae (K. pneumoniae) and the characterization of fish oil (FO) emulsion gel (EGE) containing almond shell hydrochar (AH) were investigated. Oily water of mullet liver was emulsified using tween 80, then gelled using gelatin and finally immobilized into hydrochar using an ultrasonic homogenizer. Characteristics and surface analysis of hydrochar-based emulsion gel (HEGE) were examined using FTIR and SEM. Stability, particle size distribution and zeta potential of HEGE were measured. In this study, a zeta potential of -18.46 indicated that HEGE was more stable than EGE (35.7 mV). The addition of hydrochar to the emulsion gel containing micro-droplets enabled the structure to become fully layered and stable. Time-dependent inactivation of K. pneumoniae exposed to HEGE and fixed in 6 mm-fish skin was evaluated for the first time in this study. While the highest log reduction and percent reduction in the bacterial count were achieved within 5 min with 0.87 CFU/cm2 and 86.60% with EGE, the lowest log reduction and percent reduction were achieved with 0.003 CFU/cm2 and 0.082% with HEGE in 30 min. In conclusion, the almond shell hydrochar-immobilized emulsion gel is a functional adsorbent that can inhibit K. pneumonia, and its stability and performance make it a unique candidate for further studies in this field.

Modulation of pea protein isolate nanoparticles by interaction with OSA-corn starch: Enhancing the stability of the constructed Pickering emulsions

The impact of particle concentration (0.5-2.5%) on the stability of Pickering emulsions was investigated in this work. Pickering emulsion was prepared using pea protein isolate (PPI)/octenyl succinic anhydrate corn starch (OSA-CS) composite nanoparticles (PPI/OSA-CS) as stabilizers. PPI/OSA-CS was prepared with pH adjustment and ultrasonic treatment, and the particle size was 100.05 ± 0.46 nm. The formation of PPI/OSA-CS through hydrophobic interaction and hydrogen bond was confirmed by Fourier transform infrared spectroscopy, intrinsic fluorescence spectroscopy and dissociation analysis. The results indicated that the emulsion stabilized with composite nanoparticles at 1.5% particle concentration had smaller particle size and better stability than at other concentrations. This could be attributed to the presence of sufficient composite nanoparticles wrapped around the surface of oil droplets. At high temperature (100 °C) and high ionic strength (500 mM), the emulsion remained stable. These results provide a potential method for preparing a novel and stable Pickering emulsion, which could have important applications in various fields.

Rheology, physicochemical properties, and microstructure of fish gelatin emulsion gel modified by γ-polyglutamic acid

In this work, the effect of the addition of γ-polyglutamic acid (γ-PGA) on the rheology, physicochemical properties, and microstructure of fish gelatin (FG) emulsion gel was investigated. Samples of the emulsion gel were evaluated for rheological behavior and stability prior to gelation. The mechanical properties and water-holding capacity (WHC) of the emulsion were determined after gelation. The microstructure of the emulsion gel was further examined using confocal laser scanning microscopy (CLSM). The results indicated a gradual increase in the apparent viscosity and gelation temperature of the emulsion at a higher concentration of γ-PGA. Additionally, frequency scan results revealed that on the addition of γ-PGA, FG emulsion exhibited a stronger structure. The emulsion containing 0.1% γ-PGA exhibited higher stability than that of the control samples. The WHC and gel strength of the emulsion gel increased on increasing the γ-PGA concentration. CLSM images showed that the addition of γ-PGA modified the structure of the emulsion gel, and the droplets containing 0.1% γ-PGA were evenly distributed. Moreover, γ-PGA could regulate the droplet size of the FG emulsion and its size distribution. These findings suggest that the viscoelasticity and structure of FG emulsion gels could be regulated by adjusting the γ-PGA concentration. The γ-PGA-modified FG emulsion gel also exhibited improved rheology and physicochemical properties. The results showed that γ-PGA-modified FG emulsion gel may find potential applications in food, medicine, cosmetics, and other industries.

