Preparation method of instant egg white powder

Abstract

The invention discloses a preparation method of instant egg white powder, and belongs to the technical field of food. According to the preparation method of the instant egg white powder, fresh egg white liquid is taken as a raw material, shearing homogenization, filtration, pH adjustment, ultrasonic treatment, enzymolysis and spray drying are carried out, the instant egg white powder is prepared, the shortest dispersion time is only 66s, the highest solubility reaches 95.53%, and the 24-hour stability coefficient reaches 85.34%; the egg white is modified by combining pH deviation, ultrasound and an enzymolysis technology, the technological operation is simple, the condition is mild, the instant characteristic of the egg white powder can be greatly improved, and the preparation method has huge application potential in the fields of solid beverages, health foods or functional foods.

Description

Technical Field

[0001] The present invention belongs to the technical field of food processing, and particularly relates to a preparation method of instant egg white powder. Background Art

[0002] Egg white powder has been widely used in the food industry due to its high nutritional value, low packaging cost, and easy storage and transportation. In the industrial production process of egg white powder, spray drying is the most commonly used drying method. However, since spray drying needs to be carried out at a relatively high temperature, and egg white protein is highly sensitive to heat, the protein in the egg white is prone to thermal denaturation and aggregation during this process. As a result, the produced egg white powder often has many problems such as slow dispersion speed, poor solubility, and easy caking, which seriously limits its application in functional foods and solid beverages.

[0003] Enzymatic hydrolysis, as a commonly used method to improve the functional properties of proteins, works by using proteases to cleave specific sites within the polypeptide chain of proteins, hydrolyzing the proteins into small molecular proteins, polypeptides, or amino acids, thereby reducing the protein molecular weight and changing its surface properties, and further enhancing the dispersibility, solubility, emulsifying property, foaming property, and flavor of the product. Enzymatic hydrolysis modification of proteins uses biological enzymes as catalysts, which is not only safe and environmentally friendly but also has mild reaction conditions, and can effectively avoid protein denaturation. However, the egg white protein is spherical and has a tight structure, which limits the enzymatic hydrolysis effect to a certain extent. Even if the amount of enzyme is increased or the enzymatic hydrolysis time is extended, the instant solubility of the egg white powder cannot be further improved. For example, the method disclosed in Chinese Patent CN11354545A for improving the instant solubility of egg white powder by using heat treatment technology to assist enzymatic hydrolysis, although it improves the enzymatic hydrolysis efficiency and instant solubility to a certain extent, the heat treatment process causes excessive denaturation and aggregation of egg white protein, resulting in unsatisfactory solubility of the egg white powder and the stability of the solution after dissolving in water, and a large amount of precipitation will occur during standing.

[0004] Ultrasonic treatment is a physical modification method. By means of the cavitation effect of ultrasonic waves, tiny cavities are formed inside the protein structure, thereby changing the protein structure, making it loose and porous, and exposing the internal enzyme-binding sites. However, ultrasonic treatment may also cause the exposure of hydrophobic groups originally hidden inside the protein, thereby increasing the hydrophobicity of the protein. If long-term or high-intensity ultrasonic treatment is carried out, it is easy to cause protein aggregation. Therefore, ultrasonic treatment is mostly used only as an auxiliary means. For example, the method disclosed in CN114052213A for improving the instant solubility of egg white powder by using ultrasonic treatment to assist the binding of lecithin and egg white protein, similar to heat treatment, the addition of amphiphilic molecules (lecithin) will induce the aggregation of egg white protein, resulting in poor stability of its solution system.

[0005] In summary, there are certain defects in the existing technologies for improving the instant solubility characteristics of egg white powder. There is an urgent need to develop new technologies to effectively solve this problem and broaden the application scope of egg white powder in the field of functional foods. Summary of the Invention

[0006] To solve the above problems, the object of the present invention is to provide a preparation method of instant egg white powder. This method uses pH shift combined with ultrasonic and enzymatic hydrolysis technologies to treat egg white proteins, improving the enzymatic hydrolysis efficiency, surface net charge, and hydrophilicity of egg white proteins, thereby synergistically enhancing the solubility, instant solubility, and stability of egg white powder and broadening the application scope of egg white powder in the field of functional foods.

