Ovomucin - a glycoprotein with promising potential

LC-MS characterization of N/O-glycans of α- and β-subunits of chicken ovomucin separated by SDS-PAGE

As the main active glycoprotein of egg white, the biological functions of chicken ovomucin α- and β-subunit are closely related to the structure of glycans. However, the exact composition and structure of the subunit glycans are still unknown. We obtained highly pure chicken ovomucin α-subunit and β-subunit protein bands by the strategy combined with two-step isoelectric precipitation and SDS-PAGE gel electrophoresis. The ammonia-catalyzed one-pot procedure was then used to release and capture α-and β-subunit protein glycans with 1-phenyl- 3-Methyl-5-pyrazolone (PMP). The N/O-glycans of bis-PMP derivatives were purified and analyzed by LC-MS. More importantly, an effective dual modification was performed to accurately quantify neutral and sialylated O-glycans through methylamidation of sialic acid residues and simultaneously through carbonyl condensation reactions of reducing ends with PMP. We first showed that the α-subunit protein has only N-glycosylation modification, and the β-subunit only O-glycosylation, a total of 22 N-glycans and 20 O-glycans were identified in the α- and β-subunit, respectively. In addition, the complex N-glycan (47 %) and the sialylated O-glycan (77 %) are each major types of the above subunits. Such findings in this study provide a basis for studying the functional and biological activities of chicken ovomucin glycans.

Carbon Dots Crosslinked Egg White Hydrogel for Tissue Engineering

Egg white (EW)-derived hydrogels hold promise as biomaterials for in vitro cell culture due to their ability to mimic the extracellular matrix. However, their highly cross-linked structures restrict their potential for in vivo applications, as they are unable to integrate dynamically with tissues before degradation. In this study, this limitation is addressed by introducing carbon dots (CDs) as cross-linking agents for EW in a dilute aqueous solution. The resulting CDs-crosslinked EW hydrogel (CEWH) exhibits tensile strength comparable to that of skin tissue and features a large pore structure that promotes cell infiltration. Subcutaneous implantation of CEWH demonstrated excellent integration with surrounding tissue and a degradation rate aligned with the hair follicles (HFs) regeneration cycle. This allows the long-term regeneration and establishment of an M2 macrophage-dominated immune microenvironment, which in turn promotes the re-entry of HFs into the anagen phase from the telogen phase. Additionally, CEWH demonstrated potential as a wound dressing material. Overall, this study paves the way for utilizing EW as a versatile biomaterial for tissue engineering.

Ovomucin and its hydrolysates differentially influenced colitis severity in Citrobacter rodentium-infected mice

Egg white protein ovomucin and its hydrolysates were previously reported to exhibit anti-inflammatory and anti-adhesive activities. However, their potential to regulate pathogen colonization and disease severity has not been fully characterized. To investigate the effects of ovomucin (OVM) and its hydrolysates including ovomucin-Protex 26L (OP) and -pepsin/pancreatin (OPP) on host resistance to pathogen infection, a well-documented colitis model in mice for attaching and effacing E. coli pathogens, Citrobacter rodentium, was used in the current study. C57Bl/6J female mice were fed on a basal diet supplemented with OVM or its hydrolysates for 3 weeks prior to the C. rodentium challenge, with the dietary treatments continued for seven days. Body weight was not affected throughout the experimental period. OP supplementation resulted in lower (P < 0.05) pathogen loads at 7 dpi. Attenuated colitis severity was observed in mice that received OVM and OP, as indicated by reduced colonic pathological scores and pro-inflammatory responses compared with the infected control group. In contrast, OPP consumption resulted in enhanced C. rodentium colonization and disease severity. Notably, reduced microbial diversity indices of the gut microbiota were observed in the OPP-supplemented mice compared with the OVM- and OP-supplemented groups. This study showed the potential of OVM and OP to alleviate the severity of colitis induced by infection while also suggesting the opposite outcome of OPP in mitigating enteric infection.

Biomacromolecular carriers based hydrophobic natural products for potential cancer therapy

Cancer is the second leading cause of death worldwide. It was estimated that 90 % of cancer-related deaths were attributable to the development of multi-drug resistance (MDR) during chemotherapy, which results in ineffective chemotherapy. Hydrophobic natural products plays a pivotal role in the field of cancer therapy, with the potential to reverse MDR in tumor cells, thereby enhancing the efficacy of tumor therapy. However, their targeted delivery is considered a major hurdle in their application. The advent of numerous approaches for encapsulating bioactive ingredients in the nanodelivery systems has improved the stability and targeted delivery of these biomolecules. The manuscript comprehensively analyses the nanodelivery systems of bioactive compounds with potential cancer therapy applications, including liposomes, emulsions, solid lipid nanoparticles (NPs), and polymeric NPs. Then, the advantages and disadvantages of various nanoagents in the treatment of various cancer types are critically discussed. Further, the application of multiple-compbine delivery methods to overcome the limitations of single-delivery have need critically analyzed, which thus could help in the designing nanodrug delivery systems for bioactive compounds in clinical settings. Therefore, the review is timely and important for development of efficient nanodelivery systems involving hydrophobic natural products to improve pharmacokinetic properties for effective cancer treatment.