Preparation of food-grade EDC/NHS-crosslinked gelatin nanoparticles and their application for Pickering emulsion stabilization

Herein, a safe desolvation and crosslinking method was developed to prepare food-grade bovine bone gelatin (BBG) nanoparticles for Pickering emulsion stabilization. The nanoparticle-like structures were formed by adjusting pH 9.0 and adding ethanol, and then stable nanoparticles were formed by using N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide (EDC) and N-hydroxysuccinimide (NHS) as crosslinker. Compared with other pH (2.5, 5.0, 7.0, and 12.0), pH 9.0 was the appropriate pH to prepare BBG nanoparticles. Individual nanoparticles (6.50 nm in height), oligomeric nanoparticles (13.42-22.52 nm in height), and polymeric nanoparticles (obvious liquid-precipitate separation) were formed at EDC·HCl/NHS concentrations of 6, 9-12, and 15-20 mg/mL, respectively. The oligomeric nanoparticles induced the highest emulsion creaming stability. The emulsion creaming ability increased with the increase of BBG nanoparticle concentrations. Low NaCl concentration (e.g., 100 mmol/L) could increase the emulsion creaming stability. Finally, 4 °C was the best storage temperature for fish oil-loaded Pickering emulsions.

Classification and design strategies of polysaccharide-based nano-nutrient delivery systems for enhanced bioactivity and targeted delivery: A review

Since many nutrients are highly sensitive, they cannot be absorbed and utilized efficiently by the body. Using nano-delivery systems to encapsulate nutrients is an effective method of solving the problems associated with the application of nutrients at this stage. Polysaccharides, as natural biomaterials, have a unique chemical structure, ideal biocompatibility, biodegradability and low immunogenicity. This makes polysaccharides powerful carriers that can enhance the biological activity of nutrients. However, the true role of polysaccharide-based delivery systems requires an in-depth understanding of the structural and physicochemical characteristics of polysaccharide-based nanodelivery systems, as well as effective modulation of the intestinal delivery mechanism and the latest advances in nano-encapsulation. This review provides an overview of polysaccharide-based nano-delivery systems dependent on different carrier types, emphasizing recent advances in the application of polysaccharides, a biocomposite material designed for nutrient delivery systems. Strategies for polysaccharide-based nano-delivery systems to enhance the bioavailability of orally administered nutrients from the perspective of the intestinal absorption barrier are presented. Characterization methods for polysaccharide-based nano-delivery systems are presented as well as an explanation of the formation mechanisms behind nano-delivery systems from the perspective of molecular forces. Finally, we discussed the challenges currently facing polysaccharide-based nano-delivery systems as well as possible future directions for the future.

Bacteriostatic Pickering emulsions stabilized by whey protein isolate-vanillin nanoparticles: Fabrication, characterization and stability in vitro

The purpose of this work was to prepare Pickering emulsion stabilized by bacteriostatic whey protein isolate-vanillin (WPI-Van) nanoparticles as a carrier for encapsulating vitamin E. The particle size, ζ potential, PDI were used to study the optimal preparation conditions of nanoparticles. The results showed that the optimal preparation condition was achieved at WPI/Van mass ratio of 3:1. FTIR spectra demonstrated the complexation of WPI and Van. SEM image showed spherical and slightly rough surface of nanoparticles. Inhibitory effects of nanoparticles on E. coli and S. aureus were also observed. After storage of 21 days at 4 °C, the retention rate of vitamin E in the emulsions remained 43% higher than that of unencapsulated vitamin E. Moreover, the release rate of vitamin E encapsulated in emulsions in the small intestine was 81%, indicating excellent bioaccessibility. The research can provide a new insight for production and application of antibacterial Pickering emulsions.

