Duck egg albumen: physicochemical and functional properties as affected by storage and processing

Using salted egg white in steamed bread: Impact on functional and structural characteristics

Steamed bread has long been an important part of Chinese cuisine. This study investigated the effects of salted egg white (SEW) (5, 10, 15, and 20% w/w) on the quality of steamed breads. Findings revealed that SEW notably enhanced the bread's volume and texture, with a 20% inclusion significantly boosting water retention and rheological properties, albeit reducing bread's lightness. In addition, the H-bond absorption band intensity in the Fourier transform infrared spectroscopy (FTIR) analysis showed increased peak intensities with higher SEW levels, indicative of protein structure alterations. X-ray diffraction confirmed the presence of an amylose-lipid complex. Scanning electron microscope (SEM) and Confocal laser scanning microscope (CLSM) imaging depicted a smooth, consistent protein network with SEW addition. Consumer sensory evaluation responded favourably to the SEW15 steamed bread, suggesting its potential for food industry application. Overall, the study considers SEW an effective ingredient for improving steamed bread quality.

Quality characteristics, lysozyme activity, and albumen viscosity of fresh hatching duck eggs after a week's storage at various temperatures

The study aimed to analyze the qualitative features of Cherry Valley duck' hatching eggs during storage at different temperatures. Eggs were divided into 3 equal groups with 30 eggs each: fresh egg and stored at 7 °C and 17 °C within one week. Qualitative analyses of duck eggs were carried out, considering the morphological composition, physicochemical characteristics, lysozyme activity, and albumen viscosity. The highest weight of yolk and its percentage was found in the 17 °C group. The weight and percentage of albumen were significantly the highest in the group of fresh eggs. Higher egg weight loss was observed in the group stored at higher temperatures. Higher thick albumen height and Haugh units were found in fresh eggs and eggs stored at 7 °C. Different temperatures of egg storage did not affect lysozyme activity in thick and thin albumen. Stored eggs were characterized by lower albumen viscosity only at a shear rate of 10 rpm. The higher viscosity of thick albumen compared to thin ones was demonstrated at 10 and 20 rpm shear rates. The presented research results indicate a large diversity of selected qualitative indicators of hatching duck eggs, which may affect their storage and suitability for incubation.

Changes in physicochemical parameters of duck eggs and extra-embryonic structures during incubation

Duckling embryogenesis should be deepened due to the hatching technology and its modification possibilities. Many changes occur in incubated eggs, which expose the embryo to hazards. The study aimed to analyse the physicochemical properties of eggshell, yolk, thick albumen (TA), and amniotic fluid (AF) of incubated hatching eggs from 52-week-old Cherry Valley ducks. The morphological features of 18 fresh eggs were analysed. Over 28 days, a total of 800 eggs underwent incubation. Eggshell surface temperature and egg weight loss were measured on days 1, 4, 7, 10, 14, 18, 21, and 25. Eggshell, TA, AF, and yolk were collected from eggs at incubation days 1-21 (every week). TA was collected on days 0, 1, and 7, while AF on days 7, 14, and 21. The analysis covered a range of physicochemical parameters. Eggshell thickness decreased with incubation, reaching its lowest point posthatch (P < 0.001). The highest pH for TA was recorded on day 1, while the lowest was on day 7 when comparing days 0, 1, and 7 (P < 0.001). TA pH was consistently higher than in AF (P < 0.001). However, the pH of TA was the highest on day 1 and the lowest on day 7 (P < 0.001). Yolk pH increased from days 1 to 21 (P < 0.001). There was also a noticeable in egg weight loss (0.34% daily) (P < 0.001). Vitelline membrane strength decreased from day 0 to day 1 (P < 0.001). Lysozyme activity in thick albumen on day 7 was higher than on days 0 and 1 (P < 0.001). Lysozyme activity in AF was higher on day 21 than days 7 and 14 (P < 0.001). TA viscosity was highest on day 0 and lowest on day 1, compared to other days (P < 0.001). AF viscosity and CP content exhibited an increase on day 21 as compared to days 7 and 14 (P < 0.001). The CP content in TA was notably higher on day 7 than on days 0 and 1 (P < 0.001). Polyunsaturated fatty acids declined, while monounsaturated and transfatty acids increased (P < 0.001). Viscosity and lysozyme activity increased on day 7 in TA and day 21 in AF. TA and the amniotic cavity appeared to facilitate the transfer of substances, particularly CP. Viscosity could be an indicator for optimising incubation conditions, as incorrect changes can affect embryo mortality. The results showed the different utilisation of nutrients, such as fatty acids. It could support research on the in-ovo administration of various substances.

