Egg yolk granule gels, methods of making and using same

Abstract

The application discloses an egg yolk granular gel, a preparation method and application thereof, and belongs to the technical field of food. The preparation method of the egg yolk granular gel comprises the following steps: mixing a CaCl2 solution with egg yolk particles to obtain an egg yolk particle suspension; then, ultrasonic treatment is carried out in an ice water bath to obtain an egg yolk particle dispersion; then, the egg yolk particle dispersion is heated in a water bath at 70-77 DEG C; and finally, the egg yolk particle gel is obtained after cooling. In addition, the application further provides an egg yolk granular gel prepared by the above preparation method. In addition, the application further provides the application of the egg yolk granular gel prepared by the above preparation method or the above egg yolk granular gel in preparing a gel foam. The egg yolk granular gel prepared by the application can obtain a gel foam with high foaming property and stability.

Description

Technical Field

[0001] This invention relates to the field of food technology, specifically to an egg yolk granule gel, its preparation method, and its application. Background Technology

[0002] Foam, as an important colloidal dispersion system in food, boasts advantages such as light texture, unique taste, and flavor carrying capacity. Compared to the high cholesterol content of egg yolk liquid, egg yolk particles offer the advantages of high protein and low cholesterol, better meeting the development needs of modern healthy foods. However, a key issue currently exists: the foaming property of egg yolk mainly depends on its aqueous phase (i.e., egg yolk liquid), while egg yolk particles, as the main solid component, are generally considered to impair foam stability and expansion rate due to their poor solubility in water. This limits the application of egg yolk particles in foamed foods.

[0003] Due to its dense complex structure in its natural state, EYG (egg yolk granules) has poor solubility and weak interfacial activity in the aqueous phase, making it difficult to effectively adsorb at the oil-water interface and form a stable interfacial film. Its poor emulsification performance has become an important problem restricting its application in emulsified food systems.

[0004] How to obtain highly foaming and stable gel foam from egg yolk particles is a technical problem that needs to be solved by existing technologies. Summary of the Invention

[0005] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide an egg yolk particle gel, its preparation method and application, thereby solving the technical problem of how to obtain a gel foam with high foaming properties and stability through egg yolk particles in the prior art.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a method for preparing egg yolk particle gel, comprising the following steps: mixing CaCl2 solution with egg yolk particles to obtain an egg yolk particle suspension; then sonicating in an ice-water bath to obtain an egg yolk particle dispersion; then heating the egg yolk particle dispersion in a water bath at 70-77°C; and then cooling to obtain the egg yolk particle gel.

[0007] In any embodiment, the mass concentration of the CaCl2 solution is 0.6%-2%; the mass concentration of egg yolk particles in the egg yolk particle suspension is 5-7%.

[0008] In any embodiment, the ultrasonic power is 600-900W, the ultrasonic time is 5-20min; and / or, the water bath heating time is 10-40min.

[0009] In any embodiment, the cooling temperature is 2-5°C, and the cooling time is 2-2.5 hours.

[0010] In any embodiment, the egg yolk particles are prepared by the following steps: mixing egg yolk liquid with NaCl, centrifuging at 2-5°C, taking the precipitate, and then washing the precipitate with water to obtain the egg yolk particles.

[0011] In addition, the present invention also proposes an egg yolk granule gel, which is prepared by the above preparation method.

[0012] Furthermore, the present invention also proposes the use of the egg yolk granule gel prepared by the above preparation method or the application of the above egg yolk granule gel in the production of gel foam.

[0013] In any embodiment, the above application includes: homogenizing egg yolk granule gel with a homogenizer at a speed of 12000-15000 rpm for 1.5-2 min to obtain the gel foam.

[0014] Furthermore, the present invention also proposes the application of the egg yolk granule gel prepared by the above preparation method or the egg yolk granule gel in the preparation of emulsion gel.

[0015] In any embodiment, the process includes: mixing egg yolk granule gel with an oil phase, and then homogenizing the mixture using a homogenizer at a speed of 10,000-12,000 r / min to prepare the emulsion gel.

[0016] Compared with the prior art, the beneficial effects of the present invention include: the preparation method of egg yolk particle gel proposed in the present invention includes the following steps: mixing CaCl2 solution with egg yolk particles to obtain an egg yolk particle suspension; then sonicating in an ice-water bath to obtain an egg yolk particle dispersion; then heating the egg yolk particle dispersion in a water bath at 70-75°C; and then cooling to obtain the egg yolk particle gel; Ca 2+ The synergistic effect of ultrasound significantly optimizes gel performance, reducing random curling and increasing β-sheets. The protein secondary structure transforms from disordered to ordered, with intermolecular forces primarily consisting of hydrophobic interactions and disulfide bonds, forming a denser three-dimensional gel network. Apparent viscosity and storage modulus are significantly improved. This improved gel performance directly impacts foam properties, as the dense gel framework provides physical support for the bubbles. Proteins fully unfold and are efficiently adsorbed at the air-water interface (adsorption rate up to 96.6%), forming a highly elastic rigid interfacial film that effectively inhibits bubble aggregation and disproportionation, enhancing foam stability. Simultaneously, Ca... 2+ The depolymerization effect on the natural dense structure of EYG significantly improves foaming properties, initially increasing and then decreasing with the degree of crosslinking. This is because excessive viscosity caused by over-crosslinking inhibits bubble formation. In summary, the egg yolk particle gel prepared by this invention can produce gel foams with high foaming properties and stability. Furthermore, the egg yolk particle gel prepared by this invention can produce an emulsion gel system with excellent stability. Attached Figure Description

[0017] Figure 1 This is a graph showing the particle size results of EYG dispersions under different CaCl2 concentrations in Example 1 of the present invention.

[0018] Figure 2 This is a graph showing the particle size results of EYG dispersions under ultrasonic treatment at different power levels in Example 1 of the present invention.

[0019] Figure 3 This is a surface tension diagram of EYG dispersions under ultrasonic treatment with different CaCl2 concentrations and different power in Example 1 of the present invention.

[0020] Figure 4 The graph shows the results of wettability A and surface hydrophobicity of EYG dispersion under ultrasonic treatment with different CaCl2 concentrations and different power in Example 1 of the present invention; where A: wettability of EYG dispersion; B and C: surface hydrophobicity.

[0021] Figure 5 The apparent viscosities A and B of EYG gels under ultrasonic treatment with different CaCl2 concentrations and different power in Example 1 of this invention are: G' and G'' correspond to C and D; where G' represents the storage modulus and G'' represents the loss modulus.

[0022] Figure 6 The infrared spectrum A and secondary structure B of EYG gel under ultrasonic treatment with different CaCl2 concentrations and different power are shown in Example 1 of this invention.

