Method for preparing thermostable soybean protein by adding beta-cyclodextrin and combining with preheating treatment

Abstract

The invention discloses a method for preparing thermal-stability soybean protein by adding beta-cyclodextrin and combining with preheating treatment, which comprises the following steps: uniformly dispersing soybean protein powder in water at the mass concentration of 0.5-2.0%, regulating the pH value to 6.0-8.0, uniformly dispersing beta-cyclodextrin in a protein solution at the mass concentration of 1.5-3.0%, heating at the temperature of 90-120 DEG C for 15-60 minutes, and filtering to obtain the thermal-stability soybean protein. And then carrying out acid precipitation, centrifugation, redissolution and drying to obtain the thermal-stability soybean protein. The thermal-stability soybean protein prepared by the method has good thermal stability, even if the concentration of the thermal-stability soybean protein is 10%, the solution is heated, the solution is still clear and transparent, the heated solution still has good fluidity, and the thermal-stability soybean protein prepared by the method can be widely applied to beverage containing protein, such as beverage containing protein and beverage containing protein. The protein content is increased; meanwhile, the stability of related products in the hot working process is improved.

Description

Technical Field

[0001] The invention belongs to the field of plant protein processing, and in particular relates to a method for preparing heat-stable soybean protein by adding beta-cyclodextrin and combining preheating treatment. Background Art

[0002] Soybean is the most widely planted legume with the highest economic value. Soy protein has been widely used in the field of food processing due to its rich nutritional value and excellent functional properties, especially in the fields of high-protein beverages and meal replacement foods. Therefore, the development of high-protein beverages or other related foods based on soy protein has become a research hotspot in the field of food technology.

[0003] However, in the production process of high-protein products, high-temperature sterilization is usually required to ensure food safety and extend its shelf life. However, soy protein is prone to thermal denaturation when heated, resulting in excessive aggregation between protein molecules and the formation of larger aggregates. These aggregates can cause precipitation or gelation in the product, seriously affecting the texture and taste of the food. This problem is particularly evident in systems with high protein concentrations, and has become an unavoidable technical bottleneck in the production process of high-protein foods.

[0004] Patent CN109553676A discloses a method for inhibiting the thermal denaturation and aggregation of fish myosin. The inhibition method in this invention requires the myosin to be dialyzed and kept warm with a gradient temperature increase, and a permeabilizer needs to be added during the dialysis process, and a stabilizer needs to be added during the insulation. The process is cumbersome and uses a variety of chemical reagents, which is not conducive to industrial production. Patent CN110679725A discloses a preparation process for soy protein isolate with thermal stability. In this invention, the thermal stability of soy protein isolate is improved by adding modified starch. For specific groups of people, such as diabetic patients, special attention should be paid to the intake of starchy foods. Although modified starch is modified, it still belongs to starch. Excessive intake may lead to increased blood sugar, which is not conducive to disease control.

[0005] Patent CN 109770041 A discloses a method for preparing heat-stable soy protein. The heat stability of soy protein is improved by modifying the soy protein through heat treatment, and the soy protein prepared by this method can maintain a certain heat stability at a concentration of 0.1-1.5% (w / w, g / g). However, in actual research on the performance of soy protein, it was found that the soybean meal used to extract soy protein isolate has a great influence on the stability of soy protein isolate. The higher the degree of oxidation of the soybean meal, the better the stability of the extracted soy protein isolate. The degree of oxidation of the soybean meal can be reflected by the total thiol content of the extracted soy protein isolate, such as Figure 1As shown, the higher the degree of oxidation of soybean meal, the lower the total thiol content of the extracted soy protein isolate. This may be because, in soybean meal with a higher degree of oxidation, the thiol group is oxidized into a disulfide bond, resulting in a decrease in the total thiol content of the finally extracted soy protein isolate. By studying the performance of soy protein isolate from soybean meal with different degrees of oxidation, it was found that the lower the degree of oxidation of soybean meal, the higher the total thiol content in the extracted soy protein isolate. When the total thiol content in the soy protein isolate is greater than 1.5 μmol / g, the thermal stability of the soy protein isolate is very poor. Even if the soy protein isolate with a concentration of 1% is heat-treated and modified according to the method of patent CN 109770041 A, the modified soy protein dispersion will still gel when heated at a concentration of 10%. Therefore, how to improve the thermal stability of soy protein with a high thiol content has become a difficulty in the research. Summary of the invention

