Method for preparing high-internal-phase emulsion with high freeze-thaw stability under low-salt condition

Abstract

The invention discloses a method for preparing an emulsion with high freeze-thaw stability and high internal phase under a low-salt condition. The method sequentially comprises the following steps: preparing soybean protein, preparing soybean protein stock solution, preparing thermal aggregation soybean protein, preparing konjac collagen solution, preparing a stabilizer, preparing thermal aggregation soybean protein-konjac glucomannan high internal phase emulsion under a low-salt condition, and finally preparing the thermal aggregation soybean protein-konjac glucomannan high internal phase emulsion. According to the invention, the konjac glucomannan is added to prepare the high-freeze-thaw-stability high-internal-phase emulsion based on the thermal aggregation soybean protein particles under low NaCl concentration, so that the use amount of NaCl is reduced, the good quality of the product is ensured, and the konjac glucomannan emulsion has a wide application prospect in the aspect of food. The freeze-thaw stability of the Pickering high-internal-phase emulsion prepared by the method provided by the invention is obviously improved, the Pickering high-internal-phase emulsion can still keep a stable emulsion structure after three freeze-thaw cycles, and the application range of the Pickering high-internal-phase emulsion in the field of frozen foods is expanded.

Description

Technical Field

[0001] The invention relates to the technical field of emulsion preparation, and in particular to a method for preparing a high freeze-thaw stability high internal phase emulsion under low-salt conditions. Background Art

[0002] Pickering high internal phase emulsion refers to an emulsion system with an internal oil phase volume fraction greater than 74%, and solid particles are used as stabilizers to replace traditional surfactants to stabilize the oil-water interface. Compared with traditional emulsions, Pickering high internal phase emulsions have high stability, good biocompatibility, strong controllability, and special properties that ordinary emulsions do not have. They can be applied to the surface of various foods, and can also be used to prepare animal fat substitutes and then used in food.

[0003] Although Pickering high internal phase emulsions have great potential in food applications, these high internal phase emulsions usually need to be frozen / refrigerated when applied to food systems to inhibit the growth of microorganisms to extend the shelf life or to prepare various required products (meat fat substitutes, ice cream, mayonnaise, dairy beverages, etc.). However, from the factory to the consumer, frozen foods undergo freeze-thaw cycles, which reduces the overall quality. During the freezing, storage and thawing process, the emulsion will undergo a series of physical and chemical changes, and it is very easy to undergo oil-water separation, flocculation and aggregation, and become unstable. At present, the main strategies to improve the freeze-thaw stability of Pickering emulsions are to control the growth of ice crystals (Food Research International, 2009, 42, 847-855), change the emulsion preparation method (application (patent) number: CN202310554063.0), enhance the emulsion interface structure (application (patent) number: CN202311428238.X), and add antifreeze agents (application (patent) number: CN202311354800.9). However, these strategies may have too complicated steps or require complex equipment with high costs. Therefore, it is still a challenging problem to adopt a more economical and effective method to improve the freeze-thaw stability of Pickering high internal phase emulsions.

[0004] Thermally aggregated soy protein particles are a type of food-grade solid particles that are economical and readily available in the food field and can be used to stabilize highly introverted emulsions. Previous studies have shown that the freeze-thaw stability of the stabilized highly introverted emulsions can be improved by adding a certain concentration of sodium chloride to thermally aggregated soy protein particles (Food & Function, 2017, 8, 2974-2981). However, the added sodium chloride concentration is high, which is inconsistent with the current health concept of salt reduction. Therefore, it is necessary to adopt a green, economical and efficient method to improve the freeze-thaw stability of highly introverted emulsions stabilized by soy protein particles under low-salt conditions. Summary of the invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a method for preparing a high internal phase emulsion with high freeze-thaw stability under low salt conditions. The present invention uses thermally aggregated soybean protein and konjac gum as objects to prepare a high internal phase Pickering emulsion with good freeze-thaw stability under the condition of minimum sodium chloride concentration, thereby solving the problem of improving the freeze-thaw stability of a high internal phase emulsion stabilized by soybean protein particles under low salt conditions.