Surfactant-free gelatin-stabilised biodegradable polymerised high internal phase emulsions with macroporous structures

High internal phase emulsion (HIPE) templating is a well-established method for the generation of polymeric materials with high porosity (>74%) and degree of interconnectivity. The porosity and pore size can be altered by adjusting parameters during emulsification, which affects the properties of the resulting porous structure. However, there remain challenges for the fabrication of polyHIPEs, including typically small pore sizes (∼20-50 μm) and the use of surfactants, which can limit their use in biological applications. Here, we present the use of gelatin, a natural polymer, during the formation of polyHIPE structures, through the use of two biodegradable polymers, polycaprolactone-methacrylate (PCL-M) and polyglycerol sebacate-methacrylate (PGS-M). When gelatin is used as the internal phase, it is capable of stabilising emulsions without the need for an additional surfactant. Furthermore, by changing the concentration of gelatin within the internal phase, the pore size of the resulting polyHIPE can be tuned. 5% gelatin solution resulted in the largest mean pore size, increasing from 53 μm to 80 μm and 28 μm to 94 µm for PCL-M and PGS-M respectively. In addition, the inclusion of gelatin further increased the mechanical properties of the polyHIPEs and increased the period an emulsion could be stored before polymerisation. Our results demonstrate the potential to use gelatin for the fabrication of surfactant-free polyHIPEs with macroporous structures, with potential applications in tissue engineering, environmental and agricultural industries.

Behavior of protein-polysaccharide conjugate-stabilized food emulsions under various destabilization conditions

The sensitivity of protein-stabilized emulsions to flocculation, coalescence, and phase separation under destabilization conditions (i.e., heating, aging, pH, ionic strength, and freeze-thawing) may limit the widespread use of proteins as effective emulsifiers. Therefore, there is a great interest in modulating and improving the technological functionality of food proteins by conjugating them with polysaccharides, through the Maillard reaction. The present review article highlights the current approaches of protein-polysaccharide conjugate formation, their interfacial properties, and the behavior of protein-polysaccharide conjugate stabilized emulsions under various destabilization conditions, including long-term storage, heating and freeze-thawing treatments, acidic conditions, high ionic strength, and oxidation. Protein-polysaccharide conjugates are capable of forming a thick and cohesive macromolecular layer around oil droplets in food emulsions and stabilizing them against flocculation and coalescence under unfavorable conditions, through steric and electrostatic repulsion. The protein-polysaccharide conjugates could be therefore industrially used to design emulsion-based functional foods with high physicochemical stability.

Correlation between interfacial layer properties and physical stability of food emulsions: current trends, challenges, strategies, and further perspectives

Emulsions are thermodynamically unstable systems that tend to separate into two immiscible phases over time. The interfacial layer formed by the emulsifiers adsorbed at the oil-water interface plays an important role in the emulsion stability. The interfacial layer properties of emulsion droplets have been considered the cutting-in points that influence emulsion stability, a traditional motif of physical chemistry and colloid chemistry of particular significance in relation to the food science and technology sector. Although many attempts have shown that high interfacial viscoelasticity may contribute to long-term emulsion stability, a universal relationship for all cases between the interfacial layer features at the microscopic scale and the bulk physical stability of the emulsion at the macroscopic scale remains to be established. Not only that, but integrating the cognition from different scales of emulsions and establishing a unified single model to fill the gap in awareness between scales also remain challenging. In this review, we present a comprehensive overview of recent progress in the general science of emulsion stability with a peculiar focus on interfacial layer characteristics in relation to the formation and stabilization of food emulsions, where the natural origin and edible safety of emulsifiers and stabilizers are highly requested. This review begins with a general overview of the construction and destruction of interfacial layers in emulsions to highlight the most important physicochemical characteristics of interfacial layers (formation kinetics, surface load, interactions among adsorbed emulsifiers, thickness and structure, and shear and dilatational rheology), and their roles in controlling emulsion stability. Subsequently, the structural effects of a series of typically dietary emulsifiers (small-molecule surfactants,proteins, polysaccharides, protein-polysaccharide complexes, and particles) on oil-water interfaces in food emulsions are emphasized. Finally, the main protocols developed for modifying the structural characteristics of adsorbed emulsifiers at multiple scales and improving the stability of emulsions are highlighted. Overall, this paper aims to comprehensively study the literature findings in the past decade and find out the commonality of multi-scale structures of emulsifiers, so as to deeply understand the common characteristics and emulsification stability behaviour of adsorption emulsifiers with different interfacial layer structures. It is difficult to say that there has been significant progress in the underlying principles and technologies in the general science of emulsion stability over the last decade or two. However, the correlation between interfacial layer properties and physical stability of food emulsions promotes revealing the role of interfacial rheological properties in emulsion stability, providing guidance on controlling the bulk properties by tuning the interfacial layer functionality.

