Yolk Protein Research Articles

Study on the mechanism of improving the quality of salted egg yolks by ultrasonic synergistic NaCl dry-curing

The dry separate curing of duck egg yolks was carried out by ultrasonic synergize NaCl (sodium chloride) and NaCl alone. The mechanism of the amelioration of salted egg yolk quality by ultrasonic synergistic NaCl dry-curing was studied. The quality variations of the salted egg yolks were analyzed for the same curing time and NaCl content achieved by ultrasonic synergistic NaCl curing and NaCl curing alone. The results showed that under the same salting time, the NaCl content, oil exudation and chewiness of U48-SEY (ultrasonic for 48 h-salted egg yolk) were higher than those in SEY (salted egg yolk). At the same NaCl content, the oil exudation and chewiness of U44-SEY (ultrasonic for 44 h-salted egg yolk) were still significantly increased. Compared to SEY, the soluble protein content and H0 of U44-SEY and U48-SEY were augmented. Scanning electron microscopy (SEM) indicated that the polyhedral particles in the salted egg yolks prepared by ultrasonic synergistic NaCl dry-curing were closely aligned and evenly distributed, and the salted egg yolks were sandier. Structural analysis revealed that the secondary and tertiary structures of egg yolk protein were changed although the ultrasonic synergistic NaCl dry-curing did not cause the fragmentation or aggregation of the peptide chain structure. The above results suggested that ultrasonic not only perfected the quality of salted egg yolk by promoting NaCl penetration, but also modified the structures of egg yolk protein by the action of ultrasonic itself, which prominently improved the quality of salted egg yolks.

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

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

The timings of vitellogenesis and choriogenesis in the Henosepilachna vigintioctopunctata oocytes

In order to provide a biological basis for the development of population management strategies, a critical need is to better understand the reproduction of agricultural pests. In the current paper, we timed the previtellogenesis, vitellogenesis and choriogenesis processes in Henosepilachna vigintioctopunctata (Fabricius), (Coleoptera, Coccinellidae), a serious polyphagous defoliator damaging a wide range of crops in Solanaceae and Cucurbitaceae. The female reproductive system was comprised of two ovaries, two lateral oviducts, a median oviduct, a spermathecal sac and a genital chamber. Each ovary had an average of 28 (±0.4) telotrophic meroistic ovarioles. In the ovarioles of 4-day-old females, only previtellogenesis process was observed. The vitellogenesis occurred at 5 to 7 days after female emergence, while the choriogenesis took place at 8 and 9 days post eclosion. Copulation and oviposition occurred before and at 8 days post emergence. In order to confirm the observation, HvVgR and HvVg were identified and their expression was examined. HvVgR was abundantly transcribed in the ovary, whereas HvVg was richly expressed in the fat body. The temporal expression profiles showed that the high levels of HvVgR and HvVg were accompanied with the active accumulation of yolk proteins and the occurrence of intercellular spaces among follicle cells. Moreover, only one oocyte was observed per ovariole in active vitellogenesis. The observation demonstrates that oocytes are continuously matured and the oviposition persists in females from 8 days to at least 13 days post eclosion.

Survival, Growth, and Reproduction Responses in a Three-Generation Exposure of the Zebrafish (Danio rerio) to Perfluorooctane Sulfonate.

A prior multigenerational perfluorooctane sulfonic acid (PFOS) exposure investigation in zebrafish reported adverse effects at 0.734 µg/L, among the lowest aquatic effect levels for PFOS reported to date. The present three-generation PFOS exposure quantified survival, growth, reproduction, and vitellogenin (VTG; egg yolk protein) responses in zebrafish, incorporating experimental design and procedural improvements relative to the earlier study. Exposures targeting 0.1, 0.6, 3.2, 20, and 100 µg/L in parental (P) and first filial (F1) generations lasted for 180 days post fertilization (dpf) and the second filial generation (F2) through 16 dpf. Survival decreased significantly in P and F2 generation exposures, but not in F1, at the highest PFOS treatment (100 µg/L nominal, 94-205 µg/L, measured). Significant adverse effects on body weight and length were infrequent, of low magnitude, and occurred predominantly at the highest exposure treatment. Finally, PFOS had no significant effects on P or F1 egg production and survival or whole-body VTG levels in P or F1 male fish. Overall, the predominance and magnitude of adverse PFOS effects at <1 µg/L reported in prior research were largely nonrepeatable in the present study. In contrast, the present study indicated a threshold for ecologically relevant adverse effects in zebrafish at 117 µg/L (SE 8 µg/L, n = 10) for survival and 47 µg/L (SE 11 µg/L, n = 19) for all statistically significant negative effects observed. Environ Toxicol Chem 2024;43:115-131. © 2023 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. This article has been contributed to by U.S. Government employees and their work is in the public domain in the USA.

