Method for improving gel performance of emulsion by using ternary covalent complex

Abstract

The invention discloses a method for improving the gel performance of an emulsion by using a ternary covalent complex, which comprises the following steps: preparing the ternary covalent complex which is an egg white protein-gallic acid-Arabic gum complex; preparing a ternary covalent compound into a ternary covalent compound solution, and mixing and homogenizing the ternary covalent compound solution with olive oil to obtain pre-emulsified liquid; adding myofibrillar protein into the pre-emulsion, and carrying out secondary homogenization to obtain composite sol; and removing bubbles from the composite sol, placing the composite sol in a water bath kettle for water bath cooking, and cooling to obtain the emulsion gel. The egg white protein-gallic acid-Arabic gum compound is used for improving the stability of the pre-emulsion, so that oil drops are uniformly dispersed. When the myofibrillar protein is added to prepare the gel, the compound improves the performance of the emulsion gel, and the emulsion gel has a compact structure and inhibits the loss of water, so that the hardness, elasticity and chewiness of the gel are improved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a method for improving the gel performance of an emulsion using a ternary covalent complex. Background Art

[0002] At present, consumers are becoming more and more aware of the safety and nutritional quality of food. In pursuit of health, low-fat foods and related functional foods are becoming more and more popular among consumers. Emulsified meat products contain a variety of peptides and essential amino acids, with a particularly high content of digestible lysine, and play a vital role in meeting human needs for high-nutrition protein sources. However, such products contain a large amount of cholesterol and saturated fatty acids, and long-term consumption will increase the risk of cardiovascular disease and obesity. In order to reduce the content of saturated fatty acids in emulsified meat products, researchers have long explored emulsion gels prepared with vegetable oils as a substitute for animal fat. However, vegetable oils are highly fluid, so the physical instability caused by the flow of vegetable oils must be overcome. In addition, due to the presence of more unsaturated fatty acids in vegetable oils, the challenge of preventing oxidative rancidity in the product system has also increased.

[0003] The existing technology has the following defects: the existing vegetable oils used to replace animal oils have problems such as physical instability and oxidation rancidity. Summary of the invention

[0004] Objective: To overcome the deficiencies in the prior art, the present invention provides a method for improving the performance of emulsion gel by treating a ternary covalent complex using an enzyme method combined with a Maillard reaction, and utilizing the excellent functional properties of the ternary covalent complex to improve the stability and antioxidant capacity of the emulsion gel.

[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is: In a first aspect, a method for improving the gel properties of an emulsion by using a ternary covalent complex is provided, comprising: S1. preparing a ternary covalent complex, wherein the ternary covalent complex is an egg white protein-gallic acid-gum arabic complex; the preparation method of the ternary covalent complex comprises: firstly using laccase to catalyze gallic acid grafting egg white protein to form a binary complex; then using a wet heat method to induce a Maillard reaction between gum arabic and the binary complex to prepare an egg white protein-gallic acid-gum arabic complex; S2. The ternary covalent complex is prepared into a 5-15 mg / mL ternary covalent complex solution using a phosphate buffer solution of pH 7.0, and the solution is mixed and homogenized with olive oil to obtain a pre-emulsion; S3. adding myofibrillar protein to the pre-emulsion and performing secondary homogenization to obtain a composite sol; S4. Remove bubbles from the composite sol, place it in a water bath for water bath boiling and cooling to obtain an emulsion gel.

[0006] In some embodiments, S1 specifically includes: S11, mixing the egg white protein solution and the gallic acid solution evenly, adjusting the pH to 6.9-7.1, to obtain a mixed solution; S12, adding laccase to the mixed solution to catalyze gallic acid grafting egg white protein to form a binary complex; S13, mixing the binary complex with a gum arabic solution to undergo Maillard reaction to obtain an egg white protein-gallic acid-gum arabic complex.

[0007] Furthermore, in some embodiments, at least one of the following is satisfied in S11: The concentration of the egg white protein solution is 20-25 mg / mL, and the egg white protein in the egg white protein solution is fully hydrated; the concentration of gallic acid is 2-10 mg / mL; The pH of the mixture was adjusted using 0.1 M NaOH.