[0006] To achieve the above purpose, the technical solution designed by the present invention is as follows:

[0007] The present invention provides a method for preparing a high freeze-thaw stability high internal phase emulsion under low salt conditions, comprising the following steps:

[0008] (1) Preparation of soy protein: defatted soybean meal is mixed with deionized water, adjusted to alkaline, and then continuously stirred and centrifuged, the supernatant is adjusted to acidic, and the precipitate is collected by centrifugation, and the precipitate is washed with water and centrifuged multiple times (to remove excess sodium chloride), and then re-dissolved and adjusted to neutral, and then freeze-dried to obtain soy protein;

[0009] (2) Preparation of soybean protein stock solution: dissolving the soybean protein obtained in step (1) in deionized water, and magnetically stirring at room temperature to obtain a soybean protein stock solution;

[0010] (3) Preparation of heat-aggregated soy protein stock solution: heating the soy protein stock solution obtained in step (2) in a water bath, rapidly cooling in an ice-water bath, and diluting to obtain a heat-aggregated soy protein solution;

[0011] (4) Preparation of konjac gum stock solution: dispersing konjac gum in deionized water, stirring to fully dissolve the konjac gum, and obtaining konjac gum stock solution;

[0012] (5) Preparation of stabilizer: adding the heat-aggregated soybean protein solution obtained in step (3) to the konjac gum solution obtained in step (4) to mix evenly, and adding sodium chloride to obtain a low-salt heat-aggregated soybean protein-konjac gum stabilizer;

[0013] (6) Preparation of heat-aggregated soybean protein-konjac gum high internal phase emulsion under low salt conditions: low-salt heat-aggregated soybean protein-konjac gum stabilizer and oil phase are homogenized at high speed to obtain heat-aggregated soybean protein-konjac gum high internal phase emulsion (original emulsion) under low salt conditions;

[0014] (7) Preparation of heat-aggregated soybean protein-konjac gum high internal phase emulsion: After heating the heat-aggregated soybean protein-konjac gum high internal phase emulsion (original emulsion) obtained in step (6) in a water bath, it is quickly transferred to an ice water bath for cooling to obtain a heat-aggregated soybean protein-konjac gum high internal phase emulsion, that is, a high freeze-thaw stability high internal phase emulsion.

[0015] Furthermore, in step (1), the alkaline pH value is 8, and the acidic pH value is 4.5.

[0016] The most preferred choice is: soybean protein is prepared by the following method: defatted soybean meal is mixed with deionized water at a solid-liquid ratio of 1:10 (g / mL), the pH of the solution is adjusted to 8.0 with 2mol / L NaOH, magnetic stirring is performed at room temperature for 2 hours to fully dissolve it, centrifuge at 9000×g for 15 minutes, collect the supernatant, adjust the pH to 4.5 with 2mol / L HCl, collect the precipitate after centrifugation at 9000×g for 15 minutes, wash it three times with deionized water, add deionized water after collecting the precipitate, and adjust the pH of the solution to 7.0 with 2mol / L NaOH, stir to fully dissolve and disperse the protein, and then freeze-dry to obtain soybean protein.

[0017] Furthermore, the preparation steps of the soy protein stock solution in step (2) are: dissolving the soy protein in deionized water to completely dissolve the soy protein to obtain a soy protein solution with a mass percentage concentration of 4-6%; then placing it in a 4°C refrigerator overnight for hydration, and obtaining the soy protein stock solution after the soy protein is completely hydrated, wherein the mass percentage concentration of the soy protein stock solution is 4-6%.

[0018] According to the actual situation, the pH of the soy protein solution can be adjusted to 7.0 with 1 mol / L NaOH or HCl.

[0019] Furthermore, in the step (3),

[0020] The preparation method of the heat-aggregated soy protein solution is as follows: heat the soy protein stock solution in a water bath at a temperature of 90-95°C for 10-20 minutes, quickly cool it to room temperature in an ice water bath to obtain a heat-aggregated soy protein stock solution with a concentration of 4-6%, then add deionized water for dilution, stir evenly, and obtain a heat-aggregated soy protein solution with a concentration of 2-4%.