[0006] The purpose of the present invention is to provide a method for preparing heat-stable soy protein by adding β-cyclodextrin combined with preheat treatment, so as to improve the stability of soy protein during heat treatment and solve the problem that high-concentration soy protein is easy to aggregate and gel when soy protein isolate with high thiol content (-SH group content greater than 1.5 μmol / g) is subjected to heat treatment.

[0007] The present invention uses soybean protein as a raw material, adds β-cyclodextrin thereto, and then performs a preheating treatment. Due to the influence of β-cyclodextrin and heat treatment on the spatial conformation, surface hydrophobicity and electrostatic interaction of soybean protein isolate, the stability of the soybean protein dispersion during heat treatment is greatly improved. Compared with the dispersion prepared by soybean protein isolate under the same conditions, the heat-stable soybean protein dispersion prepared by the present invention has better stability, has obvious fluidity after heating treatment, has a simple process, and is conducive to industrialization.

[0008] The present invention provides a method for preparing heat-stable soybean protein by adding β-cyclodextrin combined with preheating treatment, comprising the following specific steps:

[0009] S1. Dispersion: Take soy protein isolate, evenly disperse it in water at a mass concentration of 0.5% to 2.0%, and adjust the pH to between 6.0 and 8.0 to obtain a protein dispersion 1;

[0010] S2, mixing: taking β-cyclodextrin and uniformly dispersing it in the protein dispersion 1 to obtain the protein dispersion 2;

[0011] S3, heat treatment: heat the protein dispersion 2 obtained in step S2 at 90-120° C. for 15-60 min to obtain a protein dispersion 3;

[0012] S4, acid precipitation: adjusting the pH of the protein dispersion 3 obtained in step S3 to 4-5;

[0013] S5, centrifugation: centrifuging the product obtained in step S4 to collect the precipitate;

[0014] S6, re-dissolving: adding water to the precipitate obtained in step S5, adjusting the pH to 6.0-7.0 for dispersion and re-dissolution to obtain a protein solution;

[0015] S7, drying: drying the protein solution obtained in step S5 to obtain heat-stable soy protein.

[0016] In one embodiment of the present invention, the method for preparing soy protein isolate comprises the following steps: adding deionized water to defatted soybean meal at a weight-to-volume ratio of 1:10, adjusting the pH to 7.0-8.5, stirring at room temperature for 1 hour, centrifuging at 15800g and 4°C for 30 minutes, and taking the supernatant; adjusting the pH of the supernatant to 4.0-5.0, centrifuging at 3000-15800g and 4°C for 5-120 minutes to obtain a precipitate; dissolving the precipitate with deionized water and adjusting the pH to 7.0-8.5 to obtain a protein solution, wherein the weight ratio of the precipitate to the deionized water is 1:(3-10); drying the protein solution to obtain soy protein; wherein the drying is freeze-drying or spray-drying; the freeze-drying parameters are -50--80°C, vacuum degree 0.01Pa-50Pa, and drying 24-72h; the spray-drying parameters are: inlet air temperature 195°C, outlet air temperature 95°C, and feed rate 20mL / min.

[0017] In one embodiment of the present invention, the total thiol content of the soy protein isolate is greater than 1.5 μmol / g, preferably 3-5 μmol / g.

[0018] In one embodiment of the present invention, in step S1, HCl solution is used to adjust the pH to 6.0-8.0.

[0019] In one embodiment of the present invention, the soy protein isolate is dispersed in water for 2 to 4 hours in step S1.

[0020] In one embodiment of the present invention, in step S2, the mass concentration of β-cyclodextrin in the protein dispersion 2 is 1.5-3.0%.