[0008] Further, in some embodiments, at least one of the following is satisfied in S12: The laccase was 1.6 U / mL; The reaction conditions are 30~50℃ for 4 h~6 h.

[0009] Further, in some embodiments, at least one of the following is satisfied in S13: The concentration of the gum arabic solution is 5-20 mg / mL; The binary complex is mixed with a gum arabic solution to obtain a reaction solution, and a continuous cycle reaction is performed, wherein the cycle reaction comprises: firstly, stirring the reaction solution at 55-65° C. at 200-400 r / min for 15-25 min; then, placing the reaction solution in a water bath at 80-85° C. and stirring at 400-600 r / min for 5-15 min; after 4-6 cycles of reaction, taking out the reaction solution, terminating the reaction in an ice water bath, and obtaining an egg white protein-gallic acid-gum arabic complex.

[0010] In some embodiments, in S2, the concentration of egg white protein in the ternary covalent complex solution is preferably 10 mg / mL; In S2, the mass ratio of the ternary covalent complex solution to the olive oil is (3-5):1, preferably 4:1; In S2, the homogenization condition is 8000~12000 rpm for 2~3 min.

[0011] Furthermore, in some embodiments, in S2, the ternary covalent complex is formulated into a 5-15 mg / mL ternary covalent complex solution, and then the ternary covalent complex solution is mixed with olive oil in a mass ratio of (3-5):1, and homogenized in a homogenizer at a speed of 8000-12000 rpm for 2-3 min to obtain a pre-emulsion.

[0012] In some embodiments, in S3, the concentration of myofibrillar protein in the composite sol is 2 wt %-4 wt %; in some embodiments, in S3, the secondary homogenization condition is 8000-10000 rpm for 1-3 min.

[0013] In some embodiments, in S4, removing bubbles comprises: centrifuging the composite sol at 4° C. and 400-500 g for 2-3 min to remove bubbles; In some embodiments, in S4, water bath boiling and cooling are performed in a water bath, including: placing the composite sol after the bubbles are removed in a water bath for water bath boiling, heating the water in the water bath from room temperature to 75-90°C and maintaining it for 20-40 min; after completion, taking it out and placing it in ice water for cooling.

[0014] In the second aspect, the latex gel is prepared by the method of improving the performance of the latex gel by using the ternary covalent complex. The latex gel has a dense and uniform three-dimensional network structure.

[0015] And experiments have proved that the gel strength and water holding capacity of the emulsion prepared by the method of the present invention are significantly improved.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention uses an egg white protein-gallic acid-arabic gum complex to improve the stability of the pre-emulsion and evenly disperse the oil droplets. When myofibrillar protein is added to prepare the gel, the complex improves the performance of the gel, the emulsion gel has a compact structure, inhibits the loss of water, and improves the hardness, elasticity and chewiness of the gel. The emulsion gel prepared by the complex has a uniform milky white appearance and a smooth surface, and will not have a significant impact on the color of the final product. In addition, due to the introduction of phenolic acid and polysaccharides, the oxidation process of oil and protein during the storage period is delayed. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the specific implementation of the present invention or the technical solution in the prior art, the drawings required for use in the specific implementation or the description of the prior art are briefly introduced below.

[0018] Figure 1 Schematic diagram comparing the emulsification activity and emulsification stability of emulsions prepared from a single protein and different complexes in an example of the present invention.

[0019] Figure 2 Schematic diagram of the microstructure of emulsions prepared from a single protein and different complexes in an embodiment of the present invention.

[0020] Figure 3 Schematic diagram of water distribution of emulsion gels prepared from single protein and different complexes in an embodiment of the present invention.

[0021] Figure 4 Schematic diagram of the rheological properties of emulsion gels prepared from a single protein and different complexes in an embodiment of the present invention.

[0022] Figure 5 Schematic diagram of the microstructure of the emulsion gel prepared from a single protein and different complexes in an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram of the oxidative stability of emulsion gels prepared with a single protein and different complexes at different times in an example of the present invention.

