Preparation method of soybean protein with high emulsifying capacity and high emulsifying stability

Abstract

The invention relates to the technical field of protein preparation, in particular to a preparation method of soybean protein with high emulsifying capacity and high emulsifying stability. According to the preparation method of the soybean protein with high emulsifying capacity and high emulsifying stability, provided by the invention, the prepared protein not only has high emulsifying capacity, but also has high emulsifying stability. In the technological process, no chemical reagent is used in the whole process, grease and protein can be obtained, the processes of use of a sixth solvent, acid-base treatment, chemical reagent, high-temperature heating and the like in a traditional technology are avoided, and the method is environmentally friendly, healthy and safe and is a brand-new technological thought.

Description

Technical Field

[0001] The invention relates to the technical field of protein preparation, and in particular to a method for preparing soybean protein with high emulsification ability and high emulsification stability. Background Art

[0002] Soybean is not only an important oil crop, but also an ideal edible protein resource. Mature soybean seeds contain about 20% fat and 40% protein. Soy protein is a "high-quality protein" rich in the eight "essential amino acids" needed by the human body, rich in lysine, and is an ideal food to complement cereal protein. The results of FAO / WHO (1985) human trials showed that the essential amino acid composition of soy protein is more suitable for human needs. For people over two years old, the physiological value of soy protein is 100. Using the protein nutritional quality evaluation method PDCAAS score, soy protein, milk protein, and egg white protein all scored 1.00. In 1999, the U.S. Food and Drug Administration (FDA) issued a statement: consuming 25 grams of soy protein per day can reduce the risk of cardiovascular and cerebrovascular diseases.

[0003] Soy protein not only has high nutrition, but also has excellent functionality, such as gelling, emulsification, foaming, solubility, water retention, film-forming, etc. These functional properties give soy protein excellent processing properties, making it widely used in the food industry.

[0004] Soy protein molecules contain both hydrophilic and lipophilic groups, so they have surface activity and the ability to emulsify oil and water, and are natural green emulsifiers. Highly emulsifiable soybean protein can be used in emulsified products such as meat products, dairy products, ice cream, cheese, liquid beverages, special medical foods, etc. It has important functions such as preventing oil-water separation, fat precipitation, stabilizing product structure, ensuring product taste, and improving product shelf life. Therefore, it is of great significance to develop natural soybean protein products with good emulsification properties and green and environmentally friendly production processes. The measurement of emulsification properties includes two aspects: one is emulsification capacity and the other is emulsification stability. Emulsification capacity refers to the maximum mass of oil that can be emulsified by a unit mass of protein under certain conditions. If this capacity is exceeded, the emulsification system will be destroyed and become unstable. The greater the mass of oil that can be emulsified, the greater the emulsification capacity. Emulsification stability refers to the ability of the emulsification system to maintain an obvious stable state and not produce unstable phenomena such as two-phase stratification. The larger the emulsification capacity and the higher the emulsification stability of the emulsifier, the more guaranteed the stability of the product.

[0005] At present, the technical means for studying the emulsification ability and emulsification stability of soybean protein mainly adopt physical modification, enzymatic modification and chemical modification. The raw soybeans used are subjected to raw material extraction, acid and alkali treatment, and chemical reagent treatment, which has the following shortcomings:

[0006] ① In terms of raw materials, most of them use soy protein isolate obtained by solvent extraction and acid-base treatment. The process requires many steps of organic solvent, acid-base treatment, and heating treatment. Organic solvents and acids and alkalis will not only cause environmental pollution, but also bring about problems such as solvent residues and heavy metal residues. Acid-base treatment will also cause irreversible denaturation of proteins and loss of essential amino acids. Improper alkali treatment can also cause protein hydrolysis, cross-linking reaction, racemization reaction, and even the formation of harmful substances such as lysine.

[0007] ②The protein concentration used in ultrasonic treatment is low and the improvement is limited.

[0008] ③ Enzymatic modification has many requirements for process conditions, and strict control requirements for pH, temperature, etc. In addition, the protein after enzymatic hydrolysis will produce precipitation, resulting in protein loss. The emulsification stability of enzymatic hydrolysis may not necessarily be improved, and may even be reduced.