[0023] Figure 7 This refers to the intermolecular forces of EYG gel under ultrasonic treatment with different CaCl2 concentrations and different power in Example 1 of the present invention.

[0024] Figure 8 The images shown are: A) physical image of EYG gel foam under different CaCl2 concentrations and different power ultrasonic treatments according to Example 2 of the present invention, and B) microscopic images at 0h and 6h.

[0025] Figure 9 The foaming properties (A, B) and stability (C, D) of EYG gel foam under different CaCl2 concentrations and different power ultrasonic treatments in Example 2 of this invention are shown.

[0026] Figure 10 This refers to the amount of interfacial protein adsorption of EYG gel foam under different CaCl2 concentrations and different power ultrasonic treatments in Example 2 of the present invention.

[0027] Figure 11 These are the interfacial strain scans A and B, and interfacial frequency scans C and D of EYG gel foam under different CaCl2 concentrations and different power ultrasonic treatments in Example 2 of the present invention.

[0028] Figure 12The microstructure A and droplet sizes B and C of the EYG emulsion gel under different heating times (0, 10, 20, 30 and 40 min) and different ultrasonic times (0, 5, 10, 15 and 20 min) in Example 3 of the present invention are shown.

[0029] Figure 13 The oil-holding capacity A and B of the emulsion gel under different heating times (0, 10, 20, 30 and 40 min) and different ultrasonic times (0, 5, 10, 15 and 20 min) in Example 3 of the present invention are shown.

[0030] Figure 14 The droplet sizes are those of the emulsion gel after being heated at 25, 40, 60, and 80°C for 30 minutes under different heating times (0, 10, 20, 30, and 40 min) and different ultrasonic times (0, 5, 10, 15, and 20 min) in Example 3 of this invention.

[0031] Figure 15 The droplet sizes A, B, and microstructure C of EYG-stabilized emulsion gels treated with different heating times (0, 10, 20, 30, and 40 min) and different ultrasonic times (0, 5, 10, 15, and 20 min) in Example 3 of this invention are stored for 0, 5, 10, and 15 days, with a scale bar of 50 μm. Detailed Implementation

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of a particular range. Ranges defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60~120 and 80~110 are listed for a specific parameter, it is also expected that ranges of 60~110 and 80~120 are also included. Furthermore, if minimum range values ​​of 1 and 2 are listed, and if maximum range values ​​of 3, 4, and 5 are listed, then the following ranges are all expected: 1~3, 1~4, 1~5, 2~3, 2~4, and 2~5. In this application, unless otherwise stated, the numerical range "a~b" represents a shortened representation of any combination of real numbers between a and b, where a and b are real numbers. For example, the numerical range "0~5" indicates that all real numbers between "0~5" have been listed in this article; "0~5" is simply a shortened representation of these numerical combinations. Furthermore, when a parameter is stated as an integer ≥2, it is equivalent to disclosing that the parameter is, for example, an integer such as 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0033] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0034] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] This specific embodiment provides a method for preparing egg yolk particle gel, comprising the following steps: mixing CaCl2 solution with egg yolk particles to obtain an egg yolk particle suspension; then sonicating in an ice-water bath to obtain an egg yolk particle dispersion; then heating the egg yolk particle dispersion in a water bath at 70-77℃ for 10-40 min, and then cooling at 2-5℃ for 2-2.5 h to obtain the egg yolk particle gel; the mass concentration of the CaCl2 solution is 0.6%-2%; the mass concentration of egg yolk particles in the egg yolk particle suspension is 5-7%; the ultrasonic power is 600-900W, and the ultrasonic time is 5-20 min.

[0036] In some embodiments, the egg yolk particles are prepared by the following steps: mixing egg yolk liquid with NaCl, centrifuging at 2-5°C, taking the precipitate, and then washing the precipitate with water to obtain the egg yolk particles.

[0037] This specific embodiment also proposes an egg yolk granule gel, which is prepared by the above preparation method.

[0038] Furthermore, this specific embodiment also proposes the application of the egg yolk particle gel prepared by the above preparation method or the egg yolk particle gel in the production of gel foam, including: homogenizing the egg yolk particle gel with a homogenizer at a speed of 12000-15000 rpm for 1.5-2 min to obtain the gel foam.

[0039] Furthermore, this specific embodiment also proposes the application of the egg yolk particle gel prepared by the above preparation method or the egg yolk particle gel in the preparation of emulsion gel, including: mixing the egg yolk particle gel with the oil phase, and then homogenizing it with a homogenizer at a speed of 10000-12000 r / min to prepare the emulsion gel.

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0042] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0043] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0044] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they are performed according to the techniques or conditions described in the literature in this field or according to the product instructions. Reagents or instruments used, unless otherwise specified, are all conventional products that can be obtained commercially.

[0045] Example 1

[0046] EYG extraction Collect the egg yolks, dry the yolk membrane by rolling it on filter paper, puncture the yolk membrane with a needle, and collect the yolk liquid in a beaker. Mix with an equal mass of 0.17M NaCl, stir at 4℃ for 1 hour, centrifuge twice at 10000g for 45 minutes, and collect the precipitate. Wash the precipitate three times with deionized water (mix with an equal mass of deionized water, centrifuge at 12000g for 10 minutes, repeat three times) to remove residual NaCl, obtaining EYG.

[0047] Preparation of EYG dispersion Egg yolk particles were mixed with CaCl2 solutions of 0%, 0.6%, 0.8%, 1%, 1.4%, and 2% by mass to obtain egg yolk particle suspensions with an EYG concentration of 7%. The suspensions were then sonicated in an ice-water bath at 0W, 600W, 675W, 750W, 825W, and 900W for 10 minutes to obtain egg yolk particle dispersions.

[0048] Particle size determination The particle size of the particulate dispersion was determined using a Zetasizer Nano-ZS instrument with an equilibration time of 120 s.

[0049] Each sample should be measured at least three times in parallel.

[0050] Surface tension measurement The surface tension of the EYG dispersion was determined using a BZY-2 fully automated surface tension meter. A 20 mL sample was placed in a glass dish, and a platinum plate was immersed in the sample before being removed. Excess solution remaining on the platinum plate was wiped off with filter paper. The platinum plate was kept in contact with the gas-liquid interface and allowed to remain stationary until the reading stabilized. The surface tension value was then recorded. Each sample was measured in parallel at least three times.

[0051] Determination of wettability The wettability of the samples was tested using a DSA30 droplet shape analyzer. The freeze-dried samples were pressed into discs with a diameter of 13 mm using a tablet press. In an air environment, 4 μL of deionized water was dropped onto the surface of the discs using a high-precision micro-syringe. After equilibrium was reached, a high-speed camera captured images of the droplets, and the contact angle of the samples was calculated based on the Laplace-Young equation.