Manipulation of protein structure and bonding pattern to improve the gelling and textural quality of surimi gels from silver carp: incorporation of mosambi (Citrus limetta) peel extract

BACKGROUND

This investigation focused on the use of mosambi peel extract (MPE) fortification (at 0% to 1.50%, w/w) in silver carp surimi to improve the gelling, textural, and other physicochemical properties of the surimi.

RESULTS

The peels were extracted in ethanol (40-100% concentrations, v/v) and water. It was found that 100% ethanol had significantly (P < 0.05) higher yield and total phenolic, flavonoid, and tannin content. The fortification of MPE at optimum level (0.75%) improved the breaking force (55.1%) and gel strength (89.9%) significantly (P < 0.05) in comparison with 0% MPE gel samples. Moreover, 0.75% MPE-fortified gels had higher hydrogen and hydrophobic bonds, higher water-holding capacity, and lower sulfhydryl groups and free amino groups. The myosin heavy chain (MHC) bands in sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) disappeared completely in the MPE-fortified gels. Fortification with MPE affected the secondary structures of protein as shifting of peaks was observed in Fourier-transform infrared (FTIR) spectra. Scanning electron microscopy (SEM) images showed relatively organized finer and denser gel networks in MPE-treated gels.

CONCLUSION

The surimi gels fortified with 0.75% MPE demonstrated improved gelling properties, with an overall higher acceptability than the unfortified gels (0% MPE). The fortified gels also became enriched with bioactive polyphenols, which are generally not present in surimi. This study provides an efficient way to utilize mosambi peel to develop functional surimi and surimi-based products with improved gel ability. © 2023 Society of Chemical Industry.

Dietary supplementation of coated sodium butyrate improves growth performance of laying ducks by regulating intestinal health and immunological performance

Introduction

This study was conducted to assess the effects of dietary supplementation of coated sodium butyrate (CSB) on the growth performance, serum antioxidant, immune performance, and intestinal microbiota of laying ducks.

Methods

A total of 120 48-week-old laying ducks were randomly divided into 2 treatment groups: the control group (group C fed a basal diet) and the CSB-treated group (group CSB fed the basal diet + 250 g/t of CSB). Each treatment consisted of 6 replicates, with 10 ducks per replicate, and the trial was conducted for 60 days.

Results

Compared with the group C, the group CSB showed a significant increase in the laying rate (p&lt;0.05) of the 53-56 week-old ducks. Additionally, the serum total antioxidant capacity, superoxide dismutase activity and immunoglobulin G level were significantly higher (p&lt;0.05), while the serum malondialdehyde content and tumor necrosis factor (TNF)-a level were significantly lower (p&lt;0.05) in the serum of the group CSB compared to the group C. Moreover, the expression of IL-1b and TNF-a in the spleen of the group CSB was significantly lower (p&lt;0.05) compared to that of the group C. In addition, compared with the group C, the expression of Occludin in the ileum and the villus height in the jejunum were significantly higher in the group CSB (p&lt;0.05). Furthermore, Chao1, Shannon, and Pielou-e indices were higher in the group CSB compared to the group C (p&lt;0.05). The abundance of Bacteroidetes in the group CSB was lower than that in the group C (p&lt;0.05), while the abundances of Firmicutes and Actinobacteria were higher in the group CSB compared to the group C (p&lt;0.05).

Conclusions

Our results suggest that the dietary supplementation of CSB can alleviate egg-laying stress in laying ducks by enhancing immunity and maintaining the intestinal health of the ducks.