[0007] To achieve the above object, the following technical solutions are provided:

[0008] The first technical solution of the present invention is to provide a preparation method of instant egg white powder, and the preparation method includes the following steps:

[0009] (1) Raw material pretreatment: Select fresh eggs, separate the egg yolks and egg whites, and collect the egg white liquid;

[0010] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 9.0 - 11.0;

[0011] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white liquid after adjusting the pH value in step (2);

[0012] (4) Enzymatic hydrolysis: Transfer the egg white liquid after ultrasonic treatment in step (3) to an enzyme reactor for enzymatic hydrolysis;

[0013] (5) Spray drying: Spray dry the egg white liquid after enzymatic hydrolysis in step (4) to make egg white powder.

[0014] In one embodiment, in step (1), the separated egg white also needs to be sheared and sieved to remove foam and impurities; the shearing is performed using a high-speed shear disperser at a rotational speed of 5000 - 8000 rpm for 1 - 5 minutes, or homogenized using a high-pressure homogenizer at 15 MPa.

[0015] In one embodiment, in step (2), the adjustment is carried out using a citric acid solution or a sodium hydroxide solution.

[0016] In one embodiment, the citric acid solution is a 5% (g / mL) citric acid solution; the concentration of the NaOH solution is 0.5 - 1.0 mol / L.

[0017] In one embodiment, in step (2), the pH value is adjusted to 9.0 - 10; more preferably 9.0 - 9.5.

[0018] In one embodiment, in step (3), the ultrasonic treatment conditions are as follows: ultrasonic time is 5 - 25 min, and ultrasonic power is 0.2 - 0.8 W / mL; more preferably 0.4 - 0.6 W / mL.

[0019] In one embodiment, in step (3), the ultrasonic treatment conditions are as follows: ultrasonic time is 15 min, and ultrasonic power is 0.4 W / mL.

[0020] In one embodiment, in step (4), the enzymatic hydrolysis conditions are as follows: enzyme addition amount is 0.05 - 0.1% (g / mL), temperature is 35 - 55 °C, and time is 0.5 - 4 h.

[0021] In one embodiment, the enzyme used for enzymatic hydrolysis is protease.

[0022] In one embodiment, the protease includes one or more of neutral protease, alkaline protease, papain, trypsin, or flavor protease.

[0023] In one embodiment, in step (5), the inlet air temperature for spray drying is 160 - 180 °C, and the outlet air temperature is 70 - 90 °C.

[0024] The second technical solution of the present invention is to provide an egg white powder prepared by the above - mentioned preparation method.

[0025] The third technical solution of the present invention is to provide an application of the above - mentioned egg white powder in the fields of solid beverages, health foods, or functional foods.

[0026] Beneficial effects:

[0027] (1) The present invention uses pH shift combined with ultrasonic technology to treat egg white liquid, and then through enzymatic hydrolysis technology, the egg white protein is hydrolyzed to prepare instant egg white powder. The shortest dispersion time is only 66 s, the highest solubility reaches 95.53%, and the 24 - hour stability coefficient reaches 85.34%.

[0028] (2) The process of the present invention involves pH shift and ultrasonic technology, which is simple to operate and mild in conditions. The isoelectric points of most egg white proteins are between pH 4.5 - 6.5. Increasing the pH can regulate the unfolding and folding states of protein molecular chains, significantly enhance the net charge on the protein surface while reducing hydrophobicity, which helps the protein structure to unfold during ultrasonic treatment, expose internal groups, and prevent protein aggregation. The combination of pH shift and ultrasonic technology can significantly improve the flexibility of protein molecules, which is beneficial to the subsequent interaction between enzymes and proteins and improves the enzymatic hydrolysis efficiency.

[0029] (3) The instant egg white powder prepared by the present invention has small particle size and strong hydrophilicity, so it can be quickly dispersed in the aqueous solution, solving the application bottleneck of poor solubility and long dispersion time of egg white powder, and can be used as a food raw material or ingredient in the development of products such as solid beverages, health foods, and functional foods. Detailed implementation manners

[0030] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the scope of protection of the present invention. The following specific implementation manners further describe the present invention.