[0021] Furthermore, in step (4), the viscosity of konjac gum is 15-30 Pa.s, and the mass percentage concentration of the obtained konjac gum stock solution is 0.4-1.2%.

[0022] Furthermore, in the step (5), in the low-salt thermally aggregated soy protein-konjac gum stabilizer, the concentration of sodium chloride is 20-40 mM, the concentration of soy protein is 1-3%, and the viscosity of konjac gum is 15-30 pa.s.

[0023] Furthermore, in the step (6), the volume ratio of the low-salt heat-aggregated soy protein-konjac gum stabilizer to the oil phase is 1:3, and the oil phase is one of vegetable oils such as soybean oil, camellia oil, perilla oil, linseed oil, etc.

[0024] Furthermore, in step (6), the homogenization speed is 8000-12000 rpm and the time is 2-5 min.

[0025] Furthermore, in step (7), the water bath heating temperature is 90-100° C., and the heating time is 15-30 min.

[0026] The present invention also provides an application of the high freeze-thaw stability high internal phase emulsion prepared by the above method in the preparation of mayonnaise or saturated fat substitute.

[0027] Beneficial effects of the present invention:

[0028] (1) The heat-aggregated soy protein-konjac gum high internal phase emulsion of the present invention exhibits good freeze-thaw stability when the NaCl concentration is 20 mM, while the soy protein particles alone need to achieve good freeze-thaw stability at a NaCl concentration of more than 80 mM. Therefore, the present invention achieves the preparation of a high freeze-thaw stability high internal phase emulsion based on heat-aggregated soy protein particles at a low NaCl concentration by adding konjac gum, thereby reducing the amount of NaCl used while ensuring the good quality of the product, and has broad application prospects in food.

[0029] (2) The freeze-thaw stability of the Pickering high internal phase emulsion prepared by the method proposed in the present invention is significantly improved, and the stable emulsion structure can still be maintained after three freeze-thaw cycles, which expands the application scope of the Pickering high internal phase emulsion in the field of frozen foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the appearance of the high internal phase emulsion obtained in Comparative Examples 1-5;

[0031] Figure 2 This is the appearance of the high internal phase emulsion obtained in Example 2 and Comparative Examples 6-8 of Example 4;

[0032] Figure 3 This is the appearance of the high internal phase emulsion obtained in Examples 1-3 and Comparative Example 2; DETAILED DESCRIPTION

[0033] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand.

[0034] Example 1

[0035] A method for preparing a high freeze-thaw stability high internal phase emulsion 1 under low salt conditions, wherein the high freeze-thaw stability high internal phase emulsion 1 prepared by the method is a low-salt thermally aggregated soybean protein-konjac gum high internal phase emulsion with a konjac gum viscosity of 15 Pa.s and a sodium chloride concentration of 20 mM, and the specific steps are as follows:

[0036] S1. Preparation of soy protein: defatted soybean meal was mixed with deionized water at a solid-liquid ratio of 1:10 (g / mL), the pH of the solution was adjusted to 8.0 with 2mol / L NaOH, and magnetic stirring was performed at room temperature for 2h to fully dissolve it. Centrifugation (9000×g, 15min), the supernatant was collected, the pH was adjusted to 4.5 with 2mol / L HCl, the precipitate was collected after centrifugation (9000×g, 15min), and it was washed three times with deionized water. After collecting the precipitate, a small amount of deionized water was added, and the pH of the solution was adjusted to 7.0 with 2mol / L NaOH, and the protein was fully redissolved by stirring, and freeze-dried and stored for later use.

[0037] S2. Preparation of soy protein stock solution: Soy protein was dissolved in deionized water and magnetically stirred at room temperature for 2 h to obtain a soy protein stock solution with a concentration of 6%.

[0038] S3. Preparation of heat-aggregated soy protein stock solution: The soy protein stock solution obtained in S1 was heated in a water bath at 95°C for 15 min and then rapidly cooled to room temperature in an ice-water bath to obtain a heat-aggregated soy protein stock solution with a concentration of 6%.