[0052] Determination of surface hydrophobicity The EYG dispersion was diluted with deionized water to a dry matter concentration of 0.01–0.05 mg / mL, with five concentration gradients established for hydrophobicity determination. 3 mL of sample solution was mixed with 60 μL of 8 mmol / L ANS solution, and fluorescence intensity was measured using a fluorescence spectrophotometer. The excitation wavelength was set to 365 nm, the emission wavelength to 484 nm, and the excitation and emission slit widths to be 1 nm and 2.5 nm, respectively. A graph of fluorescence intensity versus protein concentration was plotted, and the initial slope represents the surface hydrophobicity. Each experiment was performed in triplicate.

[0053] Preparation of EYG gel EYG dispersions with different CaCl2 concentrations and ultrasonic power were heated in a 75°C water bath for 20 min, and then cooled at 4°C for 2 h to prepare EYG gels.

[0054] Determination of gel rheological properties A PP50 flat plate clamp was used, with a set gap of 1 mm. The test temperature was kept constant at 25℃ using a circulating water bath. The time interval was 0.1-100 s. -1 The samples were scanned within the shear rate range, and the apparent viscosity was recorded. The storage modulus (G') and loss modulus (G'') were collected as a function of angular frequency in the 0.1-100 rad / s range. The strain was fixed at 0.5% during the test to ensure that the measurement was within the linear viscoelastic range. All samples were measured in parallel three times.

[0055] FTIR spectral scanning The freeze-dried gel sample was thoroughly ground and mixed with KBr at a mass ratio of 1:100, and then pressed into a uniform, semi-transparent tablet. Using air as the reference background, infrared spectroscopy was performed at 4000-400 cm⁻¹. -1 Infrared spectra were collected within the wavenumber range.

[0056] Measurement of intermolecular forces in gels Two g of egg yolk gel sample was mixed with 10 mL of SA (0.05 M NaCl), SB (0.6 M NaCl), SC (0.6 M NaCl + 1.5 M urea), SD (0.6 M NaCl + 8 M urea), and SE (0.6 M NaCl + 8 M urea + 0.05 M β-mercaptoethanol). The mixture was homogenized for 1 min, then stored at 4 °C for 1 h, and then centrifuged at 10,000 rpm for 15 min. The protein content in the supernatant was determined using the biuret method. Ionic bonds, hydrogen bonds, hydrophobic interactions, and disulfide bonds represent the differences in protein content dissolved in SB and SA solutions, SC and SB solutions, SD and SC solutions, and SE and SD solutions, respectively. All samples were measured in triplicate.

[0057] Example 2

[0058] Preparation of EYG gel foam Take 10g of EYG gels with different CaCl2 concentrations and ultrasonic power into 50ml centrifuge tubes, and homogenize them at 15000rpm for 1.5min to form foam.

[0059] Observation of the microstructure of gel foam Freshly prepared foam samples and foam samples left to stand for 6 hours were smeared onto glass slides, and the microstructure of the samples was then observed using an upright microscope.

[0060] Determination of the foaming properties and stability of gel foam Foaming property is defined as the ratio of initial foam volume (V1) to initial mixed solution volume (V0). Foam stability is defined as the ratio of 6-hour foam volume (V2) to initial foam volume (V1). Each sample should be measured at least three times.

[0061] Determination of interfacial shear rheological properties The surface shear properties of the interface were determined using a rheometer. 50 mL of the sample was slowly poured into the sample tank, avoiding air bubbles and ensuring a smooth sample surface. The mixture was allowed to equilibrate for 30 minutes to allow the interfacial film to adhere. A double-cone plate clamp was used, with a frequency of 1 Hz and a strain range of 0.01%–100%, to perform strain scanning tests, recording the interface values ​​G' and G''. Within the linear viscoelastic region determined by the strain scanning, a strain value of 1% was set, with a frequency range of 0.01 Hz–10 Hz, for frequency scanning tests. Each sample was measured at least three times.

[0062] Determination of interfacial protein adsorption capacity Prepare fresh foam and allow it to stand at room temperature for 30 minutes. Then, carefully aspirate the subaqueous phase (without adsorbed protein) using a syringe. Determine the protein concentration in the subaqueous phase using the BCA method, with BSA as the standard. The interfacial adsorbed protein concentration is the difference between the initial protein concentration and the protein concentration in the subaqueous phase (without adsorbed protein), and the result is presented as a percentage. Each sample should be measured at least three times.

[0063] Example 3

[0064] Egg yolk particles were mixed with a 1% CaCl2 solution to obtain an egg yolk particle suspension, with a yolk particle concentration of 5%. The suspension was then sonicated at 750W for 10 minutes in an ice-water bath to obtain an egg yolk particle dispersion. The egg yolk particle dispersion was heated in a 75℃ water bath for 0 minutes, 10 minutes, 20 minutes, 30 minutes, and 40 minutes, respectively. The treated solution was then cooled at 4℃ overnight to obtain EYG gels with different heating times.

[0065] Egg yolk particles were mixed with a 1% (w / w) CaCl2 solution to obtain an egg yolk particle suspension, with the egg yolk particles accounting for 5% (w / w) of the suspension. The egg yolk particle suspension was sonicated at 750W in an ice-water bath for 0 min, 5 min, 10 min, 15 min, and 20 min, respectively, followed by heating in a 75℃ water bath for 0 min, 10 min, 20 min, 30 min, and 40 min, respectively. The treated solution was then cooled at 4℃ overnight to obtain EYG gels with different heating times. The CaCl2 solution was then mixed with the particle suspension to obtain EYG gels with different heating times and sonication times.

[0066] EYG gels with different heating and sonication times were used as the aqueous phase, and soybean oil was used as the oil phase. 25% aqueous phase and 75% oil phase were mixed and homogenized for 60 s using a high-speed homogenizer at 10000 r / min to prepare the emulsion gel.

[0067] Observation of the microstructure of emulsion gel Take a small amount of emulsion gel and drop it onto a glass slide, then cover it with a coverslip. Use an upright optical microscope and observe the microstructure of the emulsion gel under a 20x objective lens.

[0068] Determination of oil droplet size in emulsion gel The droplet size of the emulsion gel was determined using a Winner 2008 laser particle size analyzer, where the refractive indices of water and oil were 1.33 and 1.50, respectively. The droplet size was expressed as the volume-average diameter (d4,3). d4,3 was calculated using the following formula (1-1): (1-1) In the formula, ni is the number of droplets of the same diameter; di is the size of the droplet. The droplet size of all samples was measured at least three times.

