Microwave pretreatment enhanced the properties of ovalbumin-inulin-oil emulsion gels and improved the storage stability of pomegranate seed oil

Transglutaminase cross-linking ovalbumin-flaxseed oil emulsion gels: Properties, microstructure, and performance in oxidative stability

This study prepared emulsion gels by modifying ovalbumin (OVA)-flaxseed oil (FSO) emulsions with transglutaminase (TGase) and investigated their properties, structure and oxidative stability under different enzyme reaction times. Here, we found prolonged reaction times led to the transformation of α-helix and β-turn into β-sheet and random coil. The elasticity, hardness and water retention of the emulsion gels increased significantly, but the water-holding capacity decreased when the reaction time exceeded 4 h. Confocal laser scanning microscope (CLSM) indicated extended enzyme reaction time fostered oil droplet aggregation with proteins. Emulsion gel reduced FSO oxidation, especially after 4 h of the enzyme reaction, the peroxide value (PV) of the emulsion gel was reduced by 29.16% compared to the control. In summary, the enzyme reaction time of 4 h resulted in the formation of a dense gel structure and enhanced oxidative stability. This study provides the potential applications in functional foods and biomedical fields.

Emulsification properties of ovalbumin-fucoidan (OVA-FUC) binary complexes

The poor thermal stability and emulsifying properties of ovalbumin (OVA) limit its functional performance, but these limitations may be overcome by forming binary complexes. We prepared binary complexes of OVA and fucoidan (FUC) through electrostatic self-assembly and investigated the emulsifying properties of the complex by measuring the particle size, interfacial membrane thickness, zeta potential, and stability of the emulsion prepared with camellia oil and the complex. The OVA-FUC emulsions have a thicker interfacial membrane, lower mobility, higher viscosity, and better stability compared with the OVA emulsions. The emulsion prepared with 1.5 % OVA-FUC remained stable and homogeneous during storage. They tended to become unstable with freeze-thaw, but the oil encapsulated did not leak after coalescence occurred. With the addition of Ca2+, the OVA-FUC emulsion will be converted into a gel state. These findings indicate that OVA-FUC binary complexes can be used to prepare high-performance emulsions with great potential for development.

Dynamic changes in the aggregation-depolymerization behavior of Ovomucin-Complex and its binding to urease during in vitro simulated gastric digestion

Ovomucin-Complex extracted from egg white is expected to have a barrier function similar to gastric mucin. In this study, the dynamic changes in structure, rheological properties and binding ability of Ovomucin-Complex during in vitro simulated gastric digestion were investigated. The results from HPLC and CLSM showed that extremely acidic pH (pH = 2.0) promoted Ovomucin-Complex to form aggregation. Acid-induced aggregation may hinder its binding to pepsin, thus rendering Ovomucin-Complex resistant to pepsin. Consequently, most of the polymer structure and weak gel properties of Ovomucin-Complex retained after simulated gastric digestion as verified by HPLC, CLSM and rheological measurement, although there was a small breakdown of the glycosidic bond as confirmed by the increased content of reducing sugar. The significantly reduced hydrophobic interactions of Ovomucin-Complex were observed under extremely acidic conditions and simulated gastric digestion compared with the native. Noticeably, the undigested Ovomucin-Complex after simulated gastric digestion showed a higher affinity (KD = 5.0 ± 3.2 nm) for urease - the key surface antigen of Helicobacter pylori. The interaction mechanism between Ovomucin-Complex and urease during gastric digestion deserves further studies. This finding provides a new insight to develop an artificial physical mucus barrier to reduce Helicobacter pylori infection.

Molecular structural modification of myofibrillar protein from oyster (Crassostrea gigas) with oligosaccharides for improving its gel properties

Glycation is a promising approach to enhance protein gel characteristics in the food industry. The impact of oyster myofibrillar protein (MP) being glycosylated with six oligosaccharides (dextran [Dex]-1 kDa, 5 kDa, 6 kDa, and 10 kDa, xylan [Xyla], and xyloglucan [Xyg]) on structural properties, aggregation behavior and gel properties was investigated in this study. The findings demonstrated that oligosaccharides significantly increased the glycation degree of MP by forming a stable tertiary conformation, increasing the contents of the disulfide bond and hydrogen bonds. Additionally, particle sizes decreased and solubility increased after glycation, improving the gel's strength, water-holding capacity, thermal stability, elastic modulus, and ordered network layout. It was determined that MP-Dex 5 had the best gel properties. The gel strength and water holding capacity of MP-Dex 5 increased by 70.59% and 32.27%, respectively. Molecular dynamics simulations results showed van der Waals energy and electrostatic interactions favor myosin binding to Dex or Xyla units. This study will provide insights into the relationship between molecular structure, aggregation behavior and gel property of oyster MP-oligosaccharide couples, and expand the application of oyster MP in food gels.

Enhancing Stability and Antioxidant Activity of Resveratrol-Loaded Emulsions by Ovalbumin-Dextran Conjugates

A reliable strategy for improving the stability and shelf life of protein-stabilized systems is by covalently attaching the protein onto a polysaccharide. In this study, ovalbumin (OVA) was modified with dextran (DEX) of different molecular weights by the Maillard reaction, and was used to enhance the stability of emulsions loaded with resveratrol. The surface hydrophobicity, thermal stability, and FT-IR spectroscopy of the OVA-DEX conjugates were evaluated. The results showed that the surface hydrophobicity of OVA decreased, while the thermal stability of OVA was significantly improved after DEX covalent modification. The OVA-DEX1k-stabilized emulsion exhibited high encapsulation efficiency of resveratrol, with the value of 89.0%. In addition, OVA-DEX was considerably more effective in droplet stabilization against different environmental stresses (heat, pH, and ionic strength). After 28 days of storage at 25 °C, the OVA-stabilized emulsion showed faster decomposition of resveratrol, whereas the OVA-DEX-conjugate-stabilized emulsion had approximately 73% retention of resveratrol. Moreover, the antioxidant activity of resveratrol-loaded emulsions stabilized by OVA-DEX was higher during storage under different temperatures. These results proved that the OVA-DEX conjugates had the potential to form stable, food-grade emulsion-based delivery systems against environmental stresses, which strongly supports their potential in the field of food and biomedical applications.

