Preparation method of large yellow croaker egg protein gel under low protein solubility

Abstract

The invention discloses a preparation method of pseudosciaena crocea roe protein gel under low protein solubility. The preparation method comprises the following steps: preparing a gellan gum solution, adding pseudosciaena crocea roe protein powder, stirring at a high speed, and heating to form gel. The large yellow croaker egg protein gel is obtained on the premise of not adjusting the pH value by utilizing the methods of mixing the large yellow croaker egg protein and gellan gum, stirring and swelling at a high speed and performing thermal induction, and the prepared large yellow croaker egg protein gel has the energy storage modulus of 74-315Pa and the water-holding capacity of 97% or above at the frequency of 1Hz. The preparation method is simple in steps and convenient to operate, a traditional method that protein needs to be dissolved after pH adjustment and then gel is formed is changed, and the prepared gel has high nutritional value and good gel characteristics and can be used as novel food gel to be applied to the food industry.

Description

Technical Field

[0001] The invention relates to the technical field of aquatic product processing, and more particularly to a method for preparing a novel fish egg protein gel system, in particular to a method for preparing a large yellow croaker egg protein gel under low protein solubility. Background Art

[0002] Large yellow croaker roe is the main by-product in the processing of large yellow croaker, accounting for about 15% to 25% of the total weight of the fish, and its protein content is as high as about 59.03±0.08% (by dry weight). Large yellow croaker roe is made into feed, and the rest is discarded, which causes great waste of resources and environmental pollution. The main component of large yellow croaker roe protein isolate is vitellogenin, which has high-quality amino acid composition and functional characteristics. However, since the isoelectric point of large yellow croaker roe protein is about pH 6, and the solubility of protein in aqueous solution is only about 10%, it cannot be dissolved only by aqueous solution.

[0003] The paper "Gelation properties and molecular dynamics simulation of thermally induced large yellow croaker (Pseudosciaena crocea) roe protein isolate gels" discloses a method for preparing large yellow croaker roe protein isolate gels by thermal induction. Studies have shown that large yellow croaker roe protein can form protein gels far from the isoelectric point after heat treatment, and its gelation concentration and gelation temperature are relatively low, showing excellent gel properties. Although the protein gel prepared by this method has good properties, the protein concentration used in the preparation process of the protein gel is relatively high, reaching 100 mg / mL. The high separation protein concentration not only means high cost, but also in the process of protein gel formation, it is necessary to first adjust the pH to 7-9 to promote protein dissolution, and then induce the protein to form a gel by heating or other means, and the steps of gel formation are relatively more. CN 116420869 B discloses a method for preparing protein gel by using a protein and polysaccharide composite method. Although this method can form a protein gel with good rheological properties, this method also has the problems of high protein concentration and the need to adjust pH.

[0004] In order to solve the above problems, patent CN 115428935 B discloses a method for preparing a large yellow croaker roe protein isolate / gellan gum composite gel. Although the concentration of the protein used in this method is relatively low, on the one hand, the pH still needs to be adjusted to dissolve the protein during its preparation process. On the other hand, two additives, gellan gum and glucono-δ-lactone, are needed in the gel preparation process. The use of too many additives may reduce the proportion of protein in the gel, limiting its application in some foods. Therefore, it is necessary to develop a method that can induce protein to form a stable gel structure without adjusting pH under conditions of low protein solubility, thereby broadening the application value and application range of the protein itself. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, the present invention provides a method for preparing a large yellow croaker egg protein gel at low protein solubility, wherein large yellow croaker egg protein gel is prepared by adding large yellow croaker egg protein powder to a gellan gum solution, combining high-speed stirring, and without adjusting the pH. The method of the present invention has the characteristics of mild conditions and high production efficiency.

[0006] To achieve the above-mentioned purpose, the present invention first provides a method for preparing a large yellow croaker egg protein gel at low protein solubility, comprising the following steps:

[0007] S1. preparing a gellan gum solution: dissolving gellan gum powder in deionized water, heating in a water bath to completely dissolve the gellan gum, and then cooling to room temperature to obtain a gellan gum solution;

[0008] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution of step (1) to obtain a mixed solution;

[0009] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer and stirring at high speed;

[0010] S4, heat-induced gel formation: heating the mixed solution after stirring in step S3, and leaving it at room temperature to induce the formation of large yellow croaker egg protein / gellan gum gel.

[0011] In one embodiment of the present invention, in step (1), the gellan gum is high acyl gellan gum.

[0012] In one embodiment of the present invention, in step (1), the water bath heating temperature is 60-70° C., the heating time is 20-30 min, and the heating is stirred at a rotation speed of 200-300 rpm for 10-30 min.