[0069] Measurement of interfacial tension The interfacial tension between the aqueous phase (EYG gel) and the oil phase (soybean oil) was determined using the platinum plate method. First, the EYG gel was pre-sheared in a beaker until homogeneous. Then, the pre-sheared aqueous phase was poured into a glass dish, and 40 mL of soybean oil was added to the surface of the aqueous phase to form an oil-water interface. A platinum plate was used to pick up the sample solution, and excess solution was blotted off with filter paper. After the interfacial tensiometer completed zero-point calibration, the platinum plate was slowly lowered at a constant rate, continuously peeling the plate as it approached the oil-water interface. Once the platinum plate contacted the interface and stabilized, the interfacial tension value was read. Each sample was measured at least three times in parallel, and the average value was taken as the final result.

[0070] Determination of wettability The wettability of the samples was tested using a DSA30 droplet shape analyzer. The freeze-dried samples were compressed into 13 mm diameter discs using a tablet press. The discs were placed in a sample chamber containing 30 mL of corn oil, and air bubbles were removed. Then, 4 μL of deionized water was dropped onto the disc surface using a high-precision microsyringe. After equilibrium was reached, a high-speed camera captured images of the droplets, and the contact angle of the sample was calculated based on the Laplace-Young equation.

[0071] Determination of surface hydrophobicity Each sample was measured three times in parallel, and the average value was taken.

[0072] Determination of centrifugal stability of emulsion gel Take 4 g of the emulsion gel and place it into a 10 mL centrifuge tube. Then, place the centrifuge tube in a centrifuge and centrifuge at 8000 r / min for 30 min at room temperature. Remove the soybean oil that separates from the upper layer after centrifugation. Use the oil separation rate as the centrifugal stability and calculate it according to the following formula (1-2): OBC (%) = (1-2) In the formula, M1 is the weight after centrifugation, and M0 is the weight before centrifugation. All samples were measured three times and the average value was taken.

[0073] Determination of the thermal stability of emulsion gel Take 4 g of emulsion gel and put it into 10 mL centrifuge tubes. Place them in water baths at 40, 60 and 80 ℃ and heat for 30 min. After heating, immediately cool to room temperature and then use a laser particle size analyzer to measure the droplet size before and after heating.

[0074] Determination of the storage stability of emulsion gels Freshly prepared emulsion gels were stored at 4°C for 15 days. Samples were taken at 0, 5, 10 and 15 days of storage to determine the droplet size of each sample. Optical microscopic images of each sample were observed and recorded. Each sample was measured three times.

[0075] Results and Analysis Particle size analysis like Figure 1 and Figure 2 As shown, the particle size of EYG in its natural state is 835.3 nm, consistent with existing research results. With the increase of Ca... 2+ As the concentration gradually increased from 0% to 1%, the average particle size of the EYG dispersion showed a significant upward trend, increasing from the initial state to 2517.3 nm. This is because the high-density lipoprotein in EYG is rich in phosphoserine residues. These acidic amino acids have a large number of negatively charged phosphate groups on their side chains, which can provide binding sites for calcium ions. These ions then interact with the naturally occurring phosphoproteins in the egg yolk to form stable calcium bridge structures. Simultaneously, the calcium... 2+ As a divalent metal ion, EYG can bind to negatively charged groups (such as carboxyl groups) in protein molecules through the salt-bridge effect, forming cross-linked structures between protein molecules. However, when the concentration further increases to 2%, the particle size of the EYG dispersion decreases sharply. This is attributed to the increasing ionic strength disrupting the natural phosphorus-calcium bridges in EYG, leading to gradual deagglomeration. Under ultrasonic treatment, the particle size of the EYG dispersion shows an increasing trend with increasing power up to 750 W, indicating that ultrasonic cavitation and shearing may promote particle collisions and structural unfolding, thereby promoting the formation of Ca2+. 2+ Cross-linking with proteins. When the power was increased to 900 W, the particle size decreased slightly, which may be due to the fragmentation of some aggregates caused by excessive sonication.

[0076] Analysis of surface tension Changes in surface tension can directly reflect the interactions and aggregation states between protein molecules in solution. The surface tension changes of EYG dispersions under different CaCl2 concentrations and ultrasonic power treatments are shown in the following figures. Figure 3As shown. The surface tension of the EYG dispersion in its natural state is approximately 38 mN / m, which increases with the change in Ca... 2+ With increasing concentration, the surface tension generally shows a decreasing trend. This is attributed to Ca. 2+ It cross-links with EYG proteins, promoting protein adsorption at the interface, thereby increasing the interfacial film thickness and rigidity, and effectively reducing interfacial tension. Simultaneously, with the increase of Ca... 2+ As the concentration increases, the egg yolk particles partially dissociate, exposing internal hydrophobic lipids and protein hydrophobic groups, further enhancing the adsorption capacity of protein molecules at the interface. With increasing ultrasonic power (0–750 W), the surface tension continuously decreases, reaching its lowest value (approximately 33 mN / m) at 750 W. When the ultrasonic power is further increased to 900 W, the surface tension slightly recovers. This indicates that moderate ultrasonic treatment provides favorable conditions for calcium cross-linking. Within the 0–750 W ultrasonic power range, with increasing power, the cavitation and shearing effects of ultrasound gradually increase, resulting in a more significant stretching effect on the protein structure and exposing more Ca2+. 2+ The increased number of binding sites and hydrophobic regions enhances interfacial adsorption capacity and improves the surface activity of the system. The rebound in surface tension when the ultrasonic power is further increased to 900 W may be due to the lipoprotein decomposition caused by excessive ultrasonication and the re-encapsulation of previously exposed hydrophobic groups within the protein, leading to a decrease in the interfacial adsorption capacity of the system.

[0077] Analysis of wettability and surface hydrophobicity Contact angle (θ) can be used to characterize the wettability of protein particle surfaces, reflecting the interfacial affinity between particles and the liquid phase. Surface hydrophobicity mainly reflects the number and distribution of hydrophobic sites on the protein molecule surface, and can indirectly characterize the degree to which hydrophobic groups inside the protein are exposed to the molecular surface due to structural changes such as denaturation and aggregation. Both contact angle and surface hydrophobicity characterize changes in protein tertiary structure from the perspectives of interfacial properties and molecular surface properties, reflecting differences in protein molecule aggregation and folding, and can serve as important criteria for evaluating changes in protein structure.