[0009] ④ Chemical modification requires the addition of chemical reagents, which causes chemical reactions and introduces additional element groups. The original composition of the protein changes, posing a non-green and unhealthy safety hazard.

[0010] In summary, under the current technological status quo, the technical route for improving the emulsification ability of soy protein has many shortcomings, and the performance of the products produced will also be affected. Summary of the invention

[0011] The present invention aims to solve one of the technical problems in the related art at least to a certain extent. To this end, one object of the present invention is to provide a method for preparing soybean protein with high emulsification ability and high emulsification stability, wherein the protein obtained by the preparation method has not only high emulsification ability but also high emulsification stability. In this process, no chemical reagents are used throughout the process, and oil and protein can be obtained, avoiding the use of No. 6 solvents, acid-base treatment, chemical reagents, high-temperature heating and other processes in traditional processes. It is green, environmentally friendly, healthy and safe, and is a brand-new process idea.

[0012] To this end, the first aspect of the present invention provides a method for preparing soybean protein with high emulsification ability and high emulsification stability. In some embodiments of the present invention, the preparation method comprises:

[0013] S1: grinding soybeans to obtain slurry;

[0014] S2: performing a first centrifugation on the slurry to obtain a soy protein supernatant;

[0015] S3: performing a second centrifugation on the soy protein supernatant to obtain a stratified liquid, and retaining only the second stable layer from top to bottom in the stratified liquid;

[0016] S4: subjecting the stable layer to ultrasonic treatment and / or membrane filtration concentration to obtain soybean protein with high emulsification ability and high emulsification stability,

[0017] Wherein, the rotation speed of the second centrifugal treatment is 10000-25000 r / min, and the centrifugal time is at least 30-120 min.

[0018] According to the preparation method provided by the present invention, after soaking and grinding the protein, the protein and oil naturally present in the soybean will form an emulsified system with water, and the emulsified slurry will be centrifuged under a specific centrifugal strength and time, and the protein with good emulsification ability will continue to remain in the upper liquid to maintain a stable state, and the protein with poor emulsification ability and stability will be precipitated in the precipitate and removed. The protein and oil in the upper liquid are further separated by physical means such as ultrasound and membrane separation, and the oil is removed, so that the protein with good emulsification ability and stability can be obtained.

[0019] In some embodiments of the present invention, in step S1, when the pulping treatment is performed, the weight ratio of soybean to water in the slurry is 1:(5-10). The material-water ratio is related to the protein extraction yield, and within this ratio range, a suitable higher protein extraction yield can be obtained.

[0020] In some embodiments of the present invention, in step S1, when the pulping treatment is performed, the pulp temperature is not higher than 50°C.

[0021] In some embodiments of the present invention, in step S2, the rotation speed of the first centrifugation treatment is 5000-8000 r / min, and the centrifugation time is at least 10-20 min.

[0022] In some embodiments of the present invention, in step S4, the ultrasonic treatment is performed for 10-30 min at a power of 500-3000 W.

[0023] In some embodiments of the present invention, in step S4, the temperature for performing the ultrasonic treatment is 30-60°C.

[0024] In some embodiments of the present invention, step S4 further comprises:

[0025] S4-1: performing a third centrifugation on the product after the ultrasonic treatment to obtain a centrifuged liquid;

[0026] S4-2: Degreasing the centrifuged liquid.

[0027] In some embodiments of the present invention, step S4 further comprises:

[0028] S4-3: performing a third centrifugation on the product after the ultrasonic treatment to obtain a centrifuged liquid;

[0029] S4-4: Concentrating the centrifuged liquid by membrane filtration.

[0030] In some embodiments of the present invention, the third centrifugation treatment has a rotation speed of 5000-8000 r / min and a centrifugation time of at least 10 min, preferably 10-20 min.

[0031] In some embodiments of the invention, the method further comprises:

[0032] After membrane filtration concentration or degreasing treatment, high temperature instantaneous sterilization treatment is carried out, wherein the sterilization temperature is 135-145°C and the sterilization time is 5-30s.

[0033] In some embodiments of the present invention, after the high-temperature instantaneous sterilization treatment, the sterilized sample is dried to obtain protein solids.

[0034] It should be noted that there are many drying methods, including but not limited to spray drying, and other drying methods. After spray drying, protein powder can be obtained.