Ovomucin Hydrolysates Reduce Bacterial Adhesion and Inflammation in Enterotoxigenic Escherichia coli (ETEC) K88-Challenged Intestinal Epithelial Cells

Enterotoxigenic Escherichia coli (ETEC) K88 is the most common cause of diarrhea in neonatal and postweaning pigs. After adhering to small intestinal epithelial cells via glycoprotein receptor recognition, the pathogen can produce enterotoxins, impair intestinal integrity, trigger watery diarrhea, and induce inflammation via nuclear factor κB (NF-κB) and mitogen-activated protein kinase phosphatase (MAPK) pathways. Inhibiting ETEC K88 adhesion to cell surfaces by interfering with the receptor-fimbriae recognition provides a promising strategy to prevent the initiation and progression of infection. Ovomucin is a highly glycosylated protein in chicken egg white with diverse bioactivities. Ovomucin hydrolysates prepared by the enzymes Protex 26L (OP) and pepsin/pancreatin (OPP) were previously revealed to prevent adhesion of ETEC K88 to IPEC-J2 cells. Herein, we investigated the protective effects of ovomucin hydrolysates on ETEC K88-induced barrier integrity damage and inflammation in IPEC-J2 and Caco-2 cells. Both hydrolysates inhibited ETEC K88 adhesion to cells and protected epithelial cell integrity by restoring transepithelial electronic resistance (TEER) values. Removing sialic acids in the hydrolysates reduced their antiadhesive capacities. Ovomucin hydrolysates suppressed ETEC-induced activation of NF-κB and MAPK signaling pathways in both cell lines. The ability of ETEC K88 in activating calcium/calmodulin-dependent protein kinase 2 (CaMK II), elevating intracellular Ca2+ concentration, and inducing oxidative stress was attenuated by both hydrolysates. In conclusion, this study demonstrated the potential of ovomucin hydrolysates to prevent ETEC K88 adhesion and alleviate inflammation and oxidative stress in intestinal epithelial cells.

Quantitative proteomics provides new insights into the mechanism of improving rehydration of egg white powder by ultrasonic pretreatment

Poor rehydration is one of the key factors affecting the functional properties of egg white powder (EWP). Reducing rehydrated precipitates is important for the processing and application of EWP. In this study, effects of ultrasonic pretreatment on the physicochemical and functional properties of EWP rehydration solutions were studied with the aim of revealing the mechanism of ultrasonic pretreatment to improve rehydration. Compared with freeze-dried EWP (FD) and spray-dried EWP (SD), the percentage of ultrasonic pretreated FD (UFD) and ultrasonic pretreated SD (USD) rehydrated precipitates decreased by 13.0 % and 5.6 %, respectively, after ultrasonic pretreatment (0.25 W/mL for 10 min); and the average particle sizes of UFD and USD solutions decreased by 22.5 % and 15.5 %, respectively. Fourier transform infrared spectroscopy showed that ultrasonic pretreatment caused higher β-sheet content in the protein secondary structure of UFD rehydrated precipitates (49.2 %). Quantitative proteomic analysis revealed a decrease in the abundance of major egg white proteins (ovalbumin, ovotransferrin, ovomucoid and ovomucin) in the rehydrated precipitates of UFD, except for lysozyme. It was also shown that lysozyme-centered aggregates were disrupted in the rehydrated precipitates of UFD. Our research suggests that ultrasonic pretreatment improves EWP rehydration by reducing the interactions between high abundance proteins as well as improving the solubility of high abundance proteins.

Dietary supplementation with 2-hydroxy-4-methyl(thio) butanoic acid and DL-methionine improves productive performance, egg quality and redox status of commercial laying ducks