[0078] The water θ in EYG under natural conditions in air is very small, only about 45.2°, consistent with previously reported findings. Combined with... Figure 4 The sample without CaCl2, treated with only 750 W sonication (0%), had an θ similar to that of the naturally occurring sample, indicating that sonication alone has limited effect on disrupting the calcium-phosphorus bridges in the egg yolk particles. However, after adding 0.6% CaCl2, the θ of the EYG rapidly increased to 84.9°. Then, with the addition of CaCl2... 2+As the concentration continued to increase to 2%, θ continued to increase to approximately 103.4°. This is attributed to the fact that when the salt ion concentration in the system increases, the ions neutralize the negative charge on the protein surface, weakening the electrostatic repulsion between particles, leading to the deagglomeration of the original particle structure, releasing lipoproteins and lipid components, thereby increasing the hydrophobicity of the particle surface and correspondingly increasing the contact angle. At a CaCl2 concentration of 1%, the contact angle θ of the untreated (0 W) EYG sample had increased to approximately 78.7° compared to its natural state, indicating that at this CaCl2 concentration... 2+ At the specified concentration, the egg yolk particles had partially depolymerized. As the ultrasonic power gradually increased to 750 W, θ further increased to approximately 94°. This is because, based on the partial depolymerization of EYG, ultrasonic treatment can further promote the unfolding of the protein structure, not only increasing surface hydrophobicity and contact angle, but also exposing more hydrophobic groups to interact with ANS, thus enhancing surface hydrophobicity accordingly. However, when the ultrasonic power continued to increase to 900 W, both θ and surface hydrophobicity showed a decreasing trend. This can be attributed to excessive ultrasonication causing the exposed hydrophobic groups to refold, while simultaneously inducing lipoprotein degradation.

[0079] Analysis of gel rheological properties The rheological properties of gel samples are typically characterized using apparent viscosity and dynamic viscoelasticity. The relationship between shear rate and apparent viscosity reflects the degree of gel deformation under different shear stresses. The viscoelasticity of the gel is assessed by measuring the changes in G' and G'' with frequency under constant temperature and stress. Frequency scanning can reveal the relationship between the mechanical properties of the sample and frequency, as well as the minimal changes in intramolecular interactions, thus revealing details of the sample's structural composition. For dynamic mechanical analysis, G' and G'' are crucial variables. G' reflects the solid-state properties of the system, while G'' reflects the liquid-state properties.

[0080] Figure 5 A and Figure 5 B analyzed the variation of apparent viscosity of EYG gel with shear rate under different CaCl2 concentrations and ultrasonic treatment powers. The shear rates ranged from 0.1 to 100 s⁻¹. -1 Within the range, the apparent viscosity of all samples decreased with increasing shear rate, exhibiting typical shear thinning, which is due to the disruption of weak binding sites between protein molecules.

[0081] EYG in its natural state maintains good fluidity after heating and does not form a gel, thus exhibiting minimal apparent viscosity. The viscosity of the gel sample increases with increasing CaCl2 concentration. This is because the natural dense structure of EYG is formed by the cross-linking of HDL and phosphoproteins through calcium phosphate bridges, and its low solubility limits the construction of its gel network. Increased CaCl2 concentration significantly enhances the ionic strength of the system, leading to the gradual depolymerization of EYG into smaller active subunits such as HDL-phosphoprotein complexes and free lipoproteins, providing a sufficient material basis for gel network formation. Simultaneously, it compresses the protein double layer, shields electrostatic repulsion, and promotes the formation of hydrophobic interactions. Furthermore, the divalent CaCl2... 2+ EYG can connect negatively charged sites such as carboxyl and phosphate groups in protein molecules to form additional ionic crosslinks, resulting in a denser three-dimensional gel network. This effectively binds water in the system, reduces the degree of freedom of molecular flow, and ultimately leads to a continuous increase in gel viscosity. As the ultrasonic processing power increases, the viscosity of the EYG gel also increases. This is attributed to the direct action of the mechanical shear force generated by ultrasound and the instantaneous high-pressure cavitation microjets on the EYG, thereby altering its protein molecular structure and synergistically influencing the exogenous Ca2+. 2+ This process induces a rearrangement of the protein's spatial conformation. Hydrophobic groups are exposed from the molecule's interior to the surface, increasing the protein's hydrophobicity and generating more active sites such as amino and carboxyl groups. These sites can achieve more efficient intermolecular cross-linking through hydrophobic interactions, hydrogen bonds, and disulfide bonds, resulting in a gel network with higher cross-linking and better continuity. Simultaneously, the lipid release promoted by high-power ultrasound fills the pores of the gel network, further increasing the internal molecular flow resistance. Ultimately, this causes the viscosity of the egg yolk particle gel to increase with increasing ultrasound power.

[0082] Gel FTIR spectroscopy analysis Combination Figure 6 Amide A band 3800-3100 cm -1 The absorbance at 2925 cm⁻¹ is attributed to the stretching vibration of OH groups, and its peak position and intensity are closely related to the formation of hydrogen bonds. After ultrasonic treatment and the addition of CaCl₂, the peak position of amide A shifted towards higher wavenumbers and the peak intensity decreased, indicating a reduction in hydrogen bonds in the sample. This is attributed to the presence of numerous hydrogen bonds in the α-helix and β-sheet of the protein secondary structure. Hydrogen bonds themselves have relatively weak bond energies and are easily broken and reconstituted during gel formation. -1 and 2854 cm -1 Stretch vibrations of the methylene group were observed at 1746 cm⁻¹. -1 These three stretching vibration bands, corresponding to the C=O bonds in triglycerides, can be observed in most lipid samples. The decrease in absorption peak intensity after sonication and calcium addition treatment may be due to lipoprotein degradation, indicating that the lipoprotein structure is disrupted.

[0083] The characteristic peak of amide I band in Fourier transform infrared spectroscopy (1600-1700 cm⁻¹) -1 This is mainly attributed to the stretching vibration of C=O, whose specific vibrational frequency can reflect the specific secondary structure of peptides or proteins. (1650-1660 cm⁻¹) -1 Defined as an α-helix, 1600-1640 cm -1 Defined as β-fold, 1661–1700 cm -1 Defined as β-turn, 1640-1650 cm -1 Defined as random coiling. After applying Gaussian deconvolution fitting to the amide I band, the relative content of protein secondary structures can be calculated, thus illustrating changes in protein conformation. Figure 6 B shows the relative contents of secondary structures in different samples, indicating that Ca 2+ The addition of [a specific ingredient], sonication, and their combined use all induce changes in protein conformation. Overall, there is a trend of decreasing relative amounts of α-helices and random coils, and increasing relative amounts of β-sheets, among which Ca [a specific ingredient]... 2+ The most significant reduction in disordered structure and random coils was observed in samples treated with combined ultrasound. The reduction in intramolecular ordered α-helices reflects peptide chain unfolding, while the decrease in random coils indicates improved conformational regularity. The increase in intermolecular ordered β-sheets demonstrates enhanced intermolecular cross-linking. These results indicate that calcium ions and ultrasound treatment can synergistically drive the conformational shift from disordered to ordered proteins.