[0024] In the figure: EWP: egg white protein, GA: gallic acid, AG: gum arabic. DETAILED DESCRIPTION

[0025] The technical solution of the present invention will be described clearly and completely below in conjunction with the accompanying drawings to facilitate a better understanding of the present invention. In addition, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] The methods used in the following examples are all conventional methods unless otherwise specified, and the materials, instruments and reagents used are all conventional materials, instruments and reagents in the art unless otherwise specified, and can be obtained by those skilled in the art through commercial channels.

[0027] In the present application, the method for obtaining myofibrillar protein comprises: cutting the longissimus dorsi muscle of the pig at 4°C, removing the connective tissue and adipose tissue. Putting the muscle pieces into a tissue pounder, adding phosphate buffer (10 mM Na2HPO4·12H2O, 0.1 M NaCl, 2 mM MgCl2·6 H2O, 1 mM EGTA, pH 7.0), and pounding at a uniform speed. The obtained slurry is stirred at 4°C for 2000 min. g Centrifuge for 15 min and discard the supernatant. Repeat the above steps twice. Disperse and dissolve the precipitate with 0.1 M NaCl, mash at a constant speed for 40 s and centrifuge. Repeat the above steps for the precipitate, and filter with four layers of gauze before centrifugation to remove muscle fibers and connective tissue. The extract obtained is myofibrillar protein.

[0028] Example 1: Preparation of emulsion gel using a single protein as an emulsifier S1. Prepare pre-emulsion: Prepare a 10 mg / mL egg white protein solution using deionized water. Stir magnetically for at least 2 h and let stand overnight to ensure that the protein is fully hydrated. Then mix the egg white protein solution with olive oil (4:1, w / w) and homogenize at 12,000 rpm for 2 min in a high-speed homogenizer to obtain an egg white protein emulsion. All the above operations were performed at 4 °C.

[0029] S2. Preparation of emulsion gel: Add myofibrillar protein to the above pre-emulsion solution so that the concentration of myofibrillar protein in the system is 2wt%, homogenize at 8000 rpm for 2 min to obtain sol, then centrifuge at 500 g for 2 min to remove bubbles, and dispense into flat-bottomed glass tubes (5 cm high × 2.2 cm inner diameter). All the above operations were carried out at 4 °C. Place the sol in a water bath, heat from room temperature to 85 °C and keep it for 30 min, then take it out and cool it in an ice water bath to obtain EWP emulsion gel.

[0030] Example 2: Preparation of emulsion gel using egg white protein-gallic acid complex as emulsifier S1. Preparation of egg white protein-gallic acid complex: Prepare an egg white protein solution with a concentration of 20 mg / mL using deionized water. Stir magnetically for at least 2 h and let stand overnight to ensure that the protein is fully hydrated. Then prepare a gallic acid solution with a concentration of 6 mg / mL (relatively excessive to allow egg white protein to fully react) and mix it thoroughly with the egg white protein solution under continuous stirring. Use 0.1 M NaOH to adjust the pH of the mixture to neutral (7.0 ± 0.1). Then add laccase (1.6 U / mL) to the mixture and react at room temperature for 4 h to 6 h. After the reaction is completed, the mixture is dialyzed with deionized water at 4 °C for 48 h with a molecular weight cutoff of 12000 Da. The deionized water is replaced every 8 h to ensure that the unreacted gallic acid is completely dialyzed away. The resulting complex solution is stored at 4 °C.

[0031] S2. Preparation of pre-emulsion: The egg white protein concentration of the above-mentioned complex solution was adjusted to 10 mg / mL using a phosphate buffer solution with a pH of 7.0, and mixed with olive oil at a ratio of 4:1 (w / w). The mixture was homogenized at 12,000 rpm for 2 min using a high-speed homogenizer to obtain an egg white protein-gallic acid emulsion. The above operations were all carried out at 4 °C.

