Unveiling and application of the chicken egg proteome: An overview on a two-decade achievement

Effects of dietary protein-oxidized soybean meal and quercetin on gel properties, microstructure, molecular structure and proteomics of egg white in laying hens

This study investigated the effects of dietary protein-oxidized soybean meal (SBM) and quercetin on gel properties, microstructure, molecular structure and proteomics of egg white in laying hens. A total of 288 Hy-Line Gray laying hens (500 days) were assigned to three groups, basal diets, protein-oxidized SBM diet, and protein-oxidized SBM diet supplemented with 300 mg/kg quercetin. The results showed that dietary protein-oxidized SBM decreased egg albumen height, gel hardness, gumminess and chewiness, and free sulfhydryl levels, although differences were not significant (P > 0.05). Quercetin supplementation reversed above mentioned indicators (P < 0.05). Dietary protein-oxidized SBM significantly increased the protein secondary structure α-helix content, reduced β-turn content, and reduced foam capacity of egg white (P < 0.05), while dietary quercetin alleviated the corresponding index (P < 0.05). Quercetin improved the egg Haugh unit, potentially due to its ability to increase the levels of microfilament proteins.

Hydrolyzed egg yolk peptide alleviates ovariectomy-induced osteoporosis by regulating lipid metabolism

Osteoporosis is a systemic, progressive bone disease that causes metabolic disorders. Previous study identified the preventive effects of hydrolyzed egg yolk peptide (YPEP) on osteoporosis. However, the underlying antiosteoporosis mechanism remains unclear. Herein, 30 female rats were randomly divided into 5 groups (n = 6), including the sham, OVX, E2 (25 μg/kg/d 17β-estradiol), LYPEP (10 mg/kg/d YPEP), and HYPEP (40 mg/kg/d YPEP) groups. YPEP treatment significantly changed bone turnover marker levels and prevented the deterioration of bone structure and strength caused by ovariectomy. YPEP supplementation significantly changed endogenous metabolites related to lipid metabolism in the serum of ovariectomized rats, identifying 46 metabolites closely linked to bone biomarkers. Additionally, YPEP reduced the expression of the lipid metabolism-related protein peroxisome proliferator-activated receptor PPARγ and increased the expression of bone formation proteins BMP2 and RUNX2. Collectively, these results elucidated that YPEP improves osteoporosis by inhibiting lipogenesis to promote bone formation. This study provides novel evidence for the use of YPEP in treating osteoporosis.

Proteomic and N-glycosylation analysis of fertile egg white during storage and incubation in chickens

Proteins in egg whites play vital roles in embryonic development. Simultaneously, protein modification is affected by the surrounding environment, which ultimately affects the structure and function of proteins. Here, we measured the phenotypes of eggs at different time points during storage and incubation and used 4D label-free quantitative proteomics technology and liquid chromatography/tandem mass spectrometry (LC-MS/MS)-technique to identify the differential proteins and N-glycosylation sites in egg whites during storage and incubation. We found that the differential N-glycoproteins in the early stage of storage were mainly related to protein structure changes, antibacterial activity, and cell proliferation, and that there were more protease inhibitors in egg whites, which decreased in the later stage of storage. Finally, eleven possible protein markers and N-glycosylation sites were identified to significantly change during storage and may exert an effect on hatchability, including the proteins involved in antibacterial activity (OVOA-N855, CLU-N154, ogchi-N82, PIGR-N290, WFDC2-N120), protein structure (LOC776816), and cell proliferation (ASAH1-N173). This study provides substantial insights into the physical and molecular compositional changes in egg whites under different storage times and revealed their potential effect on chick embryo development.

Protein aggregation caused by pasteurization processing affects the foam performance of liquid egg white

Pasteurization is necessary during the production of liquid egg whites (LEW), but the thermal effects in pasteurization could cause an unavoidable loss of foaming properties of LEW. This study intended to investigate the mechanism of pasteurization processing affects the foam performance of LEW. The foaming capacity (FC) of LEW deteriorated significantly (ΔFCmax = 72.33 %) and foaming stability (FS) increased slightly (ΔFSmax = 3.64 %) under different temperature-time combinations of pasteurization conditions (P < 0.05). The increased turbidity and the decreased solubility together with the decreased absolute value of Zeta potential indicated the generation of thermally induced aggregates and the instability of the protein particles, Rheological characterization demonstrated improved viscoelasticity in pasteurization liquid egg whites (PLEW), explaining enhanced FS. The study revealed that loss in foaming properties of PLEW resulted from thermal-induced protein structural changes and aggregation, particularly affecting FC. This provided a theoretical reference for the production and processing of LEW products.

Preparation, Structural Identification, and Screening of Egg-Derived Peptides with Facilitating Alcohol Metabolism Activity

The aim of this study was to obtain egg-derived peptides with facilitating alcohol metabolism (EPs) by enzymolysis, to identify their structures, and screen small polypeptides with higher activity by molecular docking. The optimum conditions for preparing EPs with facilitating alcohol metabolism were obtained by a single factor experiment, adding 2% Protamex and performing enzymolysis for 3 h with a liquid-material ratio of 35:1. The dose-response relationship experiment showed that 800 mg/kg·bw EPs played a better role in facilitating alcohol metabolism. EPs contained 40% hydrophobic amino acids (HAA), including 9.24% Leu. Eighty-four peptides were identified by HPLC-MS/MS and four peptides with potential activation of alcohol dehydrogenase were further selected by molecular docking. The tetrapeptide Trp-Ile-Val-Asp (WIVD) with the highest binding energy reached -7.16 kcal/mol. These findings suggest that egg is a good source for the preparation of peptides with facilitating alcohol metabolism activity.