[0084] Gel chemical interaction force analysis Figure 7 Intermolecular forces in EYG gels under different CaCl2 concentrations and ultrasonic treatments were analyzed. It was evident that the intermolecular forces in the EYG gel samples were primarily disulfide bonds and hydrophobic interactions, with some ionic bonds and a small amount of hydrogen bonds. Compared to other intermolecular forces, the content of hydrogen bonds was relatively low, possibly due to the weak bond energy of hydrogen bonds, making them prone to breakage and reconstruction during gel formation. In samples without CaCl2 and without ultrasonic treatment, the intermolecular forces were mainly ionic and disulfide bonds. The ionic bonds originated from calcium phosphate bridges, and the disulfide bonds originated from apolipoproteins of HDL and LDL.

[0085] The disulfide bond content initially increased and then decreased with both CaCl2 concentration and ultrasonic power. The sample with 0.6% CaCl2 reached the peak disulfide bond content, which is attributed to the lower CaCl2 concentration. 2+ By inducing protein unfolding and exposing thiol groups, it promotes the oxidation of cysteine ​​to form intermolecular disulfide bonds. Lower concentrations of Ca... 2+ By inducing protein unfolding and exposing thiol groups, it promotes the oxidation of cysteine ​​to form intermolecular disulfide bonds. High concentrations of Ca...2+ Disulfide bond formation is inhibited through non-covalent interactions and steric hindrance. With increasing CaCl2 concentration and ultrasonic power, the ionic bond content in the gel generally shows a slow decreasing trend, with little difference between different treatment groups. The natural calcium-phosphorus bridge structure is gradually destroyed with increasing ionic strength, but exogenous Ca... 2+ It binds to negatively charged groups on the protein surface to form new ionic bridges, thus maintaining a relatively stable ionic bond content in the gel-forming sample. After ultrasonic treatment, cavitation and shear forces disrupt the original phosphorus-calcium bridges and promote protein conformational rearrangement, ultimately leading to a slight decrease in ionic bond content under high treatment intensity. Hydrophobic interactions continuously increase with increasing CaCl2 concentration and ultrasonic power. This is attributed to Ca... 2+ Electrostatic shielding weakens the electrostatic repulsion between proteins, allowing hydrophobic regions to be fully exposed and enhancing intermolecular hydrophobic aggregation. Ultrasound, by altering the conformation of EG proteins, exposes hydrophobic groups that were originally embedded inside the molecules, thus enhancing hydrophobic interactions.

[0086] Microstructure of gel foam Figure 8 Image A shows macroscopic images of EYG gel foams after inversion, treated with 750W sonication, different CaCl2 concentrations, and different sonication powers, with a CaCl2 concentration of 1%. It is clearly visible that the sample without CaCl2 and without sonication shows no foaming effect, while the samples treated with only sonication and only heating exhibit obvious flow. With increasing CaCl2 concentration and sonication power, the flowability of the gel foam significantly decreases. Samples with CaCl2 concentrations above 0.6% and sonication powers above 675W do not flow after inversion, exhibiting a stable gel state.

[0087] Gas diffusion refers to the process by which smaller bubbles transform into larger bubbles, reducing the number of smaller bubbles while increasing the size of the larger bubbles and causing them to burst. Displacement, disproportionation, and aggregation are the three main factors contributing to foam instability. Figure 8 B shows the microscopic bubble morphology of gel foam after 0 h and 6 h of storage under different calcium concentrations and ultrasonic powers. At 0 h, all samples showed a small bubble distribution. After 6 h, the bubbles in each group merged and grew to varying degrees. This is because gravity causes the liquid between the foam interfaces to flow downwards, resulting in a thinner interface and closer foam surfaces. This leads to foam aggregation and coarsening. As the foam size increases, it eventually bursts. The size of the bubbles can evaluate the stability of the foam system; larger bubbles increase the likelihood of system instability. With increasing calcium concentration, the average bubble size gradually decreased after 6 h. This is due to the Ca2+ concentration... 2+Ionic crosslinking with gel molecular chains constructs a denser three-dimensional network framework, effectively inhibiting bubble aggregation and Austronescent ripening. With increasing ultrasonic power, bubble size also showed a decreasing trend after 6 hours. On one hand, the mechanical shear force and cavitation microjets generated by ultrasound promote protein conformational rearrangement, exposing hydrophobic groups and active sites such as amino and carboxyl groups, in the Ca2+ region. 2+ The synergistic effect forms a gel network with higher cross-linking degree and better continuity. On the other hand, high-power ultrasound promotes lipid release and fills the pores of the gel network, increasing the viscosity of the gel before foaming. This not only inhibits excessive fusion of bubbles during the foaming stage, but also hinders gas diffusion and liquid film drainage through interfacial adhesion during the storage stage, ultimately delaying bubble growth and instability.

[0088] Foaming properties and stability of gel foam In food processing, excellent foaming properties are crucial for product quality control. The formation and stability of foam largely depend on the adsorption, unfolding, and orientation of proteins at the air-water interface, as well as intermolecular interactions. For example... Figure 9 As shown in Figure A, the foaming ability of EYG gel initially increases significantly with increasing CaCl2 concentration, but decreases significantly when the CaCl2 concentration exceeds 1%. Simultaneously, the foam stability of EYG gel shows a continuous increasing trend with increasing CaCl2 concentration. Previous studies have shown that exposure of hydrophobic groups enhances foaming ability because additives that interact hydrophobically with proteins can promote molecular cross-linking, thereby improving foaming performance. Figure 9 As the CaCl2 concentration increases, the egg yolk particles gradually depolymerize, exposing internal lipids and hydrophobic groups, thus improving foaming properties. However, when the CaCl2 concentration exceeds 1%, excessive cross-linking of proteins occurs, leading to a continuous increase in the viscosity of the continuous phase. This hinders gas dispersion and bubble formation, resulting in decreased foaming properties. Simultaneously, the increased viscosity of the continuous phase effectively inhibits bubble aggregation and liquid film drainage, resulting in continuously improved foam stability. With increasing ultrasonic power, the foaming properties of EYG gel decrease, while its stability continuously increases. This is attributed to the effect of ultrasound on CaCl2 concentration. 2+ The cross-linking process with EYG has a promoting effect, and the viscosity of the gel system increases due to the ultrasonic-induced lipid release.

[0089] Interfacial protein adsorption capacity Foam stability is one of the core indicators of foam application performance, and the adsorption behavior of proteins at the air-water interface plays a crucial role in determining foam stability. The greater the amount of protein adsorbed at the interface, the denser the interfacial film formed, thereby improving the mechanical strength and rupture resistance of the foam.