Curcumin-encapsulated hydrophilic gelatin nanoparticle to stabilize fish oil-loaded Pickering emulsion

Herein, pH-cycle method was explored to prepare curcumin-encapsulated hydrophilic bovine bone gelatin (BBG/Cur) nanoparticle and then the obtained nanoparticle was applied to stabilize fish oil-loaded Pickering emulsion. The nanoparticle had a high encapsulation efficiency (93.9 ± 0.5 %) and loading capacity (9.4 ± 0.1 %) for curcumin. The nanoparticle-stabilized emulsion had higher emulsifying activity index (25.1 ± 0.9 m²/g) and lower emulsifying stability index (161.5 ± 18.8 min) than BBG-stabilized emulsion. The pH affected the initial droplet sizes and creaming index values of the Pickering emulsions: pH 11.0 < pH 5.0 ≈ pH 7.0 ≈ pH 9.0 < pH 3.0. Curcumin provided obvious antioxidant effect for the emulsions, which was also dependent on pH. The work suggested pH-cycle method could be used to prepare hydrophobic antioxidant-encapsulated hydrophilic protein nanoparticle. It also provided basic information on the development of protein nanoparticles for Pickering emulsion stabilization.

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.

Gel-type emulsified muscle products: Mechanisms, affecting factors, and applications

The gel-type emulsified muscle products improve fatty acid composition, maintain the oxidative stability, and achieve a better sensory acceptability. This review emphasizes the stabilization mechanisms of these emulsified muscle products. In particular, factors associated with the stability of the emulsified muscle systems are outlined, including the processing conditions (pH and heating), lipids, and emulsifiers. Besides, some novel systems are further introduced, including the Pickering emulsions and organogels, due to their great potential in stabilizing emulsified gels. Moreover, the promising prospects of emulsion muscle products such as improved gel properties, oxidative stability, freeze-thaw stability, fat replacement, and nutraceutical encapsulation were elaborated. This review comprehensively illustrates the considerations on developing gel-type emulsified products and provides inspiration for the rational design of emulsified muscle formulations with both oxidatively stable and organoleptically acceptable performance.

Effect of extraction methods on the properties of tilapia scale gelatins

Three types of tilapia scale gelatins (hot water-pretreated gelatin, HWG; acetic acid-pretreated gelatin, AAG; and pepsin enzyme-pretreated gelatin, PEG) were extracted and their gel strength, foaming properties, and emulsifying properties were analyzed. They had different gel strength values: AAG (370 ± 10 g Bloom) > HWG (320 ± 10 g Bloom) > PEG (280 ± 10 g Bloom). The creaming index values of tilapia scale gelatin-stabilized fish oil-loaded emulsions were dependent on gelatin type (HWG ≈ AAG > PEG) at low gelatin concentration (2 mg/mL), whereas they were similar and low (8-10 %) at high gelatin concentration (10 mg/mL). Extraction methods had no consistently significant effects on the gelatin foaming properties. In summary, tilapia scale gelatins had better gel strength and foaming properties and similar or even better emulsifying properties than mammalian gelatins. Therefore, tilapia scales could be a potential source of gelatins to replace mammalian gelatins.