[0021] In one embodiment of the present invention, the centrifugal speed in step S5 is 3000-15800 g, and the centrifugal time is 20-120 min.

[0022] In one embodiment of the present invention, the weight ratio of the precipitate to water in step S6 is 1:(5-8).

[0023] In one embodiment of the present invention, the drying in step S7 is freeze drying; the freeze drying parameters are -30 to -80°C, vacuum degree 0.01Pa to 50Pa, and drying for 24 to 72h.

[0024] In one embodiment of the present invention, the drying in step S7 is spray drying, and the parameters of the spray drying are: inlet air temperature 195° C., outlet air temperature 95° C., and feed rate 20 mL / min.

[0025] The present invention also provides a heat-stable soybean protein prepared according to the method.

[0026] The present invention also provides an application of the stable soybean protein in preparing easy-to-swallow food or high-protein food.

[0027] Beneficial effects:

[0028] 1. The present invention modifies the soy protein isolate by adding β-cyclodextrin combined with preheating treatment. The prepared soy protein has excellent thermal stability. It can be diluted or undiluted, sterilized and then filled to prepare easy-to-swallow food or high-protein beverages.

[0029] 2. The present invention improves the thermal stability of soybean protein by adding β-cyclodextrin in combination with preheating treatment, so that soybean protein with a high thiol content (-SH group content greater than 1.5 μmol / g) still has fluidity after heating at a concentration of 10%; as an experimental example, by using this method to add 3.0% β-cyclodextrin to a soybean protein isolate with a thiol content of 3.46 μmol / g and a concentration of 1.5%, and preheating the mixture at 100°C for 30 minutes, the obtained heat-stable soybean protein has good fluidity after heating at a protein concentration of 10% (w / v), has better thermal stability than natural soybean protein isolate, and can be used to improve the texture of high-protein foods. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 These are the measurement results of total thiol content of soy protein isolate extracted from soybean meal with different oxidation degrees, where soybean meal 1 is soybean meal with a low oxidation degree, and soybean meal 2 is soybean meal with a high oxidation degree.

[0031] Figure 2 The elastic modulus measurement result of the heat-stable soy protein solution obtained in Example 1 of the present invention after heating.

[0032] Figure 3 The viscosity measurement result of the heat-stable soy protein solution obtained in Example 1 of the present invention after heating.

[0033] Figure 4The elastic modulus measurement result of the heat-stable soy protein solution obtained in Example 2 of the present invention after heating.

[0034] Figure 5 The viscosity measurement result of the heat-stable soy protein solution obtained in Example 2 of the present invention after heating.

[0035] Figure 6 The elastic modulus measurement result of the heat-stable soy protein solution obtained in Example 3 of the present invention after heating.

[0036] Figure 7 The viscosity measurement result of the heat-stable soy protein solution obtained in Example 3 of the present invention after heating.

[0037] Figure 8 The elastic modulus measurement result of the heat-stable soy protein solution obtained in Comparative Example 1 of the present invention after heating.

[0038] Fig. 9 The viscosity measurement result of the heat-stable soy protein solution obtained in Comparative Example 1 of the present invention after heating.

[0039] Fig.10 Schematic diagram of the fluidity of the heat-stable soy protein solution obtained in Example 1 of the present invention after heating.

[0040] Fig.11 Schematic diagram of the fluidity of the heat-stable soy protein solution obtained in Example 2 of the present invention after heating.

[0041] Fig.12 Schematic diagram of the fluidity of the heat-stable soy protein solution obtained in Example 3 of the present invention after heating.

[0042] Fig.13 Schematic diagram of the fluidity of the heat-stable soy protein solution obtained in Comparative Example 1 of the present invention after heating. DETAILED DESCRIPTION

[0043] The present invention is further introduced and illustrated by means of specific embodiments, comparative examples and accompanying drawings.