This experiment aimed to study the effects of supplemental methionine sources, 2-hydroxy-4 methyl(thio) butanoic acid (HMTBa) and DL-Methionine (DL-Met), on productive performance, egg quality, and redox status of laying ducks. A total of 792 healthy 25-wk-old Longyan laying ducks with similar body weights were randomly allotted to 11 treatment groups. Each treatment group had 6 replicates of 12 ducks. The trial lasted for 16 wk. Ducks were fed a basal deficient diet (Met: 0.24%; Met + Cys: 0.51%) or supplemented with DL-Met or HMTBa at 0.05%, 0.12%, 0.19%, 0.26%, and 0.33% of diet, respectively. Compared with the basal diet, supplementation with either DL-Met or HMTBa increased the average egg weight, egg mass, and decreased feed to egg ratio during the whole trial period (P < 0.05). Albumen weight and its ratio to total egg weight were increased, but yolk and shell ratio, albumen height, Haugh unit and shell breaking strength were decreased (P < 0.05). Dietary DL-Met or HMTBa supplementation increased taurine, methionine, leucine, tryptophan and arginine content, and decreased serine and lysine content in plasma (P < 0.05). The redox status of laying ducks was improved by enhancing the glutathione peroxidase and catalase activities, glutathione content and its ratio relative to glutathione (oxidized) content and decreasing malondialdehyde content and increasing mRNA expression of superoxide dismutase-1, glutathione peroxidase-1, hemeoxygenase-1 and nuclear factor-like 2 in liver and ileum with the supplementation of DL-Met or HMTBa (P < 0.05). Liver health status measured by average area proportion lipid droplet was improved with supplementation of DL-Met or HMTBa (P < 0.05). Villus height and villus height to crypt depth ratio in the ileum and the ileal gene expression of tight junction protein and occludin were increased with DL-Met or HMTBa supplementation (P < 0.05). Taken together, these results suggested that the efficacy of dietary supplementation of HMTBa was similar to DL-Met, and it ranged from 98% to 100% for productive performance and egg albumen ratio in laying ducks (25 to 41 wk).

Exploring the binding effect and mechanism of glycyrrhizin to ovomucin by combining spectroscopic analysis and molecular docking

Ovomucin (OVM) is an ideal natural macromolecular glycoprotein extracted from eggs with good adhesion. Based on the defect that glycyrrhizin (GL) has good antiviral activity but fast metabolism, this study aimed to explore the binding effect and mechanism of GL to OVM, using multi-spectroscopic techniques, isothermal titration calorimetry (ITC), and molecular docking. The adhesion ability of OVM to the hydrophilic interface and GL was first demonstrated by dual polarization interferometry (DPI) analysis and binding capacity assay, and the OVM-GL complex exhibited a similar affinity for the spike protein of COVID-19. The spectroscopic results show that GL can quench the inherent fluorescence and change the glycosidic bond and secondary structure of OVM. The ITC measurements suggested that the binding was exothermic, the hydrogen bond was the dominant binding force for forming OVM-GL. Finally, molecular docking results indicated that GL has hydrogen bond interaction with several amino acid residues located in α-OVM and β-OVM while embedding into the hydrophobic pocket of OVM via hydrophobic interactions. In conclusion, OVM can adhere to the hydrophilic interface and bind to GL through hydrogen bonding and hydrophobic interactions to form a stable complex, that is expected to be helpful in virus prophylaxis.

Quantitative proteomic analysis of chicken egg white and its components

The protein profiles and properties of chicken egg white and its three components (thick egg white, TKEW; thin egg white, TNEW; and chalaza, CLZ) were comprehensively compared. The proteomes of TNEW and TKEW are relatively similar, but the abundance of mucin-5B and mucin-6 (the two subunits of ovomucin) is significantly higher in TKEW than in TNEW (42.97% and 870.04%, respectively), while the lysozymes in TKEW are 32.57% higher (p < 0.05) than those in TNEW. Meanwhile, the properties (including the spectroscopy, viscosity, and turbidity) of TKEW and TNEW are significantly different. Comprehensively, it is speculated that the electrostatic interactions between lysozyme and ovomucin are the main reason for the high viscosity and turbidity of TKEW. Compared with egg white sample (EW), CLZ has a higher abundance of insoluble proteins (mucin-5B, 4.23-fold; mucin-6, 6.89-fold) and a lower abundance of soluble proteins (ovalbumin-related protein X, 89.35% lower than EW; ovalbumin-related protein Y, 78.51% lower; ovoinhibitor, 62.08% lower; riboflavin-binding protein, 93.67% lower). These compositional differences should explain the insolubility of CLZ. These findings are important references for deepening the research and development of egg white in the future, such as the thinning of egg white, the molecular basis of changes in egg white properties, and the differential application of TKEW and TNEW.

Effects of cadmium, lead, mercury, chromium, and selenium co-treatment on egg quality and fatty acids

This study aimed to reveal the effect of selenium (Se) and heavy metals (chromium (Cr), cadmium (Cd), lead (Pb), and mercury (Hg)) on the quality, fatty acids, and 13 kinds of ions in the egg yolk and albumen. Four experimental groups were established, including a control group (control; basal diet), Se group (basal diet + Se), heavy metals group (basal diet + CdCl₂ + Pb(NO₃)₂ + HgCl₂ + CrCl₃), and Se + heavy metal (HM) group (basal diet + Se + CdCl₂ + Pb(NO₃)₂ + HgCl₂ + CrCl₃). Se supplementation significantly increased the experimental egg yolk percentage since Se accumulation mainly occurred in the yolks of the eggs. The Cr content in the yolks of the Se + heavy metal groups decreased at 28 days, while a significant reduction was evident in the Cd and Hg levels of the Se + heavy metal yolks compared to the heavy metal group at 84 days. The complex interactions between the elements were analyzed to determine the positive and negative correlations. Se displayed a high positive correlation with Cd and Pb in the yolk and albumen, while the heavy metals minimally affected the fatty acids in the egg yolk.

