Investigating the mechanism of antioxidants as egg white powder flavor modifiers.

BACKGROUND: The uses of egg white powder (EWP) are restricted because of its odor. It is necessary to find a method to improve its flavor. In this paper, three different antioxidants - green tea extract (GTE), sodium ascorbate (SA), and glutathione (GSH) - were selected to modify the flavor. The physicochemical and structural properties of EWP were investigated to study the mechanism of the formation and release of volatile compounds. RESULTS: Antioxidants can modify the overall flavor of EWP significantly, inhibiting the generation or release of nonanal, 3-methylbutanal, heptanal, decanal, geranyl acetone, and 2-pemtylfuran. A SA-EWP combination showed the lowest concentration of 'off' flavor compounds; GTE-EWP and GSH-EWP could reduce several 'off' flavor compounds but increased the formation of geranyl acetone and furans. The changes in the carbonyl content and the amino acid composition confirmed the inhibition of antioxidants with the oxidative degradation of proteins or characteristic amino acids. The results of fluorescence spectroscopy and Fourier transform infrared (FTIR) spectroscopy provided structural information regarding EWP, which showed the release of volatile compounds decreased due to structural changes. For example, the surface hydrophobicity increased and the protein aggregation state changed. CONCLUSIONS: Antioxidants reduce the 'off' flavor of EWP in two ways: they inhibit protein oxidation and Maillard reactions (they inhibit formation of 3-methylbutanal and 2-pemtylfuran) and they enhance the binding ability of heat-denatured proteins (reducing the release of nonanal, decanal, and similar compounds). © 2023 Society of Chemical Industry.

Effect of salting and dehydration treatments on the physicochemical and gel properties of hen and duck egg yolks, plasma and granules.

BACKGROUND: Salted hen egg yolks are less oily and less flavorful than salted duck egg yolks. However, hen eggs have a more adequate market supply and have a broader application prospect than duck eggs. In the present study, egg yolks, plasma, and granules were dehydrated by adding 1% NaCl to simulate traditional curing process of salted egg yolk. The changes in the pickling process of hen egg yolks (HEY) and duck egg yolks (DEY) plasma and granules were compared to reveal the gelation mechanism and the underlying causes of quality differences in salted HEY and DEY. Salted HEY can be compared with the changes in DEY during the pickling process to provide a theoretical basis for the quality improvement of salted HEY to salted DEY. RESULTS: The results showed that both plasma and granules were involved in gel formation, but exhibited different aggregation behaviors. Based on the intermolecular forces, the HEY proteins achieved aggregation mainly through hydrophobic interactions and DEY proteins mainly through covalent binding. According to spin-spin relaxation time, HEY gels immobilized a large amount of lipid and interacted strongly with lipids. DEY gels showed much free lipid and had weak interaction with lipid. The microstructure showed that HEY proteins were easily unfolded to form a homogeneous three-dimensional gel network structure after salting, whereas heterogeneous aggregates were formed to hinder the gel development in DEY. Changes in protein secondary structure content showed that pickling can promote the transformation of the α-helices to ß-sheets structure in HEY gels, whereas more α-helices structure was formed in DEY gels. CONCLUSION: The present study has demonstrated that different gelation behaviors of hen and duck egg yolk proteins (especially in plasma) through salting treatment led to the difference in the quality of salted HEY and DEY. © 2024 Society of Chemical Industry.

Fabrication mechanism and functional properties of ovalbumin fibrils prepared by acidic heat treatment.

BACKGROUND: Ovalbumin (OVA), accounting for 50% of proteins in egg white, is a kind of high-quality protein with excellent nutritional and processing functions. Acid heat treatment will induce the deformation and filtration of OVA, endowing it with improved functionality. However, the molecular kinetic process during the fibrillation of OVA and the application of the fabricated OVA fibrils (OVAFs) have not been thoroughly studied and revealed. RESULTS: In this study, the fabrication mechanism and the application OVAFs as an interfacial stabilizer and polyphenol protector were investigated. Acidic (pH 3.0) heat treatment was used to induce the fibrillation of OVA, and thioflavin T fluorescence intensity, molecular weight distribution, and the tertiary and secondary structures of OVAF samples were recorded to determine the fibrillation efficiency and the molecular mechanism. The results showed that, in the initial stage of fibrillation, OVA first hydrolyzed to oligopeptides, accompanied by the exposure of hydrophobic domains. Then, oligopeptides were connected by disulfide bonds to form primary fibril monomers. Hydrophobic interaction and hydrogen bonding may participate in the further polymerization of the fibrils. The fabricated OVAFs were characterized by a ß-sheet-rich structure and possessed improved emulsifying, foaming, and polyphenol protection ability. CONCLUSION: The research work was meaningful for exploring the application of globular water-soluble OVA in an emerging nutritious food with novel texture and sensory properties. © 2023 Society of Chemical Industry.