[0032] S3. Preparation of emulsion gel: Add myofibrillar protein to the above pre-emulsion solution to make the concentration of myofibrillar protein in the system 2%, homogenize at 8000 rpm for 2 min to obtain sol, then centrifuge at 500 g for 2 min to remove bubbles, and dispense into flat-bottomed glass tubes (5 cm high × 2.2 cm inner diameter). All the above operations were carried out at 4 °C. Place the sol in a water bath, heat from room temperature to 85 °C and keep it for 30 min, then take it out and cool it in an ice water bath to obtain EWP-GA emulsion gel.

[0033] Example 3: Preparation of emulsion gel using egg white protein-gallic acid-gum arabic complex as emulsifier S1. Preparation of egg white protein-gallic acid-gum arabic complex: Prepare an egg white protein solution with a concentration of 20 mg / mL using deionized water. Stir magnetically for at least 2 h and let stand overnight to ensure that the protein is fully hydrated. Then prepare a gallic acid solution with a concentration of 6 mg / mL (relatively excessive to allow the egg white protein to react fully) and mix it thoroughly with the egg white protein solution under continuous stirring. Use 0.1 M NaOH to adjust the pH of the mixture to neutral (7.0 ± 0.1). Then add laccase (1.6 U / mL) to the mixture and react at room temperature for 4 h to 6 h. After the reaction is completed, the mixture is dialyzed with deionized water at 4 °C for 48 h with a molecular weight cutoff of 12000 Da. The deionized water is replaced every 8 h to ensure that the unreacted gallic acid is completely dialyzed out. The obtained complex was mixed with a 10 mg / mL gum arabic solution and subjected to continuous cycle reaction. The specific steps were as follows: first, the mixture was stirred at a low speed for 20 min at 60 °C; then, it was placed in an 83 °C water bath and stirred rapidly for 10 min. After 5 cycles, it was taken out and the reaction was terminated in an ice water bath to obtain an egg white protein-gallic acid-gum arabic complex.

[0034] S2. Preparation of pre-emulsion: The egg white protein concentration in the above-mentioned complex solution was adjusted to 10 mg / mL using a phosphate buffer solution with a pH of 7.0, and mixed with olive oil at a ratio of 4:1 (w / w). The mixture was homogenized at 12,000 rpm for 2 min using a high-speed homogenizer to obtain an egg white protein-gallic acid-gum arabic pre-emulsion. The above operations were all carried out at 4 °C.

[0035] S3. Preparation of emulsion gel: Add myofibrillar protein to the above pre-emulsion solution to make the myofibrillar protein concentration in the system 2%, homogenize at 8000 rpm for 2 min to obtain sol, then centrifuge at 500 g for 2 min to remove bubbles, and dispense into flat-bottomed glass tubes (5 cm high × 2.2 cm inner diameter). All the above operations were carried out at 4 °C. Place the sol in a water bath, heat from room temperature to 85 °C and keep it for 30 min, then take it out and cool it in an ice water bath to obtain EWP-GA-AG emulsion gel.

[0036] The present invention selects gallic acid with high antioxidant activity and gum arabic with large molecular weight to modify egg white protein to improve the application value of the protein. However, the materials used are not limited to the selected gallic acid and gum arabic. All polyphenolic substances with phenolic rings can be used as substrates for laccase catalysis, and reducing sugars containing carbonyl groups can induce Maillard reaction with proteins.

[0037] The emulsion gels prepared from single protein, binary complex and ternary complex were compared and the results are as follows: (1) Emulsifying activity and emulsifying stability of emulsions prepared from single protein and different complexes like Figure 1 As shown in Figure 2, the emulsifying activity of the egg white protein EWP emulsified group was 33.05 ± 0.83 m 2 / g, and the emulsifying activity of the EWP-GA composite emulsified group was 37.78 ± 0.48 m 2 / g. This indicates that the grafting of gallic acid GA onto protein will improve the emulsification activity of the emulsion. The emulsification stability of the EWP-GA complex emulsification group also has a similar trend. This may be because the gallic acid GA modification changes the structure of the protein, causing the protein spatial structure to unfold and thus expand the coverage on the surface of the oil droplets. In addition, the EWP-GA-AG complex emulsification group has higher emulsification activity and emulsification stability than the EWP-GA complex emulsification group, which are increased by 50.63% and 21.25%, respectively. This is because gum arabic AG is covalently bound to the surface of the EWP-GA complex to improve its surface activity, form a sticky film to wrap the oil droplets, and improve the emulsification efficiency. At the same time, the EWP-GA-AG complex increases the viscosity of the entire system, which can effectively inhibit the movement and migration of oil droplets, and gum arabic AG provides a larger steric hindrance and enhances the repulsive effect between droplets. It has better stability against droplet aggregation than the EWP-GA complex, so it can prevent the mutual aggregation of droplets and improve the stability of the emulsion.