[0013] In one embodiment of the present invention, the concentration of the gellan gum solution in step S1 is 3-7 mg / mL.

[0014] In one embodiment of the present invention, the large yellow croaker egg protein described in step S2 is obtained by referring to the protein extraction method in the patent application number 201811034409.X.

[0015] In one embodiment of the present invention, in the mixed solution of step S2, the concentration of large yellow croaker egg protein is 33-37 mg / mL.

[0016] In one embodiment of the present invention, the rotation speed of the high-speed stirring in step S3 is 1000-1200 rpm, and the stirring time is 30 min.

[0017] In one embodiment of the present invention, the heating temperature in step S4 is 85-90° C., the heating time is 30-35 min, and the standing time at room temperature is 10-16 h.

[0018] The invention also discloses a large yellow croaker egg protein gel prepared according to the method.

[0019] In one embodiment of the present invention, the storage modulus of the large yellow croaker egg protein gel at a frequency of 1 Hz is 74 to 315 Pa.

[0020] Beneficial effects:

[0021] 1. Large yellow croaker egg protein has low solubility in water and cannot form gel by simple heating. The present invention adopts a method of adding large yellow croaker egg protein to a high acyl gellan gum solution and stirring at high speed to obtain large yellow croaker egg protein gel without adjusting pH. The prepared large yellow croaker egg protein gel has a storage modulus of 74 to 315 Pa at a frequency of 1 Hz and a water holding capacity of more than 97%, while the untreated large yellow croaker egg protein cannot form gel and has a modulus of only 0.05 Pa, and cannot lock moisture.

[0022] 2. The present invention develops a method for preparing large yellow croaker egg protein gel at low protein solubility. The preparation conditions are mild, the steps are simple, and no harmful substances are generated during the preparation process. The method of the present invention effectively broadens the gel formation conditions of large yellow croaker egg protein.

[0023] 3. The method of the present invention improves the utilization rate of by-products in the processing of large yellow croaker, fully develops and utilizes the functional characteristics of its protein, promotes the high-value development of the large yellow croaker industry, and reduces pollution to the environment.

[0024] 4. The operation process of the present invention is simple, does not require complicated equipment, improves production efficiency, and is suitable for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1This is a diagram showing the interaction mechanism of large yellow croaker egg protein alone and with gellan gum during high-speed stirring and heating.

[0026] Figure 2 The appearance of large yellow croaker egg protein and large yellow croaker egg protein / gellan gum gel prepared in Examples 1 to 3 and Comparative Examples 1 to 3.

[0027] Figure 3 The rheological properties of large yellow croaker egg protein and large yellow croaker egg protein / gellan gum gel in Examples 1 to 3.

[0028] Figure 4 The rheological properties of the large yellow croaker egg protein / gellan gum gel in Comparative Examples 1 to 3. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to these embodiments.

[0030] The experimental methods used in the examples of the present invention are conventional methods unless otherwise specified. The materials used in the examples are commercially available unless otherwise specified.

[0031] The high acyl gellan gum used in the examples of the present invention was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a product number of G875406. The low acyl gellan gum used in Comparative Example 3 was purchased from Shanghai Maclean Biochemical Technology Co., Ltd., with a product number of G821481.

[0032] The large yellow croaker egg protein in the specific embodiment of the present invention is obtained by referring to the extraction method of egg yolk protein in Example 1 of the patent application number 201811034409.X.

[0033] Storage modulus test method of gel:

[0034] Refer to Yan, JN, Shang, WH, Zhao, J., et al. Gelation and microstructural properties of protein hydrolysates from trypsin-treated male gonad ofscallop (Patinopecten yessoensis) modified by κ-Carrageenan / K + [J]. Food Hydrocolloids, 2019, 91, 182-189 The method uses a rheometer to detect the storage modulus G' of the gel.

[0035] Method for determining the water holding capacity of gel:

[0036] Place 1 g of gel sample in a 10 mL centrifuge tube, then centrifuge at 6000×g for 10 min. Use filter paper to absorb the centrifuged water and weigh it. Calculate the water holding capacity according to the following formula: water holding capacity = (total mass of gel and centrifuge tube after centrifugation - mass of centrifuge tube) / (total mass of gel and centrifuge tube before centrifugation - mass of centrifuge tube)×100%.

[0037] Example 1

[0038] A method for preparing large yellow croaker egg protein gel at low protein solubility comprises the following steps:

[0039] S1. Prepare gellan gum solution: dissolve high acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 3 mg / mL, heat in a water bath at 60° C. for 20 min, stir at 200 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0040] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 37 mg / mL;

[0041] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer, and stirring at high speed at 1000 rpm for 30 min;

[0042] S4, heat-induced gel formation: the mixed solution described in step S3 is heated at 85° C. for 30 min, and placed at room temperature for 14 h to induce the formation of large yellow croaker egg protein / gellan gum gel.