Changes in partial properties of glycosylated egg white powder during storage.

BACKGROUND: Glycosylation is an effective method to modify protein. However, there is a lack of research on the property changes of glycosylated protein during storage. In the present study, the changes in the physicochemical, functional, and structural properties of xylo-oligosaccharide (XOS) glycosylated egg white powder (EWP) (XOS-EWP conjugates) prepared with different glycosylation conditions (XOS/EWP ratio and reaction time) were investigated when stored at 25 °C and 60% relative humidity. RESULTS: In the 12 weeks of storage, the degree of grafting, browning, and the formation of Maillard reaction products of XOS-EWP conjugates increased. The increase in XOS/EWP ratio and reaction time led to an increase in protein aggregation, though a decrease in solubility, due to increased degree of glycosylation and structural changes. Furthermore, improved gel hardness of XOS-EWP conjugates deteriorated, while improved emulsification ability was kept stable during storage. For the sample with a lower XOS/EWP ratio and reaction time, the gel hardness and emulsifying properties underwent little or no deterioration even improving during storage. The results could be attributed to the limited degree of glycosylation, further unfolding of the protein structure, increased surface hydrophobicity of protein, and improved thermal characteristics. CONCLUSION: During storage, the Maillard reaction would continue to occur in the glycosylated EWP, further affecting the performance of modified EWP. Modified EWP prepared under different glycosylation conditions performed differently during storage. Modified EWP with a larger XOS/EWP ratio and reaction time meant it was harder to maintain good performance. Modified EWP with a smaller XOS/EWP ratio and reaction time changed significantly to better performances. © 2022 Society of Chemical Industry.

Gel properties of okara dietary fiber-fortified soy protein isolate gel with/without NaCl.

BACKGROUND: Soy protein isolate (SPI) is widely used as an alternative to animal-based protein, and its gelling property is essential for producing plant protein-based foods. Insoluble dietary fiber has been used to improve the properties of protein gels. RESULTS: Effects of partial replacement of SPI by okara dietary fiber (ODF) on the gelling properties of ODF-fortified SPI gels with and without 0.1 m NaCl were investigated. The presence of ODF hindered the SPI self-aggregation and reduced the surface hydrophobicity of SPI. The presence of ODF reduced the hydrophobic interaction and improved the proportion of disulfide bonds in the gels. In the microstructure, the swollen ODF promoted the local aggregation of SPI at 0.1 m NaCl. Texture profile analysis showed that 5% and 10% ODF improved the SPI gel hardness in the absence of NaCl, whereas only 5% ODF improved the gel hardness at 0.1 m NaCl. The results of low-field nuclear magnetic resonance imaging revealed that ODF shortened the T2 relaxation time of the free water in the gel. The gel of ODF-10 had the highest storage modulus. CONCLUSION: Using an appropriate amount of ODF to replace SPI could improve the quality of SPI gel and increase the dietary fiber content in the product. In addition, the appropriate ratio of ODF/SPI varied in different solution environments. © 2022 Society of Chemical Industry.

Improved retention ratio and bioaccessibility of lutein loaded in emulsions stabilized by egg yolk granules-lecithin complex.

BACKGROUND: Egg yolk granules (EYGs)-soy lecithin (SL) complex is a newly developed delivery system that is effective for improving the storage stability of hydrophobic bioactive compounds. However, the formation mechanism of EYGs and SL complex and its effect on the gastrointestinal fate of lutein-loaded emulsions needs to be investigated further. RESULTS: Adding SL greatly improved the surface activity of the EYGs, as evidenced by reduced surface tension and an increased adsorption rate to the oil/water interface. Hydrophobic interaction was the dominant force in the formation of EYG-SL complex, with hydrogen and ionic bonds playing complementary roles. Using the EYG-SL complex, stable oil-in-water emulsions were formed and exhibited an enhanced retention ratio and bioaccessibility of lutein after simulated digestion. Correlation analysis demonstrated that the additional anti-oxidant activity as a result of EYGs was responsible for the high retention of lutein, whereas low surface tension facilitated the micellization of bioaccessible lutein. CONCLUSION: The present study shows that the EYG and SL have a synergistic effect with respect to improving the retention ratio and bioaccessibility of lutein in emulsions stabilized by EYG-SL complex after digestion and this will guide the development of value-added oil-in-water emulsion products using protein-lecithin complex as a promising nutrient delivery vehicle. © 2022 Society of Chemical Industry.