[0038] (2) Microstructure of emulsions prepared from single protein and different complexes The microstructure of the prepared emulsion was observed using an optical microscope. Figure 2 It can be seen that the emulsion prepared by unmodified EWP has a larger particle size and irregular shape. This is because the emulsification ability of EWP is limited and is not enough to completely wrap the oil droplets. The oil phase is lighter and tends to move upward, so the number of oil droplets at the bottom of the emulsion is small. The emulsification ability of EWP modified by GA has been slightly improved. The number of droplets in the image has increased, but the droplet size is uneven. When the EWP-GA-AG complex is used as an emulsifier, the emulsification activity and stability of the emulsion are significantly improved. The result reflected in the image is that the number of large droplets decreases, the number of small droplets increases, and the total number of droplets increases. This is because the addition of AG promotes faster adsorption of proteins to the interface, reduces surface activity, and is conducive to fully wrapping the oil droplets, so that the particle size of the emulsion is maintained at a relatively small level.

[0039] (3) Texture properties of emulsion gels prepared from single protein and different complexes The TPA test results are shown in Table 1.

[0040] Table 1

[0041] Different lowercase letters indicate significant differences among different treatment groups ( P <0.05).

[0042] As shown in Table 1, compared with the single protein group, the EWP-GA and EWP-GA-AG complex emulsified groups have higher hardness, adhesion, elasticity and chewiness. Among them, the EWP-GA-AG complex has a more significant effect, which is 1.65, 3.30, 3.01 and 2.02 times that of the EWP group. On the one hand, it may be because the EWP-GA-AG complex can form a dense interface film on the surface of the oil droplet, reduce the adsorption of MP at the interface, and allow more myofibrillar proteins to participate in the formation of the gel network; at the same time, the emulsion droplets are evenly distributed and have a small particle size, and have strong stability, which increases the gel strength. On the other hand, it may be that the free complex in the system is filled into the protein gel network, and combines with the protein through covalent and non-covalent interactions to form a tight structure, thereby enhancing the strength of the gel.

[0043] (4) Comparison of color difference between emulsion gels prepared from single protein and different complexes Table 2

[0044] Different lowercase letters indicate significant differences among different treatment groups ( P <0.05).

[0045] As shown in Table 2, the addition of EWP-GA complex increased the brightness value of the latex gel ( L *) significantly reduced, the redness value (a *) becomes negative, the yellowness value ( b *) increased significantly. This may be because gallic acid turns dark green after oxidation and interacts with the protein and oil in the system, making the color of the emulsion gel system darker. Compared with the EWP-GA complex, the brightness value of the emulsion gel prepared by the EWP-GA-AG complex ( L *) and redness value ( a *) rebound, yellowness value ( b *) decreased significantly. This is because the EWP-GA-AG complex has a better emulsifying ability, which makes the oil phase evenly dispersed in the gel system and increases the reflective area. At the same time, gum arabic has a large steric hindrance, which hinders the interaction between phenolic acid and protein and oil.