[0031] The test methods involved in the present invention:

[0032] 1. Test method for degree of hydrolysis

[0033] The degree of hydrolysis of egg white protein is determined according to the o-phthalaldehyde (OPA) method. The specific method is as follows:

[0034] Add 3 mL of OPA reagent (dissolve 3.810 g of sodium tetraborate and 100 mg of SDS in 75 mL of deionized water, successively add 2 mL of absolute ethanol containing 80 mg of o-phthalaldehyde and 88 mg of DTT, and then make up to 100 mL with deionized water) into a test tube. Dilute the sample with deionized water at 25 - 30 °C to (1 mg / mL), and then take 400 μL and add it into the test tube. Oscillate and mix well. After accurately reacting for 2 min, measure the absorbance at 340 nm. Calculate the degree of hydrolysis of the protein in the sample according to the standard curve.

[0035] 2. Test method for dispersion time

[0036] Measure 20 mL of deionized water at room temperature (25 - 30 °C) into a beaker, place it on a magnetic stirrer, and stir at a speed of 700 rpm. Weigh 1 g of the sample and pour it into the beaker. Observe the dispersion of the sample in water, and record the time from when the sample first contacts the water to when it is completely dispersed in the water, which is the dispersion time.

[0037] 3. Test method for solubility

[0038] The solubility of egg white powder is determined by the centrifugal precipitation method. The specific method is as follows:

[0039] Accurately weigh 1 g of the sample (accurate to 0.01 g), and dissolve the sample in a centrifuge tube with 20 mL of deionized water at room temperature (25 - 30 °C). Place the centrifuge tube in a water bath at 30 °C for 5 min, and then centrifuge the centrifuge tube at 8000 rpm for 15 min. Carefully pour out the supernatant without disturbing the precipitate at the bottom, and transfer the remaining precipitate in the centrifuge tube to an oven at 110 °C to dry to a constant weight. Weigh the mass of the dried precipitate to calculate the solubility of the sample.

[0040] 4. Test method for solution stability coefficient

[0041] Weigh 0.5 g of the sample and dissolve it thoroughly in 50 mL of deionized water at 25 - 30 °C, and measure the absorbance at the maximum absorption wavelength. Place the sample solution in a 10 mL centrifuge tube. After standing for 24 h, use a pipette to aspirate the solution at the "6 mL" scale line and measure the absorbance at the maximum absorption wavelength. Calculate the ratio of the absorbance of the solution after standing to the absorbance of the freshly dissolved solution to obtain the solution stability coefficient.

[0042] Alkaline protease, 200,000 U / g, purchased from Nanning Pangbo Bioengineering Co., Ltd.

[0043] Example 1

[0044] A preparation method of instant egg white powder, comprising the following steps:

[0045] (1) Raw material pretreatment: Select fresh eggs, separate egg yolks and egg whites, and collect egg whites; shear evenly with a high-speed shearer at a shear speed of 5000 rpm for 1 min for every 100 mL of egg white; then filter with a 100-mesh sieve to remove foam and impurities to obtain egg white liquid;

[0046] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 9 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution;

[0047] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white liquid prepared in step (2), with an ultrasonic time of 15 min and an ultrasonic power of 0.4 W / mL; in order to prevent temperature fluctuations, use a constant temperature water bath to maintain the temperature of the egg white liquid at 35 °C;

[0048] (4) Enzymatic hydrolysis: Take the egg white liquid obtained in step (3) and transfer it to an enzyme reactor for enzymatic hydrolysis; select alkaline protease, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL, based on the egg white liquid), 50 °C, 4 h;

[0049] (5) Spray drying: Spray dry the egg white liquid prepared in step (4) to make egg white powder; the inlet temperature of spray drying is 180 °C and the outlet temperature is 80 °C.

[0050] Example 2

[0051] A method for preparing instant egg white powder, comprising the following steps:

[0052] (1) Raw material pretreatment: Select fresh eggs, separate egg yolks and egg whites, and collect the egg whites; shear evenly with a high-speed shearer at a shear speed of 5000 rpm for 1 minute for every 100 mL of egg white; then filter through a 100-mesh sieve to remove foam and impurities to obtain egg white liquid;

[0053] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 9 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution;

[0054] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white liquid prepared in step (2): ultrasonic time is 15 minutes, ultrasonic power is 0.2 W / mL; in order to prevent temperature fluctuations, maintain the temperature of the egg white liquid at 35 °C using a constant temperature water bath;

[0055] (4) Enzymatic hydrolysis: Transfer the egg white liquid obtained in step (3) to an enzyme reactor for enzymatic hydrolysis; select alkaline protease, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50 °C, 4 h;

[0056] (5) Spray drying: Spray dry the egg white liquid prepared in step (4) to make egg white powder; the inlet air temperature for spray drying is 180 °C, and the outlet air temperature is 80 °C.