Recombinant mucin biotechnology and engineering

Mucins represent a largely untapped class of polymeric building block for biomaterials, therapeutics, and other biotechnology. Because the mucin polymer backbone is genetically encoded, sequence-specific mucins with defined physical and biochemical properties can be fabricated using recombinant technologies. The pendent O-glycans of mucins are increasingly implicated in immunomodulation, suppression of pathogen virulence, and other biochemical activities. Recent advances in engineered cell production systems are enabling the scalable synthesis of recombinant mucins with precisely tuned glycan side chains, offering exciting possibilities to tune the biological functionality of mucin-based products. New metabolic and chemoenzymatic strategies enable further tuning and functionalization of mucin O-glycans, opening new possibilities to expand the chemical diversity and functionality of mucin building blocks. In this review, we discuss these advances, and the opportunities for engineered mucins in biomedical applications ranging from in vitro models to therapeutics.

Natural Multi-Enriched Eggs with n-3 Polyunsaturated Fatty Acids, Selenium, Vitamin E, and Lutein

The research investigates the possibilities of enriching eggs with n-3 polyunsaturated fatty acids, selenium, vitamin E, and lutein. The research was carried out on 100 TETRA SL laying hens divided into two groups (C and E). Hens in treatment C (control group) were fed a standard feeding mixture that contained 5% soybean oil, 0.32 mg/kg organic selenium, 25.20 mg/kg vitamin E, and 20.5 mg/kg lutein (Marigold flower extract). Hens in treatment E (experimental group) were fed a mixture in which soybean oil was replaced by 1.5% fish oil + 1.5% rapeseed oil + 2.0% linseed oil. The content of other nutricines amounted to 0.47 mg/kg organic selenium, 125.2 mg/kg vitamin E, and 120.5 mg/kg lutein. Portions of total n-3 polyunsaturated fatty acids in enriched eggs were significantly increased when compared to conventional eggs (480.65:204.58 mg/100 g; p < 0.001). The content of selenium, vitamin E, and lutein was significantly higher (p < 0.001) in enriched eggs than in conventional eggs. The content of selenium in egg albumen was increased by 1.81 times, and in the yolk, it was increased by 1.18 times. At the same time, the content of vitamin E was 2.74 times higher, and lutein was 8.94 times higher in enriched eggs than in conventional eggs.

Phytogenic Antioxidants Prolong n-3 Fatty Acid-Enriched Eggs’ Shelf Life by Activating the Nrf-2 Pathway through Phosphorylation of MAPK

Helpful for human health, omega-3 (n-3)-enriched eggs are preferred by consumers. However, antioxidants should be added to the hen’s diet to prevent n-3 fatty acid oxidation due to their unsaturated bonds. A study was designed to investigate the effects of different antioxidants on performance, egg quality, fatty acid profile, oxidation parameters, gene expression, and magnum morphology. A total of 450 hens were divided into five dietary groups. Wheat–flaxseed was used for the basic diet (control) and supplemented with vitamin E (VE), chlorogenic acid (CA), polyphenol (PF), and lutein (L). The experiment lasted for 10 weeks. The eggs were collected on the 5th week and were analyzed for quality, oxidative stability, and fatty acid (FA) content, being stored for 0 d, 7 d, 14 d, 21 d, 28 d, 35 d, and 42 d. The results showed that supplemental VE, PF, CA, and L improved the egg weight and hen day egg production compared to the control group (p < 0.05). The VE, PF, and L groups significantly (p < 0.05) reduced the malondialdehyde (MDA) and maintained the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and total antioxidant capacity (T-AOC) in the egg yolk. The albumen height and Haugh unit were maintained in the egg yolk till 35 days of storage by the VE, PF, and L groups, while the CA group reduced the albumen quality after 21 d storage. The VE, PF, CA, and lutein maintained the content of alpha-linolenic acid (ALA), during the whole storage period. The total n-3 FA and docosahexaenoic acid (DHA) were retained in the egg yolk till 35 and 28 days of storage, respectively, and slightly decreased after 35 and 28 days in the L groups. The total n-6 (Tn-6) FA was maintained in the yolk till 28 days of storage in the CA and PF groups, respectively. The VE, PF, and L groups upregulated the expression of Nrf-2, P38MAPK, HO-1, SOD-1, and GSH-Px as compared to the CA and control groups. The VE, PF, and L groups significantly increased the magnum primary folds and epithelium height as compared to CA and the control. Thus, it was concluded that the use of PF and L is better at preventing egg quality deterioration and lipid oxidation, maintaining more than 300 mg/egg n-3 FA during storage, by activating the Nrf-2 pathway through the phosphorylation of P38MAPK, and enhancing the phase-2 antioxidant defense enzymes, namely, SOD, GSH-Px, and HO-1.