Effect of transglutaminase on ovalbumin emulsion gels as carriers of encapsulated probiotic bacteria

BACKGROUND

The use of emulsion gels to protect and deliver probiotics has become an important topic in the food industry. This study used transglutaminase (TGase) to regulate ovalbumin (OVA) to prepare a novel emulsion gel. The effects of OVA concentration and the addition of TGase on the microstructure, rheological properties, water-holding capacity, and stability of the emulsion gels were investigated.

RESULTS

With the addition of TGase and the increasing OVA, the particle size of the emulsion gels decreased significantly (P < 0.05). The gels with TGase exhibited greater water holding, hardness, and chewiness to some extent by forming a more uniform and stable system. After simulated digestion, the survival rate of Bifidobacterium lactis embedded in OVA emulsion gels improved significantly in comparison with the oil-water mixture as a result of the protective effect of the emulsion gel encapsulation.

CONCLUSION

By increasing the OVA content and adding TGase, the rheological characteristics, stability, and encapsulation capability of the OVA emulsion gel could be enhanced, providing a theoretical basis for the use of emulsion gels to construct probiotic delivery systems. © 2023 Society of Chemical Industry.

Fibrous whey protein mediated homogeneous and soft-textured emulsion gels for elderly: Enhancement of bioaccessibility for curcumin

Homogeneous and soft-textured food gels are critical for designing precise and personalized nutrient food for elderly. Effects of whey protein morphology (fibrous and granular) with/without NaCl addition on oil-water state and texture properties of protein emulsion gels were investigated, to explore the feasibility of developing homogeneous and soft-textured food for elderly. Lower gelation temperature and higher stability of its emulsion droplets, resulted in fibrous whey protein emulsion gels (FWPG) had even distribution of embedded oil droplets, compared to native whey protein emulsion gels. FWPG had the lowest hardness and chewiness, and exhibited better tolerance to the harden effects of NaCl on emulsion gels. FWPG can deliver curcumin more effectively during simulated gastrointestinal digestion, as evidenced by higher retention ratio and enhancement of bioaccessibility (increased by ∼ 20 %). This study provided new strategy to fabricate a homogenous emulsion gel using fibrous whey protein and to design multi-nutrient food gels for elderly.

Preparation and characterization of zein-caseinate-pectin complex nanoparticles for encapsulation of curcumin: pectin extracted by high-speed shearing from passion fruit (Passiflora edulis f. flavicarpa) peel

BACKGROUND

Pectin extracted by high-speed shearing from passion fruit peel (HSSP) is a potentially excellent wall material for encapsulating curcumin, which has multiple advantages over pectin prepared by heated water extraction. HSSP was used to fabricate complex nanoparticles of zein-sodium caseinate-pectin for encapsulation of curcumin in this study. The influence of heating on the physicochemical properties of the composite nanoparticles was also investigated, as well as the effect of composite nanoparticles on the encapsulation efficiency, antioxidant activity and release characteristics of curcumin.

RESULTS

The nanoparticles were formed through electrostatic interactions, hydrogen bonds and hydrophobic interactions between the proteins and HSSP. A temperature of 50 °C was more favorable for generating compact and small-sized nanoparticles, which could effectively improve the encapsulation efficiency and functional properties. Moreover, compared to other pectin used in the study, the nanoparticles prepared with HSSP showed the best functionality with a particle size of 234.28 ± 0.85 nm, encapsulation rate of 90.22 ± 0.54%, free radical scavenging rate of 78.97% and strongest protective capacity in simulated gastric fluid and intestinal release effect.

CONCLUSION

Zein-sodium caseinate-HSSP is effective for encapsulating and delivering hydrophobic bioactive substances such as curcumin, which has potential applications in the functional food and pharmaceutical industries. © 2024 Society of Chemical Industry.

Effect of soluble dietary fiber on soy protein isolate emulsion gel properties, stability and delivery of vitamin D3

Emulsion gels with denser network microstructure and stronger mechanical properties have attracted increasing attentions for delivering lipophilic compounds. In this study, the effect of three distinct soluble dietary fiber (inulin (IN), resistant dextrin (RD) and stachyose (ST)) on the rheological, mechanical and microstructural properties of soy protein isolate (SPI) emulsion gel were firstly investigated. Compared with RD and IN, ST significantly accelerated water holding capacity and thermal stability, which exhibited more compact microstructure and more uniform emulsified oil droplets. Subsequently, the stability and bioavailability of vitamin D3 (VD3) in different delivery systems (medium chain triglycerides (MCT) embedding, SPI-ST emulsion embedding, SPI emulsion gel embedding and SPI-ST emulsion gel embedding) were continue evaluated. In vitro simulated digestion experiment demonstrated that the bioaccessibility of encapsulated VD3 in SPI-ST emulsion gel (69.95 %) was much higher than that of free embedding (48.99 %). In vivo pharmacokinetic experiment revealed that the bioavailability of VD3 was significantly enhanced in SPI-ST gel (p < 0.05), with the AUC0-24h value of 25-OH VD3 (the main circulating form of VD3) were 1.34-fold, 1.23-fold higher than that of free embedding, MCT embedding, respectively. These findings provide a possible approach for the development of high protein/fiber functional foods containing enhanced hydrophobic bioactives.