[0044] Example 1

[0045] A method for preparing heat-stable soybean protein is as follows:

[0046] S1. Dispersion: Take soy protein isolate and evenly disperse it in water at a mass concentration of 1.0% for 3 h, and adjust the pH to 7.0 with 2 mol / L NaOH to obtain protein dispersion 1;

[0047] S2, mixing: taking β-cyclodextrin with a mass concentration of 1.5% and uniformly dispersing it in the protein dispersion 1 to obtain the protein dispersion 2;

[0048] S3, heat treatment: heat the protein dispersion 2 obtained in step S2 at 100° C. for 30 min to obtain protein dispersion 3;

[0049] S4, acid precipitation: the pH of the protein dispersion 3 obtained in step S3 is adjusted to 4.5 with 1 mol / L HCl;

[0050] S5, centrifugation: centrifuge the product obtained in step S4 at 3000 g for 60 min to collect the precipitate;

[0051] S6, redissolution: add water to the precipitate obtained in step S5 at a weight ratio of 1:5, adjust the pH to 7.0 with 2 mol / L NaOH, and disperse and redissolve to obtain protein dispersion 4;

[0052] S7, drying: the protein dispersion 4 obtained in step S6 is subjected to vacuum freeze drying (-30°C, 0.01Pa, 48h) to obtain heat-stable soy protein;

[0053] Wherein, the total thiol content of the soy protein isolate in step S1 is 3.46 μmol / g, and the preparation method of the soy protein isolate is:

[0054] Deionized water was added to defatted soybean meal at a ratio of 1:10 (w / v, g / mL), and the pH was adjusted to 8.5 with 2mol / LNaOH solution. The mixture was stirred at room temperature for 1 hour, and centrifuged at 15800g and 4°C for 30 minutes to obtain a supernatant. The supernatant was adjusted to pH 5.0 with 2mol / LHCl, and centrifuged at 6000g and 4°C for 15 minutes to obtain a soybean protein precipitate. The soybean protein precipitate was dissolved with deionized water for 3 hours, and the pH of the protein solution was adjusted to 8.5 with 2mol / LNaOH. The protein solution was freeze-dried to obtain soybean protein, and the freeze-drying was specifically -50°C, 0.01Pa, and 24 hours.

[0055] The heat-stable soy protein prepared in this example was prepared into an aqueous solution with a protein concentration of 10.0% (w / v). The solution was heated at 100°C for 30 minutes, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured. At the same time, untreated soy protein isolate was taken as a control (soy protein group). At the same protein concentration, it was heated at 100°C for 30 minutes, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured. The elastic modulus measurement results are shown in FIG. Figure 2 As shown in FIG. 1 , the elastic modulus of the untreated soy protein isolate after heating is significantly higher than that of the heat-stable soy protein mixture prepared in this example. Figure 3 As shown in FIG. 1 , the viscosity of the heat-stable soy protein mixture prepared in this example after heating is much lower than that of the untreated soy protein isolate. Fig.10As shown, the bottle on the left-hand side-soy protein isolate forms a hot gel after heating, and the bottle on the right-soy protein mixture prepared in this embodiment is still fluid after heating. In summary, the heat-stable soy protein mixture prepared in this embodiment has high thermal stability and still has fluidity even after being heated at 100°C for 30 minutes, and can be used to prepare easy-to-swallow foods and protein beverages.

[0056] Example 2

[0057] A method for preparing heat-stable soybean protein is as follows:

[0058] S1. Dispersion: Take soy protein isolate and evenly disperse it in water at a mass concentration of 1.0% for 3 h, and adjust the pH to 7.0 with 2 mol / L NaOH to obtain protein dispersion 1;

[0059] S2, mixing: taking β-cyclodextrin with a mass concentration of 3.0% and uniformly dispersing it in the protein solution 1 to obtain a protein dispersion 2;

[0060] S3, heat treatment: heat the protein dispersion 2 obtained in step S2 at 120° C. for 15 min to obtain protein dispersion 3;

[0061] S4, acid precipitation: the pH of the protein dispersion 3 obtained in step S3 is adjusted to 4.5 with 1 mol / L HCl;

[0062] S5, centrifugation: centrifuge the product obtained in step S4 at 3000 g for 60 min to collect the precipitate;