[0046] (5) Water distribution of emulsion gels prepared from single protein and different complexes The results are as follows Figure 3 The relaxation time T2 of all samples has four characteristic peaks, corresponding to the four states of water, namely bound water (T 2b , 1-10 ms), slightly movable water (T 21 , 10-100 ms), moderately mobile water (T 22 , 100-1000ms) and free water (T 23 , 1000-4000 ms). According to the change of T2 in the figure, it can be seen that the gel composition has a significant effect on the water distribution state in the gel. Compared with the EWP group, the addition of EWP-GA complex and EWP-GA-AG complex increased the bound water (T 2b ) and slightly movable water (T 21 ) slightly shifts to a shorter relaxation time, and free water (T 23 ) slightly shifts towards longer relaxation times. Shorter relaxation times indicate tighter binding of water to the gel matrix and stronger interactions, while longer relaxation times represent poor gel stability and loose structure. The relaxation time of moderately mobile water after adding the complex (T 22 ) had no significant difference compared with the control ( P> 0.05), but the peak gradually increased and the peak width became larger. T 22 The peak value was the largest in all treatment groups, indicating that the mobility of water molecules in the gel was significantly reduced after the addition of the complex.

[0047] (6) Rheological properties of emulsion gels prepared from single protein and different complexes The dynamic viscoelastic changes occurring during the formation of the three emulsion gel networks were detected by a rotational rheometer. Figure 4Rheological analysis (G' and G'') of composite sols containing EWP and different composites under heating at 20-80 ℃. It can be seen from the figure that the G' and G'' values ​​of all sample groups show the same trend with the change of temperature. Compared with EWP, the EWP-GA composite significantly increased the G' and G'' values. This shows that the introduction of polyphenols promotes the gelation of myofibrillar protein and improves the viscoelasticity of the gel. It may be that during the thermal induction process, polyphenols interact with proteins to form protein aggregates with higher molecular weight, resulting in an increase in G' and G'' values. The EWP-GA-AG composite group has higher G' and G'' values, which may be that the incorporation of polysaccharides can absorb water in the myofibrillar protein sol through hydrogen bonds and evenly distribute it throughout the gel network structure, thereby enhancing the gelation ability.

[0048] (7) Microstructure of emulsion gels prepared from single protein and different complexes like Figure 5 As shown in the figure, the emulsion gel formed by the EWP control group and the EWP-GA complex group presents a normal three-dimensional network structure, and the skeleton formed by protein cross-linking and the pores in the network structure can be clearly seen, indicating that the EWP-GA complex has little effect on the microstructure of the gel. The EWP-GA-AG complex group significantly changed the microstructure of the gel. It can be seen from the figure that the pores are reduced, the structure is tight, and the network skeleton unique to the protein gel cannot be observed. This is because the ternary complex, as the filling material of the myofibrillar protein gel network, is tightly combined with the protein through covalent and non-covalent means to form a denser structure, which improves the texture characteristics and water retention of the gel system.

[0049] (8) Oxidative stability of emulsion gels prepared from single protein and different complexes at different times In order to test the oxidative stability of the three emulsion gels, the gels were stored in a refrigerator at 4 °C for 7 days, and the thiobarbituric acid value (TBARS), carbonyl content, and Schiff base strength of the gels before and after storage were measured. Figure 6 It can be seen that the TBARS values ​​of each group were low before storage and the differences were small. After 7 days of storage, the TBARS values ​​of each group increased significantly, among which the EWP group had the highest TBARS value, indicating that the degree of oil oxidation in this group was high during storage, and the secondary oxidation products of oil produced increased the TBARS value. Compared with the EWP group, the TBARS values ​​of the EWP-GA complex and EWP-GA-AG complex groups decreased by 39.65% and 41.40%, respectively, indicating that the covalent complex can improve the phenomenon of oil oxidation in the emulsion gel during storage.

[0050] The carbonyl content had a similar trend, with little difference between the groups before storage. After storage, the EWP group had the highest carbonyl content, while the EWP-GA complex and EWP-GA-AG complex groups could significantly delay protein oxidation and reduce carbonyl content. Among them, the effect of the EWP-GA-AG complex was more significant. Schiff base, as a co-oxidation product of oil and protein, can reflect the overall oxidation degree of the gel system. The results showed that the addition of the complex can effectively delay the oxidation of the system, especially the EWP-GA-AG complex. Before and after storage, the EWP-GA-AG complex group had the lowest Schiff base strength.