Interaction mechanisms of edible film ingredients and their effects on food quality

Traditional food packaging has problems such as nondegradable and poor food safety. Edible films play an important role in food packaging, transportation and storage, having become a focus of research due to their low cost, renewable, degradable, safe and non-toxic characteristics. According to the different materials of edible films substrate, edible films are usually categorized into proteins, polysaccharides and composite edible films. Functional properties of edible films prepared from different substrate materials also vary, single substrate edible films are defective in some aspects. Functional ingredients such as proteins, polysaccharides, essential oils, natural products, nanomaterials, emulsifiers, and so on are commonly added to edible films to improve their functional properties, extend the shelf life of foods, improve the preservation of sensory properties of foods, and make them widely used in the field of food preservation. This paper introduced the classification, characteristics, and modification methods of common edible films, discussed the interactions among the substrate ingredients of composite edible films, the influence of functional ingredients on the properties of edible films, and the effects of modified edible films on the quality of food, aiming to provide new research ideas for the wide application and further study of edible films.

Utilizing protein nanofibrils as a scaffold for enhancing nutritional value in toned milk

Toned milk is a lower-fat, healthier alternative to whole milk that still contains all essential nutrients. A number of methods have been developed to improve the functionality of toned milk and make it more appealing to the consumers. However, these methods often involve extensive processing techniques and can be expensive. Therefore, alternative methods are needed. Proteins are well known for their ability to form well-defined nanofibril materials that can be used as a scaffold for various applications. In this article, a straightforward self-assembly process was used to load inulin into protein nanofibrils, creating unique composite nanofibrils. Characterization using AFM and SEM revealed well-defined composite nanofibrils with an average diameter of 4-6 nm and lengths ranging from 0.25 μm up to 10 μm. FT-IR and in-vitro release assays show that inulin was successfully attached to prepared protein nanofibrils. The composite nanofibrils were tested on toned milk to enhance the physico/chemical properties and nutritional values. The findings can be applied to the food industry to create a number of novel functional food products cost-effectively.

Physicochemical properties and in vitro digestion behavior of emulsion gels stabilized by rice bran protein aggregates: Effects of heating time and induction methods

To investigate the effects of heating time and induction methods on the physicochemical properties and in vitro digestion behavior of emulsion gels, rice bran protein aggregates (RBPAs) were formed by acid-heat induction (90 °C, pH 2.0) and the emulsion gels were further prepared by adding GDL or/and laccase for single/double cross-linked induction. Heating time affected the aggregation and oil/water interfacial adsorption behavior of RBPAs. Suitable heating (1-6 h) was conducive to faster and more adsorption of aggregates at the oil/water interface. While excessive heating (7-10 h) resulted in protein precipitation, which inhibited the adsorption at the oil/water interface. The heating time at 2, 4, 5 and 6 h was thus chosen to prepare the subsequent emulsion gels. Compared with the single cross-linked emulsion gels, the double-cross-linked emulsion gels showed higher water holding capacity (WHC). After simulated gastrointestinal digestion, the single/double cross-linked emulsion gels all exhibited slow-release effect on free fatty acid (FFA). Moreover, the WHC and final FFA release rate of emulsion gels were closely related to the surface hydrophobicity, molecular flexibility, sulfhydryl, disulfide bond and interface behavior of RBPAs. Generally, these findings proved the potential of emulsion gels in designing fat alternatives, which could provide a novel technique for the fabrication of low-fat food.

Recent Trends in Improving the Oxidative Stability of Oil-Based Food Products by Inhibiting Oxidation at the Interfacial Region

In recent years, new approaches have been developed to limit the oxidation of oil-based food products by inhibiting peroxidation at the interfacial region. This review article describes and discusses these particular approaches. In bulk oils, modifying the polarity of antioxidants by chemical methods (e.g., esterifying antioxidants with fatty alcohol or fatty acids) and combining antioxidants with surfactants with low hydrophilic–lipophilic balance value (e.g., lecithin and polyglycerol polyricinoleate) can be effective strategies for inhibiting peroxidation. Compared to monolayer emulsions, a thick interfacial layer in multilayer emulsions and Pickering emulsions can act as a physical barrier. Meanwhile, high viscosity of the water phase in emulsion gels tends to hinder the diffusion of pro-oxidants into the interfacial region. Furthermore, applying surface-active substances with antioxidant properties (such as proteins, peptides, polysaccharides, and complexes of protein-polysaccharide, protein-polyphenol, protein-saponin, and protein-polysaccharide-polyphenol) that adsorb at the interfacial area is another novel method for enhancing oil-in-water emulsion oxidative stability. Furthermore, localizing antioxidants at the interfacial region through lipophilization of hydrophilic antioxidants, conjugating antioxidants with surfactants, or entrapping antioxidants into Pickering particles can be considered new strategies for reducing the emulsion peroxidation.