Egg quality, hatchability, gosling quality, and amino acid profile in albumen and newly-hatched goslings' serum as affected by egg storage

In modern poultry husbandry, storing fertilized eggs is a common measure to cope with the variable demands of the market and the maximum hatching capacity of the hatchery. However, this measure is harmful to the hatchability of eggs and the quality of newly hatched birds. Knowledge about the effects of storing fertilized eggs on the performance of goslings is still limited. The objective of this study was to investigate the effects of storing fertilized eggs on egg quality, hatchability, gosling quality, hatching weight, post-hatching growth performance, and amino acid profile in albumen and newly hatched goslings' serum. A total of 1,080 fertilized goose eggs (Jilin White goose) with a similar egg weight (126.56 ± 0.66 g) were used in this study. All eggs were distributed into 3 groups with 24 replicates per group and 15 eggs per replicate. The differences between groups were the storage duration of eggs (0, 7, or 14 d). We found that the Haugh unit, yolk weight, and eggshell weight decreased linearly, whereas the albumen pH increased linearly, with storage duration. Prolonging storage duration had negative effects on hatchability, hatching weight, post-hatching growth performance parameters, and gosling quality in a time-dependent manner. The analysis of the amino acid profile in albumen and newly-hatched goslings' serum showed that the amino acid content increased linearly with storage duration. Additionally, eggs stored for 14 d had the worst performance for all measured parameters. Therefore, we concluded that the storage of fertilized eggs negatively affects egg quality and post-hatching gosling quality. To produce high-quality goslings, it is necessary to shorten the storage duration for fertilized eggs.

Use of Incinerated Eggshells to Produce Pidan

Preserved eggs (pidans) are used in traditional Chinese cuisines. However, the alkaline conditions and metal ions generated during its preparation have caused some concerns. This study developed an innovative process for pidan processing using incinerated eggshell powder, an abundant by-product that can generate a highly alkaline solution and provide calcium ions (Ca2+). Either 0.5, 3, or 5% of the eggshell powder solution was used for basic pickling. Different combinations of ZnSO4 (0.175%), MgCl2 (0.08%), and CuSO4 (0.16%) were added. Duck eggs were pickled for 25 days at 25–27 °C, followed by 14 days of ripening. The pidan processed in 5% eggshell powder containing 0.175% ZnSO4 demonstrated the closest physiochemical and sensory characteristics to commercial pidans. Thus, the results offer a new technique to manufacture pidans and reduce the harmful impact of metal ions on human health and the environment.

Modification methods and applications of egg protein gel properties: A review

Egg protein (EP) has a variety of functional properties, such as gelling, foaming, and emulsifying. The gel characteristics provide a foundation for applications in the food industry and research on EP. The proteins denature and aggregate to form a dense three-dimensional gel network structure, with a process influenced by protein concentration, pH, ion type, and strength. In addition, the gelation properties of EP can be altered to varying degrees by applying different treatment conditions to EP. Currently, modification methods for proteins include physical modification (heat-induced denaturation, freeze-thaw modification, high-pressure modification, and ultrasonic modification), chemical modification (glycosylation modification, phosphorylation modification, acylation modification, ethanol modification, polyphenol modification), and biological modification (enzyme modification). Pidan, salted eggs, egg tofu, and other egg products have unique sensory properties, due to the gel properties of EP. In accessions, EP has also been used as a new ingredient in food packaging and biopharmaceuticals due to its gel properties. This review will further promote EP gel research and provide guidance for its full application in many fields.

Phosphoproteomic analysis of duck egg yolk provides novel insights into its characteristics and biofunctions

BACKGROUND

Although the importance of phosphorylation in the function of proteins is known, investigation of the protein phosphorylation of duck egg yolk (DEY) is still very limited. This study aimed to conduct a detailed phosphoproteomic study of DEY using immobilized metal affinity chromatography and ultra-high liquid chromatography tandem mass spectrometry.