[0090] like Figure 10The adsorption capacity of interfacial proteins was determined by measuring the sub-aqueous phase protein content after foam preparation and storage at room temperature for 30 min. EYG samples without CaCl2 addition and without ultrasonic treatment had extremely low interfacial protein adsorption capacity because their internal calcium phosphate bridge structure remained largely intact, maintaining a large, dense aggregate state, making stable adsorption at the air-water interface impossible and hindering quantitative determination. EYG samples treated only with ultrasonic treatment also showed limited adsorption at the air-water interface due to insufficient destruction of the calcium phosphate bridge structure and incomplete depolymerization, resulting in an adsorption capacity of only 16.1%. Samples with only 1% CaCl2 addition also exhibited low adsorption capacity due to insufficient interfacial protein cross-linking and poor interfacial film stability. However, with the synergistic increase of CaCl2 concentration and ultrasonic power, the adsorption capacity of interfacial proteins showed a significant upward trend. The sample with 1% CaCl2 addition and ultrasonic treatment at 750 W achieved an adsorption capacity of 96.6%, with the highest adsorption capacity reaching 99.4% among all tested samples. This result indicates that CaCl2... 2+ The synergistic effect with ultrasound is key to achieving efficient adsorption of EYG proteins at the air-water interface: when Ca... 2+ When the concentration and ultrasonic power are insufficient, the degree of depolymerization and interfacial cross-linking of EYG protein are limited, making it difficult to form a stable adsorption layer at the air-water interface. With the enhancement of the synergistic effect of the two, the protein molecules depolymerize more fully and the interfacial cross-linking is tighter. The amount of protein adsorbed at the air-water interface and the strength of the interfacial film increase simultaneously, eventually forming a dense and elastic interfacial film, which provides a solid structural basis for improving foam stability.

[0091] Analysis of interfacial shear rheological properties In foam systems, the mechanical properties of the gas-water interface directly affect bubble formation, drainage rate, and rupture process. Therefore, interfacial shear rheological parameters are important indicators for evaluating foam performance. Foam stability is closely related to interfacial shear rheological properties; a high elastic modulus helps the foam resist shear deformation, thus improving stability. When the interfacial elastic modulus is low, the interface is prone to shear deformation, leading to bubble rupture. Similarly, when the interfacial viscoelasticity is high, the interface can absorb external energy, thereby delaying the rupture process.

[0092] Select samples that can form stable gel foams for interfacial shear rheology testing, such as... Figure 11 As shown, the results clearly demonstrate the effects of different CaCl2 concentrations and ultrasonic power on the structural stability of the EYG gel foam air-water interface. Strain scanning results ( Figure 11 A and Figure 11(B) indicates that the interface G' of all samples was consistently higher than that of the interface G'', and both increased with increasing CaCl2 concentration and ultrasonic power. This suggests that protein molecules constructed a highly elastic rigid film at the air-water interface, with continuously increasing strength, effectively limiting bubble size changes by acting as a physical barrier to inhibit foam disproportionation. Frequency scan results ( Figure 11 C and Figure 11 D) Further verification of the interfacial membrane's performance from a dynamic mechanical perspective: As the CaCl2 concentration and ultrasonic power increase, the characteristic frequency of the modulus crossover point increases significantly, indicating that the sample can maintain elastic characteristics at higher deformation rates, and the interfacial membrane has the ability to quickly resist transient disturbances; at the same time, in the low-frequency region, the interface G' is much higher than the interface G'' and remains stable, proving that the system has successfully formed a durable and stable elastic interfacial skeleton, which is crucial for suppressing the coarsening and rupture of bubbles during storage.

[0093] Interfacial shear rheology is an important method for evaluating foam stability, and the viscoelastic parameters of the interface directly determine the foam's ability to resist external forces and extend its lifespan. This study confirms that Ca... 2+ The induced interfacial network possesses a high elastic modulus, enabling it to absorb external energy and resist shear deformation, thereby significantly improving foam stability. The results of this study demonstrate that through Ca... 2+ Crosslinking and ultrasonic-assisted treatment can effectively control the long-term stability of gel foam by enhancing the interfacial shear rheological properties.

[0094] Microstructure and droplet size of emulsion gel Figure 12 The microstructure and droplet size of EYG-stabilized emulsion gels were shown under different heating times (0, 10, 20, 30, and 40 min) and different ultrasonic times (0, 5, 10, 15, and 20 min). The smaller and more uniform the droplet size of the emulsion, the higher the emulsion stability is generally; conversely, large droplets will accelerate stratification, flocculation, and aggregation.

[0095] Microstructural observation revealed that, in its natural state, the EYG emulsion droplets were the largest and unevenly distributed. This is attributed to the high degree of particle aggregation and weak interfacial hydrophobicity caused by the naturally dense phosphorus-calcium bridge cross-linking structure of EYG, making it difficult to effectively adsorb at the oil-water interface and form a stable interfacial film, resulting in poor emulsification performance. After sonication or heating alone, the droplet size decreased, but significant droplet coalescence and size inhomogeneity remained. Compared to single treatments, the droplets in samples treated with a combination of sonication and heating were more densely packed, significantly smaller, and more uniformly distributed. Droplet size analysis showed that the emulsion droplet size initially decreased and then increased with prolonged heating or sonication time. Both the heating alone and the combined treatment groups reached their minimum droplet size after 20 minutes of heating, while both sonication alone and the combined treatment groups reached their minimum droplet size after 10 minutes of sonication. Further extension of the treatment time caused the droplets to increase in size again, and the combined treatment group failed to form a stable emulsion gel after 40 minutes of heating or 20 minutes of sonication, thus making it impossible to observe the microstructure and measure the droplet size. This phenomenon may be attributed to the fact that heating can promote the unfolding of EYG protein conformation and expose hydrophobic groups, while ultrasound can promote molecular rearrangement and cross-linking by changing protein conformation, thus synergistically improving emulsification performance; however, excessive heating or excessive ultrasound can cause excessive denaturation and aggregation of proteins, destroying the gel network and interfacial stability, ultimately leading to instability of the emulsion system.

[0096] Analysis of the centrifugal stability of emulsion gel The centrifugal stability of emulsion gels was evaluated using OBC (Original Bipolar Cryometry). Figure 13 Under different heating and sonication treatment times, the oil-holding capacity (OBC) of EYG emulsion gels showed a trend of first increasing and then decreasing. The OBC reached its maximum value after 20 min of heating and 10 min of sonication, indicating that the centrifugal stability of the emulsion gel was optimal at these times. The OBC of the emulsion gel is affected by the droplet size, viscosity, and interfacial adsorbed protein layer. Smaller emulsion droplets form stronger gel structures and are less prone to aggregation. Therefore, emulsions with stronger gel structures can maintain their structural integrity during centrifugation and exhibit higher OBC. Moderate heating and sonication treatment can reduce droplet size and enhance interfacial protein adsorption and gel network strength, thereby effectively binding the oil phase during centrifugation; while excessive treatment will destroy the integrity of the gel structure, leading to a significant decrease in OBC. This is consistent with the droplet size and viscoelasticity results of EYG emulsion gels.