Elastic and transparent ovalbumin hydrogels formed via succinylation combined with pH-shifting treatment

Ovalbumin (OVA) is a model protein with extensive research on structure and function, however, the application of OVA in food processing is limited due to its low gelation properties. In this study, thermally-induced highly transparent and elastic hydrogels from OVA pretreated by succinylation combined with pH-shifting method were reported. Transmission electron microscope (TEM) and free sulfhydryl groups determination revealed that the pretreatment induced the stretching of the protein structure and promoted the formation of preliminary aggregates. Further heating the pretreated OVA suspension resulted in a homogeneous and macroporous gel network with thin connecting walls. Such homogeneous gel network structures may be related to the effective modulation of the thermal aggregation efficiency of proteins by succinylation and the high level of protein unfolding by pH-shifting treatments, which synergistically allowed for more active sites to be created during heating to facilitate intermolecular interactions, including hydrogen bonding and hydrophobic interactions. Notably, the method resulted in a 507.14% increase in elasticity, a 60.74% increase in water holding capacity of the OVA hydrogels compared to the native OVA hydrogels without pretreatment. Also, the hydrogels were transparent with 73.11% light transmittance. In conclusion, succinylation and pH-shifting combined treatment could be an effective method for the preparation of OVA hydrogels with superior gelation properties.

Research advance of non-thermal processing technologies on ovalbumin properties: The gelation, foaming, emulsification, allergenicity, immunoregulation and its delivery system application

Ovalbumin (OVA) is the most abundant protein in egg white, with excellent functional properties (e.g., gelling, foaming, emulsifying properties). Nevertheless, OVA has strong allergenicity, which is usually mediated by specific IgE thus results in gut microbiota dysbiosis and causes atopic dermatitis, asthma, and other inflammation actions. Processing technologies and the interactions with other active ingredients can influence the functional properties and allergic epitopes of OVA. This review focuses on the non-thermal processing technologies effects on the functional properties and allergenicity of OVA. Moreover, the research advance about immunomodulatory mechanisms of OVA-mediated food allergy and the role of gut microbiota in OVA allergy was summarized. Finally, the interactions between OVA and active ingredients (such as polyphenols and polysaccharides) and OVA-based delivery systems construction are summarized. Compared with traditional thermal processing technologies, novel non-thermal processing techniques have less damage to OVA nutritional value, which also improve OVA properties. OVA can interact with various active ingredients by covalent and non-covalent interactions during processing, which can alter the structure or allergic epitopes to affect OVA/active components properties. The interactions can promote OVA-based delivery systems construction, such as emulsions, hydrogels, microencapsulation, nanoparticles to encapsulate bioactive components and monitor freshness for improving foods quality and safety.

Fabrication and characterization of gelatin-EGCG-pectin ternary complex: formation mechanism, emulsion stability, and structure

BACKGROUND

Protein-polyphenol-polysaccharide ternary complex particles have better emulsion interfacial stability compared to protein-polysaccharide binary complexes. However, knowledge is scarce when it comes to the fabrication of protein-polyphenol-polysaccharide ternary complexes as interfacial stabilizers and the interactions between the three substances. In the present work, ternary complexes were prepared using gelatin, high methoxyl pectin, and epigallocatechin gallate (EGCG) as raw materials. The effect of different influencing factors on the formation process of ternary complexes was investigated by varying different parameters. physicochemical stability, emulsifying properties, and structural characteristics were analyzed.

RESULTS

The ternary complex had a smaller particle size (275 nm) and polydispersity index (0.112) when the mass concentration ratio of gelatin to high methoxyl pectin was 9:1, addition of EGCG was 0.05%, pH value was 3.0, and ionic strength was 10 mmol L^-1 . Meanwhile, the complex had the highest emulsifying stability index (691.75 min) and emulsifying activity index (22.96 m²  g^-1 ). Scanning electron microscopical observation demonstrated that the addition of EGCG promoted the dispersion of ternary complex more uniformly, and effectively reduced the agglomeration phenomenon. The discrepancy in fluorescence intensity suggested that interactions between EGCG and gelatin occurred, which altered the protein spatial conformation of gelatin. Fourier transform infrared spectroscopic analysis elucidated that hydrogen bond interaction was the primary non-covalent interaction between EGCG and gelatin-high methoxyl pectin binary complex.

CONCLUSION

The aforementioned results purposed to provide some theoretical reference and basis for the rational design of stable protein-polyphenol-polysaccharide ternary complexes. © 2022 Society of Chemical Industry.

Preparation of an LZ-OEO Compound Antibacterial Gel and the Effect of Microwave Treatment on Its Structure and Stability

Composite gels prepared with ovalbumin (OVA) as basic materials have been gradually utilized in food and biological fields. However, the structure and function of gels made from natural materials are not perfect, especially the hardness, viscoelasticity and water-holding capacity of gels, which are easily affected by various factors (pH, NaCl, etc.). In order to improve the antibacterial effect and safety of gels, and on the basis of exploring the bacteriostatic formula of lysozyme-oregano essential oil (LZ-OEO), the influence of microwave treatment on the stability of the composite bacteriostatic material gel was emphatically investigated and discussed so as to develop a new bacteriostatic gel material. The results revealed that the LZ-OEO antibacterial gel prepared by adding 20% OEO, with a ratio of 3:2 between OVA and LZ, was more stable after microwave treatment, and the synergistic antibacterial effect was significantly improved. That is, the OVA and LZ-OEO composite gel processed using a 350 W microwave treatment for 1 min had the highest hardness, the water-holding capacity reached 78.05% and a dense and ordered network structure was formed. In addition, the compound gel displayed excellent antibacterial effects against Staphylococcus aureus and Escherichia coli. The experimental findings in this study effectively expands the application scope of lysozyme antibacterial materials and provides a more favorable technical foundation for future development and utilization.