Study on gel properties of lysozyme-free egg white before and after Lactiplantibacillus plantarum fermentation.

BACKGROUND: Isolation of lysozyme from egg white (EW) using ion exchange resin adsorption method generates large quantities of lysozyme-free egg white (LFEW) with poor gelling property. To maximize the applications of LFEW, the effect of Lactiplantibacillus plantarum fermentation on the gel properties of LFEW was investigated in this study. RESULTS: The fermentation efficiency of LFEW with lysozyme removed was significantly improved, and the sugar removal rate (2 g kg-1 Lactiplantibacillus plantarum, 37 °C, 7 h) was more than 90%. Removal of lysozyme resulted in increased stability and surface hydrophobicity of EW. After Lactiplantibacillus plantarum fermentation, the stability of EW decreased, and the average particle size and surface hydrophobicity increased. In addition, by comparing the gel properties of EW and LFEW before and after fermentation at different pH, it was found that the hardness, elasticity, and water holding capacity (WHC) of EW gel increased significantly. The removal of lysozyme effectively improved the WHC and springiness of the EW gel and promoted the formation of a denser network structure with smaller pores. After Lactiplantibacillus plantarum fermentation treatment, LFEW gel hardness decreased, with loose and porous network structure, no browning occurred after autoclaving. CONCLUSION: This study provided the direction and theoretical basis for producing a fermented LFEW gel with pleasing texture and appearance. © 2022 Society of Chemical Industry.

Preparation and characterization of W1 /O/W2 emulsions stabilized by glycated and heat-modified egg white proteins.

BACKGROUND: Water-in-oil-in-water (W1 /O/W2 ) emulsions stabilized by protein-carbohydrate complexes were prepared from an inner water phase (W1 ), an oil phase (O) and an outer water phase (W2 ). The complexes consisted of heat-induced aggregates (HIAs) of isomalto-oligosaccharide/egg white protein Maillard conjugates. The effects of polyglycerol ester of polyricinoleic acid (PGPR) concentration, HIA concentration, W1 -to-O volume ratio and W1 /O-to-W2 volume ratio on the properties of the W1 /O/W2 emulsions were systematically investigated. RESULTS: At sufficiently high PGPR concentrations (>2%), the emulsions possess a high negative charge (≈-44 mV). The encapsulation efficiency of the emulsions, which was determined by incorporating a hydrophilic yellow dye in the inner water phase prior to homogenization, was relatively high (up to 93%) and did not change significantly during 14-day storage at 4 °C. All emulsions were fluids that exhibited shear thinning behavior. CONCLUSION: Overall, this study shows that nature-derived emulsifiers can be used to create W1 /O/W2 emulsions suitable for application in the food industry. In addition, we provided a viable strategy to encapsulate water-soluble nutrients. © 2022 Society of Chemical Industry.

Study on functional improvement of freeze-thaw egg yolk pellet by enzymatic hydrolysis.

Freeze-thaw egg yolk pellet (FYP) could be produced as a by-product in the process of egg yolk immunoglobulin (IgY) extraction. The FYP contained many superior nutritional components like fresh egg yolk, but it has poor functionalities because of protein denaturation resulted from freezing treatment during IgY extraction. For the purpose of comprehensive utilization of egg yolk resources, FYP was subjected to enzymatic hydrolysis with alcalase to produce FYP hydrolysates (FYPh) with four enzyme concentrations of 250, 500, 1000 and 2000 U/g for improved functional properties. And then FYPh was spray dried to obtain hydrolyzed egg yolk pellet powder (HYP). Solubility, emulsifying property and surface hydrophobicity of HYP were investigated. The results showed that enzymatic hydrolysis could lead to noticeable changes in surface hydrophobicity, microstructure, solubility and emulsifying properties of HYP compared with the control group without enzymatic hydrolysis treatment. Solubility and emulsification stability index generally increased from 19 g/100 g, 12.33 to 87 g/100 g, 76.63 with increasing degree of hydrolyze, respectively. This study demonstrated that the functional properties of FYP could be effectively improved when the enzyme addition amount reached 1000 U/g. HYP prepared under this condition owes desirable solubility and emulsification, and has the potential of application in food industry.