Recent progress in fish oil-based emulsions by various food-grade stabilizers: Fabrication strategy, interfacial stability mechanism and potential application

Fish oil, rich in a variety of long-chain ω-3 PUFAs, is widely used in fortified foods due to its broad-spectrum health benefits. However, its undesired characteristics include oxidation sensitivity, poor water solubility, and fishy off-flavor greatly hinder its exploitation in food field. Over the past two decades, constructing fish oil emulsions to encapsulate ω-3 PUFAs for improving their physicochemical and functional properties has undergone great progress. This review mainly focuses on understanding the fabrication strategies, stabilization mechanism, and potential applications of fish oil emulsions, including fish oil microemulsions, nanoemulsions, double emulsions, Pickering emulsions and emulsion gels. Furthermore, the role of oil-water interfacial stabilizers in the fish oil emulsions stability will be discussed with a highlight on food-grade single emulsifiers and natural complex systems for achieving this purpose. Additionally, its roles and applications in food industry and nutrition field are delineated. Finally, possible innovative food trends and applications are highlighted, such as novel fish oil-based delivery systems construction (e.g., Janus emulsions and nutraceutical co-delivery systems), exploring digestion and absorption mechanisms and enhancing functional evaluation (e.g., nutritional supplement enhancer, and novel fortified/functional foods). This review provides a reference for the application of fish oil-based emulsion systems in future precision diet intervention implementations.

Effects of antioxidant types on the stabilization and in vitro digestion behaviors of silver carp scale gelatin-stabilized fish oil-loaded emulsions

Lipid oxidation is a major challenge in the development and storage of lipid-containing food products. In this work, we extracted aquatic gelatin from silver carp scales and studied the effects of antioxidant types (water-soluble and lipid-soluble types) on the stabilization, lipid oxidation, and in vitro digestion behaviors of silver carp scale gelatin-stabilized fish oil-loaded emulsions. Vitamin C (VC), a water-soluble antioxidant, and vitamin E (VE), a lipid-soluble antioxidant, had no obvious effects on the appearance, droplet size distribution, and droplet stability of the emulsion. VC slowed the liquid-gel transition of the emulsions at room temperature. The emulsion creaming stability decreased with the increase of VC concentration, whereas it increased with the increase of VE concentration. Lipid oxidation hierarchy of emulsion groups at room temperature were VC<VE<control<pure oil. Free fatty acids were mainly released from the silver carp scale gelatin-stabilized emulsions in the simulated intestinal fluid. Moreover, compared with the control group, VC increased the free fatty acid release percentages, whereas VE decreased them. This work provided useful information for developing antioxidants in the field of food science and in value-added utilization research of aquatic by-products.

Pickering Emulsion Stabilized by Tea Seed Cake Protein Nanoparticles as Lutein Carrier

To effectively deliver lutein, hydrothermally prepared tea seed cake protein nanoparticles (TSCPN) were used to fabricate Pickering emulsion, and the bioaccessibility of lutein encapsulated by Pickering emulsion and the conventional emulsion was evaluated in vitro. The results indicated that the average size and absolute value of zeta potential of TSCPN increased along with the increase in the protein concentration, and 2% protein concentration was adopted to prepare TSCPN. With the increase in the concentration of TSCPN, the size of Pickering emulsion decreased from 337.02 μm to 89.36 μm, and when the TSCPN concentration was greater than 0.6%, all emulsions exhibited good stability during the 14 days storage. Combined with the microstructure result, 1.2% TSCPN was used to stabilize Pickering emulsion. With the increase in ionic concentration (0-400 mM), the particle size of the emulsions increased while the absolute value of zeta potential decreased. TSCPN-based Pickering emulsion was superior to the conventional emulsion for both lutein encapsulation (96.6 ± 1.0% vs. 82.1 ± 1.4%) and bioaccessibility (56.0 ± 1.1% vs. 35.2 ± 1.2%). Thus, TSCPN-based Pickering emulsion in this study have the potential as an effective carrier for lutein.