[0039] S4. Preparation of heat-aggregated soy protein solution: The soy protein stock solution obtained in S3 was diluted with deionized water and stirred evenly to obtain a heat-aggregated soy protein solution with a concentration of 3.2%.

[0040] S5. Preparation of konjac gum solution: dissolve konjac gum with a viscosity of 15 Pa.s in deionized water, and stir at room temperature to obtain a konjac gum solution with a concentration of 0.8%.

[0041] S6. The heat-aggregated soy protein solution obtained in S4 is mixed with the konjac gum solution obtained in S5 in a ratio of 1:1, and sodium chloride is added and stirred evenly to obtain a low-salt heat-aggregated soy protein-konjac gum mixed solution with a sodium chloride concentration of 20 mM, a heat-aggregated soy protein concentration of 1.6% and a konjac gum concentration of 0.4%.

[0042] S7. The low-salt heat-aggregated soy protein-konjac gum mixture obtained in S6 and soybean oil (the volume ratio of the heat-aggregated soy protein-konjac gum mixture to soybean oil is 1:3) are homogenized at 10000r / min for 2min using a high-speed disperser to obtain a uniform milky white semisolid, i.e., a low-salt heat-aggregated soy protein-konjac gum high internal phase emulsion (original emulsion), wherein the volume fraction of the oil phase in the emulsion is 75%.

[0043] S8. The low-salt heat-aggregated soy protein-konjac gum high internal phase emulsion (original emulsion) obtained in the step is strictly sealed, fixed in 100° C. boiling water and heated for 15 minutes, and then immediately transferred to an ice bath to achieve a rapid drop in temperature, thereby obtaining the low-salt heat-aggregated soy protein-konjac gum high internal phase emulsion 1 after heating treatment.

[0044] Example 2

[0045] The method for preparing high freeze-thaw stability high internal phase emulsion 2 under low salt conditions is basically the same as the method in Example 1, except that:

[0046] In step S5, konjac glucomannan with a viscosity of 22 Pa.s is selected to finally obtain a konjac glucomannan solution with a konjac glucomannan concentration of 0.4%.

[0047] The high freeze-thaw stability high internal phase emulsion 2 prepared by the method is a low-salt thermally aggregated soybean protein-konjac gum high internal phase emulsion 2 with a konjac gum viscosity of 22 Pa.s and a konjac gum concentration of 0.4%.

[0048] Example 3

[0049] The method for preparing high freeze-thaw stability high internal phase emulsion 3 under low salt conditions is basically the same as the method in Example 1, except that:

[0050] In step S5, konjac glucomannan with a viscosity of 30 Pa.s is selected to finally obtain a konjac glucomannan solution with a konjac glucomannan concentration of 0.4%.

[0051] The high freeze-thaw stability high internal phase emulsion 3 prepared by the method is a low-salt thermally aggregated soybean protein-konjac gum high internal phase emulsion 3 with a konjac gum viscosity of 30 Pa.s and a konjac gum concentration of 0.4%.

[0052] Example 4

[0053] The method for preparing high freeze-thaw stability high internal phase emulsion 4 under low salt conditions is basically the same as the method of Example 2, except that:

[0054] In step S6, the sodium chloride concentration in the low-salt thermally aggregated soy protein-konjac gum mixture is 40 mM.

[0055] The high freeze-thaw stability high internal phase emulsion 4 prepared by the method is a low-salt thermally aggregated soybean protein-konjac gum high internal phase emulsion 4 with a sodium chloride concentration of 40 mM, a konjac gum viscosity of 30 pa.s, and a konjac gum concentration of 0.4%.

[0056] Comparative Examples 1-5

[0057] The preparation method of heat-aggregated soybean protein high internal phase emulsions 1-5 with different salt concentrations comprises the following steps:

[0058] S1. Preparation of soy protein: defatted soybean meal was mixed with deionized water at a solid-liquid ratio of 1:10 (g / mL), the pH of the solution was adjusted to 8.0 with 2mol / L NaOH, and magnetic stirring was performed at room temperature for 2h to fully dissolve it. Centrifugation (9000×g, 15min), the supernatant was collected, the pH was adjusted to 4.5 with 2mol / L HCl, the precipitate was collected after centrifugation (9000×g, 15min), and it was washed three times with deionized water. After collecting the precipitate, a small amount of deionized water was added, and the pH of the solution was adjusted to 7.0 with 2mol / L NaOH, and the protein was fully redissolved by stirring, and freeze-dried and stored for later use.