RESULTS

A total of 253 phosphorylation sites assigned to 66 phosphoproteins were identified in DEY, of which VTG-1, VTG-2, and fibrinogen alpha chain were found to be the highly phosphorylated proteins in DEY. The biological functions of the identified phosphoproteins were illuminated through gene ontology analysis, which showed that they were mainly involved in binding, catalytic, immune response, and metabolic activity. S-X-E and S-X-S were found to be the most conserved serine motifs of phosphorylation in DEY. The comparison of DEY phosphoproteins with those of chicken egg yolk (CEY) revealed that differences mostly involved molecular functions and biological processes. The comparison also revealed a higher phosphorylation level in DEY proteins.

CONCLUSION

The higher phosphorylation level in DEY proteins than that in CEY proteins are supposed to help enhance duck growth performance and biological activities (e.g. antibacterial and antioxidant ability) for better adapting the humid environment the duck lived. © 2021 Society of Chemical Industry.

Preservation of duck eggs through glycerol monolaurate nanoemulsion coating

Duck eggs have a short storage life. In this study, water-washed duck eggs and glycerol monolaurate (GML) coated duck eggs were stored at 25 °C for 70 days (away from light). The water-washed duck eggs started to lose weight from the 4th week. At the same time, Haugh unit and egg yolk index of the water-washed duck eggs started decreasing. The normal GML coating solution (NGML), the higher concentration GML diluent (HGML), and the lower concentration GML diluent (LGML) showed different preservation effects. Among them, NGML showed the strongest protection effect against spoilage of duck eggs. After 70-days storage, the weight loss rate of the NGML coated duck eggs was <6%, which was 4 times lower than that of the water-washed duck eggs; the Haugh unit and the surface morphology were also better than that of the water-washed duck eggs. Furthermore, the total colonies in NGML coated sample was >4 log CFU/g less than that was found in the water-washed samples (Control). The HGML and LGML coating agents were less effective but they might be suitable for the short storage of duck eggs due to the lower cost. Overall, this study provides a sound basis for the preparation and utilization of GML coating solution. The GML coating method is able to extend the shelf life of duck eggs by more than 6 weeks.

Effects of (-)-Epigallocatechin-3-gallate on the Functional and Structural Properties of Soybean Protein Isolate

In the present study, soy protein isolate (SPI) was noncovalently modified by (-)-epigallocatechin-3-gallate (EGCG), and its foaming, emulsifying, and antioxidant properties were all significantly increased. Fluorescence analysis revealed that the fluorescence quenching of SPI by EGCG was static quenching. EGCG mainly changed the folding state of SPI around Trp and Tyr residues, and the binding site was closer to Trp. UV-vis spectra further proved that more hydrophobic residues of SPI were exposed to a hydrophilic microenvironment. Circular dichroism spectra indicated that the contents of ordered structures were transforming into random coils with the reduce of α-helix, β-sheet, and β-turns by 3.8%, 2.0%, and 1.2%, respectively. Meanwhile, the binding stoichiometry of two molecules of EGCG per one molecule of SPI was obtained from isothermal titration calorimetry, and the interaction was a spontaneous endothermic process with a noncovalent complex preferentially formed. According to thermodynamic parameters and molecular docking model, hydrophobic force and hydrogen bonds were considered to be the main interaction forces between SPI and EGCG. Overall, after modification through the high affinity to EGCG, the structure of SPI became looser and exposed more active groups, thus resulting in an improvement of its foaming, emulsifying, and antioxidant properties.

Gel properties of salty liquid whole egg as affected by preheat treatment

Heat treatment is an indispensable processing step of seasoned liquid egg. The effects of preheat treatment (60-75 °C) on gel properties of liquid whole egg (LWE) at different NaCl concentrations (0-3%, w/w) were investigated to provide guidance for the production of salty LWE. Results showed that LWE exhibited higher particle size after heating, with coincidental increases in surface hydrophobicity and decreases in protein solubility. While LWE with NaCl added exhibited increase in protein solubility and decrease in particle size of aggregates. Electrophoresis and optical microscopy showed that NaCl would induce the transformation of egg granules from insoluble form to soluble form, inhibiting the aggregation of LWE proteins during preheat treatment, reflected by the reduced particle size. The analysis of gel aggregated force and texture indicated that NaCl addition and preheat treatment can improve gelling properties of LWE synergistically by strengthening the hydrophobic interaction and hydrogen bonds.