Effect of carbon numbers and structures of monosaccharides on the glycosylation and emulsion stabilization ability of gelatin

Herein, the effect of saccharide glycosylation by nine monosaccharides on bovine bone gelatin for the stabilization of fish oil-loaded emulsions was explored. The gelatin modification was analyzed and then the emulsifying properties of monosaccharide-modified gelatins were analyzed at pH 9.0 and 3.0. The results demonstrated that glycosylated gelatin structure, droplet stability, creaming stability, and liquid-gel transition time were dependent on monosaccharide carbon numbers, monosaccharide structures, and solution pH. Glycosylation modification of gelatins did not obviously change the emulsion droplet stability at pH 9.0, whereas it increased the emulsion droplet stability at pH 3.0. Glycosylation modification of gelatins did not obviously change the emulsion creaming index values (5.1%-8.4% at pH 9.0 and 25.8%-33.1% at pH 3.0). Three-carbon and four-carbon monosaccharides glycosylation significantly increased emulsion liquid-gel transition times. This work provided useful information to understand the effects of carbon numbers and structures of monosaccharides on the protein modification.

Effect of Coconut Protein and Xanthan Gum, Soybean Polysaccharide and Gelatin Interactions in Oil-Water Interface

We report on our study of the interactions between coconut protein extracted from coconut meat and three hydrocolloids (gelatin, xanthan gum, and soybean polysaccharide) and their interfacial adsorption and emulsification properties. We used Zeta potential, fluorescence spectroscopy scanning and ITC to investigate the interactions between a fixed concentration (1%) of coconut protein and varying concentrations of hydrocolloid. Through the interfacial tension and interfacial viscoelasticity, the interfacial properties of the hydrocolloid and coconut protein composite solution were explored. The physical stability of the corresponding emulsion is predicted through microstructure and stability analysis. Xanthan gum forms a flocculent complex with coconut protein under acidic conditions. Soy polysaccharides specifically bind to coconut protein. Under acidic conditions, this complex is stabilized through the steric hindrance of soy polysaccharides. Due to gelatin-coconut protein interactions, the isoelectric point of this complex changes. The interfacial tension results show that as time increases, the interfacial tensions of the three composite solutions decrease. The increase in the concentration of xanthan gum makes the interfacial tension decrease first and then increase. The addition of soybean polysaccharides reduces the interfacial tension of coconut protein. The addition of xanthan gum forms a stronger elastic interface film. Emulsion characterization showed that the gelatin-added system showed better stability. However, the addition of xanthan gum caused stratification quickly, and the addition of soybean polysaccharides also led to instability because the addition of polysaccharides led to a decrease in thermodynamic compatibility. This research lays the foundation for future research into coconut milk production technology.

Structural and emulsion stabilization comparison of four gelatins from two freshwater and two marine fish skins

This study analyzed the structural and emulsion stabilization properties of two freshwater and two marine fish skin gelatins: Chinese longsnout catfish skin gelatin (CLCSG), silver carp skin gelatin (SCSG), salmon skin gelatin (SSG), and Alaska pollack skin gelatin (APSG). Their gel strengths (Bloom values) were: 361 ± 1 (SCSG) > 253 ± 4 (CLCSG) > 69 ± 1 (SSG) > 36 ± 2 (APSG). Higher molecular weights and α/β subunit contents of gelatins might induce higher gel strengths. Both creaming and droplet stability were completely the same to the contents of imino acids, β-sheet percentages, and β-turn percentages, whereas they were completely the opposite to random coil percentages. The emulsion stabilization mechanisms involved an "fish skin source - protein chemical composition - protein secondary structure - protein functional properties - emulsion stability" route. This study provided useful knowledges for gelatin science and for the comprehensive utilization of aquatic by-products in gelatin industry.