[0057] Example 3

[0058] A method for preparing instant egg white powder, comprising the following steps:

[0059] (1) Raw material pretreatment: Select fresh eggs, separate egg yolks and egg whites, and collect the egg whites; shear evenly with a high-speed shearer at a shear speed of 5000 rpm for 1 minute for every 100 mL of egg white; then filter through a 100-mesh sieve to remove foam and impurities to obtain egg white liquid;

[0060] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 9 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution;

[0061] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white liquid prepared in step (2); ultrasonic time is 15 minutes, ultrasonic power is 0.6 W / mL; in order to prevent temperature fluctuations, maintain the temperature of the egg white liquid at 35 °C using a constant temperature water bath;

[0062] (4) Enzymatic hydrolysis: Transfer the egg white solution obtained in step (3) to an enzyme reactor for enzymatic hydrolysis; select alkaline protease, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50 °C, 4 h;

[0063] (5) Spray drying: Spray dry the egg white solution prepared in step (4) to obtain egg white powder; the inlet air temperature for spray drying is 180 °C, and the outlet air temperature is 80 °C.

[0064] Example 4

[0065] A method for preparing instant egg white powder, comprising the following steps:

[0066] (1) Raw material pretreatment: Select fresh eggs, separate the egg yolks and egg whites, and collect the egg whites; shear evenly with a high-speed shearer at a shear speed of 5000 rpm, shear for 1 min for every 100 mL of egg white; then filter through a 100-mesh sieve to remove foam and impurities to obtain an egg white solution;

[0067] (2) pH adjustment: Adjust the pH value of the egg white solution obtained in step (1) to 9 with a 5% (g / mL) citric acid solution or a 0.5 mol / L NaOH solution;

[0068] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white solution prepared in step (2), with an ultrasonic time of 5 min and an ultrasonic power of 0.4 W / mL; in order to prevent temperature fluctuations, maintain the temperature of the egg white solution at 35 °C using a constant temperature water bath;

[0069] (4) Enzymatic hydrolysis: Transfer the egg white solution obtained in step (3) to an enzyme reactor for enzymatic hydrolysis; select alkaline protease, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50 °C, 4 h;

[0070] (5) Spray drying: Spray dry the egg white solution prepared in step (4) to obtain egg white powder; the inlet air temperature for spray drying is 180 °C, and the outlet air temperature is 80 °C.

[0071] Example 5

[0072] A method for preparing instant egg white powder, comprising the following steps:

[0073] (1) Raw material pretreatment: Select fresh eggs, separate the egg yolks and egg whites, and collect the egg whites; shear evenly with a high-speed shearer at a shear speed of 5000 rpm, shear for 1 min for every 100 mL of egg white; then filter through a 100-mesh sieve to remove foam and impurities to obtain an egg white solution;

[0074] (2) pH adjustment: Adjust the pH value of the egg white solution obtained in step (1) to 9 with a 5% (g / mL) citric acid solution or a 0.5 mol / L NaOH solution;

[0075] (3) Ultrasonic treatment: The egg white solution obtained in step (2) is subjected to ultrasonic treatment for 25 min at an ultrasonic power of 0.4 W / mL. To prevent temperature fluctuations, a constant temperature water bath is used to maintain the temperature of the egg white solution at 35°C.

[0076] (4) Enzymatic hydrolysis: The egg white solution obtained in step (3) is transferred to an enzyme reactor for enzymatic hydrolysis. Alkaline protease is selected, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50°C, 4 h.

[0077] (5) Spray drying: The egg white solution obtained in step (4) is made into egg white powder by spray drying. The inlet air temperature for spray drying is 180°C, and the outlet air temperature is 80°C.

[0078] Example 6

[0079] A method for preparing instant egg white powder, comprising the following steps:

[0080] (1) Raw material pretreatment: Select fresh eggs, separate the egg yolks and egg whites, and collect the egg whites. Use a high-speed shearer to shear evenly at a shear speed of 5000 rpm for 1 min for every 100 mL of egg white. Then filter through a 100-mesh sieve to remove foam and impurities to obtain an egg white solution.

