Alcohol method soybean protein concentrate modification method

Abstract

The invention discloses a method for modifying soybean protein concentrate through an alcohol method, and belongs to the technical field of soybean protein processing. The method solves the problems that the protein molecular structure of the alcohol-method soybean protein concentrate is changed, a large number of hydrophobic groups are exposed, and the nitrogen dissolution index is reduced. The modification method comprises the following steps: dissolving alcohol-process soybean protein concentrate in deionized water to prepare a soybean protein concentrate solution; adjusting the pH value of the soybean protein concentrate solution to 4.5-6, adding cellulase under a constant-temperature water bath condition, and reacting for 1-2 hours to obtain a mixed solution; the pH value of the mixed solution is adjusted to 6-8, and the mixed solution is placed in a constant-temperature magnetic stirring water bath kettle for magnetic stirring and heating; cooling the heated mixed solution to room temperature, and then carrying out ultrasonic treatment; and freeze-drying the mixed solution after ultrasonic treatment to obtain the modified soybean concentrated protein powder. The modification method of the alcohol-process soybean protein concentrate can improve the solubility of the alcohol-process soybean protein, and is suitable for the technical field of soybean protein processing.

Description

Technical Field

[0001] The present invention belongs to the technical field of soybean protein processing, and particularly relates to a method for modifying soy protein concentrate. Background Art

[0002] The production process of alcohol-processed soy protein concentrate uses ethanol to remove the alcohol-soluble sugars in the raw materials and produces a concentrated protein product with a protein content of about 70%. Although the protein content of alcohol-processed soy protein concentrate is very high, due to the action of ethanol during the processing, the protein molecular structure changes, a large number of hydrophobic groups are exposed, and the nitrogen solubility index (NSI) decreases, which affects its application in the food industry. Summary of the Invention

[0003] The present invention discloses a method for modifying alcohol-processed soy protein concentrate, which solves the problems that the protein molecular structure of alcohol-processed soy protein concentrate changes, a large number of hydrophobic groups are exposed, and the nitrogen solubility index decreases.

[0004] The technical solution of the present invention is as follows:

[0005] A method for modifying alcohol-processed soy protein concentrate, the method comprising the following steps:

[0006] Step 1: Dissolve alcohol-processed soy protein concentrate in deionized water to prepare a soy protein concentrate solution with a mass fraction of 3% - 10%;

[0007] Step 2: Adjust the pH value of the soy protein concentrate solution to 4.5 - 6, add cellulase under the condition of a constant temperature water bath at 35°C - 45°C, and react for 1 - 2 h to obtain a mixed solution; the addition amount of the cellulase is 1% - 2% of the mass of the alcohol-processed soy protein concentrate;

[0008] Step 3: Adjust the pH value of the mixed solution to 6 - 8, place the mixed solution in a constant temperature magnetic stirring water bath at a temperature of 85°C - 95°C for magnetic stirring, and heat for 20 - 40 minutes;

[0009] Step 4: Cool the heated mixed solution to room temperature, and then perform ultrasonic treatment;

[0010] Step 5: Freeze-dry the ultrasonically treated mixed solution to obtain modified soy protein concentrate powder.

[0011] Further, the mass fraction of the alcohol-processed soy protein concentrate solution in Step 1 is 7%.

[0012] Further, in Step 2, the pH is adjusted to 5.

[0013] Further, the constant temperature water bath temperature in Step 2 is 40°C.

[0014] Further, the addition amount of cellulase in step 2 is 1.5% of the mass of the alcohol-processed soy protein concentrate, and the reaction time is 2 h.

[0015] Further, in step 3, the pH is adjusted to 7.

[0016] Further, in step 3, the water bath temperature is 85°C to 90°C.

[0017] Further, in step 3, the heating time is 30 minutes.

[0018] Further, in step 4, the conditions for ultrasonic treatment are a power of 300 - 600 W, an ultrasonic temperature of 10°C - 25°C, and an ultrasonic frequency of 20 - 40 KHz.

[0019] Further, in step 4, the conditions for ultrasonic treatment are a power of 400 - 500 W, an ultrasonic temperature of 20°C, and an ultrasonic frequency of 40 KHz.

[0020] The present invention provides a method for modifying alcohol-processed soy protein concentrate. Through the synergistic effect of two methods, namely the heating method and the ultrasonic method, the secondary and tertiary structures of soy protein concentrate are fully destroyed, thereby improving the properties of alcohol-processed soy protein concentrate, significantly enhancing the solubility of alcohol-processed soy protein concentrate, providing new ideas for actual production, and expanding the application of alcohol-processed soy protein concentrate in the food industry. Specific Embodiments

[0021] To enable those skilled in the art to better understand the technical solutions and their advantages of the present invention, the present application will be described in detail below, but it is not intended to limit the protection scope of the present invention.

[0022] Example 1

[0023] Dissolve the alcohol-processed soy protein concentrate in deionized water to prepare a soy protein concentrate solution with a mass fraction of 7%. Adjust the pH value of the soy protein concentrate solution to 5, and then add cellulase accounting for 1.5% of the mass of the alcohol-processed soy protein concentrate under the condition of a constant water bath at 40°C, and react for 2 h to obtain a mixed solution. Adjust the pH value of the mixed solution to 7, place the mixed solution in a constant-temperature magnetic stirring water bath pot, carry out water bath heating at 85°C and carry out magnetic stirring. Taking the central temperature as the standard, after reaching the specified temperature, heat for 30 minutes. After the heated mixed solution is cooled to room temperature, carry out ultrasonic treatment: the power is 400 W, the ultrasonic temperature is 20°C, and the ultrasonic frequency is 40 KHz. Freeze-dry the mixed solution after ultrasonic treatment to obtain modified soy protein concentrate powder. The nitrogen solubility index of the protein powder is measured to be 76%.