[0035] The method for preparing soybean protein with high emulsification ability and high emulsification stability provided by the present invention has the following beneficial effects:

[0036] ①Avoid the use of chemical reagents and adopt purely natural, green and environmentally friendly methods to extract protein.

[0037] In the traditional protein extraction process, the oil must first be removed by organic solvents. The use of organic solvents not only poses safety risks such as explosion risks, but also leaves a certain amount of residue in the protein raw materials. Solvents such as hydrochloric acid and sodium hydroxide are also used in traditional protein extraction processes. Strong acids and alkalis can cause protein hydrolysis and denaturation to a certain extent, producing harmful substances. As people's concept of green, healthy, and pure natural green food gradually strengthens, the use of chemical methods will be increasingly questioned.

[0038] ② Do not use enzymatic or chemical methods to improve emulsification.

[0039] There is a certain uncertainty in improving emulsification by enzymatic means. The types of enzymes and process routes required are relatively demanding and strict. In addition, the emulsification stability of protein after enzymatic hydrolysis will be reduced. In addition, enzymatic hydrolysis will also expose more groups, producing undesirable flavors such as bitterness. Chemical modification will increase the introduction of chemicals and groups, which is more potential safety hazards.

[0040] ③ Use physical means to grade and screen proteins to obtain proteins with different emulsification abilities.

[0041] Soy protein itself has many different components, and each component has its own functional strengths. By physically screening and separating the protein with strong emulsifying ability, and removing the components with weak emulsifying ability, a protein component with good emulsifying ability and stability can be obtained. The scheme of the present invention is used to obtain a high emulsifying protein, and its emulsifying ability can reach 160ml / g protein when measured by the emulsifying force method. The emulsifying stability remains almost stable after long-term placement. Therefore, the method of the present invention can prepare a protein product with excellent emulsifying ability and emulsifying stability.

[0042] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0044] Figure 1 Three different routes for preparing soy protein are shown. DETAILED DESCRIPTION

[0045] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0046] It should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. Further, in the description of the present invention, unless otherwise specified, the meaning of "plurality" is two or more.

[0047] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0048] In order to make the present invention more easily understood, certain technical and scientific terms are specifically defined below. Unless otherwise clearly defined elsewhere in this document, all other technical and scientific terms used herein have the meanings commonly understood by those skilled in the art to which the present invention belongs.

[0049] In this document, the terms “include” or “comprising” are open expressions, that is, including the contents specified in the present invention but not excluding other contents.

[0050] As used herein, the terms "optionally", "optional" or "optionally" generally mean that the subsequently described event or circumstance may but need not occur, and that the description includes instances where the event or circumstance occurs and instances where it does not.

[0051] According to a specific embodiment of the present invention, the method for preparing soybean protein with high emulsification ability and high emulsification stability provided by the present invention adopts natural soybeans as raw materials, removes part of the oil through soaking, refining, centrifugation, ultrasound, membrane separation process, high temperature instantaneous sterilization, and spray drying to obtain protein powder.

[0052] According to a more specific embodiment of the present invention, the method for preparing soybean protein with high emulsification capacity and high emulsification stability provided by the present invention comprises soaking soybeans in water, grinding, separating the dregs, and then centrifugally classifying the obtained slurry by different centrifugal strengths and centrifugal times. The obtained classified liquid is then subjected to auxiliary treatment by ultrasonic, centrifugal, membrane separation and other means to remove grease and obtain a protein product, which is then subjected to high temperature instant sterilization and spray drying to obtain a protein powder.

[0053] The main purpose of the present invention is to invent an improved, innovative, green and environmentally friendly technical means to avoid the shortcomings of the existing technical means. It is used to prepare a soybean protein product with high emulsification ability and high emulsification stability, and is a regulated technical route, through which the emulsification ability and emulsification stability of the desired product can be controlled.