Antioxidant Activity of Egg Yolk Protein Hydrolysates Obtained by Enzymatic and Sub-Critical Water Hydrolysis

Obtaining peptides with antioxidant properties by enzymatic hydrolysis has been widely described; however, the use of non-enzymatic methods to obtain peptides with antioxidant capacities has been poorly investigated. In this study, non-soluble proteins obtained from delipidated egg yolk granules were hydrolyzed with trypsin, and with a non-enzymatic method using sub-critical water hydrolysis under a non-oxidizing (nitrogen) and oxidizing (oxygen) atmosphere. The effect of the sub-critical water hydrolysis on the amino acids’ composition of the hydrolysates was assessed. Furthermore, the antioxidant capacities of the hydrolysates were evaluated using the ABTS•+ scavenging assay, the DPPH radical scavenging activity assay, and by measuring the reducing power of the peptides, the peptides’ ferrous ion chelating capacities, and the antioxidant effect of the peptides on beef homogenates. The hydrolysate obtained by sub-critical water hydrolysis under a nitrogen stream showed similar or better results in the antioxidant tests than those obtained using trypsin hydrolysis, except in the ferrous chelating capacity, where the trypsin hydrolysate showed the best performance. The oxidizing environment promoted by the oxygen in the other sub-critical water hydrolysis method tested produced the peptides with the lowest antioxidant capacities, due to changes in the primary structure of the peptides. These results suggest that the sub-critical water hydrolysis method under a nitrogen stream, in comparison with the enzymatic hydrolysis, is a reliable method to obtain peptides with good antioxidant capacities.

The effects of dietary amino acid balance on post-embryonic development in a lubber grasshopper

Effects of dietary protein quality on insect development (not just growth) are unclear. Dietary amino acid blends matching yolk proteins support reproduction and juvenile development in Drosophila melanogaster. We matched amino acids to vitellogenin and tested development of juvenile male lubber grasshoppers, which do not produce vitellogenin. Last instars were fed classic dry diets with amino acids substituted for proteins. Matching amino acids to vitellogenin allowed molting to adulthood, while an unmatched isonitrogenous diet did not. Health on dry diets was poor, so we developed wet diets with agar, horse feed, and amino acids. Juveniles fed these diets matched to vitellogenin developed comparably to juveniles fed lettuce. However, wet diets with amino acids dissimilar to vitellogenin (low-quality) slowed development but maintained size at adulthood. We observed no compensatory feeding on low-quality diets. Theory suggests accumulation of proteins permits development. To detect a threshold, we started last juvenile instars on high-quality diets, then abruptly switched them to low-qualities diets. When switched to the poor-quality diet at 6d, grasshoppers molted at a similar age (∼17d) to grasshoppers continuously on the high-quality diet. Total hemolymph proteins levels were unaffected by the timing of diet switches. Last, methionine is essential but can be noxious at high levels. Diets with low-quality protein except for methionine slowed growth early but did not alter the time or size at molt. Overall, the feeding threshold is solely due to essential amino acids, and low-quality protein diets slowed development but did not affect adult size.

A protein chimera for dsRNA binding and delivery into oocytes for large-scale gene silencing in crustacean aquaculture