State-of-the-art strategies and applied perspectives of enzyme biocatalysis in food sector - current status and future trends

With the recent progress in biotechnology, a wide variety of novel enzymes with unique physicochemical properties and diverse applications has been introduced, and new application list continues to extend in the future. Enzymes obtained from microorganisms, including bacteria, fungi, yeast are widely applied in numerous food formulations for intensifying their texture and taste. Owing to several desirable characteristics such as easy, cost-efficient and stable production, microbial-derived enzymes are preferred source in contrast to animals or plants. Enzymatic processes have a considerable impact in controlling the characteristics such as (1) physiochemical properties, (2) rheological functionalities, (3) facile process as compared to the chemical-based processing, (4) no or minimal consumption of harsh chemicals, (5) overall cost-effective ratio, (6) sensory and flavor qualities, and (7) intensifying the stability, shelf life and overall quality of the product, etc. in the food industry. Also, enzyme-catalyzed processing has also been designed for new food applications such as extraction of bioactive compounds, nutrient-rich and texture improved foods production, and eliminating food safety hazards. Herein, we reviewed recent applications of food-processing enzymes and highlighted promising technologies to diversify their application range in food industries. Immobilization technology enabled biocatalysts to be used cost-effectively due to reusability with negligible or no activity loss. Integrated progress in novel enzyme discovery, and recombinant DNA technology, as well as protein engineering and bioprocess engineering strategies, are believed to rapidly propagate biocatalysis at industrial-scale food processing or green and sustainable chemical manufacturing.

Efficacy of cold plasma in producing Salmonella-free duck eggs: effects on physical characteristics, lipid oxidation, and fatty acid profile

Concerns related to foodborne pathogens necessitate the decontamination of avian eggs. Conventional decontamination methods, such as egg washing, usually use health-threatening chemicals (e.g. chlorine). Hence, innovative chemical-free decontamination approaches are interesting for the food industry, especially to decontaminate commonly Salmonella infected products such as duck eggs. The present study is the first attempt to evaluate the effectiveness of cold plasma against Salmonella enterica inoculated on the surface of duck eggshell. In this regard, Salmonella-contaminated duck eggs were treated by arc plasma for 10, 20, 30, and 40 s. The bacteria count, eggshell strength, color, pH, Haugh unit, acid value (AV), thiobarbituric acid reactive substances (TBARS), and fatty acid profile of the plasma-treated samples were then compared with those of untreated sample. According to the results, all the plasma treatments significantly decreased the Salmonella population and longer treatment times enhanced the bactericidal effects of plasma. A maximum bacterial reduction of 4.1 log cycle was observed when plasma was applied for 40 s. Furthermore, plasma treatments did not deteriorate the quality parameters of eggs such as eggshell strength, eggshell color, yolk color, Haugh unit, AV, and TBARS. These findings introduced arc plasma as an emerging tool for improving the safety of duck eggs with good potential for industrial application.

Identification of the Duck Egg White N-Glycoproteome and Insight into the Course of Biological Evolution

Protein glycosylation is a ubiquitous posttranslational modification that modulates protein properties, thereby influencing bioactivities within a system. Duck egg white (DEW) proteins exhibit diverse biological properties compared with their chicken egg white (CEW) counterparts, which might be related to glycosylation. N-Glycoproteome analysis of DEW was conducted, and a total of 231 N-glycosites from 68 N-glycoproteins were identified. Gene ontology analysis was used to elucidate the biofunctions of DEW N-glycoproteins and compare them with those of CEW, which showed that the differences mostly involved molecular functions and biological processes. The biological functions of DEW N-glycoproteins were illuminated through bioinformatics analysis and comparison with CEW orthologues, which showed different allergenicities and antibacterial abilities. These divergences might be initiated by specific alterations in glycosylation, which can enhance the proteolysis resistance and protein steric hindrance. These results provide new insights for discovering the effects of N-glycosylation on biofunctions during the divergence of homologous proteins.