[0063] S6, re-dissolving: adding water to the precipitate obtained in step S5 at a weight ratio of 1:3, adjusting the pH to 7.0 with 2 mol / L NaOH for dispersion and re-dissolution, to obtain protein dispersion 4;

[0064] S7, drying: the protein dispersion 4 obtained in step S6 is subjected to vacuum freeze drying (-80° C., 0.01 Pa, 24 h) to obtain heat-stable soy protein;

[0065] Wherein, the total thiol content of the soy protein isolate in step S1 is 3.46 μmol / g, and the preparation method of the soy protein isolate is:

[0066] Deionized water was added to defatted soybean meal at a ratio of 1:10 (w / v, g / mL), and the pH was adjusted to 8.5 with 2mol / LNaOH solution. The mixture was stirred at room temperature for 1 hour, and centrifuged at 15800g and 4°C for 30 minutes to obtain a supernatant. The supernatant was adjusted to pH 5.0 with 2mol / LHCl, and centrifuged at 6000g and 4°C for 15 minutes to obtain a soybean protein precipitate. The soybean protein precipitate was dissolved with deionized water for 3 hours, and the pH of the protein solution was adjusted to 8.5 with 2mol / LNaOH. The protein solution was freeze-dried to obtain soybean protein, and the freeze-drying was specifically -50°C, 0.01Pa, and 24 hours.

[0067] The heat-stable soy protein prepared in this example was prepared into an aqueous solution with a protein concentration of 8.0% (w / v), and the solution was heated at 100°C for 30 minutes, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured; at the same time, untreated soy protein isolate was taken as a control (soy protein group), heated at 100°C for 30 minutes at the same protein concentration, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured; the elastic modulus measurement results are shown in FIG. Figure 4 As shown in FIG. 1 , the elastic modulus of the untreated soy protein isolate after heating is significantly higher than that of the heat-stable soy protein mixture prepared in this example. Figure 5 As shown in FIG. 1 , the viscosity of the heat-stable soy protein mixture prepared in this example after heating is much lower than that of the untreated soy protein isolate. Fig.11 As shown, the soy protein isolate in the left bottle forms a hot gel after heating, and the heat-stable soy protein mixture prepared in this example in the right bottle remains in a fluid state after heating. In summary, the modified soy protein prepared in this example has a high thermal stability.

[0068] Example 3

[0069] A method for preparing heat-stable soybean protein is as follows:

[0070] S1. Dispersion: Take soy protein isolate and evenly disperse it in water at a mass concentration of 1.5% for 3 hours, and adjust the pH to 7.0 with 2 mol / L NaOH to obtain protein dispersion 1;

[0071] S2, mixing: taking β-cyclodextrin with a mass concentration of 3.0% and uniformly dispersing it in the protein solution 1 to obtain a protein dispersion 2;

[0072] S3, heat treatment: heat the protein dispersion 2 obtained in step S2 at 120° C. for 15 min to obtain protein dispersion 3;

[0073] S4, acid precipitation: the pH of the protein dispersion 3 obtained in step S3 is adjusted to 4.5 with 1 mol / L HCl;

[0074] S5, centrifugation: centrifuge the product obtained in step S4 at 3000 g for 60 min to collect the precipitate;

[0075] S6, re-dissolving: adding water to the precipitate obtained in step S5 at a weight ratio of 1:3, adjusting the pH to 7.0 with 2 mol / L NaOH for dispersion and re-dissolution, to obtain protein dispersion 4;

[0076] S7, drying: the protein dispersion 4 obtained in step S6 is subjected to vacuum freeze drying (-80° C., 0.01 Pa, 24 h) to obtain heat-stable soy protein;

[0077] Wherein, the total thiol content of the soybean protein in step S1 is 3.46 μmol / g, and the preparation method of the soybean protein isolate is:

[0078] Deionized water was added to defatted soybean meal at a ratio of 1:10 (w / v, g / mL), and the pH was adjusted to 8.5 with 2mol / LNaOH solution. The mixture was stirred at room temperature for 1 hour, and centrifuged at 15800g and 4°C for 30 minutes to obtain a supernatant. The supernatant was adjusted to pH 5.0 with 2mol / LHCl, and centrifuged at 6000g and 4°C for 15 minutes to obtain a soybean protein precipitate. The soybean protein precipitate was dissolved with deionized water for 3 hours, and the pH of the protein solution was adjusted to 8.5 with 2mol / LNaOH. The protein solution was freeze-dried to obtain soybean protein, and the freeze-drying was specifically -50°C, 0.01Pa, and 24 hours.