The Quality Characteristics Formation and Control of Salted Eggs: A Review

Salted egg, a traditional characteristic processed egg product in China, is popular among consumers at home and abroad. Salted egg quality characteristics formation primarily includes the hydration of egg white, the solidification of egg yolk, the unique color and flavor of salted egg yolk, and the formation of white, fine, and tender egg whites and loose, sandy, and oily egg yolks after pickling and heating. The unique quality characteristics of salted eggs are mostly caused by the infiltration dehydration of salt, the intermolecular interaction of proteins, and the oxidation of lipids. In recent years, to solve the problems of salted eggs having high salinity, long production cycle, and short storage period, the pickling technology for salted egg has been improved and researched, which has played a significant role in promoting the scientific production of salted eggs. This paper summarizes the mechanisms of salted egg quality characteristics formation and factors influencing quality, with a perspective of providing a theoretical basis for the production of high-quality salted eggs.

Functional Properties and Extraction Techniques of Chicken Egg White Proteins

Chicken egg whites contain hundreds of proteins, and are widely used in the food, biological and pharmaceutical industries. It is highly significant to study the separation and purification of egg white proteins. This review first describes the structures and functional properties of several major active proteins in egg whites, including ovalbumin, ovotransferrin, ovomucoid, lysozyme, ovomucin, ovomacroglobulin and avidin. Then, the common techniques (including precipitation, chromatography and membrane separation) and some novel approaches (including electrophoresis, membrane chromatography, aqueous two-phase system and molecular imprinting technology) for the separation and purification of egg white proteins broadly reported in the current research are introduced. In addition, several co-purification methods for simultaneous separation of multiple proteins from egg whites have been developed to improve raw material utilization and reduce costs. In this paper, the reported techniques in the last decade for the separation and purification of chicken egg white proteins are reviewed, discussed and prospected, aiming to provide a reference for further research on egg proteins in the future.

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.

Natural Products of Plants and Animal Origin Improve Albumen Quality of Chicken Eggs

Albumen quality is recognized as one of the major yardsticks in measuring egg quality. The elasticity of thick albumen, a strong bond in the ovomucin-lysozyme complex, and excellent biological properties are indicators of high-quality albumen. The albumen quality prior to egg storage contribute to enhance egg’s shelf life and economic value. Evidence suggests that albumen quality can deteriorate due to changes in albumen structure, such as the degradation of β-ovomucin subunit and O-glyosidic bonds, the collapse of the ovomucin-lysozyme complex, and a decrease in albumen protein-protein interaction. Using organic minerals, natural plants and animal products with antioxidant and antimicrobial properties, high biological value, no residue effect and toxicity risk could improve albumen quality. These natural products (e.g., tea polyphenols, marigold extract, magnolol, essential oils, Upro (small peptide), yeast cell wall, Bacillus species, a purified amino acid from animal blood, and pumpkin seed meal) are bio-fortified into eggs, thus enhancing the biological and technological function of the albumen. Multiple strategies to meeting laying hens’ metabolic requirements and improvement in albumen quality are described in this review, including the use of amino acids, vitamins, minerals, essential oils, prebiotics, probiotics, organic trace elements, and phytogenic as feed additives. From this analysis, natural products can improve animal health and consequently albumen quality. Future research should focus on effects of these natural products in extending shelf life of the albumen during storage and at different storage conditions. Research in that direction may provide insight into albumen quality and its biological value in fresh and stored eggs.

Potential Implications of Natural Antioxidants of Plant Origin on Oxidative Stability of Chicken Albumen during Storage: A Review

Enhanced albumen quality is reflected in increased thick albumen height, albumen weight, and Haugh unit value, while the antimicrobial, antioxidant, foaming, gelling, viscosity, and elasticity attributes are retained. Improved albumen quality is of benefit to consumers and to the food and health industries. Egg quality often declines during storage because eggs are highly perishable products and are most often not consumed immediately after oviposition. This review provides insights into albumen quality in terms of changes in albumen structure during storage, the influence of storage time and temperature, and the mitigation effects of natural dietary antioxidants of plant origin. During storage, albumen undergoes various physiochemical changes: loss of moisture and gaseous products through the shell pores and breakdown of carbonic acid, which induces albumen pH increases. High albumen pH acts as a catalyst for structural changes in albumen, including degradation of the β-ovomucin subunit and O-glycosidic bonds, collapse of the ovomucin-lysozyme complex, and decline in albumen protein–protein interactions. These culminate in declined albumen quality, characterized by the loss of albumen proteins, such as ovomucin, destabilized foaming and gelling capacity, decreased antimicrobial activity, albumen liquefaction, and reduced viscosity and elasticity. These changes and rates of albumen decline are more conspicuous at ambient temperature compared to low temperatures. Thus, albumen of poor quality due to the loss of functional and biological properties cannot be harnessed as a functional food, as an ingredient in food processing industries, and for its active compounds for drug creation in the health industry. The use of refrigerators, coatings, and thermal and non-thermal treatments to preserve albumen quality during storage are limited by huge financial costs, the skilled operations required, environmental pollution, and residue and toxicity effects. Nutritional interventions, including supplementation with natural antioxidants of plant origin in the diets of laying hens, have a promising potential as natural shelf-life extenders. Since they are safe, without residue effects, the bioactive compounds could be transferred to the egg. Natural antioxidants of plant origin have been found to increase albumen radical scavenging activity, increase the total antioxidant capacity of albumen, reduce the protein carbonyl and malondialdehyde (MDA) content of albumen, and prevent oxidative damage to the magnum, thereby eliminating the transfer of toxins to the egg. These products are targeted towards attenuating oxidative species and inhibiting or slowing down the rates of lipid and protein peroxidation, thereby enhancing egg quality and extending the shelf life of albumen.