[0054] According to a specific embodiment of the present invention, the preparation method of soybean protein with high emulsification ability and high emulsification stability provided by the present invention is specifically referred to Figure 1 Middle Route 1, including:

[0055] S1: grinding soybeans to obtain slurry, wherein the weight ratio of soybeans to water in the slurry is 1:(5-10), and during the grinding process, the slurry temperature is not higher than 50° C.;

[0056] S2: performing a first centrifugal treatment on the slurry at a speed of 5000-8000 r / min and a centrifugal time of 10-20 min to obtain a soybean protein supernatant;

[0057] S3: performing a second centrifugation on the soy protein supernatant at a rotation speed of 10000-25000 r / min and a centrifugation time of 30-120 min to obtain a stratified liquid, and only retaining the second stable layer from top to bottom in the stratified liquid;

[0058] S4: subjecting the stabilizing layer to ultrasonic treatment for 10-30 min, at a power of 500-3000 W and a temperature of 30-60° C. to obtain an ultrasonically treated product;

[0059] S5: performing a third centrifugation on the product after the ultrasonic treatment at a rotation speed of 5000-8000 r / min and a centrifugation time of 10-20 min to obtain a centrifuged liquid;

[0060] S6: Degreasing the centrifuged liquid;

[0061] S7: After degreasing, high temperature instantaneous sterilization is performed, wherein the sterilization temperature is 135-145°C and the sterilization time is 5-30s;

[0062] S8: Drying the sterilized sample to obtain soybean protein solids with high emulsification ability and high emulsification stability.

[0063] According to a specific embodiment of the present invention, the preparation method of soybean protein with high emulsification ability and high emulsification stability provided by the present invention is specifically referred to Figure 1 Middle Route 2, including:

[0064] S1: grinding soybeans to obtain slurry, wherein the weight ratio of soybeans to water in the slurry is 1:(5-10), and during the grinding process, the slurry temperature is not higher than 50° C.;

[0065] S2: performing a first centrifugal treatment on the slurry at a speed of 5000-8000 r / min and a centrifugal time of 10-20 min to obtain a soybean protein supernatant;

[0066] S3: performing a second centrifugation on the soy protein supernatant at a rotation speed of 10000-25000 r / min and a centrifugation time of 30-120 min to obtain a stratified liquid, and only retaining the second stable layer from top to bottom in the stratified liquid;

[0067] S4: performing membrane filtration and concentration on the stabilization layer;

[0068] S5: subjecting the liquid after membrane filtration and concentration to high-temperature instantaneous sterilization, wherein the sterilization temperature is 135-145° C. and the sterilization time is 5-30 seconds;

[0069] S6: Drying the sterilized sample to obtain soybean protein solids with high emulsification ability and high emulsification stability.

[0070] According to a specific embodiment of the present invention, the preparation method of soybean protein with high emulsification ability and high emulsification stability provided by the present invention is specifically referred to Figure 1Middle Route 3, including:

[0071] S1: grinding soybeans to obtain slurry, wherein the weight ratio of soybeans to water in the slurry is 1:(5-10), and during the grinding process, the slurry temperature is not higher than 50° C.;

[0072] S2: performing a first centrifugal treatment on the slurry at a speed of 5000-8000 r / min and a centrifugal time of 10-20 min to obtain a soybean protein supernatant;

[0073] S3: performing a second centrifugation on the soy protein supernatant at a rotation speed of 10000-25000 r / min and a centrifugation time of 30-120 min to obtain a stratified liquid, and only retaining the second stable layer from top to bottom in the stratified liquid;

[0074] S4: subjecting the stabilizing layer to ultrasonic treatment for 10-30 min, at a power of 500-3000 W and a temperature of 30-60° C. to obtain an ultrasonically treated product;

[0075] S5: performing a third centrifugation on the product after the ultrasonic treatment at a rotation speed of 5000-8000 r / min and a centrifugation time of 10-20 min to obtain a centrifuged liquid;

[0076] S6: performing membrane filtration, concentration and defatting on the centrifuged liquid,

[0077] S7: After membrane filtration and concentration, high temperature instantaneous sterilization is performed, wherein the sterilization temperature is 135-145° C. and the sterilization time is 5-30 seconds;

[0078] S8: Drying the sterilized sample to obtain soybean protein solids with high emulsification ability and high emulsification stability.