RNA interference (RNAi) is one of the most intensively used gene silencing techniques for gene function studies and biotechnology applications. However, the gonads, specifically the ovary, of arthropods appear to be intractable to efficient gene silencing. In this article, we report the development of a tool for specific binding and delivery of double-stranded (ds) RNA to the crustacean oocyte for gene silencing. The tool, an oocyte-specific silencing protein chimera, which we designated OSSCot, is composed of a dsRNA-binding domain retrieved from a specific Macrobrachium rosenbergii dsRNA binding protein and 24-amino acid peptide derived from the yolk protein, vitellogenin. The results of the in vitro and in vivo examinations carried out in this study indicate that an OSSCot-piggybacked dsRNA specifically enters the oocytes. The results also indicate that the OSSCot protein protects the dsRNA from degradation by endonucleases in the ovary. When OSSCot was linked to the specific PAX6-like dsRNA of M. rosenbergii (where PAX6 is the master gene for eye development) and injected into the hemolymph of vitellogenic females, the expression of the RNAi enzyme machinery was enhanced, and eye development was impaired in the embryos of the treated females. These findings validate the concept of exploiting OSSCot to piggyback a functional dsRNA into crustacean oocytes for gene silencing. The newly developed tool will find application for oocyte-specific gene silencing in other crustacean species and for research and biotechnology applications.

Optimization of Egg Yolk Protein Hydrolysis by RSM and Properties of Hydrolysates

The effect of temperature, pH, and the enzyme-to-substrate ratio (E/S) on the degree of hydrolysis (DH) of lecithin-free egg yolk (LFEY) protein was optimized by using response surface methodology (RSM). A factorial design was applied to maximize DH and the initial reaction rate (V0). The DH values varied from 16 to 36 % and V0 from 69 to 287 g/L h in the range of tested conditions. The pH was the variable with a major influence on DH and V0. Under the optimized conditions (60°C, pH 9, and E/S=0.35 AU/g) most of the peptides in the hydrolysates had a molecular weight (MW) lower than 12 kDa since the first 10 min of the reaction. Hydrolysates collected after 60 min of the reaction contained mostly oligopeptides (MW&lt;3.5 kDa) with potential antioxidant activity. These hydrolysates might be used as ingredients in high-protein nutritional supplements or the formulation of clinical nutritional products.

Changes in physicochemical properties, molecular structure and microstructure during vacuum assisted quick pickling of low-NaCl salted eggs

In order to clarify the quality formation process of low-NaCl salted eggs (LSEs) under the dual action of vacuum and salt, changes of physicochemical properties, molecular structure, and microstructures of egg white as well as interior and exterior yolks were systematically studied. Results showed that the salt content of egg whites and egg yolks increased to around 5% and 1% respectively, which were only about half of their traditional counterparts. Exterior yolk exudes more oil than the interior yolk, which was consistent with the observation of a more compact microstructure by scanning electron microscopy (SEM). Rheological testing demonstrated a significant increase in the viscosity of yolks but a decrease of egg whites. At the molecular level, proteins of egg white and yolk had gone through the process of denaturation and aggregation, but their change tendencies of free sulfhydryl group, surface hydrophobicity and secondary structure were slightly different. In summary, vacuum assisted two-stage pickling could effectively shorten the ripening time of salted eggs and reduce salt content without compromising their good quality.

Metabolome and Transcriptome Association Analysis Reveals the Link Between Pigmentation and Nutrition Utilization in the Juveniles of Sea Cucumber Holothuria leucospilota.

The sea cucumber Holothuria leucospilota is an economically and ecologically important tropical species. Following development into juveniles, H. leucospilota undergoes a color change from white to black, involving a pigmentation process for over a period of several months. In this study, a combination of liquid chromatography-tandem mass spectrometry (LC-MS/MS) and Next-Generation sequencing (NGS) were employed to investigate the changes in metabolomic and transcriptomic profiles during pigmentation in H. leucospilota juveniles. The metabolomic analysis identified a total of 341 metabolites, of which 52 were found to be differentially regulated (P < 0.05 and VIP > 1), with 27 being upregulated in white individuals and 25 in black individuals. Additionally, 632 differentially expressed genes (DEGs) were identified, with 380 genes upregulated in white samples and 252 genes upregulated in black samples. Interestingly, the melanin content and tyrosinase transcript levels did not display significant differences between the two groups. Metabolomic data suggested the involvement of the linoleic acid metabolic pathway in pigmentation. Transcriptomic analysis, coupled with realtime PCR validation, revealed a decrease in the transcript levels of digestive enzymes like α-amylase, maltase-glucoamylase, and trehalase after the juveniles changed to black. Furthermore, the mRNA expressions of major yolk proteins showed a decline, indicating a shift in the accumulation of protein nutrient sources. Overall, our findings suggest that during the pigmentation process in H. leucospilota, no significant changes were observed in the classical melanin pathway, while notable alterations were observed in their nutritional status. This study provides valuable insights into the regulatory mechanisms of pigmentation in marine organisms.