Mechanism of differences in characteristics of thick/thin egg whites during storage: Physicochemical, functional and molecular structure characteristics analysis

This study systematically analyzed and compared thechanges of physicochemical, functional and molecular structural characteristics between thick egg white (KEW) and thin egg white (NEW) during storage. Analysis of physicochemical properties showed that moisture content decreased significantly with the increase of pH during storage. KEW was gradually thinning, while NEW was closer to Newtonian fluid. Functional properties indicated that KEW thermal gel was gradually hard and brittle with the properties of NEW. KEW had better emulsifying property than NEW, and NEW had superior foaming ability. The α-helix and β-sheet in the FT-IR spectrum showed a downward trend, revealing secondary structure changed from order to disorder. Enhancement of fluorescence intensity indicated the structural unfolding and exposure of tryptophan residues. SDS-PAGE proved that OVO might be related to the difference between KEW and NEW characteristics. This study provided new idea and reference value for egg storage and diversified utilization of egg white.

Natural Biomaterials from Biodiversity for Healthcare Applications

Natural biomaterials originating during the growth cycles of all living organisms have been used for many applications. They span from bioinert to bioactive materials including bioinspired ones. As they exhibit an increasing degree of sophistication, natural biomaterials have proven suitable to address the needs of the healthcare sector. Here the different natural healthcare biomaterials, their biodiversity sources, properties, and promising healthcare applications are reviewed. The variability of their properties as a result of considered species and their habitat is also discussed. Finally, some limitations of natural biomaterials are discussed and possible future developments are provided as more natural biomaterials are yet to be discovered and studied.

Recent Advances in Applications of Bioactive Egg Compounds in Nonfood Sectors

Egg, a highly nutritious food, contains high-quality proteins, vitamins, and minerals. This food has been reported for its potential pharmacological properties, including antibacterial, anti-cancer, anti-inflammatory, angiotensin-converting enzyme (ACE) inhibition, immunomodulatory effects, and use in tissue engineering applications. The significance of eggs and their components in disease prevention and treatment is worth more attention. Eggs not only have been known as a "functional food" to combat diseases and facilitate the promotion of optimal health, but also have numerous industrial applications. The current review focuses on different perceptions and non-food applications of eggs, including cosmetics. The versatility of eggs from an industrial perspective makes them a potential candidate for further exploration of several novel components.

Soybean β-conglycinin and catfish cutaneous mucous p22 glycoproteins deteriorate sporangial cell walls of Pseudoperonospora cubensis and suppress cucumber downy mildew

BACKGROUND

Cucumber plants suffer from a serious threatening disease, downy mildew, throughout the growing seasons irrespective of the weather temperature. The causal agent, Pseudoperonospora cubensis, tends to evolve rapidly upon sequential applications of chemical fungicides and generate new progeny possessing tolerance to such fungicides. Glycoproteins represent an environmentally safe alternative for chemically synthetized fungicides and do not trigger fungicide resistance. We studied the antifungal activity of four glycoproteins namely soybean β-conglycinin, chickpea vicilin, duck egg ovomucin and catfish p22 against P. cubensis. Ten commercial fungicides of different chemical groups were used as positive controls of glycoprotein treatments.

RESULTS

The results revealed that soybean β-conglycinin and catfish p22 glycoproteins possess significant antifungal activity against P. cubensis. The amount of disease suppression caused by β-conglycinin and p22 was comparable to the highly efficient chemical fungicides containing copper oxychloride, cymoxanil and fosetyl Al as active ingredients. Vicilin and ovomucin were less efficient biocides as they gave moderate suppression of disease severity. However, all tested glycoproteins provided full protection for the newly emerged cucumber leaves. Microscopic examination of glycoprotein-treated leaves inferred the ability of catfish p22 and soybean β-conglycinin to disrupt the integrity of sporangial cell walls of P. cubensis rendering them non-viable compared to untreated ones. Expression levels of total phenolic compounds and the antioxidant enzymes catalase, superoxide dismutase and peroxidase were elevated upon glycoproteins application, which infers their involvement in disease suppression.