Drying methods affect physicochemical and functional characteristics of Clanis Bilineata Tingtauica Mell protein

Clanis Bilineata Tingtauica Mell Protein (CBTMP) was a kind of natural full-price protein which has a bright application prospect in the food industry. Since the functional properties of protein can be significantly affected by drying method, this study aims to explore the effect of different drying methods, namely freeze drying (FD), vacuum drying (VD),and hot-air drying (HD) on the structure and functional properties of CBTMP. The results showed that the degree of oxidation of CBTMP was found to be in the following order: HD &gt; VD &gt; FD. Functional characteristics revealed that the CBTMP prepared by VD had relatively high foaming ability (150.24 ± 5.34°C) among three drying methods. However, the stability of emulsion and rheological properties prepared by FD was superior to other samples. Differential scanning calorimeter (DSC) showed CBTMP made by HD had the relatively good thermal stability (Tp = 91.49 ± 0.19 °C), followed by VD and FD. Digestive properties reflected that heating treatment could significantly increase its degree of hydrolysis in vitro. To sum up, the research could provide experimental guidance and theoretical support for the preparation method and utilization of CBTMP.

Reducing the potential allergenicity of amandin through binding to (-)-epigallocatechin gallate

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Amandin (AMP) binding to EGCG changed protein structure.

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AMP bound to EGCG primarily through glutamate and cysteine residues.

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Alkaline and free radical methods dented AMP allergenic, but the principles differed.

Potential allergenicity of amandin was reduced by binding amandin with (−)-epigallocatechin gallate (EGCG) via alkaline, free radical, ultrasound-assisted alkaline, and ultrasound-assisted free radical methods. These results of total phenol content, free sulfhydryl group, free amino group, surface hydrophobicity, and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicated that amandin might be covalently bound to EGCG through reactive groups such as sulfhydryl and amino groups, or non-covalently through hydrophobic interactions. Fourier transformed infrared (FT-IR) spectroscopy and fluorescence spectroscopy revealed structural changes of amandin-EGCG conjugate, which also caused significant reduction in potential allergenicity of amandin. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) found that amandin bound to EGCG mainly through cysteine and glutamate residues, and linear epitope for amandin was reduced. This provided a new method and theoretical basis of hypoallergenic almond food.

Egg white protein-based delivery system for bioactive substances: a review

Some bioactive substances in food have problems such as poor solubility, unstable chemical properties and low bioavailability, which limits their application in functional food. Recently, many egg white protein-based delivery carriers have been developed to improve the chemical stability, biological activity and bioavailability of bioactive substances. This article reviewed the structure and properties of several major egg white proteins commonly used to construct bioactive substance delivery systems. Several common carrier types based on egg white proteins, including hydrogels, emulsions, micro/nanoparticles, aerogels and electrospinning were then introduced. The biological functions of common bioactive substances, the limitations, and the role of egg white protein-based delivery systems were also discussed. At present, whole egg white protein, ovalbumin and lysozyme are most widely used in delivery systems, while ovotransferrin, ovomucoid and ovomucin are less developed and applied. Egg white protein-based nanoparticles are currently the most commonly used delivery carriers. Egg white protein-based hydrogels, emulsions, and microparticles are also widely used. Future research on the application of various egg white proteins in developed new delivery systems will provide more choices for the delivery of various bioactive substances.

Formation mechanism of high-viscosity gelatinous egg white among "Fenghuang Egg": Phenomenon, structure, and substance composition

"Fenghuang Egg" is a special egg product incubated for 12 days by fertilized hen eggs. Its egg white contains high-viscosity and excellent thermal gel strength. A comparative study on the differences in gel properties, structure, and substance composition between fresh egg white (FEW) and "Fenghuang egg" gelatinous egg white (GEW) was carried out. Experimental results showed GEW had better apparent viscosity, as well as the hardness, cohesiveness and water holding capacity (WHC) of thermal gel; the content and size of aggregate structure increased significantly in GEW, and a fibrous dense network composed of numerous spherical nanoparticles connected in series was formed after heating. In addition, it also discovered that more water molecules in GEW existed in the form of bound water. A total of 41 proteins changed significantly in FEW and GEW, Mucin 6 might be the main reason for the enhanced viscosity of GEW, and OVA might be the dominant protein differentiating the thermal gel properties between FEW and GEW. This study revealed that the differences in gel properties and structures between FEW and GEW were closely related to the content of highly glycosylated globular proteins, laying a theoretical foundation for the application of high-viscosity egg whites.

Effect of ball milling-assisted glycosylation modification on the structure and foaming property of egg white protein

The effect of different glycosylation degrees on molecular structure and foaming property of egg white protein (EWP) was investigated using ball milling-assisted glycosylation. The results showed the foaming ability (FA) and foam stability (FS) of EWP improved when the degree of glycosylation was increased. In particular, FA of ball milling-assisted glycosylation of EWP enhanced by 39.9% and 28.8%, and the FS increased by 28.7% and 24.0% compared with EWP and ball milling egg white protein (BE) at 150 min of reaction. Sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE) analysis could reflect the grafting degree of EWP and glucose molecules from the side. When EWP was fully grafted with glucose, endogenous fluorescence and free sulfhydryl groups indicated that tertiary structure of EWP was depolymerized, and Fourier transform infrared spectroscopy showed the secondary structure tended to change from order to disorder. The results of this study indicated that ball milling-assisted glycosylation modification was a practical method to improve the foaming property of EWP. PRACTICAL APPLICATION: EWP has great FA and FS, making it indispensable in the baking industry. In this study, ball milling-assisted glycosylation was used to improve the foaming property of EWP, and the molecular structure of EWP with different degrees of glycosylation was fully resolved. The results demonstrated that ball milling, as a physical pretreatment, can fully unfold the structure of EWP. When sugar molecules were fully grafted, the particle size of EWP reduced, solubility increased, and the stability of system improved, thus enhancing the foaming property of EWP. The results can provide theoretical basis for improving the foaming property of EWP and provide a reference value for its industrial application.