Tracking transformation behavior of soluble to insoluble components in liquid egg yolk under heat treatment and the intervention effect of xylitol

The heat sensitivity of egg yolk limits its application, and xylitol can improve its thermal stability. The soluble and insoluble components of egg yolk and egg yolk containing xylitol treated at different temperatures were explored from the aspects of thermal instability behavior characterization and structure property. Magnetic resonance imaging and low field nuclear magnetic resonance showed that increased temperature induced liberation and transfer of hydrogen protons. Meanwhile, the apparent viscosity of soluble components increased, while that of insoluble components decreased. Microstructure showed that heat treatment induced aggregation and lipid transfer. SDS-PAGE showed that heat treatment induced aggregation and transformation of γ-livetin and apo-LDL. The change in crystal structure, Raman spectroscopy, and 3D fluorescence spectra showed that heat treatment resulted in the unfolding of yolk proteins, especially plasma proteins. Xylitol could alleviate transformation of components by stabilizing protein structure, alleviating the damage in protein integrity and elevation in aggregation size.

Corticotropin-releasing factor-like diuretic hormone acts as a gonad-inhibiting hormone in adult female, Rhodnius prolixus.

Within insects, corticotropin-releasing factor/diuretic hormones (CRF/DHs) are responsible for the modulation of a range of physiological and behavioural processes such as feeding, diuresis, and reproduction. Rhopr-CRF/DH plays a key role in feeding and diuresis in Rhodnius prolixus, a blood-gorging insect and a vector for human Chagas disease. Here, we extend our understanding on the role of this neurohormone in reproduction in adult female R. prolixus. Double-label immunohistochemistry displays co-localized staining of CRF-like and the glycoprotein hormone (GPA2/GPB5) subunit GPB5-like immunoreactivity in the same neurosecretory cells (NSCs) in the mesothoracic ganglionic mass (MTGM) and in their neurohemal sites in adult female R. prolixus, suggesting these peptides could work together to regulate physiological processes. qPCR analysis reveals that the transcript for Rhopr-CRF/DH receptor 2 (Rhopr-CRF/DH-R2) is expressed in reproductive tissues and fat body (FB) in adult female R. prolixus, and its expression increases post blood meal (PBM), a stimulus that triggers diuresis and reproduction. Using RNA interference, transcript expression of Rhopr-CRF/DH-R2 was knocked down, and egg production monitored by examining the major yolk protein, vitellogenin (Vg), the number and quality of eggs laid, and their hatching ratio. Injection of dsCRFR2 into adult females reduces Rhopr-CRF/DH-R2 transcript expression, accelerates oogenesis, increases the number of eggs produced, and reduces hatching rate in female R. prolixus. Downregulation of Rhopr-CRF/DH-R2 leads to an increase in the transcript expression of RhoprVg1 in the fat body and ovaries, and increases the transcript level for the Vg receptor, RhoprVgR, in the ovaries. A significant increase in Vg content in the fat body and in the hemolymph is also observed. Incubation of isolated tissues with Rhopr-CRF/DH leads to a significant decrease in transcript expression of RhoprVg1 in the fat body and RhoprVg1 in the ovaries. In addition, Rhopr-CRF/DH reduces transcript expression of the ecdysteroid biosynthetic enzymes and reduces ecdysteroid titer in the culture medium containing isolated ovaries. These results suggest the involvement of the CRF-signaling pathway in reproduction, and that Rhopr-CRF/DH acts as a gonad-inhibiting hormone in the adult female R. prolixus, as previously shown for the colocalized glycoprotein, GPA2/GPB5.

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.

The physicochemical features of eggshell, thick albumen, amniotic fluid, and yolk during chicken embryogenesis