[0079] The heat-stable soy protein prepared in this example was prepared into an aqueous solution with a protein concentration of 9.0% (w / v), and the solution was heated at 100°C for 30 minutes, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured; at the same time, untreated soy protein isolate was taken as a control (soy protein group), heated at 100°C for 30 minutes at the same protein concentration, cooled and placed in a refrigerator at 4°C for 24 hours, and then the elastic modulus and viscosity were measured; the elastic modulus measurement results are shown in FIG. Figure 6 As shown in FIG. 1 , the elastic modulus of the untreated soy protein isolate after heating is significantly higher than that of the heat-stable soy protein mixture prepared in this example. Figure 7 As shown in FIG. 1 , the viscosity of the heat-stable soy protein mixture prepared in this example after heating is much lower than that of the untreated soy protein isolate. Fig.12 As shown, the soy protein isolate in the left bottle forms a hot gel after heating, and the heat-stable soy protein mixture prepared in this example in the right bottle remains in a fluid state after heating. In summary, the modified soy protein prepared in this example has a high thermal stability.

[0080] Comparative Example 1

[0081] The method for preparing preheated modified soybean protein comprises the following steps:

[0082] S1. Dispersion: Disperse soy protein isolate in water at a mass concentration of 1% and adjust the pH to 7.0 with 2 mol / L HCl to obtain a protein dispersion 1;

[0083] S2, heat treatment: heating the protein dispersion 1 obtained in step S1 at 100° C. for 60 min to obtain protein dispersion 2;

[0084] S3, acid precipitation: cool the protein dispersion 2 obtained in step S2 to room temperature, and adjust the pH to 4.0 using 2 mol / L HCl;

[0085] S4, centrifugation: centrifuge the product obtained in step S3 at 10000 g for 30 min to collect the precipitate;

[0086] S5, re-dissolving: adding water to the precipitate obtained in step S4 at a weight ratio of 1:8, adjusting the pH to 8.0 with 2 mol / L NaOH for dispersion and re-dissolution to obtain a protein solution;

[0087] S6, drying: spray drying the protein solution obtained in step S5 (inlet air temperature 195°C, outlet air temperature 95°C, feed rate 20 mL / min) to obtain heat-stable soy protein;

[0088] Wherein, the total thiol content of the soy protein isolate in step S1 is 3.46 μmol / g, and the preparation method of the soy protein isolate is:

[0089] Deionized water is added to defatted soybean meal at a ratio of 1:10 (w / v, g / mL), the pH is adjusted to 8.5 with a 2mol / L NaOH solution, the mixture is stirred at room temperature for 1 hour, and the mixture is centrifuged at 15800g and 4°C for 30 minutes to obtain a supernatant; the supernatant is adjusted to pH 5.0 with 2mol / L HCl, and the mixture is centrifuged at 6000g and 4°C for 15 minutes to obtain a soybean protein precipitate; the soybean protein precipitate is dissolved with deionized water for 3 hours, and the pH of the protein solution is adjusted to 8.5 with 2mol / L NaOH, and the protein solution is freeze-dried to obtain soybean protein, and the freeze-drying is specifically performed at -50°C, 0.01Pa, and 24 hours;