Effect of NaCl on the Rheological, Structural, and Gelling Properties of Walnut Protein Isolate-κ-Carrageenan Composite Gels

In this study, we discovered that a certain concentration of Na⁺ (15 mM) significantly improved the bond strength (12.94 ± 0.93 MPa), thermal stability (72.68 °C), rheological properties, and textural attributes of walnut protein isolate (WNPI)-κ-carrageenan (KC) composite gel. Electrostatic force, hydrophobic interaction, hydrogen bond, and disulfide bond were also significantly strengthened; the α-helix decreased, and the β-sheet increased in the secondary structure, indicating that the protein molecules in the gel system aggregated in an orderly manner, which led to a much denser and more uniform gel network as well as improved water-holding capacity. In this experimental research, we developed a new type of walnut protein gel that could provide technical support for the high-value utilization and quality control of walnut protein.

Study on the mechanism of mulberry polyphenols inhibiting oxidation of beef myofibrillar protein

In order to explore the mechanism of mulberry polyphenols inhibiting the oxidation of myofibrillar protein (MP), the effect of mulberry polyphenols on the structure and physicochemical properties of MP in the oxidation system was investigated. The results revealed that the content of carbonyl group and sulfhydryl group of MP was notably reduced, while the Zeta potential, storage modulus G' and surface hydrophobicity were improved when the addition of mulberry polyphenol was 0.5%. SDS-PAGE showed an irreducible aggregation of mulberry polyphenols with proteins. Fluorescence spectroscopy and FT-IR analysis manifested that mulberry polyphenols promoted the unfolding of protein structure and the transformation of α-helix to β-turn structure. Scanning electron microscopy (SEM) observed that oxidation with polyphenols facilitated the cross-linking and aggregation of MP more tightly. Nevertheless, excessive addition (≥1.0%) weakened its gel properties. Thus, to maintain the good quality of meat products, both polyphenols addition and oxidation intensity should be controlled simultaneously.

Ultrasound-assisted pH-shifting remodels egg-yolk low-density lipoprotein to enable construction of a stable aqueous solution of vitamin D3

Egg-yolk low-density lipoprotein (LDL) has a natural liposome structure. Using ultrasound-assisted pH-shifting (pH 12), a naturally safe and stable aqueous solution of vitamin D₃ (VD₃) was constructed employing LDL as the carrier. Images from electron microscopy showed that pH-shifting remodeled LDL molecules, resulting in a dramatic reduction in particle size (∼50%) and an increase in specific surface area, which reduced the turbidity (27.7%) and provided new interfaces for VD₃ loading. Fluorescence analyses showed that the binding of VD₃ to LDL under pH-shifting was strong, involved quenching, and the binding constant was 6.19 × 10⁴ M⁻¹. Thermogravimetric analysis and Fourier transform-infrared spectroscopy showed that pH-shifting hydrolyzed the esters in LDL to fatty acid salts, and the maximum weight loss of LDL occurred from 381.9 °C to 457.0 °C. Ultrasonic treatment enhanced the binding of LDL and VD₃ (binding constant increased to 2.56 × 10⁷ M⁻¹), reduced the particle size, and increased the ζ-potential of the complex between LDL and VD₃, thereby resulting in the improvement of solution stability and storage stability of VD₃. Ultrasound-assisted pH-shifting could remodel LDL to construct a stable aqueous solution of VD₃, which showed the potential of LDL as a carrier for lipid-soluble components.

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pH-shifting remodels LDL and results in a reduction in particle size.

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Under pH-shifting, VD₃ was bound stably to LDL with strong affinity.

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pH-shifting remodeled LDL can be used to encapsulate active ingredients.

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The binding of VD₃ to LDL was enhanced by ultrasonic treatment.

Molecular structure modification of ovalbumin through controlled glycosylation with dextran for its emulsibility improvement

Ovalbumin (OVA) is a high nutritious protein, but the poor emulsibility limited its application. The present study glycosylated OVA with dextran (Dex) by controlled wetheating (60-90 °C for 3 h). Temperature was an inductive factor for glycosylation degree (DG and browning intensity), and higher temperature could accelerate the reaction. Variations in molecular structure of OVA were analyzed by SDS-PAGE, FTIR, fluorescence spectroscopy and UV spectroscopy, which verified successes in the generation of glycoconjugate with more flexible structure. Emulsifying activity index (EAI) and emulsion stability index (ESI) for the emulsion of OVA-Dex glycoconjugates were significantly enhanced with the increasing of glycosylation temperature. Moreover, confocal laser scanning results revealed that the emulsion exhibited smaller size and more uniform distribution, and slower transmission profiles were checked by LUMiSizer centrifugal analysis as well, confirming the emulsibility improvement of OVA. Thus, controlled glycosylation reaction is an available method to improve the emulsifying properties of OVA.

Quantitative proteomic analyses during formation of chicken egg yolk

A quantitative comparison of the proteomes during different periods of the formation of egg yolk, from yellow follicles (YF), small hierarchical follicles (9-12 mm, SF), and the largest hierarchical follicle (LF), was performed. The abundance of major egg yolk proteins (apolipoprotein B and vitellogenins) changed significantly during the yolk formation, and several protein hydrolases and isomerases, which may be related to the processing of egg yolk proteins, also varied significantly. The binding proteins for three vitamins (retinol, riboflavin, and vitamin D) and cholesterol were all most abundant in the LF period, suggesting that these nutrients were transported mainly at the final period of the egg yolk formation. Immunoglobulins decreased and complement proteins increased as formation progressed, indicating the dynamic nature of the egg yolk immune system. These results are helpful for understanding the nutrient composition, the formation of assembly structure, the preservation and processing properties of egg yolk.