[0051] The above description is only a preferred embodiment of the present invention, but it is not a limitation of the embodiments of the present invention. It should be understood by those skilled in the art that any modification, equivalent substitution and improvement based on the present invention, without departing from the creative concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A method for improving the gel properties of an emulsion by using a ternary covalent complex, characterized in that: The following steps are involved: S1. preparing a ternary covalent complex, wherein the ternary covalent complex is an egg white protein-gallic acid-gum arabic complex; the preparation method of the ternary covalent complex comprises: firstly using laccase to catalyze gallic acid grafting egg white protein to form a binary complex; then using a wet heat method to induce a Maillard reaction between gum arabic and the binary complex to prepare an egg white protein-gallic acid-gum arabic complex; S2. The ternary covalent complex is prepared into a 5-15 mg / mL ternary covalent complex solution using a phosphate buffer solution of pH 7.0, and the solution is mixed and homogenized with olive oil to obtain a pre-emulsion; S3. adding myofibrillar protein to the pre-emulsion and performing secondary homogenization to obtain a composite sol; S4. Remove bubbles from the composite sol, place it in a water bath for water bath boiling and cooling to obtain an emulsion gel.

2. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 1, characterized in that: S1 specifically includes: S11, mixing the egg white protein solution and the gallic acid solution evenly, adjusting the pH to 6.9-7.1, to obtain a mixed solution; S12, adding laccase to the mixed solution to catalyze gallic acid grafting egg white protein to form a binary complex; S13, mixing the binary complex with a gum arabic solution to undergo Maillard reaction to obtain an egg white protein-gallic acid-gum arabic complex.

3. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 2, characterized in that: S11 satisfies at least one of the following: The concentration of the egg white protein solution is 20-25 mg / mL, and the egg white protein in the egg white protein solution is fully hydrated; the concentration of gallic acid is 2-10 mg / mL; The pH of the mixture was adjusted using 0.1 M NaOH.

4. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 2, characterized in that: S12 satisfies at least one of the following: The laccase was 1.6 U / mL; The reaction conditions are 30~50℃ for 4 h~6 h.

5. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 2, characterized in that: S13 specifically includes: the concentration of the gum arabic solution is 5-20 mg / mL; the binary complex is mixed with the gum arabic solution to obtain a reaction solution, and a continuous cycle reaction is performed, wherein the cycle reaction includes: first, the reaction solution is stirred at 55-65°C at 200-400 r / min for 15-25 min; then, the reaction solution is placed in a water bath at 80-85°C and stirred at 400-600 r / min for 5-15 min; after 4-6 cycles of reaction, the reaction solution is taken out and the reaction is terminated in an ice water bath to obtain an egg white protein-gallic acid-gum arabic complex.

6. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 1, characterized in that: In S2, the concentration of egg white protein in the ternary covalent complex solution is 10 mg / mL; And / or, the mass ratio of the ternary covalent complex solution to the olive oil is (3-5):1, preferably 4:1; And / or, the homogenization condition is 8000-12000 rpm for 2-3 min.

7. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 1, characterized in that: In S3, the concentration of myofibrillar protein in the composite sol was 2 wt %-4 wt %; And / or, the secondary homogenization condition is 8000~10000 rpm for 1~3 min.

8. The method for improving the gel properties of an emulsion by using a ternary covalent complex according to claim 1, characterized in that: In S4, removing bubbles includes: centrifuging the composite sol at 4°C and 400-500 g for 2-3 min to remove bubbles; And / or, boiling and cooling in a water bath, including: placing the composite sol after removing bubbles in a water bath for boiling in a water bath, heating the water in the water bath from room temperature to 75-90° C. and maintaining it for 20-40 min; after the boiling, taking out and cooling in ice water.

9. An emulsion gel, characterized in that: The method is prepared by any one of claims 1 to 8.

10. The emulsion gel according to claim 9, characterized in that The emulsion gel has a dense and uniform three-dimensional network structure.

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