The study aimed to analyze the hatching egg and physiochemical features of eggshells, thick albumen, amniotic fluid, and yolk during the incubation of Ross 308 chicken eggs. Eggs (n=755) were incubated for 21 d. Quality analysis of fresh eggs was performed. Eggshells, albumen, and yolk were collected from fresh eggs and incubation d 1, 7, and 14. Eggshell thickness and strength, pH, vitelline membrane strength, fatty acid (FA) in the yolk, pH, viscosity, lysozyme activity, and crude protein content in thick albumen and amniotic fluid were analyzed. Hatching parameters were calculated. Egg weight loss was constant (8.04% overall). Lower egg surface temperature was found on d 7 compared to d 4, 14, and 18. A lower thickness of posthatch eggshells was found. The strength of the vitelline membrane significantly decreased within 24 h (by over 58%). During incubation, there was a decrease in thick albumen/amniotic fluid pH; an opposite trend was found in yolk pH. The vitelline membrane strength was negatively correlated with the albumen pH. Lysozyme activity was higher in fresh thick albumen and up to 2 wk of incubation. On d 7, the lowest activity was found in the amniotic fluid. On d 14, lysozyme activity increased in amniotic fluid. The higher viscosity of the thick albumen was demonstrated on d 7 and 14 of incubation. The lowest viscosity in amniotic fluid was found on the same days. Crude protein content was higher in thick albumen (d 7 and 14) and lowest in amniotic fluid on d 7. The FA content changed between d 0 and 14. The results indicate different use of FA, where PUFA decreased. Eggshell is used in the last week of incubation. The thick albumen is reduced, while the biological value of amniotic fluid is increasing. Lysozyme activity, viscosity, and crude protein content may be interdependent. It may indicate the flow of substances and the transfer of functions from the thick albumen to the amniotic fluid during chicken embryogenesis.

Study on the Mechanism of Modified Cellulose Improve the Properties of Egg Yolk gel

Natural fiber is not suitable for modifying yolk gel as a modifier because of its large size and high compactness. In this study, two kinds of modified cellulose were selected to improve the thermal gel properties of yolk. The results showed that the two kinds of cellulose promoted the formation of ordered structure in yolk gel. The ordered gel network not only improved the texture properties and rheological properties, but also improved the water retention of yolk gel significantly. CMC and CNFC at the same concentration, the modification effect of CMC on yolk gel was better than CNFC because of its excellent dispersion. However, high concentration of CNFC (1.20–1.60%) disrupted the cross-linking and ordered structure formation of yolk protein, and the quality of gel was significantly reduced.

Egg Yolk as a New Source of Peptides with Antioxidant and Antimicrobial Properties.

A significant increase in interest in food-derived peptides obtained mostly through enzymatic reactions has been observed in the past few years. One of the best sources of bioactive peptides are defatted egg yolk proteins, which can potentially find application as high-quality nutritional supplements for infants with cow's milk protein intolerance and as natural preservatives. The aim of this study was to obtain peptides from defatted egg yolk protein, to study their antioxidant and antimicrobial properties, and to identify peptides with bioactive properties To control the course of the process, MALDI-TOF/MS (matrix-assisted laser desorption/ionization time-of flight/mass spectrometry) spectra were also examined. The peptide mixture obtained through enzyme digestion was tested for its antioxidant properties by measuring the scavenging activity in 2,2-diphenyl-1-picrylhydrazyl radical (DPPH•), 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation decolorization (ABTS•+), and ferric reducing activity (FRAP) assays. Antimicrobial activity was also studied. The peptide mixture exhibited significant antioxidant activity: DPPH-1776.66 ± 32.99, ABTS-390.43 ± 8.92, and FRAP-16.45 ± 0.19. The inhibition of bacterial growth by two concentrations of the peptide mixture was examined. The best result was obtained in Bacillus cereus, with an inhibition zone of 20.0 ± 1.0 and 10.7 ± 0.6 mm at the concentrations of 50 and 25 mg/mL, respectively. The results of the study suggest that the mixture of egg yolk peptides may exhibit a number of health-promoting properties.

Functional analysis of the cell cycle protein E gene (ccne) in ovarian development of the white ridgetail prawn, Exopalaemon carinicauda

To investigate the function of the cell cycle Cyclin E gene (ccne) in the ovarian development of Exopalaemon carinicauda, the gene was cloned using the RACE technique, and the relative expression of ccne was analyzed in different tissues at different stages of ovarian development. The effect of knocking down the expression of ccne on yolk protein vitellogenin (vg) was also investigated at ovarian developmental stage II using RNAi. The results showed that the full-length cDNA sequence of ccne in E. carinicauda (1692 bp, with a 5′UTR of 127 bp, a 3′UTR of 299 bp, and an ORF of 1266 bp) could encode a total of 421 amino acids, with a predicted protein molecular weight of 48.04 kDa and a theoretical isoelectric point of 6.28. The relative expression of ccne was high during all stages of ovarian development, with the highest expression occurring in stage III. In addition, the phylogenetic tree showed that E. carinicauda and Penaeus monodon were clustered into one branch. Knocking down the ccne expression inhibited the expression of vg, meaning that the expression of ccne and vg were positively correlated. In situ hybridization showed that ccne was abundantly expressed in ova, thus inferring that ccne plays a regulatory role and is involved in nutrient accumulation and transport in the ovaries of E. carinicauda.

