Method for improving emulsifying capacity of silkworm pupa protein

Abstract

The invention discloses a method for improving emulsifying capacity of silkworm pupa protein, which comprises the following steps: mixing silkworm pupa protein with deionized water to form dispersion liquid, then adjusting the pH value to 11-12, heating to 45-65 DEG C, keeping for 30 minutes, then quickly cooling to room temperature, adjusting the pH value to 7, and carrying out spray drying to obtain modified silkworm pupa protein. The solubility of the modified silkworm pupa protein can reach 70% or above, the emulsifying activity is 5-5.5 m < 2 > / g, the emulsifying stability is 78-84 minutes, and the modified silkworm pupa protein is obviously superior to unmodified protein. According to the method for improving the emulsifying capacity of the silkworm pupa protein, the solubility and the emulsifying property of the silkworm pupa protein are effectively improved, the application range of the silkworm pupa protein is widened, and the method can be widely applied to the functional application fields of food industrialization and medicines.

Description

Technical Field

[0001] The invention belongs to the field of medical technology, and particularly relates to a method for improving the emulsification ability of silkworm pupa protein. Background Art

[0002] Silkworm pupa protein is a byproduct of the silk reeling industry. It is a complete protein with a ratio of essential amino acids to non-essential amino acids of 0.73, which is higher than the amino acid pattern of the ideal protein proposed by WHO / FAO (0.6). At present, silkworm pupa protein has been found to have antioxidant, anti-tumor and immune-enhancing biological activities. Due to the thermal processing of the silk reeling process, silkworm pupa protein is denatured, resulting in low protein solubility and poor emulsification ability, which greatly limits the food industrialization and functional application of silkworm pupa protein in the medical field.

[0003] The Chinese patent application number CN202311522718.2 describes a method for improving the foaming property of soy protein by combining pH shift with heat treatment. This method extracts soy protein isolate by the traditional alkali dissolution and acid precipitation method, then performs pH shift treatment on the protein, and then performs heat treatment, and then adjusts the pH of the solution to neutral. This method can effectively change the structure of soy protein and improve its foaming property, thereby broadening the application of soy protein in the food industry. However, the patent mainly focuses on the improvement of the foaming property of soy protein, and does not directly involve the improvement of the solubility and emulsification ability of silkworm pupa protein.

[0004] In addition, a study explored the effect of pH shift combined with heat treatment on the emulsification properties of soy protein isolate. The study found that pH shift combined with heat treatment can significantly improve the emulsification activity of soy protein isolate, but long-term treatment will reduce the emulsification stability. This shows that the combination of pH shift and heat treatment has a significant effect on the emulsification properties of protein, but the study did not specifically target silkworm pupa protein.

[0005] Therefore, developing a method to improve the emulsifying ability of silkworm pupa protein is of great significance for the application of silkworm pupa protein in food industrialization and medicine. Summary of the invention

[0006] The present invention aims to provide a method for improving the emulsification ability of silkworm pupa protein, which improves the physicochemical and functional activities of the protein by combining pH shift and heating, which is superior to the improvement of the solubility and emulsification function of the protein by a single treatment method.

[0007] In order to solve the above problems, the technical solution adopted by the present invention is as follows:

[0008] A method for improving the emulsification ability of silkworm pupa protein comprises the following steps:

[0009] a. Mix the silkworm pupa protein with deionized water at a solid-liquid ratio of 2% to form a uniform silkworm pupa protein dispersion;

[0010] b. The pH of the silkworm pupa protein dispersion was adjusted to 11 to 12, stirred for 2 hours, heated at a temperature range of 45 to 65 ° C for 30 minutes, and then rapidly cooled to room temperature to obtain a silkworm pupa protein solution;

[0011] c. The pH of the silkworm pupa protein solution was adjusted to 7, and the stirring was continued for 1 hour, and then dried to obtain modified silkworm pupa protein.

[0012] Furthermore, the silkworm pupa protein is prepared from defatted and pulverized silkworm pupa raw materials by an alkali dissolution and acid precipitation method, wherein the alkali dissolution and acid precipitation method includes using a pH 8 NaOH solution to dissolve the silkworm pupa protein raw material, and then using HCl to adjust the pH to 4.5 to precipitate the protein.