[0081] (2) pH adjustment: The pH value of the egg white solution obtained in step (1) is adjusted to 10.0 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution.

[0082] (3) Ultrasonic treatment: The egg white solution obtained in step (2) is subjected to ultrasonic treatment for 15 min at an ultrasonic power of 0.4 W / mL. To prevent temperature fluctuations, a constant temperature water bath is used to maintain the temperature of the egg white solution at 35°C.

[0083] (4) Enzymatic hydrolysis: The egg white solution obtained in step (3) is transferred to an enzyme reactor for enzymatic hydrolysis. Alkaline protease is selected, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50°C, 4 h.

[0084] (5) Spray drying: The egg white solution obtained in step (4) is made into egg white powder by spray drying. The inlet air temperature for spray drying is 180°C, and the outlet air temperature is 80°C.

[0085] Comparative Example 1

[0086] Steps (2) to (4) in Example 1 are omitted, and other conditions or parameters are the same as those in Example 1.

[0087] Comparative Example 2

[0088] Step (2) in Example 1 is omitted, and other conditions or parameters are the same as those in Example 1.

[0089] Comparative Example 3

[0090] Omit step (3) in Example 1, and keep other conditions or parameters the same as those in Example 1.

[0091] Comparative Example 4

[0092] Omit step (4) in Example 1, and keep other conditions or parameters the same as those in Example 1.

[0093] Comparative Example 5

[0094] A preparation method of instant egg white powder, comprising the following steps:

[0095] (1) Raw material pretreatment: Select fresh eggs, separate egg yolks and egg whites, and collect the egg whites; after shearing evenly, filter with a 100-mesh sieve to remove foam and impurities, obtaining egg white liquid;

[0096] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 8.0 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution;

[0097] (3) Ultrasonic treatment: Perform ultrasonic treatment on the egg white liquid prepared in step (2), with an ultrasonic time of 15 min and an ultrasonic power of 0.4 W / mL; in order to prevent temperature fluctuations, maintain the temperature of the egg white liquid at 35 °C using a constant temperature water bath;

[0098] (4) Enzymatic hydrolysis: Transfer the egg white liquid obtained in step (3) to an enzyme reactor for enzymatic hydrolysis; select alkaline protease, and the enzymatic hydrolysis conditions are: addition amount 0.05% (g / mL), 50 °C, 4 h;

[0099] (5) Spray drying: Spray dry the egg white liquid prepared in step (4) to obtain egg white powder; the inlet temperature of spray drying is 180 °C, and the outlet temperature is 80 °C.

[0100] Comparative Example 6

[0101] A preparation method of instant egg white powder, comprising the following steps:

[0102] (1) Raw material pretreatment: Select fresh eggs, separate egg yolks and egg whites, and collect the egg whites; after shearing evenly, filter with a 100-mesh sieve to remove foam and impurities, obtaining egg white liquid;

[0103] (2) pH adjustment: Adjust the pH value of the egg white liquid obtained in step (1) to 7.0 with 5% (g / mL) citric acid solution or 0.5 mol / L NaOH solution;

[0104] (3) Ultrasonic treatment: The egg white solution obtained in step (2) was subjected to ultrasonic treatment for 15 min at an ultrasonic power of 0.4 W / mL. To prevent temperature fluctuations, a constant temperature water bath was used to maintain the temperature of the egg white solution at 35 °C.

[0105] (4) Enzymatic hydrolysis: The egg white solution obtained in step (3) was transferred to an enzyme reactor for enzymatic hydrolysis. Alkaline protease was selected, and the enzymatic hydrolysis conditions were: addition amount 0.05% (g / mL), 50 °C, 4 h.

[0106] (5) Spray drying: The egg white solution prepared in step (4) was made into egg white powder by spray drying. The inlet air temperature for spray drying was 180 °C, and the outlet air temperature was 80 °C.