Changes in microbial, chemical, physical and techno-functional properties of liquid egg yolk during hyperbaric storage

The effects of hyperbaric storage (HS) at 200 MPa on the microbial, chemical, physical and techno-functional properties of liquid egg yolk were investigated and compared to refrigeration. Inoculated Salmonella enterica (3.35 ± 0.12 logCFU g−1) and Staphylococcus aureus (2.78 ± 0.19 logCFU g−1) resulted below the detection limit after 24 and 48 h HS, respectively. Liquid egg yolk oxidative status remained unaffected for up to 28 days under pressure, probably due to the presence of egg yolk antioxidants. The decrease in egg yolk denaturation enthalpy and the increase in aromatic amino acid exposure indicated that egg yolk proteins unfolded according to structural changes other than those observed during refrigeration. Liquid egg yolk viscosity progressively increased during HS, eventually leading to gelling. Protein modification did not affect liquid egg yolk foaming and emulsifying properties but impaired its solubility and thermally-induced gelling. HS could be used for microbial decontamination of liquid egg yolk while maintaining oxidative stability and the typical capacity to stabilize foams and emulsions.

Silencing of novel TtVtg6-like induced ovarian cell apoptosis in ancient chelicerate Tachypleus tridentatus

Vitellogenin (Vtg) serves as the precursor of yolk protein and exhibits widespread distribution in tissues, including in the ovary of both vertebrates and invertebrates. Vtg plays a critical role in facilitating oocyte maturation and embryonic development following oviposition. In this study, we have successfully elucidated the complete transcript sequence of TtVtg6-like from an ancient chelicerate Tachypleus tridentatus. The TtVtg6-like transcript encompassed a length of 4887 bp and encoded 1629 amino acids residues. Notably, TtVtg6-like was found to contain 25 exons. Furthermore, the molecular weight and isoelectric point of TtVtg6-like were determined to be 191.6 KDa and 6.73, respectively. Subsequent mRNA expression analysis demonstrated the specific expression of TtVtg6-like in ovary and yellow connective tissue. In addition, TtVtg6-like was located and distributed in both ovary and yellow connective tissue. Intriguingly, employing an siRNA approach to silence TtVtg6-like resulted in a decrease in TtVtg6-like transcription levels. Concomitantly, TtVtg6-like silencing led to increase production of ROS, ultimately resulting in DNA damage and cell apoptosis within the ovarian primary cell. The induction of apoptosis ovarian primary cells due to TtVtg6-like silencing was further corroborated through TUNEL assay and flow cytometry analysis. Overall, our findings underscore the significance of TtVtg6-like in ovarian cell development, revealing its potential association with ovarian cell apoptosis. Consequently, the insights gained from this study contribute to the future exploration of vitellogenesis and ovarian development in T. tridentatus.

Characterization of Pickering emulsions stabilized by delipidated egg yolk granular protein nanoparticles crosslinked with ultraviolet radiation

In this study, delipidated egg yolk proteins were used for the first time to prepare nanoparticles by the self-assembling method at pH 8.0, then treated with UV-C as a crosslinking agent, and their stability tested at pH 7.0, which is a more convenient pH for food applications. According to the results obtained, non-irradiated nanoparticles had a size of 431.8 ± 75.7 nm at pH 7.0, but the 10 min UV-C irradiated nanoparticles had an average size of 139.7 ± 5.9 nm. These nanoparticles also showed a high resistance to destabilization by SDS, urea or DTT and noticeable antioxidant and ferrous chelating activities. Pickering emulsions prepared at the nanoparticle concentration of 1 % (w/w) showed the smallest average droplet size and the lowest Turbiscan stability index value after 80 days of storage. All in all, these results have important implications for the utilisation of these proteins as a conventional Pickering emulsifying agent.