Influence of chitosan on the emulsifying properties of egg yolk hydrolysates: study on creaming, thermal and oxidative stability.

BACKGROUND: Egg yolk, as a natural emulsifier, is widely used in high-oil-phase food systems, such as mayonnaise and salad. However, the application of egg yolk in an oil-in-water system is still limited due to poor emulsifying stability. To improve the emulsifying capacity of egg yolk, the effect of chitosan addition sequence and concentration on emulsifying properties (creaming stability, thermal tolerance and oxidation resistance) of egg yolk hydrolysates were investigated. RESULTS: Stacking sequence of multilayer materials has an influence on properties of composite emulsions. The composite emulsions with egg yolk hydrolysis dominate at the interface (functioning on reducing interfacial tension), and chitosan layered on the surface (providing steric hindrance) displayed better stability. Little chitosan addition (0.5 g × kg-1 , w/w) was unhelpful for the dispersion of emulsion droplets as a result of bridging flocculation. At a chitosan concentration of 2 g kg-1 (w/w), the composite emulsion possesses the best stability. When chitosan concentration was higher than 2 g kg-1 (w/w), depletion flocculation would occur. Hydrolyzed egg yolk prepared composite emulsions possessed better thermal resistance, but with poorer oxidative stability as compared to natural egg yolk. In combination with chitosan it also displayed a negative effect on the oxidative stability of the emulsion system. CONCLUSION: The research revealed the effect of chitosan addition on the physical and chemical stability of emulsions prepared with egg yolk hydrolysates. The results could provide guidance on expanding the application of egg yolk as an emulsifier in water-abundant food systems such as beverages. © 2021 Society of Chemical Industry.

Changes in stability and in vitro digestion of egg-protein stabilized emulsions and ß-carotene gels in the presence of sodium tripolyphosphate.

BACKGROUND: Egg proteins are effective emulsifiers and gelators in food systems. However, the physicochemical stability and control release properties of egg-protein stabilized emulsions and gels need to be further improved. The potential of sodium tripolyphosphate (St) to improve the functionality of egg proteins was evaluated. RESULTS: The emulsions with St had smaller particle sizes and higher zeta potential, leading to better physical stability. Furthermore, the oxidation stability increased with increasing St contents, possibly due to its metal chelating capacity and the improved emulsifying activity of whole-egg dispersions. Phosphate had a positive impact on the chemical stability of ß-carotene in whole-egg liquids and gels, decreasing the degradation during thermal treatment. The gel made with St was firm and broke down slowly, leading to a low rate of digestion and ß-carotene release in simulated gastric fluid. CONCLUSION: This study shows that St is useful to improve the egg proteins stabilized emulsions and gels, which is applicable in the development of emulsion-based food grade gel products. © 2021 Society of Chemical Industry.

Degradation of 5-methyltetrahydrofolate in model and egg yolk systems and strategies for its stabilization.

In this study, the stability of 5-methyltetrahydrofolate (5-MTHF) in the model system and folate-enriched egg yolk and strategies for 5-MTHF stabilization were investigated. The oxygen, temperature and light affect the stability of 5-MTHF in the model system, among which oxygen is the main factor. In thermal pasteurization and spray-drying with normal air media, 5-MTHF is sensitive to oxidation, with the retention rate of blank group only reaching 74.96% ± 1.28%. The addition of vitamin C or vitamin E can protect 5-MTHF in egg yolk from degradation and the latter has a better protective effect. By adding 0.2% (w/v) vitamin E to egg yolk liquid, the retention rate of 5-MTHF during thermal pasteurization and spray-drying with normal air media were 94.16% ± 0.48% and 84.80% ± 0.82% respectively. Additionally, the spray-drying technique with inert gas media (N2) was also an effective method to improve the stability of the 5-MTHF in egg yolk. Our study explored the factors affecting the stability of 5-MTHF in both model systems and egg yolk liquid and provided effective strategies for the protection of 5-MTHF during the processing of egg.

Changes in microbial, physiochemical, and functional properties of pasteurized liquid whole egg during refrigerated storage.