[0059] S2. Preparation of soy protein stock solution: Soy protein was dissolved in deionized water and magnetically stirred at room temperature for 2 h to obtain a soy protein stock solution with a concentration of 6%.

[0060] S3. Preparation of heat-aggregated soy protein stock solution: The soy protein stock solution obtained in S1 was heated in a water bath at 95°C for 15 min and then rapidly cooled to room temperature in an ice-water bath to obtain a heat-aggregated soy protein stock solution with a concentration of 6%.

[0061] S4. Preparation of heat-aggregated soy protein solution: The soy protein stock solution obtained in S3 was diluted with deionized water and stirred evenly to obtain a heat-aggregated soy protein solution with a concentration of 1.6%.

[0062] S5. Preparation of heat-aggregated soy protein: different concentrations of sodium chloride (their concentration gradient was 0mM, 20mM, 40mM, 60mM, 80mM sodium chloride) 0-80mM were added to the heat-aggregated soy protein solution to obtain heat-aggregated soy protein 1-5;

[0063] S6. Preparation of heat-aggregated soy protein high internal phase emulsion: The heat-aggregated soy protein 1-5 obtained in S5 and soybean oil were homogenized at a volume ratio of 1:3 using a high-speed disperser at 10,000 r / min for 2 minutes to obtain a uniform milky white semisolid, which is the heat-aggregated soy protein high internal phase emulsion 1-5.

[0064] Comparative Examples 6-8

[0065] The preparation method of heat-aggregated soybean protein konjac gum high internal phase emulsion 6-8 with different salt concentrations is basically the same as the steps of Example 4, except that it comprises the following steps:

[0066] S6. Preparation of low-salt heat-aggregated soy protein-konjac gum mixture: The heat-aggregated soy protein solution obtained in S4 was mixed with the konjac gum solution obtained in S5 in a ratio of 1:1, and different concentrations of sodium chloride were added and stirred evenly to obtain low-salt heat-aggregated soy protein-konjac gum mixtures 6-8 with sodium chloride concentrations of 0, 60mM, and 80mM, respectively; their heat-aggregated soy protein concentrations were both 1.6% and konjac gum concentrations were both 0.4%.

[0067] 1. Comparison of thermally aggregated soybean protein high internal phase emulsions 1-5 prepared in comparative examples 1-5

[0068] Take 25g of heat-aggregated soybean protein high internal phase emulsions 1-5 respectively, place them in 10ml glass sample bottles, freeze them at -20℃ for 22h, then transfer them to a 30℃ water bath and let them stand for 2h to thaw, the freezing and thawing process is regarded as one freeze-thaw cycle, and freeze-thaw cycles are repeated 3 times.

[0069] like Figure 1 As shown, for the high internal phase emulsion stabilized by single soy protein particles, after one freeze-thaw cycle, the emulsions with a sodium chloride concentration in the range of 0-60 mM (i.e., thermally aggregated soy protein high internal phase emulsions 1-4) showed obvious oil-water separation, while the high internal phase emulsion with a sodium chloride concentration of 80 mM (i.e., thermally aggregated soy protein high internal phase emulsion 5) showed good freeze-thaw stability; this indicates that single soy protein particles need to be prepared under NaCl conditions above 80 mM to obtain a high internal phase emulsion with good freeze-thaw stability.

[0070] 2. Comparison of high freeze-thaw stability high internal phase emulsions 2 and 4 prepared in Examples 2-4 and high internal phase emulsions 6-8 prepared in Comparative Examples 6-8 using thermally aggregated soybean protein konjac gum

[0071] 25 g of high freeze-thaw stability high internal phase emulsions 2 and 4 and heat-aggregated soy protein konjac gum high internal phase emulsions 6-8 were taken and placed in 10 ml glass sample bottles, respectively. They were frozen at -20°C for 22 hours, then transferred to a 30°C water bath and allowed to stand for 2 hours to thaw. The freezing and thawing process was regarded as one freeze-thaw cycle, and the freeze-thaw cycles were repeated 3 times.