[0024] Example 2

[0025] Dissolve soy protein concentrate by the alcohol method in deionized water to prepare a soy protein concentrate solution with a mass fraction of 7%. Adjust the pH value of the soy protein concentrate solution to 5, and add cellulase accounting for 1.5% of the mass of the soy protein concentrate by the alcohol method under the condition of a constant temperature water bath at 40 °C, and react for 2 h to obtain a mixed solution. Adjust the pH value of the mixed solution to 7, place the mixed solution in a constant temperature magnetic stirring water bath pot, carry out water bath heating and magnetic stirring at 85 °C, based on the central temperature, after reaching the specified temperature, heat for 30 minutes. After the heated mixed solution is cooled to room temperature, carry out ultrasonic treatment: the power is 500 W, the ultrasonic temperature is 20 °C, and the ultrasonic frequency is 40 KHz. Freeze-dry the ultrasonically treated mixed solution to obtain modified soy protein concentrate powder. The nitrogen solubility index of the protein powder is measured to be 78%.

[0026] Example 3

[0027] Dissolve soy protein concentrate by the alcohol method in deionized water to prepare a soy protein concentrate solution with a mass fraction of 7%. Adjust the pH value of the soy protein concentrate solution to 5, and add cellulase accounting for 1.5% of the mass of the soy protein concentrate by the alcohol method under the condition of a constant temperature water bath at 40 °C, and react for 2 h to obtain a mixed solution. Adjust the pH value of the mixed solution to 7, place the mixed solution in a constant temperature magnetic stirring water bath pot, carry out water bath heating and magnetic stirring at 90 °C, based on the central temperature, after reaching the specified temperature, heat for 30 minutes. After the heated mixed solution is cooled to room temperature, carry out ultrasonic treatment: the power is 400 W, the ultrasonic temperature is 20 °C, and the ultrasonic frequency is 40 KHz. Freeze-dry the ultrasonically treated mixed solution to obtain modified soy protein concentrate powder. The nitrogen solubility index of the protein powder is measured to be 91%.

[0028] Example 4

[0029] Dissolve soy protein concentrate by the alcohol method in deionized water to prepare a soy protein concentrate solution with a mass fraction of 7%. Adjust the pH value of the soy protein concentrate solution to 5, and add cellulase accounting for 1.5% of the mass of the soy protein concentrate by the alcohol method under the condition of a constant temperature water bath at 40 °C, and react for 2 h to obtain a mixed solution. Adjust the pH value of the mixed solution to 7, place the mixed solution in a constant temperature magnetic stirring water bath pot, carry out water bath heating and magnetic stirring at 90 °C, based on the central temperature, after reaching the specified temperature, heat for 30 minutes. After the heated mixed solution is cooled to room temperature, carry out ultrasonic treatment: the power is 500 W, the ultrasonic temperature is 20 °C, and the ultrasonic frequency is 40 KHz. Freeze-dry the ultrasonically treated mixed solution to obtain modified soy protein concentrate powder. The nitrogen solubility index of the protein powder is measured to be 96%.

[0030] The above are only specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of changes or substitutions, which should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims described above.

Claims

1. A modification method of alcohol-processed soy protein concentrate, characterized in that, The method includes the following steps: Step 1: Dissolve the alcohol-processed soy protein concentrate in deionized water to prepare a soy protein concentrate solution with a mass fraction of 3% - 10%. Step 2: Adjust the pH value of the soy protein concentrate solution to 4.5 - 6, add cellulase under the condition of a constant temperature water bath at 35°C - 45°C, and react for 1 - 2 h to obtain a mixed solution; the addition amount of the cellulase is 1% - 2% of the mass of the alcohol-processed soy protein concentrate. Step 3: Adjust the pH value of the mixed solution to 6 - 8, place the mixed solution in a constant temperature magnetic stirring water bath at a temperature of 85°C - 95°C for magnetic stirring, and heat for 20 - 40 minutes. Step 4: Cool the heated mixed solution to room temperature, and then perform ultrasonic treatment. Step 5: Freeze-dry the mixed solution after ultrasonic treatment to obtain the modified soy protein concentrate powder.

2. The method according to claim 1, characterized in that, In the step 1, the mass fraction of the alcohol-processed soy protein concentrate solution is 7%.

3. The method according to claim 1, characterized in that, In the step 2, the pH is adjusted to 5.

4. The method according to claim 1, characterized in that, In the step 2, the constant temperature water bath temperature is 40°C.

5. The method according to claim 1, characterized in that, In the step 2, the addition amount of the cellulase is 1.5% of the mass of the alcohol-processed soy protein concentrate, and the reaction time is 2 h.

6. The method according to claim 1, characterized in that, In the step 3, the pH is adjusted to 7.

7. The method according to claim 1, characterized in that, In the step 3, the water bath temperature is 85°C - 90°C.

8. The method according to claim 1, characterized in that, In the step 3, the heating time is 30 minutes.

9. The method according to claim 1, characterized in that, In the step 4, the conditions of ultrasonic treatment are a power of 300 - 600 W, an ultrasonic temperature of 10°C - 25°C, and an ultrasonic frequency of 20 - 40 KHz.

10. The method according to claim 1, characterized in that, In the step 4, the conditions of ultrasonic treatment are a power of 400 - 500 W, an ultrasonic temperature of 20°C, and an ultrasonic frequency of 40 KHz.