CONCLUSION

This report emphasizes the direct and indirect roles of glycoproteins in safe management of cucumber downy mildew disease. © 2021 Society of Chemical Industry.

Adsorption and purification performance of lysozyme from chicken egg white using ion exchange nanofiber membrane modified by ethylene diamine and bromoacetic acid

A high-performance polyacid ion exchange (IEX) nanofiber membrane was used in membrane chromatography for the recovery of lysozyme from chicken egg white (CEW). The polyacid IEX nanofiber membrane (P-BrA) was prepared by the functionalization of polyacrylonitrile (PAN) nanofiber membrane with ethylene diamine (EDA) and bromoacetic acid (BrA). The adsorption performance of P-BrA was evaluated under various operating conditions using Pall filter holder. The results showed that optimal conditions of IEX membrane chromatography for lysozyme adsorption were 10% (w/v) of CEW, pH 9 and 0.1 mL/min. The purification factor and yield of lysozyme were 402 and 91%, respectively. The adsorption process was further scaled up to a larger loading volume, and the purification performance was found to be consistent. Furthermore, the regeneration of IEX nanofiber membrane was achieved under mild conditions. The adsorption process was repeated for five times and the adsorption capacity of adsorber was found to be unaffected.

Dietary green tea powder supplementation enriched egg nutrients and physicochemical property in an indigenous chicken breed

Dietary supplementation of green tea changes the antioxidative capacity of chickens. However, the effect of green tea supplementation in the diet on egg quality and the consequent change in processing capacity is still not well known. The aim of this study was to determine whether green tea powder (GTP) supplementation could affect egg quality, egg antioxidant capacity, and sensory and egg processing characteristics. Huainan partridge chickens (1,080) at 20 wk old were divided into 2 groups, one group fed a basal diet (control) and one group fed a basal diet plus 10 g kgˆ-1 GTP for 12 wk. After the levels of yolk cholesterol had been determined, chickens from the control group were further divided into low- and high-cholesterol groups and were fed a basal diet or a diet with 10 g kgˆ-1 GTP by orthogonal design. After 4 wk, the egg processing characteristics were investigated. Egg specific gravity, shell strength, shell thickness, albumin height, Haugh unit (HU) and cholesterol content were significantly lower in the GTP group than in the control group (P < 0.05). Egg weight, albumin height, yolk color, and HU increased in a time-dependent manner in both the control and GTP groups (P < 0.01). The yolk C16:0, C20:0, C18:1, C18:2, and polyunsaturated fatty acid (PUFA) contents were higher in the GTP group than in the control group (P < 0.05). Egg whites from the GTP group showed increased radical scavenging activity (P < 0.05). Egg appearance and texture from the GTP group were more preferred than those of the control group (P < 0.05). Eggs from the GTP group had lower hardness, chewiness, and water retention capacity than those of eggs from the control group (P < 0.05). Eggs from the GTP group with high yolk cholesterol showed lower chewiness than those from the basal diet group (P < 0.05). The results suggested that GTP supplementation could enrich the PUFA content in egg yolks, improve the overall taste, and change processing characteristics.

Potential role of ovomucin and its peptides in modulation of intestinal health: A review

Intestinal dysfunction, which may cause a series of metabolic diseases, has become a worldwide health problem. In the past few years, studies have shown that consumption of poultry eggs has the potential to prevent a variety of metabolic diseases, and increasing attention has been directed to the bioactive proteins and their peptides in poultry eggs. This review mainly focused on the biological activities of an important egg-derived protein named ovomucin. Ovomucin and its derivatives have good anti-inflammatory, antioxidant, immunity-regulating and other biological functions. These activities may affect the physical, biological and immune barriers associated with intestinal health. This paper reviewed the structure and the structure-activity relationship of ovomucin，the potential role of ovomucin and its derivatives in modulation of intestinal health are also summarized. Finally, the potential applications of ovomucin and its peptides as functional food components to prevent and assist in the pretreatment of intestinal health problems are prospected.

Differential proteomic analysis revealed crucial egg white proteins for hatchability of chickens

For healthy development, an avian embryo needs the nutritional and functional molecules maternally deposited in avian eggs. Egg white not only provides nutritional components but also exhibits functional properties, such as defenses against microbial invasion. However, the roles of the more detailed messages in embryo development remain unclear. In this study, a tandem mass tag labeling quantitation approach was used to innovatively identify the differential proteins in the egg whites of fresh eggs produced by hens with divergent high/low hatchability and in the egg whites of embryonated eggs with healthy and dead embryos. A total of 378 proteins were quantified in egg white, which is the most complete proteome identified for egg white to date, and up to 102 differential proteins were identified. GO enrichment, pathway, and hierarchical clustering analysis revealed some of the differential proteins that are the main participants in several biological processes, including blood coagulation, intermediate filament, antibacterial activity, and neurodevelopment. A list of 11 putative protein biomarkers, such as keratin (KRT19, KRT12, KRT15, and KRT6A), which is involved in cell architecture, and fibrinogen (fibrinogen alpha chain, fibrinogen beta chain, and fibrinogen gamma chain), which is related to blood coagulation, were ultimately screened. The current study screened egg white proteins that can predict low hatchability and embryonic death and deciphered the role of these proteins in embryonic development, which is meaningful for the comprehensive understanding of embryonic growth.