[0013] Furthermore, the drying process is carried out by a spray drying method, and the conditions of the spray drying process are that the inlet air temperature is set to 140±5°C, the outlet temperature is set to 80±5°C, and the feed flow rate is set to 6mL / min.

[0014] Furthermore, the solubility of the modified silkworm pupa protein is above 70%, the emulsification activity is 5 to 5.5 m2 / g, and the emulsification stability is 78 to 84 minutes.

[0015] Furthermore, the material-liquid ratio refers to the ratio of the mass of the silkworm pupa protein raw material to the volume of deionized water.

[0016] The beneficial effects of the present invention are as follows: the present invention provides a method for improving the emulsification ability of silkworm pupa protein, and the silkworm pupa protein is subjected to a heat-assisted pH shift treatment. In the process of the protein being treated with extreme alkalinity and then restored to a neutral environment, the protein structure unfolds and refolds, making the protein structure relatively loose, thereby improving the solubility and emulsification of the protein. In addition, heat treatment is a very common physical processing technology currently used in food processing technology research, which can assist in improving the flexibility of protein refolding. The present invention uses a combination of pH shift and heating to improve the physical and chemical as well as functional activity of the protein, which is better than a single treatment method for improving the solubility and emulsification function of the protein. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0018] Figure 1 A schematic diagram showing a comparison of protein solubility in a method for improving the emulsification ability of silkworm pupa protein according to the present invention;

[0019] Figure 2This is a schematic diagram comparing the emulsifying activity (EAI) and emulsifying stability (ESI) of a protein in a method for improving the emulsifying ability of silkworm pupa protein according to the present invention. DETAILED DESCRIPTION

[0020] In the following detailed description of the embodiments, some specific details are proposed to allow those skilled in the art to have a more thorough understanding of the present invention. However, it should be clear to those skilled in the art that the implementation of the present invention may not be limited to only these specific details. In other cases, well-known technical solutions are not described in detail to avoid ambiguity in the relevant details of the following embodiments.

[0021] Embodiment 1:

[0022] Preparation method of modified silkworm pupa protein:

[0023] a. The silkworm pupae were defatted and crushed with n-hexane, and then dissolved in a pH 8 NaOH solution at a material-liquid ratio of 1:14 for 4 hours, and then adjusted to pH 4.5 with HCl to obtain silkworm pupae protein;

[0024] b. Mix the silkworm pupa protein with deionized water at a solid-liquid ratio of 2% to form a uniform silkworm pupa protein dispersion;

[0025] c. The pH of the silkworm pupa protein dispersion was adjusted to 11, stirred for 2 hours to ensure uniform mixing, heated at 65 ° C for 30 minutes, and then rapidly cooled to room temperature to obtain a silkworm pupa protein solution;

[0026] d. The pH of the silkworm pupa protein solution was adjusted to 7, stirring was continued for 1 hour, and then spray-dried. The drying conditions were an inlet air temperature of 140±5°C, an outlet temperature of 80±5°C, and a feed flow rate of 6mL / min to obtain modified silkworm pupa protein.

[0027] Embodiment 2:

[0028] The preparation method of this embodiment is the same as that of embodiment 1, but in step c, the pH of the silkworm pupa protein dispersion is adjusted to 12 and heated at 45° C. for 30 minutes.

[0029] The present invention carries out the determination of solubility, emulsification activity and emulsification stability of the prepared modified silkworm pupa protein as follows:

[0030] 1. Test methods and conditions

[0031] 1. Solubility test: Weigh an appropriate amount of modified silkworm pupa protein, add deionized water, stir evenly, separate the undissolved protein residue by high-speed centrifugation, and take the supernatant for protein concentration determination.

[0032] 2. Emulsification activity (EAI) and emulsification stability (ESI) test: The modified silkworm pupa protein solution was mixed with vegetable oil, emulsified using a high-speed stirrer, and then the turbidity and stability of the emulsion were measured.