[0079] According to an embodiment of the present invention, a method for preparing soybean protein with high emulsification capacity and high emulsification stability uses natural non-genetically modified soybeans, soaks them at a certain temperature, time, and water ratio, grinds them, separates the dregs, and then centrifuges the obtained slurry through different centrifugal strengths and centrifugal times. The obtained classified liquid is then treated with ultrasound, centrifugation, membrane separation, etc. to remove grease and obtain a protein product, which is then sterilized at high temperature and spray-dried to obtain protein powder. Figure 1 Medium technology route. The protein obtained by this method has not only high emulsification ability, but also high emulsification stability. In this process, no chemical reagents are used throughout the process, and oil and protein can be obtained, avoiding the use of No. 6 solvents, acid and alkali treatment, chemical reagents, high-temperature heating and other processes in traditional processes. It is green, environmentally friendly, healthy and safe, and is a new process idea.

[0080] The scheme of the present disclosure will be explained below in conjunction with the examples. Those skilled in the art will appreciate that the following examples are only used to illustrate the present disclosure and should not be considered to limit the scope of the present disclosure. Where specific techniques or conditions are not indicated in the examples, the techniques or conditions described in the literature in this area or the product instructions are used. Where the manufacturers of reagents or instruments are not indicated, they are all conventional products that can be obtained commercially.

[0081] Determination method of emulsification ability and emulsion stability:

[0082] 1. Materials and Methods:

[0083] 1.1 Materials and Reagents:

[0084] Soybean salad oil: Fulinmen first-grade soybean salad oil

[0085] 1.2 Instruments and equipment:

[0086] Conductivity meter: Shanghai Youke Instrument Co., Ltd.

[0087] High speed emulsifier: Silverson Machines Ltd

[0088] 1.3 Experimental methods

[0089] 1.3.1 Determination of emulsifying ability

[0090] Prepare a 1% protein solution, stir it with a magnetic stirrer for 60 minutes, measure 50 ml of the protein solution, add 20 ml of soybean salad oil, emulsify and homogenize with a high-speed emulsifier at a speed of 10,000 rpm, add soybean salad oil while emulsifying, and measure the change in the conductivity of the system at the same time. When the conductivity drops to zero, it is the end point. Repeat 3 times, take the average value, and calculate the standard deviation.

[0091] Emulsifying capacity EA = total oil amount / protein amount (ml / g protein)

[0092] 1.3.2 Determination of emulsion stability (ES)

[0093] Prepare a 1% soy protein solution, stir it at room temperature to fully dissolve it, add soy salad oil with a maximum emulsification capacity of 80%, emulsify it with a high-speed emulsifier (10000rpm) for 1min, centrifuge it at 4000rpm for 10min, measure the volume of the final emulsion, and calculate its emulsification stability.

[0094] Emulsion stability ES = (final emulsion volume / initial emulsion volume) × 100%

[0095] Example 1

[0096] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 8 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 800 parts, grind with a colloid mill, and control the slurry temperature below 60°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 8000r / min for 20 minutes. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0097] The second step of centrifugation is to centrifuge the supernatant obtained from the first step in a high-speed centrifuge, the temperature is maintained at 55°C, the speed is 18000r / min, and the centrifugation time is 30min. After the centrifugation, the soy milk will be divided into 4 layers from top to bottom, remove the first layer of foam and the third and fourth layers of sediment, and keep the second stable layer.

[0098] The stabilizing layer was treated in an ultrasonic device for 30 minutes, with a power of 1000 W and a temperature of 60°C. After the treatment, it was centrifuged in a centrifuge at a speed of 8000 r / min for 20 minutes. The centrifuged liquid was treated with an ultrafiltration membrane with a molecular weight cutoff of 200 kDa to retain the retained component. The concentration was stopped when the solid content of the retained component was 12%.

[0099] The retained components were sterilized by UHT at 135°C for 15 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0100] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 1 below:

[0101] Table 1

[0102] sample Emulsifying ability EA Emulsion stability ES Example 1 166.17±1.23 96.8％

[0103] Example 2

[0104] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 6 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 600 parts, grind with a colloid mill, and control the slurry temperature below 50°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 8000r / min for 15 minutes. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0105] The second step of centrifugation is to centrifuge the supernatant obtained from the first step in a high-speed centrifuge, maintain the temperature at 50°C, rotate at 10,000 r / min, and centrifuge for 60 minutes. After the centrifugation, the soy milk will be divided into 4 layers from top to bottom, remove the first layer of foam and the third and fourth layers of sediment, and keep the second stable layer.