BACKGROUND: Liquid eggs have the advantages of high hygiene security, easy use, and convenient transportation, but their shelf life is only limited to 2~3 weeks. The microbial, physiochemical, and functional properties of pasteurized LWE were investigated in this study to evaluate the quality of pasteurized liquid whole egg (LWE) during refrigerated storage. RESULTS: The tested shelf life of the pasteurized LWE was 16 days when stored at 4 °C. During refrigerated storage, Pseudomonas gradually became the dominant bacterium in LWE following lactic acid bacteria, although the initial number of Pseudomonas after pasteurization was relatively limited (< 10 CFU mL-1 ). A total of 23 strains, including six Pseudomonas strains, were obtained. The pH of pasteurized LWE decreased with the growth of microorganisms, while the content of total volatile basic nitrogen (TVB-N) increased curvilinearly. The average particle size increased almost continuously until the sample reached its shelf life. The functional properties of pasteurized LWE were also reduced after a week of refrigerated storage at 4 °C when the microorganisms in pasteurized LWE entered an exponential growth period and the TVB-N content of pasteurized LWE reached its first peak. CONCLUSION: During refrigerated storage, Pseudomonas was the dominant bacterium in LWE next to lactic acid bacteria. After a week of refrigerated storage at 4 °C, the particle size of LWE increased, while the functional properties of LWE reduced. This study provides a basis for extending the shelf life of liquid egg products in future research. © 2020 Society of Chemical Industry.

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.

The targeted development of collagen-active peptides based on composite enzyme hydrolysis: a study on the structure-activity relationship.

Fish collagen, derived from sustainable sources, offers a valuable substrate for generating peptides with diverse biofunctionalities. In this study, alkaline, papain, and ginger protease were used to enzymatically hydrolyze fish skin collagen. The peptide molecular weight distribution and sequence were measured using HPLC and ICP-MS-MS, with papain/alkaline protease (AP) and papain/alkaline/ginger protease (APG) hydrolyzed samples compared. As the results showed, the incorporation of ginger protease was useful for increasing the degree of hydrolysis, with the content of <400 Da peptides increasing from 49.82% to 58.56%. The identified peptide sequence in the APG sample had more proline at the C-terminal. The peptides were separated into two components (different in molecular weight) using gel column chromatography. The molecular weight distribution, amino acid composition, ACE inhibitory activity, and fibroblast proliferation activity of the collected components were measured. In comparison, the contents of proline and hydroxyproline in the larger peptides decreased obviously after combined hydrolysis by ginger protease, reflecting the formation of a peptide sequence of smaller molecular weight containing glycine and hydroxyproline. The combined hydrolysis of ginger protease was beneficial for the improvement of the ACE inhibitory activity of the sample. However, the fibroblast proliferation activity of AP was higher than that of APG, indicating that further hydrolysis by ginger protease may destroy the hydroxyproline at the end of the peptide sequence. This study proposed a creative directional hydrolysis method and provided practical guidance for the production of collagen peptides with enhanced functional activity.

Chicken Egg White Gels: Fabrication, Modification, and Applications in Foods and Oral Nutraceutical Delivery.

Chicken egg white (EW) proteins possess various useful techno-functionalities, including foaming, gelling or coagulating, and emulsifying. The gelling property is one of the most important functionalities of EW proteins, affecting their versatile applications in the food and pharmaceutical industries. However, it is challenging to develop high-quality gelled foods and innovative nutraceutical supplements using native EW and its proteins. This review describes the gelling properties of EW proteins. It discusses the development and action mechanism of the physical, chemical, and biological methods and exogenous substances used in the modification of EW gels. Two main applications of EW gels, i.e., gelling agents in foods and gel-type carriers for nutraceutical delivery, are systematically summarized and discussed. In addition, the research and technological gaps between modified EW gels and their applications are highlighted. By reviewing the new modification strategies and application trends of EW gels, this paper provides insights into the development of EW gel-derived products with new and functional features.

The differential non-covalent binding of epicatechin and chlorogenic acid to ovotransferrin and the enhancing efficiency of immunomodulatory activity.

Seeking safe and environmentally friendly natural immunomodulators is a pressing requirement of humanity. This study investigated the differential binding characteristics of two polar polyphenols (PP), namely epicatechin (EC) and chlorogenic acid (CA), to ovotransferrin (OVT), and explored the relationship between structural transformations and immunomodulatory activity of OVT-PP complexes. Results showed that CA exhibited a stronger affinity for OVT than EC, mainly driven by hydrogen bonds and van der Waals forces. Complexation-induced conformational variations in OVT, including static fluorescence quenching, increased microenvironment polarity surrounding tryptophan and tyrosine residues, and the transition from disordered α-helix to stable ß-sheet. Furthermore, the structural conformation transformation of OVT-PP complexes facilitated the enhancement of immunomodulatory activity, with the OVT-CA (10:2) complex demonstrating the best immunomodulatory activity. Principal component analysis (PCA) and Pearson correlation analysis revealed the immunomodulatory activities of the OVT-PP complexes were influenced by surface hydrophobicity (negatively correlated), ß-sheet percentage and polyphenol binding constants. It could be inferred that PP complexation increased the surface polarity of OVT, consequently enhancing its immunomodulatory activity by promoting cell membrane affinity and antigen recognition. This study provides valuable guidance for effectively utilizing polyphenol-protein complexes in enhancing immunomodulatory activity.