[0107] Result analysis

[0108] The performance of the egg white powder prepared in the examples and comparative examples was measured, and the results are as follows:

[0109] Table 1. Statistical table of hydrolysis degree, dispersion rate, solubility and stability coefficient of egg white powder

[0110]

[0111] As can be seen from the results in Table 1, the comparison results between Example 1 and Comparative Examples 1-4 show that: Comparative Example 1 is the original egg white powder, with the worst dispersion time, solubility and dispersion stability; Comparative Example 2 used ultrasonic pretreatment combined with enzymatic hydrolysis technology to modify the egg white, and the prepared egg white powder had a dispersion time of 102.1 s, a solubility of 91.61%, and a 24-hour stability coefficient of 80.87%; Comparative Example 3 used pH shift combined with enzymatic hydrolysis technology to modify the egg white, and the prepared egg white powder had a dispersion time of 132.6 s, a solubility of 89.75%, and a 24-hour stability coefficient of 79.05%; Comparative Example 4 used pH shift combined with ultrasonic technology to modify the egg white, and the prepared egg white powder had a dispersion time of 165.5 s, a solubility of 83.73%, and a 24-hour stability coefficient of 69.01%; The egg white powder prepared by pH shift, ultrasonic pretreatment assisted enzymatic hydrolysis had a shorter dispersion time, higher solubility and stability coefficient. Compared with the egg white enzymatic hydrolysate without pH adjustment (Comparative Example 2) and without ultrasonic pretreatment (Comparative Example 3), the egg white enzymatic hydrolysate pretreated with pH shift and ultrasonic (Example 1) had a higher hydrolysis degree, indicating that after ultrasonic pretreatment, the sensitivity of egg white protein to enzymatic hydrolysis increased and the enzymatic hydrolysis efficiency increased.

[0112] As can be seen from Table 1, when the egg white was modified by using the pH offset, ultrasound combined with enzymatic hydrolysis technology, the obtained egg white powder had the shortest dispersion time of only 66.3 s, the highest solubility of up to 95.53%, and the 24-hour stability coefficient of 86.34%. In addition, although pH adjustment was also carried out in Comparative Example 5 (pH adjusted to 8) and Comparative Example 6 (pH adjusted to 7), the relatively neutral pH environment restricted the activity of alkaline protease on the one hand, and on the other hand, the pH was relatively closer to the isoelectric point of egg white protein, with relatively low hydrophilicity and surface net charge, resulting in low electrostatic repulsion and easy aggregation of proteins during the ultrasound process.

[0113] The embodiments provided above are not intended to limit the scope covered by the present invention, nor are the described steps intended to limit their execution order. Obvious improvements made by those skilled in the art to the present invention in combination with the existing common general knowledge also fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing instant egg white powder, characterized in that: The preparation method comprises the following steps: (1) Raw material pretreatment: select fresh eggs, separate the yolk and egg white, and collect the egg white liquid; (2) adjusting pH: adjusting the pH value of the egg white solution obtained in step (1) to 9.0 to 11.0; (3) ultrasound: subjecting the egg white solution after adjusting the pH value in step (2) to ultrasound treatment; (4) Enzymatic hydrolysis: transferring the egg white solution after ultrasonic treatment in step (3) to an enzyme reactor for enzymatic hydrolysis; (5) spray drying: the egg white liquid after enzymatic hydrolysis in step (4) is spray dried to prepare egg white powder.

2. The preparation method according to claim 1, characterized in that: In step (2), the pH is adjusted by using citric acid solution or sodium hydroxide solution.

3. The preparation method according to claim 1, characterized in that: In step (2), the pH value is adjusted to 9.0-10.

0.

4. The preparation method according to claim 1, characterized in that: In step (3), the ultrasonic treatment conditions are: ultrasonic time 5 to 25 min, ultrasonic power 0.2 to 0.8 W / mL.

5. The preparation method according to claim 1, characterized in that: In step (3), the ultrasonic treatment conditions are: ultrasonic time 15 to 25 min, ultrasonic power 0.4 to 0.6 W / mL.

6. The preparation method according to claim 1, characterized in that: In step (4), the enzymatic hydrolysis conditions are: enzyme addition amount 0.05-0.1%, g / mL; 35-55° C., 0.5-4h.

7. The preparation method according to claim 1, characterized in that: In step (4), the enzyme used in the enzymatic hydrolysis is a protease.

8. The preparation method according to claim 1, characterized in that: In step (5), the spray drying air inlet temperature is 160-180°C, and the air outlet temperature is 70-90°C.

9. The egg white powder prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the egg white powder according to claim 9 in the preparation of solid beverages, health foods or functional foods.

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