[0072] like Figure 2 As shown: for the high internal phase emulsion stabilized by konjac gum soy protein particles, after 2 freeze-thaw cycles, under the condition of no salt addition (i.e., heat-aggregated soy protein konjac gum high internal phase emulsion 6), there is obvious oil-water phase separation and demulsification, which is not obvious as the salt concentration increases. In contrast, the emulsion with 20mM sodium chloride added (high freeze-thaw stability high internal phase emulsion 2) shows good freeze-thaw stability.

[0073] 3. Comparison of high freeze-thaw stability high internal phase emulsions 1-3 (Examples 1, 2, 3) and heat-aggregated soybean protein high internal phase emulsion 2 (Comparative Example 2)

[0074] Take 25g of high freeze-thaw stability high internal phase emulsion 1-3 and heat-aggregated soy protein high internal phase emulsion, respectively, and place them in 10ml glass sample bottles. Freeze at -20℃ for 22h, then transfer to a 30℃ water bath and let stand for 2h to thaw. The freeze-thaw process is regarded as one freeze-thaw cycle, and freeze-thaw cycles are repeated 3 times.

[0075] The results are as follows Figure 3 As shown, after 3 cycles of repeated freeze-thaw, the emulsion system of high freeze-thaw stability emulsion 1, 2, 2 (embodiment 1, 2, 3) has no obvious change, and no oil layer is separated out on the surface, and there is no demulsification phenomenon, indicating that the emulsion has good freeze-thaw stability. And the high internal phase emulsion 2 (comparative example 2) stabilized by heat aggregation soybean protein shows obvious oil analysis phenomenon after 1 freeze-thaw cycle, indicating that the addition of konjac gum can improve the freeze-thaw stability of the high internal phase emulsion stabilized by soybean protein particles under low salt conditions.

[0076] from Figures 1 to 3 It can be clearly seen that the high internal phase emulsions prepared in Examples 1, 2, 3, 4, and Comparative Examples 1-8 all have a milky white appearance, exhibit gel-like properties, and have no oil separation. When the small glass bottle containing the emulsion is inverted, all samples can adhere to the bottom of the bottle, showing a self-sustaining appearance, which may be a typical feature of the high internal phase emulsion.

[0077] 4. Oil separation analysis of high freeze-thaw stability high internal phase emulsions 1-3 and thermally aggregated soybean protein high internal phase emulsion 2

[0078] In order to quantify its freeze-thaw stability, the frozen and thawed samples were centrifuged at 1,000g for 10 minutes to observe the oil separation of the samples. At the same time, the oil binding capacity of the samples was calculated as follows:

[0079]

[0080] Where: W t ——weight of sample before centrifugation; W f ——The weight of the sample after centrifugation;

[0081] 100——Unit conversion factor.

[0082] Table 1 Oil binding capacity of thermally aggregated soybean protein with different viscosities of konjac gum to stabilize high internal phase emulsions

[0083] Konjac Gum Viscosity (Pa.S) Freeze-thaw-1 Freeze-thaw-2 Freeze-thaw-3 Comparative Example 2 0 52.82％ 41.51％ 36.97％ Example 1 15 95.53％ 93.26％ 90.34％ Example 2 20 99.89％ 96.59％ 94.07％ Example 3 30 99.95％ 98.20％ 95.38％

[0084] The results showed that compared with the high internal phase emulsion stabilized by single thermally aggregated soy protein, the oil binding capacity of the emulsion with the addition of konjac gum gradually increased, and the freeze-thaw stability was significantly higher than that of the high internal phase emulsion stabilized by single thermally aggregated soy protein. The greater the viscosity of the added konjac gum, the greater the oil binding capacity. The konjac gum added in Example 3 had the largest viscosity, and the highest oil binding capacity after 3 freeze-thaw cycles, indicating that the addition of konjac gum was beneficial to improving the freeze-thaw stability of the high internal phase emulsion, and the higher the viscosity of the konjac gum, the more obvious the improvement effect.