The Golden Egg: Nutritional Value, Bioactivities, and Emerging Benefits for Human Health

Egg is an encapsulated source of macro and micronutrients that meet all requirements to support embryonic development until hatching. The perfect balance and diversity in its nutrients along with its high digestibility and its affordable price has put the egg in the spotlight as a basic food for humans. However, egg still has to face many years of nutritionist recommendations aiming at restricting egg consumption to limit cardiovascular diseases incidence. Most experimental, clinical, and epidemiologic studies concluded that there was no evidence of a correlation between dietary cholesterol brought by eggs and an increase in plasma total-cholesterol. Egg remains a food product of high nutritional quality for adults including elderly people and children and is extensively consumed worldwide. In parallel, there is compelling evidence that egg also contains many and still-unexplored bioactive compounds, which may be of high interest in preventing/curing diseases. This review will give an overview of (1) the main nutritional characteristics of chicken egg, (2) emerging data related to egg bioactive compounds, and (3) some factors affecting egg composition including a comparison of nutritional value between eggs from various domestic species.

Recently isolated antidiabetic hydrolysates and peptides from multiple food sources: a review

Diabetes, a metabolic syndrome of global importance has been on a progressive rise in recent years. Several pharmacological approaches have been made, which have proved effective, but with underlying side effects. Bioactive hydrolysates (BHs) and peptides (BPs) from food sources, however, have shown the relative advantage of imparting less adverse effects. Furthermore, BHs and BPs from food have been discovered to impart their antidiabetic potentials through one or more mechanisms such as inhibition of digestive enzymes, inhibition of the antigenic enzyme - Dipeptyl peptidase IV (DPP-IV), decrease in blood glucose levels and increase in insulin uptake. Several plants and animal sources have been used as protein sources for the isolation of antidiabetic hydrolysates and peptides through different mechanisms and analytical techniques. This review integrates recent research information about several popular and unconventional food sources of BHs and BPs, their isolation techniques, antidiabetic effects and protein profiles. In addition, the fractionation technique(s) employed in each study and inhibition potentials of BHs and BPs are reviewed. This article is intended to supplement accessible scholarly literature and intellectual awareness on the subject of food-oriented approach for the management of diabetes.

Protein-Resistant Property of Egg White Ovomucin under Different pHs and Ionic Strengths

Ovomucin is a mucin-type glycoprotein accounting for 3.5% (w/w) of total egg white proteins. The purpose of the study was to explore the potential of ovomucin as a protein-resistant material. Using bovine serum albumin (BSA) as a model protein, ovomucin decreased the fluorescence intensities of the adsorbed BSA from 10.90 ± 2.18 to 0.67 ± 0.75, indicating its protein-resistant property. To understand the underlying mechanism, pure repulsive forces between ovomucin and model proteins (e.g., BSA and ovomucin) at various pHs (2.0, 6.0, and 7.2) and ionic strengths (0.1, 10, and 150 mM NaCl) were measured using a surface forces apparatus. Further studies by using atomic force microscope imaging, zeta potential, and dynamic light scattering suggested that the protein-resistant property of ovomucin was mainly attributed to strong electrostatic and steric repulsions between protein layers. This work has demonstrated that ovomucin has antifouling potential with broad applications in the areas of food processing industry and biomedical implants.

Pulsed electric fields treatment at different pH enhances the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white

This research investigated the effects of pulsed electric fields (PEF) (1.4-1.7 kV/cm, 653-695 kJ/kg) and heating (60 and 80 °C for 10 min) at different pH (4, 5, 7, and 9) on the antioxidant and anti-inflammatory activity of ovomucin-depleted egg white (OdEW) after in vitro gastrointestinal hydrolysis. PEF and heating (80 °C for 10 min) at pH 4 enhanced the antioxidant activity of the whole hydrolysates, chemically determined using DPPH and ORAC assays. Furthermore, the anti-inflammatory activity of protein hydrolysates was assessed in lipopolysaccharide-stimulated HT-29 cells using ELISA assay. PEF and heating at pH 4 enhanced the anti-inflammatory activity of the whole hydrolysates dose-dependently. Hydrolysates at 1 mg/ml showed similar inhibition (35.5% and 35.9%) of interleukin-8 production, due to PEF treatment and heating (80 °C for 10 min), respectively. Results indicated that prior PEF treatment can analogously enhance both antioxidant and anti-inflammatory activity of OdEW hydrolysates to heating, with potentially reduced thermal input.