[0043] The gel prepared in this example has a storage modulus value of 315 Pa and a water holding capacity of 97.8% under a frequency of 1 Hz.

[0044] Example 2

[0045] A method for preparing large yellow croaker egg protein gel at low protein solubility comprises the following steps:

[0046] S1. Prepare gellan gum solution: dissolve high acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 5 mg / mL, heat in a water bath at 65° C. for 25 min, stir at 250 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0047] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 35 mg / mL;

[0048] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer, and stirring at high speed at 1100 rpm for 30 min;

[0049] S4, heat-induced gel formation: the mixed solution described in step S3 is heated at 85° C. for 30 min, and placed at room temperature for 16 h to induce the formation of large yellow croaker egg protein / gellan gum gel.

[0050] The gel prepared in this example has a storage modulus value of 167 Pa and a water holding capacity of 98.3% under a frequency of 1 Hz.

[0051] Example 3

[0052] A method for preparing large yellow croaker egg protein gel at low protein solubility comprises the following steps:

[0053] S1. Prepare gellan gum solution: dissolve high acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 7 mg / mL, heat in a water bath at 70° C. for 30 min, stir at 300 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0054] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 33 mg / mL;

[0055] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer and stirring at high speed at 1200 rpm for 30 min;

[0056] S4, heat-induced gel formation: heating the mixed solution described in step S3 at 90° C. for 30 min, and leaving it at room temperature for 10 h to induce the formation of large yellow croaker egg protein / gellan gum gel;.

[0057] The gel prepared in this example has a storage modulus value of 74 Pa and a water holding capacity of 99.4% under a frequency of 1 Hz.

[0058] Comparative Example 1

[0059] A method for preparing large yellow croaker egg protein gel comprises the following steps:

[0060] S1. Prepare gellan gum solution: dissolve high acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 2 mg / mL, heat in a water bath at 70° C. for 30 min, stir at 300 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0061] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 28 mg / mL;

[0062] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer, and stirring at a constant speed of 1200 rpm for 30 min;

[0063] S4, heat-induced gel formation: heating the mixed solution described in step S3 at 85° C. for 30 min, and leaving it at room temperature for 10 h to induce the formation of large yellow croaker egg protein / gellan gum gel;

[0064] The gel prepared in Comparative Example 1 has a storage modulus value of 32 Pa and a water holding capacity of 98.3% under a frequency of 1 Hz.

[0065] Comparative Example 2

[0066] A method for preparing large yellow croaker egg protein gel comprises the following steps:

[0067] S1. Prepare gellan gum solution: dissolve high acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 3 mg / mL, heat in a water bath at 70° C. for 30 min, stir at 300 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0068] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 37 mg / mL;

[0069] S3, uniform stirring: placing the mixed solution described in step S2 on a magnetic stirrer, and uniformly stirring at 200 rpm for 30 min;

[0070] S4, heat-induced gel formation: the mixed solution described in step S3 is heated at 85° C. for 30 min, and placed at room temperature for 10 h to induce the formation of large yellow croaker egg protein / gellan gum gel.

[0071] The gel prepared in Comparative Example 2 has a storage modulus value of 54 Pa and a water holding capacity of 98.0% under a frequency of 1 Hz.

[0072] Comparative Example 3

[0073] A method for preparing large yellow croaker egg protein gel comprises the following steps:

[0074] S1. Prepare gellan gum solution: dissolve low acyl gellan gum powder in deionized water to make the concentration of gellan gum solution 3 mg / mL, heat in a water bath at 70° C. for 30 min, stir at 300 rpm while heating, until the gellan gum is completely dissolved, and then cool to room temperature;

[0075] S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution obtained in step S1 to obtain a mixed solution, wherein the concentration of large yellow croaker egg protein in the mixed solution is 37 mg / mL;

[0076] S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer and stirring at high speed at 1200 rpm for 30 min;

[0077] S4, heat-induced gel formation: heating the mixed solution described in step S3 at 85° C. for 30 min, and leaving it at room temperature for 10 h to induce the formation of large yellow croaker egg protein / gellan gum gel;

[0078] The gel prepared in Comparative Example 3 has a storage modulus value of 8 Pa under a frequency of 1 Hz, and is in a flowing state and cannot lock in moisture.

[0079] Table 1 Rheological properties and water holding capacity of large yellow croaker egg protein gel

[0080]

[0081] The rheological properties and water holding capacity of the gels prepared in the examples of the present invention and the comparative examples were analyzed respectively.