Effect of ultrasonic pretreatment on the emulsification properties of Clanis Bilineata Tingtauica Mell protein

Clanis Bilineata Tingtauica Mell Protein (CBTMP) is a naturally high-quality insect protein resource, while its poor emulsification has limited its application in food industry. In order to change the present situation, in this research, the ultrasonic pretreatment (0 W, 200 W, 400 W, 600 W, and 800 W) method was used to improve the emulsification properties of CBTMP. Results indicated that ultrasound treatment especially at 400 W could significantly change the particle sizes, further increase the content of sulfhydryl group and surface hydrophobicity. The emulsification properties of emulsions were enhanced (from 4.16 ± 1.07 m²/g to 27.62 ± 2.20 m²/g) by sonicated CBTMP solution. Moreover, the physical stability of the emulsions to salt stress and centrifugation treatment was also promoted. Additionally, rheology revealed that a stronger network was formed at 400 W and all samples exhibited frequency-dependent and amplitude-dependent properties. The experiment demonstrated that ultrasound pretreatment was an effective means to improve the emulsification properties of CBTMP and it could provide a promising perspective for the application of CBTMP in food industry.

Physicochemical, structural and adhesion properties of walnut protein isolate-xanthan gum composite adhesives using walnut protein modified by ethanol

Low-sugar and high-protein adhesives have broad market application prospects, while natural plant proteins have confronted technical bottlenecks due to their poor adhesion. In this study, the effects of ethanol with different concentrations (0-80%) on the adhesion properties of walnut protein isolate-xanthan gum (WNPI-XG) composite adhesives were investigated. Results showed the bonding strength of WNPI-XG treated with 40% ethanol reached 12.55 MPa, the denaturation temperature and the surface hydrophobicity increased to 87.91 and 185.07 respectively, displaying the best rheological and texture properties. It also indicated appropriate concentration of ethanol (40%) didn't change the molecular weight of WNPI-XG, but greatly strengthened the fluorescence intensity, leading changes in contents of reactive sulfhydryl groups, electrostatic forces, hydrophobic interactions, hydrogen bonds and disulfide bonds. Furthermore, the treatment also facilitated a conformation conversion of the secondary structures from β-sheet to α-helix, promoting the full unfolding of protein molecules. The microstructure analysis showed after 40% ethanol treatment, the WNPI structure was uniform, the surface of WNPI-XG adhesive was flat and smooth, combined more closely with water molecules. By analyzing the influence of ethanol treatment on adhesion of WNPI-XG, the research laid a theoretical foundation for protein modification, providing good technical references for its development and utilization.

Study on the emulsification and oxidative stability of ovalbumin-pectin-pumpkin seed oil emulsions using ovalbumin solution prepared by ultrasound

Pumpkin seed oil (PSO), which is a valuable compound with high nutritional value used for the prevention of various chronic diseases, is prone to oxidation. In this work, small and uniform (su) ovalbumin (OVA) and pectin (PEC) were used to stabilize PSO in the form of an emulsion. The results showed that suOVA-PEC-PSO emulsion with a droplet size of 9.82 ± 0.05 μm was successfully self-assembled from PSO, PEC, and suOVA solution (with a droplet size of 230.13 ± 14.10 nm) treated with 300 W ultrasound, owing to the formation of a more stable interfacial film on the surface of droplets. The interfacial, rheological, emulsifying, and antioxidant properties of the suOVA-PES-PSO emulsions were excellent, owing to the synergistic effects between PEC and suOVA solution. Moreover, the physical stability of the suOVA-PEC-PSO emulsions to salt stress, a freeze-thaw cycle, and heat treatment was also increased and the oxidation of linolenic acid was notably delayed. These results have extended the food-related applications of OVA and PSO, and provide a promising foundation for further exploration of the self-assembly of composite emulsions by small and uniform proteins.

New insights into food O/W emulsion gels: Strategies of reinforcing mechanical properties and outlook of being applied to food 3D printing

3D printing technology has been widely used in food processing with its advantages of customized food design, personalized nutrition design, and simplified food supply chain. Food emulsion gels have application value and prospects in food 3D printing due to their promising properties, including biodegradability, biocompatibility, as well as dual characteristics of emulsions and biopolymer gels. Food emulsion gels with appropriate mechanical properties, as a new type of food inks, expand the types and functions of the inks. However, food emulsion gels without adequate reinforced mechanical properties may suffer from defects in shape, texture, mouthfeel, and functionality during 3D printing and subsequent applications. Therefore, it is necessary to summarize the strategies to improve the mechanical properties of food emulsion gels. According to the methods of characterizing the mechanical properties of emulsion gels, this article summarizes four strategies for improving the mechanical properties of emulsion gels through two ways: inside-out (reinforcement of interface and reinforcement of cross-linking) and outside-in (physical approaches and environmental regulations), as well as their basic mechanisms. The application status and future research trends of emulsion gels in food 3D printing are finally discussed.