Whole transcriptome analysis reveals the key genes and noncoding RNAs related to follicular atresia in broilers

Broodiness, a maternal behavior, is accompanied by the atresia of follicles and the serious degradation of poultry reproductive performance. The comparison of follicles between brooding and laying hens is usually an ideal model for exploring the regulation mechanism of follicle atresia. In this study, we selected three brooding hens and three laying hens to collect their follicles for whole transcriptome sequencing. The results demonstrated different expression patterns between the follicles of brooding hens and laying hens. In the top 10 differentially expressed genes with the highest expression, MMP10 was relatively low expressed in the follicles of brooding hens, but other nine genes were relatively highly expressed, including LRR1, RACK1, SPECC1L, ABHD2, COL6A3, RPS17, ATRN, BIRC6, PGAM1 and SPECC1L. While miR-21-3p, miR-146a-5p, miR-142-5p and miR-1b-3p were highly expressed in the follicles of brooding hen, miR-106-5p, miR-451, miR-183, miR-7, miR-2188-5p and miR-182-5p were lowly expressed in brooding hen. In addition, we identified 124 lncRNAs specifically expressed in the follicles of brooding hens and 147 lncRNAs specifically expressed in the follicles of laying hens. Our results may provide a theoretical basis for further exploration of the molecular mechanism of broodiness in broilers.

Current State of Milk, Dairy Products, Meat and Meat Products, Eggs, Fish and Fishery Products Authentication and Chemometrics

Food fraud is a matter of major concern as many foods and beverages do not follow their labelling. Because of economic interests, as well as consumers' health protection, the related topics, food adulteration, counterfeiting, substitution and inaccurate labelling, have become top issues and priorities in food safety and quality. In addition, globalized and complex food supply chains have increased rapidly and contribute to a growing problem affecting local, regional and global food systems. Animal origin food products such as milk, dairy products, meat and meat products, eggs and fish and fishery products are included in the most commonly adulterated food items. In order to prevent unfair competition and protect the rights of consumers, it is vital to detect any kind of adulteration to them. Geographical origin, production methods and farming systems, species identification, processing treatments and the detection of adulterants are among the important authenticity problems for these foods. The existence of accurate and automated analytical techniques in combination with available chemometric tools provides reliable information about adulteration and fraud. Therefore, the purpose of this review is to present the advances made through recent studies in terms of the analytical techniques and chemometric approaches that have been developed to address the authenticity issues in animal origin food products.

Egg White and Yolk Protein Atlas: New Protein Insights of a Global Landmark Food

(1) Background: The chicken egg is an animal product of great agronomic interest. The egg white and yolk constitute high-quality protein sources for humans with high digestibility and well-balanced amino acid profiles. Despite the egg white and yolk protein's undisputed value, research to unravel their full proteome content and its properties is still ongoing. We aimed to exhaustively analyze the proteome of egg white and yolk by applying intrinsic proteomics and bioinformatics approaches in order to unravel the full protein potential of this landmark food. (2) Methods: A total of 45 freshly laid, unfertilized, chicken eggs were subjected to nanoLC-MS/MS Orbitrap analysis following a peptide pre-fractionation step. A comprehensive bioinformatics processing step was undertaken towards elucidating potential activities and roles of identified molecules. In parallel, the literature was mined concerning all reported egg white and yolk protein identifications. (3) Results: Our analysis revealed 371 and 428 new proteins, reported for the first time to be present in the egg white and yolk, respectively. From the bioactivity standpoint, egg white and yolk proteins showed high enrichment for antioxidant and anti-inflammatory processes, while exerting high relevance for the apoptosis and focal adhesion pathways. (4) Conclusions: Egg white and yolk proteins exert diverse and multifaceted properties. A total of 799 proteins were reported for the first time as being part of the egg and yolk. Our novel protein data enriched those already published in the literature and the first ever chicken egg white and yolk Protein Atlas, comprising 1392 protein entries, was generated. This dataset will provide a cornerstone reference for future studies involving egg proteins.

Quantitative metabolome analysis of boiled chicken egg yolk

Boiling has important effects on the texture of chicken eggs, but its effects on egg nutrients have not been systematically investigated. In this study, changes in the metabolites of egg yolks boiled under different heating intensities were quantified and compared by metabolomic analysis. A total of 797 metabolites were identified, and the abundance of 162 metabolites changed significantly after boiling. The significant reduction of L-lysine and D-fructose suggested that Maillard reactions occurred in over-boiled egg yolks. Egg yolk endogenous enzymes might induce a partial hydrolysis of proteins and phospholipids during the warm-up period of boiling, as the abundance of dipeptides, lysophospholipids, and free fatty acids was significantly increased in boiled egg yolks. Boiling increased the detectable abundance of fat-soluble vitamins, riboflavin, and biotin, possibly by altering the complex structure of protein-lipid-lipophilic compounds or denaturing vitamin-binding proteins. The results of metabolomic analyses provide important information for understanding the nutritional changes of egg yolk boiled under different heating intensities.