Egg Yolk Selenopeptides: Preparation, Characterization, and Immunomodulatory Activity.

In this study, egg yolk selenium peptides (Se-EYP) were prepared using double-enzyme hydrolysis combined with a shearing pretreatment. The properties of the selenopeptides formed were then characterized, including their yield, composition, molecular weight distribution, antioxidant activity, in vitro digestion, and immunomodulatory activity. The peptide yield obtained after enzymatic hydrolysis using a combination of alkaline protease and neutral protease was 74.5%, of which 82.6% had a molecular weight <1000 Da. The selenium content of the lyophilized solid product was 4.01 µg/g. Chromatography-mass spectrometry analysis showed that 88.6% of selenium in Se-EYP was in the organic form, of which SeMet accounted for 60.3%, SeCys2 for 21.8%, and MeSeCys for 17.9%. After being exposed to in vitro simulated digestion, Se-EYP still had 65.1% of oligopeptides present, and the in vitro antioxidant activity was enhanced. Moreover, Se-EYP exhibited superior immune detection indices, including immune organ index, level of immune factors in the serum, histopathological changes in the spleen, and selenium content in the liver. Our results suggest that Se-EYP may be used as selenium-enriched ingredients in functional food products.

Studies on the Properties and Stability Mechanism of Double Emulsion Gels Prepared by Heat-Induced Aggregates of Egg White Protein-Oligosaccharides Glycosylation Products.

Multiple emulsions can dissolve some substances with different properties, such as hydrophilicity and lipophilicity, into different phases. They play an important role in protection, controlled release and targeted release of the encapsulated substances. However, it's poor stability has always been one of the main problems restricting its application in the food industry. For this reason, a heat-induced aggregate (HIA) of Maillard graft product of isomalto-oligosaccharides (IMO), as well as egg white protein (EWP), was used as hydrophilic emulsifier to improve the stability of W1/O/W2 emulsions. Moreover, gelatin was added into the internal aqueous phase (W1) to construct W1/O/W2 emulsion-gels system. The encapsulation efficiency of HIA-stabilized W1/O/W2 emulsions remained nearly unaltered, dropping by only 0.86%, significantly outperforming the conjugates and physical mixture of IMO and EWP in terms of encapsulation stability. The emulsion-gels system was constructed by adding 5% gelatin in the W1, and had the highest EE% and good salt and heat stability after 30 days of storage. This experiment provides guidance for improving the stability of W1/O/W2 emulsions system and its application in the package delivery of functional substances in the food field.

Characterization of physical properties, volatile compounds and aroma profiles of different salted egg yolk lipids.

Salted egg yolks (SEY) have a desirable and unique flavor with multiple underlying applications in food processing, and their abundant lipids contribute to a creamy and pleasant aroma. However, it is important to maintain the stability of the SEY flavor, which depends to a large extent on the egg species and the processing method. This study aimed to extract different SEY lipids with conventional solvents, analyze the fatty acid composition, and screen the volatile compounds to elucidate the flavor differences between salted hen eggs and duck eggs. Compared to ethanol extraction, acetone-extracted lipids had lower acid value and viscosity, and almost had no phospholipid content. Fatty acid analysis revealed that the highest content of fatty acid in SEY lipids was oleic acid, followed by palmitic acid and linoleic acid, while there were significant variations of different SEY lipids in the fatty acid profiles. The volatile compounds were identified by headspace solid-phase microextraction-gas chromatography-mass spectrometry (HS-SPME-GC-MS), and the overall odor was detected by the electronic nose (E-nose). A total of 27 volatile compounds were analyzed in SEY lipids and divided into 8 chemical classes. The aldehydes, furans and pyrazines were decreased, and the hydrocarbons were increased compared with untreated SEY. The combination of the physical properties and flavor evaluation of SEY lipids could provide a theoretical basis for the extension of the characteristic flavor matrix in SEY.