[0082] Figure 1 The diagram shows the interaction mechanism of large yellow croaker egg protein alone and with gellan gum during high-speed stirring and heating. Without the addition of gellan gum, large yellow croaker egg protein cannot be dissolved in water due to its poor solubility, forming a precipitate. After high-temperature heating, the cross-linking between protein molecules is promoted to form macromolecular aggregates, but no gel can be formed. However, after adding it to the gellan gum solution, during the high-speed stirring process, the protein molecules and the gellan gum molecules are fully combined, and the gellan gum molecules are negatively charged. The two form a complex through electrostatic interaction. At the same time, the presence of gellan gum limits the aggregation between protein molecules, so that a stable gel network structure can be formed after heating.

[0083] The appearance of large yellow croaker egg protein / gellan gum gel is as follows Figure 1As shown, large yellow croaker egg protein represents large yellow croaker egg protein without gellan gum (concentration is 40 mg / mL), and Examples 1 to 3 represent large yellow croaker egg protein / gellan gum gels prepared by Examples 1 to 3, respectively. Comparative Examples 1 to 3 represent large yellow croaker egg protein / gellan gum gels prepared by Comparative Examples 1 to 3, respectively. The large yellow croaker egg protein / gellan gum gel prepared by the present invention presents a non-flowing gel form and has no insoluble substances, but the large yellow croaker egg protein alone does not form a gel, and there are more insoluble precipitates inside. Except for Comparative Example 2, Comparative Example 1 presents a slightly flowing state, and Comparative Example 3 presents a flowing state. This result shows that the large yellow croaker egg protein gel can be effectively prepared under the condition of low protein solubility by the method of this patent.

[0084] Figure 3 The frequency scanning curve results of large yellow croaker egg protein and large yellow croaker egg protein / gellan gum gel are shown in Figure 1. Large yellow croaker egg protein represents large yellow croaker egg protein (concentration is 40 mg / mL) without gellan gum, and Examples 1 to 3 represent large yellow croaker egg protein / gellan gum gel prepared in Examples 1 to 3, respectively. The results show that the gel storage modulus G' obtained in this patent is significantly improved compared with the untreated large yellow croaker egg protein, which is 1480 to 6300 times. These results further prove that the method of this patent can prepare large yellow croaker egg protein gel under low protein solubility conditions, and the gel prepared in this patent has good rheological properties.

[0085] Figure 4 The frequency scanning curve results of large yellow croaker egg protein / gellan gum gel, comparative examples 1 to 3 respectively represent large yellow croaker egg protein / gellan gum gel prepared in comparative examples 1 to 3, and the results show that the storage modulus G' of the gel obtained in the comparative example is lower than that in the embodiment, which is only 8 to 54 Pa. These results further prove that the gel prepared in this patent has good rheological properties.

[0086] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing large yellow croaker egg protein gel at low protein solubility, characterized in that, The steps include: S1. preparing a gellan gum solution: dissolving gellan gum powder in deionized water, heating in a water bath to completely dissolve the gellan gum, and then cooling to room temperature to obtain a gellan gum solution; S2, adding large yellow croaker egg protein: adding large yellow croaker egg protein powder to the gellan gum solution of step (1) to obtain a mixed solution; S3, high-speed stirring: placing the mixed solution described in step S2 on a magnetic stirrer and stirring at high speed; S4, heat-induced gel formation: heating the mixed solution after stirring in step S3, and leaving it at room temperature to induce the formation of large yellow croaker egg protein / gellan gum gel.

2. The preparation method according to claim 1, characterized in that: In step (1), the gellan gum is high acyl gellan gum.

3. The preparation method according to claim 1, characterized in that: In step (1), the water bath heating temperature is 60-70° C., the heating time is 20-30 min, and the mixture is stirred at a rotation speed of 200-300 rpm for 10-30 min during heating.

4. The preparation method according to claim 1, characterized in that: The concentration of the gellan gum solution in step S1 is 3-7 mg / mL.

5. The preparation method according to claim 1, characterized in that: In the mixed solution described in step S2, the concentration of large yellow croaker egg protein is 33-37 mg / mL.

6. The preparation method according to claim 1, characterized in that: The rotation speed of the high-speed stirring in step S3 is 1000-1200 rpm, and the stirring time is 30 min.

7. The preparation method according to claim 1, characterized in that: The heating temperature in step S4 is 85-90° C., the heating time is 30-35 min, and the standing time at room temperature is 10-16 h.

8. Large yellow croaker egg protein gel prepared according to the method according to any one of claims 1 to 7.

9. The large yellow croaker egg protein gel according to claim 8, characterized in that The storage modulus of the large yellow croaker egg protein gel at a frequency of 1 Hz is 74-315 Pa.

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