[0106] The stabilizing layer was treated in an ultrasonic device for 30 minutes, with a power of 2000W and a temperature of 60°C. After the treatment, it was centrifuged in a centrifuge at a speed of 8000r / min for 20 minutes. The centrifuged liquid was treated with an ultrafiltration membrane with a molecular weight cutoff of 200kDa to retain the retained component. The concentration was stopped when the solid content of the retained component was 15%.

[0107] The retained components were sterilized by UHT at 145°C for 10 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0108] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 2 below:

[0109] Table 2

[0110] sample Emulsifying ability EA Emulsion stability ES Example 2 182.35±1.03 95.2％

[0111] Example 3

[0112] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 6 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 600 parts, grind with a colloid mill, and control the slurry temperature below 80°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 8000r / min for 20 minutes. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0113] The second step of centrifugation is to centrifuge the supernatant obtained from the first step in a high-speed centrifuge, maintain the temperature at 50°C, rotate at 10,000 r / min, and centrifuge for 30 minutes. After the centrifugation, the soy milk will be divided into 4 layers from top to bottom, remove the first layer of foam and the third and fourth layers of sediment, and keep the second stable layer.

[0114] The stabilizing layer was treated in an ultrasonic device for 30 minutes, with a power of 3000 W and a temperature of 40°C. After the treatment, it was centrifuged in a centrifuge at a speed of 8000 r / min for 10 minutes. The centrifuged liquid was treated with an ultrafiltration membrane with a molecular weight cutoff of 200 kDa, and the retained component was retained. The concentration was stopped when the solid content of the retained component was 13%.

[0115] The retained components were sterilized by UHT at 140°C for 8 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0116] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 3 below:

[0117] Table 3

[0118] sample Emulsifying ability EA Emulsion stability ES Example 3 176.46±0.89 96.3％

[0119] Example 4

[0120] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 8 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 1000 parts, grind with a colloid mill, and control the slurry temperature below 60°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 5000r / min and a centrifugal time of 15min. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0121] The second step of centrifugation is to centrifuge the supernatant obtained from the first step in a high-speed centrifuge, maintain the temperature at 40°C, rotate at 18000r / min, and centrifuge for 60 minutes. After the centrifugation, the soy milk will be divided into 4 layers from top to bottom, remove the first layer of foam and the third and fourth layers of sediment, and keep the second stable layer.

[0122] The stable layer was treated with an ultrafiltration membrane with a molecular weight cutoff of 200 kDa to centrifuge the liquid, retaining the retained component. The concentration was stopped when the solid content of the retained component reached 12%.

[0123] The retained components were sterilized by UHT at 138°C for 15 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0124] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 4 below:

[0125] Table 4

[0126] sample Emulsifying ability EA Emulsion stability ES Example 4 160.63±0.45 89.0％

[0127] Comparative Example 1

[0128] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 6 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 600 parts, grind with a colloid mill, and control the slurry temperature below 80°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 8000r / min for 20 minutes. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0129] The second step of centrifugation is to centrifuge the supernatant obtained from the first step of centrifugation in a disc centrifuge, the temperature is maintained at 50°C, and the speed is 9500r / min. After the centrifugation, the soy milk will be separated into a light phase layer and a heavy phase layer, and the heavy phase layer is retained.

[0130] The heavy phase layer was treated in an ultrasonic device for 30 minutes, with a power of 3000W and a temperature of 40°C. After the treatment, the mixture was centrifuged at a speed of 8000r / min for 10 minutes. The centrifuged liquid was treated with an ultrafiltration membrane with a molecular weight cutoff of 200kDa to retain the retained component. The concentration was stopped when the solid content of the retained component was 13%.

[0131] The retained components were sterilized by UHT at 140°C for 8 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0132] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 5 below:

[0133] Table 5

[0134] sample Emulsifying ability EA Emulsion stability ES Comparative Example 1 101.2±0.68 56.7％

[0135] Comparative Example 2

[0136] Take 100 parts by weight of natural non-GMO soybeans, add 300 parts by weight of softened water, soak at 4°C for 6 hours, drain the water, and take out the soaked soybeans. Add softened water to make the total mass of the soaked soybeans and water 600 parts, grind with a colloid mill, and control the slurry temperature below 80°C. After completion, centrifuge the ground soybean milk in a centrifuge at a speed of 8000r / min for 20 minutes. After the first step of centrifugation, take out the supernatant and discard the dregs.