[0097] Analysis of the thermal stability of emulsion gel The thermal stability of emulsion gels is evaluated by measuring the droplet size of the emulsion after heating in a water bath at 40, 60, and 80°C for 30 min. Figure 14The droplet sizes of EYG-stabilized emulsion gels after heat treatment with different heating and sonication times are shown. It is evident that the droplet size of all samples increased after heat treatment. This is because heat treatment accelerates the Brownian motion of oil droplets, intensifying collisions and aggregation, leading to a significant increase in particle size. Moderate heating or sonication pretreatment of the aqueous EYG before emulsification promotes cross-linking between protein molecules, strengthens the three-dimensional scaffold structure of the gel, and effectively restricts droplet movement and aggregation. Notably, at 80℃, the emulsion droplet size increased significantly, and the naturally stable EYG emulsion demulsified, making droplet size unmeasurable. The droplet sizes of emulsions treated at 40℃ and 60℃ showed only a slight increase compared to freshly prepared emulsions. This is attributed to the fact that the denaturation temperature of EYG is around 76℃; the 80℃ 30 min heat treatment caused rapid denaturation and aggregation of most proteins in the EYG, resulting in protein desorption at the interface, droplet coalescence, and demulsification. Emulsions treated at other temperatures maintained good structural integrity.

[0098] Analysis of the storage stability of emulsion gels To investigate the storage stability of EYG emulsion gels, all emulsions were stored for 15 days, and changes in droplet size and microstructure were measured. Figure 15 The droplet size of all EYG emulsion gels increased during storage. This phenomenon can be attributed to the thermodynamically unstable nature of emulsion gels, where droplets spontaneously undergo flocculation, aggregation, phase separation, and Ostwald ripening during storage. Naturally stable EYG emulsions exhibit significant demulsification after more than 5 days of storage, making it impossible to determine droplet size and microstructure after 10 and 15 days of storage. However, emulsion gels pretreated with moderate heating (20 min) and ultrasound (10 min) maintained structural integrity throughout the 15-day storage period, without demulsification, and showed a significantly smaller increase in droplet size. Microstructural observation further confirmed that the pretreated group maintained a relatively small and uniform droplet distribution after storage. This indicates that moderate heating and ultrasound pretreatment can effectively bind oil droplets and inhibit their aggregation by strengthening protein cross-linking and gel network structure, thereby significantly improving the long-term storage stability of EYG emulsion gels.

[0099] Example 3 investigated the effects of ultrasonic time and heating time on Ca. 2+- The effects of ultrasonic treatment on the structure, emulsification properties, and stability of EYG gels. An emulsion gel prepared using EYG pretreated with ultrasound for 10 min and heat for 20 min as the aqueous phase exhibited the smallest droplet size and most uniform distribution, while also displaying higher apparent viscosity and stronger solid-like gel properties (G' > G"). It achieved optimal centrifugal stability and showed minimal droplet size growth after heat treatment at 40℃ and 60℃, demonstrating good thermal stability. It maintained structural integrity after 15 days of storage at 4℃, exhibiting excellent long-term storage stability. These results indicate that moderate ultrasonic (10 min) and heat (20 min) treatments can synergistically optimize the properties of EYG gels and enhance interfacial activity, thus successfully constructing a stable emulsion gel system. This provides a theoretical and technical basis for expanding the application of egg yolk particles in emulsion-based functional food materials.

[0100] This invention studies Ca 2+ The effects of concentration and ultrasonic power on the structure, gel properties, and foam performance of EYG. 2+ At low concentrations (≤1%), electrostatic shielding induces the depolymerization of naturally dense EYG, exposing internal hydrophobic groups and active sites; simultaneously, the cavitation effect of ultrasound synergistically promotes protein conformation unfolding and Ca2+. 2+ Crosslinking with EYG. When Ca 2+ When the concentration increases to above 1%, excessively high ionic strength becomes the dominant factor, leading to further depolymerization of the original EYG structure. 2+ The synergistic effect of ultrasound significantly optimizes gel performance, reducing random coiling, increasing β-sheets, and transforming the protein secondary structure from disordered to ordered. Intermolecular forces are mainly hydrophobic interactions and disulfide bonds, forming a denser three-dimensional gel network, significantly improving apparent viscosity and storage modulus. Improved gel performance directly affects foam properties; the dense gel framework provides physical support for bubbles; proteins fully unfold and are efficiently adsorbed at the air-water interface (adsorption capacity reaches 96.6%), forming a highly elastic rigid interfacial film that effectively inhibits bubble aggregation and disproportionation, enhancing foam stability. Simultaneously, Ca... 2+ The depolymerization effect on the natural dense structure of EYG significantly improves foaming properties, initially increasing and then decreasing with the degree of crosslinking, as excessive viscosity due to over-crosslinking inhibits bubble formation. Considering overall stability, at 1% Ca... 2+ The foaming performance is optimal at 750 W. In summary, this invention constructs a Ca... 2+ Crosslinked EYG gel foam materials and emulsion gels.

[0101] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing egg yolk granule gel, characterized in that, Includes the following steps: A suspension of egg yolk particles was obtained by mixing CaCl2 solution with egg yolk particles; then, the suspension was sonicated in an ice-water bath to obtain a dispersion of egg yolk particles. The dispersion of egg yolk particles was then heated in a water bath at 70-75°C and then cooled to obtain a gel of egg yolk particles. The mass concentration of the CaCl2 solution was 0.6%-2%; the sonication power was 600-900W; the sonication time was 5-20 min; and the water bath heating time was 10-40 min.

2. The method for preparing egg yolk granule gel according to claim 1, characterized in that, The egg yolk particle suspension has a mass concentration of 5-7%.

3. The method for preparing egg yolk granule gel according to claim 1, characterized in that, The cooling temperature is 2-5℃, and the cooling time is 2-2.5h.

4. The method for preparing egg yolk granule gel according to claim 1, characterized in that, The egg yolk particles are prepared by the following steps: mixing egg yolk liquid with NaCl, centrifuging at 2-5℃, taking the precipitate, and then washing the precipitate with water to obtain the egg yolk particles.

5. A yolk granule gel, characterized in that, It is prepared by the preparation method according to any one of claims 1-4.

6. The use of the egg yolk granule gel prepared by the preparation method according to any one of claims 1-4 or the egg yolk granule gel according to claim 5 in the production of gel foam.

7. The application according to claim 6, characterized in that, include: The egg yolk granule gel was homogenized using a homogenizer at a speed of 12000-15000 rpm for 1.5-2 minutes to obtain the gel foam.

8. The use of the egg yolk granule gel prepared by the preparation method according to any one of claims 1-4 or the egg yolk granule gel according to claim 5 in the preparation of emulsion gels.

9. The application according to claim 8, characterized in that, include: The egg yolk granule gel and the oil phase were mixed, and then homogenized using a homogenizer at a speed of 10000-12000 r / min to prepare the emulsion gel.

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