[0085] Although the above embodiments have been described in detail, they are only a part of the embodiments of the present invention, not all of them. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all belong to the protection scope of the present invention.

Claims

1. A method for preparing a high freeze-thaw stability high internal phase emulsion under low salt conditions, characterized in that: The following steps are involved: (1) defatted soybean meal is mixed with deionized water, adjusted to alkaline, and then continuously stirred and centrifuged, the supernatant is adjusted to acidic, and the precipitate is collected by centrifugation, the precipitate is washed with water and centrifuged multiple times, and then re-dissolved and adjusted to neutral, and then freeze-dried to obtain soybean protein; (2) dissolving the soy protein obtained in step (1) in deionized water, and magnetically stirring at room temperature to obtain a soy protein stock solution; (3) heating the soy protein stock solution obtained in step (2) in a water bath, rapidly cooling in an ice water bath, and diluting to obtain a thermally aggregated soy protein solution; (4) after konjac gum is dissolved and dispersed in deionized water, stirring is carried out so that konjac gum is fully dissolved to obtain konjac gum stock solution; (5) adding the heat-aggregated soybean protein solution obtained in step (3) to the konjac glucomannan solution obtained in step (4) to mix uniformly, and adding sodium chloride to obtain a low-salt heat-aggregated soybean protein-konjac glucomannan stabilizer; (6) low-salt heat-aggregated soybean protein-konjac glucomannan stabilizer is mixed with oil phase high-speed homogenization to obtain a heat-aggregated soybean protein-konjac glucomannan high internal phase emulsion under the low-salt condition; (7) After the heat-aggregated soybean protein-konjac gum high internal phase emulsion obtained in step (6) is heated in a water bath, it is rapidly transferred to an ice-water bath for cooling to obtain the heat-aggregated soybean protein-konjac gum high internal phase emulsion.

2. The method according to claim 1, characterized in that In the step (1), the alkaline pH value is 8, and the acidic pH value is 4.

5.

3. The method according to claim 1, characterized in that In the step (2), the preparation steps of the soy protein stock solution are: The soy protein is dissolved in deionized water to completely dissolve the soy protein to obtain a soy protein solution with a mass percentage concentration of 4-6%; then the soy protein is placed in a 4°C refrigerator overnight for hydration to obtain a soy protein stock solution after the soy protein is completely hydrated, wherein the mass percentage concentration of the soy protein stock solution is 4-6%.

4. The method according to claim 1, characterized in that: In the step (3), the preparation method of the heat-aggregated soybean protein solution is as follows: The soy protein stock solution is heated in a water bath at 90-95° C. for 10-20 minutes, and quickly cooled to room temperature in an ice water bath to obtain a heat-aggregated soy protein stock solution with a concentration of 4-6%. Deionized water is then added for dilution, and stirred evenly to obtain a heat-aggregated soy protein solution with a concentration of 2-4%.

5. The method according to claim 1, characterized in that: In the step (4), the viscosity of konjac gum is 15-30 Pa.s, and the mass percentage concentration of the obtained konjac gum stock solution is 0.4-1.2%.

6. The method according to claim 1, characterized in that In the step (5), in the low-salt heat-aggregated soy protein-konjac gum stabilizer, the concentration of sodium chloride is 20-40 mM, the concentration of soy protein is 1-3%, and the viscosity of konjac gum is 15-30 pa.s.

7. The method according to claim 1, characterized in that In the step (6), the volume ratio of the low-salt heat-aggregated soybean protein-konjac gum stabilizer to the oil phase is 1:3, and the oil phase is one of vegetable oils such as soybean oil, camellia oil, perilla oil, linseed oil, etc.

8. The method according to claim 1 or 7, characterized in that: In the step (6), the homogenization speed is 8000-12000 rpm and the time is 2-5 min.

9. The method according to claim 1, characterized in that: In the step (7), the water bath heating temperature is 90-100° C. and the heating time is 15-30 min.

10. Use of the high freeze-thaw stability high internal phase emulsion prepared by the method of claim 1 in the preparation of mayonnaise or saturated fat substitute.

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