[0137] The second step of centrifugation is to centrifuge the supernatant obtained from the first step in a common centrifuge, maintain the temperature at 50°C, rotate at 8000r / min, and centrifuge for 30 minutes. After the centrifugation, the soy milk will be divided into 4 layers from top to bottom, remove the first layer of foam and the third and fourth layers of sediment, and keep the second stable layer.

[0138] The stabilizing layer was treated in an ultrasonic device for 30 minutes, with a power of 3000 W and a temperature of 40°C. After the treatment, it was centrifuged in a centrifuge at a speed of 8000 r / min for 10 minutes. The centrifuged liquid was treated with an ultrafiltration membrane with a molecular weight cutoff of 200 kDa, and the retained component was retained. The concentration was stopped when the solid content of the retained component was 13%.

[0139] The retained components were sterilized by UHT at 140°C for 8 seconds, and the sterilized liquid was spray dried to obtain protein powder.

[0140] According to the above-mentioned emulsifying ability and emulsifying stability determination method, the emulsifying ability and emulsifying stability of the obtained protein powder were determined. The results are shown in Table 6 below:

[0141] Table 6

[0142] sample Emulsifying ability EA Emulsion stability ES Comparative Example 2 111.4±0.72 50.7％

[0143] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", "some implementation schemes" or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0144] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations of the present invention. A person skilled in the art may change, modify, replace and vary the above embodiments within the scope of the present invention.

Claims

1. A method for preparing soybean protein with high emulsification ability and high emulsification stability, characterized in that: include: S1: grinding soybeans to obtain slurry; S2: performing a first centrifugation on the slurry to obtain a soy protein supernatant; S3: performing a second centrifugation on the soy protein supernatant to obtain a stratified liquid, and retaining only the second stable layer from top to bottom in the stratified liquid; S4: subjecting the stable layer to ultrasonic treatment and / or membrane filtration concentration to obtain soybean protein with high emulsification ability and high emulsification stability, Wherein, the rotation speed of the second centrifugal treatment is 10000-25000 r / min, and the centrifugal time is at least 30-120 min.

2. The preparation method according to claim 1, characterized in that: In step S1, when the pulping process is performed, the weight ratio of soybeans to water in the pulp is 1: (5-10).

3. The preparation method according to claim 1, characterized in that: In step S1, when the pulping treatment is performed, the pulp temperature is not higher than 50°C.

4. The preparation method according to claim 1, characterized in that: In step S2, the first centrifugal treatment has a rotation speed of 5000-8000 r / min and a centrifugal time of at least 10-20 min.

5. The preparation method according to claim 1, characterized in that: In step S4, the ultrasonic treatment is performed for 10-30 minutes at a power of 500-3000W.

6. The preparation method according to claim 1, characterized in that: In step S4, the temperature for performing the ultrasonic treatment is 30-60°C.

7. The preparation method according to claim 1, characterized in that: Step S4 further comprises: S4-1: performing a third centrifugation on the product after the ultrasonic treatment to obtain a centrifuged liquid; S4-2: Degreasing the centrifuged liquid.

8. The preparation method according to claim 1, characterized in that: Step S4 further comprises: S4-3: performing a third centrifugation on the product after the ultrasonic treatment to obtain a centrifuged liquid; S4-4: Concentrating the centrifuged liquid by membrane filtration.

9. The preparation method according to claim 7 or 8, characterized in that: The third centrifugal treatment has a rotation speed of 5000-8000 r / min and a centrifugal time of at least 10 min.

10. The preparation method according to any one of claims 1 to 7, characterized in that: The method further comprises: After membrane filtration concentration or degreasing treatment, high temperature instantaneous sterilization treatment is carried out, wherein the sterilization temperature is 135-145°C and the sterilization time is 5-30s; Optionally, after the high-temperature instantaneous sterilization treatment, the sterilized sample is dried to obtain protein solids.

Images