Effect of L-calcium lactate, zinc lactate, and ferric sodium EDTA on the physicochemical and functional properties of liquid whole egg

The study aimed to evaluate the physicochemical and functional properties of liquid whole egg (LWE) with L-calcium lactate (L-Ca), zinc lactate (L-Zn), and sodium ferric EDTA (NaFeEDTA), and to compare with NaCl addition to determine the application potential of these mineral supplements. Results showed that salts addition significantly influenced the foaming, emulsifying, and gelling properties of LWE, which was possible through affecting the pH, particle size, surface hydrophobicity, apparent viscosity, and solubility. The addition of all the four salts reduced pH but increased the d_4,3 diameter of LWE. Additionally, the addition of 200 mM L-Ca and 6 mM L-Zn significantly improved the emulsifying capacity by 41.73% and 13.6%, the foaming capacity by 26.57% and 10%, and the protein solubility by 13.89% and 12.70%, respectively. In the meantime, mineral supplements tend to produce lower hardness gel, especially with 25 mM L-Ca and 8 mM L-Zn, and the hardness was decreased from 2401.13 to 1138.29 and 1175.59 g, respectively. A relative decrease in hardness was desirable in gelled egg products. Moreover, the addition of NaCl and L-Ca showed a higher redness and yellowness, but the addition of NaFeEDTA showed an undesirable color in dark brown, which may be not accepted by the public. In summary, L-Ca and L-Zn had great potential for application in LWE, which was more appropriate than adding NaCl. This study provides a basis for improving the functional properties of LWE products in the future. PRACTICAL APPLICATION: The addition of L-Ca and L-Zn to liquid whole egg (LWE) could improve the foaming and emulsifying capacity of LWE as well as produce a lower hardness gel, which may be more conducive to the production of cake, custards, and meat products. Meantime, it is more in line with people's pursuit of a healthy diet.

Ovomucin may be the key protein involved in the early formation of egg-white thermal gel

Clarification of the mechanism of heat-induced gel formation by proteins under natural food systems could provide important references for the regulation of food texture. In the present study, the proteins involved in the early stage (heating at 72 °C for 8 min) of egg-white thermal gel (EWG) formation were studied quantitatively through comparative proteomic analysis. We discovered that the abundance of ovalbumin and ovomucoid increased significantly (p < 0.01), whereas that of ovotransferrin, lysozyme, ovomucin (mucin 5B and mucin 6) decreased significantly (p < 0.01), in the supernatant of EWG. If the initial interaction of egg white proteins was altered by ultrasonic pretreatment, the abundance of ovomucin and lysozyme in the supernatant of EWG increased, and was accompanied by the change from a solid gel to a fluid gel. Based on these results, we hypothesize that ovomucin has a key role in the formation and regulation of EWG properties.

Improvement of quality and flavor of salted egg yolks by ultrasonic assisted cooking

Physicochemical, texture indexes, microstructure and volatiles were used to characterize the changes in quality, structure and flavor of cooked salted egg yolks (SEYs) with or without ultrasonic treatment. Experimental results indicated that ultrasonic significantly increased cooking (water) loss, oil exudation, lipids oxidation (TBARS), accelerated the doneness of cooked SEYs and then promoted the generation of volatiles. These results were further confirmed by the improvement of thermal stability, the changes in color, secondary structure of proteins, water distribution and mobility. Meanwhile, more "fragments" and "cracks" were observed in scanning electron microscope (SEM) and the decrease in gumminess and chewiness were detected using texture profile analysis (TPA), inducing that the migration of lipids and collapse of gel network were intensified. Moreover, ultrasonic treatment decreased the content of sodium chloride in SEYs. Therefore, it was concluded that the doneness, quality and flavor of cooked SEYs were improved by ultrasonic treatment, which could be used as an effective and alternative method for the production of SEYs with good flavor, sandy and oily texture.

Binding mechanism and functional evaluation of quercetin 3-rhamnoside on lipase

The interaction between lipase and quercetin 3-rhamnoside was studied by fluorescence spectroscopy, enzyme kinetics, and molecular dynamics simulation. The results showed that quercetin 3-rhamnoside had a strong quenching effect on the intrinsic fluorescence of lipase. The binding constant decreased with increasing temperature, and the number of binding sites approached 1. Thermodynamic parameters indicated that hydrogen bonding and van der Waals forces are the dominant forces when the interaction occurs. Circular dichroism spectroscopy and infrared spectroscopy proved that the ligand perturbed the structure of lipase. Enzyme kinetics results showed that quercetin 3-rhamnoside inhibited lipase, and the inhibitory effect was dose-dependent. Molecular dynamics simulation further explained the interaction mechanism and inhibitory effect. This study confirmed the inhibitory effect of quercetin 3-rhamnoside on lipase explained their binding mechanism, which will contribute to guiding the development of fat-reducing functional foods.

Depolymerization of chicken egg yolk granules induced by high-intensity ultrasound

The effects of high-intensity ultrasound (HIU) treatment-induced depolymerization of chicken egg yolk granules were investigated. The results showed that the yolk granules were depolymerized after HIU treatment, and the average particle size was significantly reduced from 289.4 nm (untreated) to 181.4 nm (270-W HIU treatment). All contents of dry matter, protein, calcium and phosphorus in the supernatant of the HIU-treated yolk granule solution increased, which suggests that HIU treatment increases the dissolution of yolk granule components. Spectroscopic analysis showed that HIU treatment increased the polarity of the microenvironment and enhanced the hydrogen bond force of yolk granules. These changes induced by HIU treatment collectively enhanced the zeta potential, decreased the free sulfhydryl group content, and slightly improved the emulsifying activity index of yolk granules. The present study reveals the depolymerization effect of HIU treatment on egg yolk granules and can inspire new potential applications of egg yolk granules.