[0033] 2. Test Results

[0034] 1. Test results of Example 1

[0035] (1) Solubility test results: Figure 1 As shown, the solubility of modified silkworm pupa protein (SPPM1) in deionized water is significantly improved to 70%, which is 30% higher than that of unmodified silkworm pupa protein (SPP). The solubility bar of SPPM1 is significantly higher than that of SPP, indicating that the modification treatment effectively improves the solubility of the protein.

[0036] (2) Emulsifying activity (EAI) and emulsifying stability (ESI) test results

[0037] like Figure 2 As shown in the data, the emulsifying activity and emulsifying stability of the modified silkworm pupa protein (SPPM1) were improved. The emulsifying activity (EAI) increased from 0.5㎡ / g of SPP to more than 5.5㎡ / g, and the emulsifying stability (ESI) increased from 40 minutes of SPP to 80 minutes, demonstrating that the emulsifying performance of SPPM1 is significantly better than that of SPP, proving the effectiveness of the modification treatment in improving the emulsifying performance.

[0038] 2. Test results of Example 2

[0039] (1) Solubility test results: Figure 1 As shown in the figure, the solubility of modified silkworm pupa protein (SPPM2) in deionized water is significantly improved to more than 70%, which is 30% higher than the solubility of unmodified silkworm pupa protein (SPP) and slightly higher than SPPM1. The solubility bar of SPPM2 is higher than that of SPP and SPPM1, indicating that the modification treatment further effectively improves the solubility of the protein.

[0040] (2) Emulsifying activity (EAI) and emulsifying stability (ESI) test results

[0041] like Figure 2 As shown in the figure, the emulsifying activity and emulsifying stability of the modified silkworm pupa protein (SPPM2) were improved. The emulsifying activity (EAI) increased from 0.5㎡ / g of SPP to 6㎡ / g, and the emulsifying stability (ESI) increased from 40 minutes of SPP to 78 minutes, demonstrating that the emulsifying performance of SPPM2 is significantly better than that of SPP, proving the effectiveness of the modification treatment in improving the emulsifying performance.

[0042] The test results of the examples show that, compared with silkworm pupa protein (SPP), the solubility, emulsification activity and emulsification stability of the modified silkworm pupa protein are greatly improved, which provides important technical support for the application of silkworm pupa protein in the food industry and the medical field.

[0043] Based on the above ideal embodiments of the present invention, the relevant staff can make various changes and modifications without departing from the technical concept of the present invention through the above description. The technical scope of the present invention is not limited to the contents of the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A method for improving the emulsification ability of silkworm pupa protein, characterized in that: The following steps are involved: a. Mix the silkworm pupa protein with deionized water at a solid-liquid ratio of 2% to form a uniform silkworm pupa protein dispersion; b. The pH of the silkworm pupa protein dispersion was adjusted to 11 to 12, stirred for 2 hours, heated at a temperature range of 45 to 65 ° C for 30 minutes, and then rapidly cooled to room temperature to obtain a silkworm pupa protein solution; c. The pH of the silkworm pupa protein solution was adjusted to 7, and the stirring was continued for 1 hour, and then dried to obtain modified silkworm pupa protein.

2. A method for improving the emulsification ability of silkworm pupa protein according to claim 1, characterized in that: The silkworm pupa protein is prepared from defatted and pulverized silkworm pupa raw materials by an alkali dissolution and acid precipitation method, wherein the alkali dissolution and acid precipitation method includes using a pH 8 NaOH solution to dissolve the silkworm pupa protein raw materials, and then using HCl to adjust the pH to 4.5 to precipitate the protein.

3. The method for improving the emulsification ability of silkworm pupa protein according to claim 1, characterized in that: The drying process is carried out by a spray drying method, and the conditions for the spray drying process are that the inlet air temperature is set to 140±5°C, the outlet temperature is set to 80±5°C, and the feed flow rate is set to 6mL / min.

4. The method for improving the emulsification ability of silkworm pupa protein according to claim 1, characterized in that: The solubility of the modified silkworm pupa protein is above 70%, the emulsification activity is 5 to 5.5 m2 / g, and the emulsification stability is 78 to 84 minutes.

5. The method for improving the emulsification ability of silkworm pupa protein according to claim 1, characterized in that: The material-liquid ratio refers to the ratio of the mass of the silkworm pupa protein raw material to the volume of deionized water.

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