Improvement of O/W emulsion performance by adjusting the interaction between gelatin and bacterial cellulose nanofibrils

This study was designed to improve the stability of medium internal phase emulsion by adjusting the electrostatic interaction between gelatin (GLT) and TEMPO-oxidized bacterial cellulose nanofibrils (TOBC). The influences of polysaccharide-protein ratio (1:10, 1:5, and 1:2.5) and pH (3.0, 4.7, 7.0, and 11.0) on the emulsion properties were investigated. The droplet size of TOBC/GLT-stabilized emulsion was increased with the TOBC proportion increasing at pH 3.0-11.0. Additionally, emulsion had a larger droplet size at pH 4.7 (the electrical equivalence point pH of mixtures). However, the addition of TOBC significantly improved the emulsion stability. The emulsions prepared with TOBC/GLT mixtures (mixing ratio of 1:2.5) at pH 3.0-7.0 were stable without creaming during the storage. It was because the formation of nanofibrils network impeded the droplet mobility, and the emulsion viscosity and viscoelastic modulus were increased with the addition of TOBC. These findings were meaningful to modulate the physical properties of emulsions.

Anhydride structures affect the acylation modification and emulsion stabilization ability of mammalian and fish gelatins

In this work, ring-like anhydrides (C4, C5, and C6) with different sizes and succinic anhydrides (C4, C10, C12, C14, and C16) with different side chain lengths were used to modify bovine bone gelatin (BBG) and cold-water fish skin gelatin (CFG), and the effect of acylated gelatins on fish oil-loaded emulsions stability was explored. The results showed that the degree of N-acylation decreased with increased ring sizes or side chain lengths, and the surface hydrophobicity of acylated gelatins increased with increased anhydride carbon numbers. Acylated CFGs had higher droplet stability and lower liquid-gel transition time than acylated BBGs. Only BBG-C12 had a slight increase on the creaming stability among these acylated gelatins. These results demonstrated that the gelatins could be modified by all the anhydrides and their emulsion stabilization ability was dependent on the gelatin type and anhydride structure. The results could be beneficial for protein-based emulsifier development and application.

Preparation, characterization, and application of polysaccharide-based emulsions incorporated with lavender essential oil for skin-friendly cellulosic support

This study aimed to develop polysaccharide-based emulsions incorporated with lavender essential oil and their application on cellulosic support for patches obtaining. The lavender essential oil has been added to emulsions as an active compound mainly due to its antimicrobial properties. In this study, emulsions were used to deliver active ingredients (lavender essential oil). The chemical composition of essential oil was analyzed using gas chromatography-mass spectrometry (GC/MS). A total of seven emulsions (RiACL) were evaluated by determining rheological parameters and microbiological analysis. One of the emulsions (R7ACL) was applied to cellulosic support to obtain non-irritating textiles with controlled release of the active compound and moisturizing effects. Obtained cellulosic support was analyzed in terms of active compound controlled release, toxicity and antimicrobial testing, and skin analysis in healthy volunteers. It was found that the cellulosic supports treated with O/W emulsions are non-irritating, have softness and moisturizing effects, and can be used safely in topical applications for patches obtaining.

Recent Advances in Gelatin-Based Nanomedicine for Targeted Delivery of Anti-Cancer Drugs

Nanoparticles based on natural polymers are utilized for the development of a wide range of drug delivery systems (DDS) in the current era. Gelatin-based nanoparticles, for example, are a remarkable cancer therapy with high efficacy and specificity. This paper reviews the recent advancements in gelatin-based nanomedicine for use in cancer therapeutics. Due to the characteristics features of gelatin, such as biocompatibility, biodegradability, stability, and good surface properties, these nanoparticles provide high therapeutic potency in cancer nanomedicine. The surface of gelatin can be modified in a number of ways using various ligands to explore the platform for the development of a more novel DDS. Various methods are available for the preparation of gelatin nanomedicine discussed in this review. In addition, various cross-linkers to stabilized nanocarriers and stimuli base gelatin nanoparticles are reviewed. Furthermore, recent advances and research in gelatin-based nanomedicine are discussed. Also, some drawbacks and challenges are evaluated. In general, this paper paves the pathway to identify the details about the gelatin-based DDS for cancer therapy.