[0090] The modified soy protein prepared in this comparative example was prepared into an aqueous solution with a protein concentration of 10% (w / v, g / mL), and the aqueous solution was heated at 100°C for 30 minutes, cooled and placed in a 4°C refrigerator for 24 hours, and the elastic modulus and viscosity were measured; at the same time, soy protein isolate was taken as a control (soy protein group), prepared into an aqueous solution with a protein concentration of 10% (w / v, g / mL), heated at 100°C for 30 minutes, cooled and placed in a 4°C refrigerator for 24 hours, and the elastic modulus and viscosity were measured; the elastic modulus measurement results are as follows Figure 8 The viscosity measurement results are shown in Fig. 9As shown, the modified protein prepared in this comparative example gelled after heat treatment, and the elastic modulus and viscosity values ​​were slightly lower than those of the soy protein isolate solution after heating; Fig.13 It is intuitively shown that both the soy protein isolate on the left and the modified soy protein dispersion on the right are gelled, indicating that the modified soy protein prepared in this comparative example has poor thermal stability.

[0091] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing heat-stable soybean protein by adding β-cyclodextrin combined with preheating treatment, characterized in that: The specific steps include: S1. Dispersion: Take soy protein isolate, evenly disperse it in water at a mass concentration of 0.5% to 2.0%, and adjust the pH to between 6.0 and 8.0 to obtain a protein dispersion 1; S2, mixing: taking β-cyclodextrin and uniformly dispersing it in the protein dispersion 1 to obtain the protein dispersion 2; S3, heat treatment: heat the protein dispersion 2 obtained in step S2 at 90-120° C. for 15-60 min to obtain a protein dispersion 3; S4, acid precipitation: adjusting the pH of the protein dispersion 3 obtained in step S3 to 4-5; S5, centrifugation: centrifuging the product obtained in step S4 to collect the precipitate; S6, re-dissolving: adding water to the precipitate obtained in step S5, adjusting the pH to 6.0-7.0 for dispersion and re-dissolution to obtain a protein solution; S7, drying: drying the protein solution obtained in step S5 to obtain heat-stable soy protein.

2. The method according to claim 1, characterized in that The method for preparing soybean protein isolate comprises the following steps: adding deionized water to defatted soybean meal at a weight-to-volume ratio of 1:10, adjusting the pH value to 7.0-8.5, stirring at room temperature for 1 hour, centrifuging at 15800 g and 4°C for 30 minutes, and taking a supernatant; adjusting the pH value of the supernatant to 4.0-5.0, centrifuging at 3000-15800 g and 4°C for 5-120 minutes to obtain a precipitate; dissolving the precipitate with deionized water and adjusting the pH value to 7.0-8.5 to obtain a protein solution, wherein the weight ratio of the precipitate to the deionized water is 1:(3-10); drying the protein solution to obtain soybean protein; wherein the drying is freeze drying or spray drying; the freeze drying parameters are -50--80°C, vacuum degree 0.01 Pa-50 Pa, and drying for 24-72 hours; the spray drying parameters are: inlet air temperature 195°C, outlet air temperature 95°C, and feed rate 20 mL / min.

3. The method according to claim 1, characterized in that The total thiol content of the soy protein isolate is greater than 1.5 μmol / g.

4. The method according to claim 1, characterized in that: In step S1, the soy protein isolate is dispersed in water for 2 to 4 hours, and the pH is adjusted to 6.0 to 8.0 using HCl solution.

5. The method according to claim 1, characterized in that In step S2, the mass concentration of β-cyclodextrin in the protein dispersion 2 is 1.5-3.0%.

6. The method according to claim 1, characterized in that The centrifugal speed in step S5 is 3000-15800 g, and the centrifugal time is 20-120 min.

7. The method according to claim 1, characterized in that The mass ratio of the precipitate to water in step S6 is 1:(5-8).

8. The method according to claim 1, characterized in that The drying in step S7 is freeze drying or spray drying; the freeze drying parameters are -30 to -80°C, vacuum degree 0.01Pa to 50Pa, and drying for 24 to 72 hours; the spray drying parameters are: inlet air temperature 195°C, outlet air temperature 95°C, and feed rate 20mL / min.

9. The heat-stable soybean protein prepared according to the method according to any one of claims 1 to 8.

10. Use of the heat-stable soybean protein according to claim 9 in preparing easy-to-swallow food or high-protein food.

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