Antioxidant bean protein powder and preparation method thereof

Abstract

The invention belongs to the technical field of food processing, and particularly relates to antioxidant bean protein powder and a preparation method thereof.The preparation method comprises the steps that glycinin and beta-conglycinin powder are weighed according to a certain mass ratio; dissolving glycinin and beta-conglycinin powder in a buffer solution together, and adjusting the pH value to 8.0; adding sodium tripolyphosphate into the solution, stirring and homogenizing; and freeze-drying the homogenized solution to obtain the antioxidant bean protein powder. Based on different proportions of glycinin and beta-conglycinin, the oxidation resistance of a bean protein product can be effectively improved, and the functionality of the bean protein product is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and particularly relates to antioxidant bean protein powder and a preparation method thereof. Background Art

[0002] During food processing, transportation and storage, many chemical reactions occur in food ingredients and products. Among them, the deterioration of food quality caused by protein oxidation has attracted considerable attention. Protein oxidation is a reaction in which certain specific amino acids or polypeptide chains undergo electron removal under the action of reactive oxygen or secondary oxidation products. Studies have found that protein oxidation not only affects the structure of the protein, but also changes its processing properties, technical functions and nutritional aspects, and even has an important impact on human health and safety.

[0003] Soy protein contains balanced essential amino acids and is considered to be a high-quality protein. It also has outstanding foaming, dissolving and emulsifying abilities, so the demand for soy protein as a food ingredient is increasing. However, once soy protein is exposed to free radicals or lipid hydroperoxides produced by lipid oxidation, it is easily oxidized during protein processing and storage. After oxidative attack, soy protein undergoes conformational transformation and forms oxidized aggregates, resulting in reduced solubility, emulsifying ability and interfacial activity of soy protein. So far, there have been many basic studies on improving protein oxidation at home and abroad, but most of them are adding synthetic and natural antioxidants. However, they are costly and affect the digestibility of protein in the gastrointestinal tract. Therefore, it is urgent to develop a bean protein powder with strong antioxidant ability for food addition, so as to improve the antioxidant capacity of food. Summary of the invention

[0004] In order to solve the above technical problems, the present invention provides an antioxidant bean protein powder and a preparation method thereof.

[0005] The present invention is achieved by providing a method for preparing an antioxidant bean protein powder, comprising the following steps:

[0006] Step 1: Weigh soybean globulin and β-conglycinin powders according to a certain mass ratio;

[0007] Step 2: Dissolve the soybean globulin and β-conglycinin powders in a buffer solution and adjust the pH to 8.0;

[0008] Step 3: Add sodium tripolyphosphate to the solution obtained in step 2, stir and homogenize;

[0009] Step 4: freeze-dry the homogenized solution in step 3 to obtain antioxidant bean protein powder.

[0010] Preferably, in step 1, the mass ratio of glycinin to β-conglycinin is 0.5-1.8:1.

[0011] Preferably, in step 2, the buffer is PBS buffer, and the final protein concentration in the buffer is 4 mg / mL.

[0012] Preferably, in step 3, the amount of sodium tripolyphosphate added is 5-8% (m / v).

[0013] Preferably, in step 3, after adding sodium tripolyphosphate, the stirring conditions are: stirring speed 100-500 r / min, stirring time 60-120 min, stirring temperature 25-50°C.

[0014] The invention provides an antioxidant bean protein powder, which is prepared based on the above method.

[0015] Compared with the prior art, the advantages of the present invention are:

[0016] Provided are an antioxidant soy protein powder and a preparation method thereof, which can effectively improve the antioxidant property of the soy protein product and enhance its functionality based on different ratios of soy globulin and β-conglycinin. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The color changes of the oxidized proteins of the three samples of Example 1 (a), Example 2 (b), and Example 3 (c);

[0018] Figure 2 These are electron microscopic images of proteins of three samples of Example 1 (a), Example 2 (b), and Example 3 (c);

[0019] Figure 3 The antioxidant capacity test results of the three samples of Example 1 (a), Example 2 (b), and Example 3 (c) are shown. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0021] β-conglycinin (7S) and glycinin (11S) are the two main components of soy protein, and the 11S / 7S ratio plays a key role in maintaining the functional properties of soy protein. For example, the emulsifying ability of a protein mixture rich in the 7S component is better than that of a protein mixture rich in the 11S component, and the gel strength is positively correlated with the 7S abundance. However, studies have found that phosphorylated 7S and 11S globulins exhibit good antioxidant properties during oxidation. Therefore, the present invention develops a phosphorylated 11S / 7S globulin antioxidant protein powder based on different content ratios.

[0022] Embodiment 1:

[0023] An antioxidant bean protein powder, the preparation method is as follows:

[0024] Step 1: Weigh soybean globulin and β-conglycinin powders at a mass ratio of 0.5:1;

[0025] Step 2: Dissolve the soybean globulin and β-conglycinin powders in PBS buffer. The final protein concentration in the buffer is 4 mg / mL and the pH is adjusted to 8.0.

[0026] Step 3: Add 8% (m / v) sodium tripolyphosphate to the solution obtained in step 2, stir at 30°C for 2 h at a speed of 150 r / min, and homogenize;

[0027] Step 4: freeze-dry the homogenized solution in step 3 to obtain antioxidant bean protein powder.

[0028] Embodiment 2:

[0029] An antioxidant bean protein powder, the preparation method is as follows:

[0030] Step 1: Weigh soybean globulin and β-conglycinin powders at a mass ratio of 0.8:1;

[0031] Step 2: Dissolve the soybean globulin and β-conglycinin powders in PBS buffer. The final protein concentration in the buffer is 4 mg / mL and the pH is adjusted to 8.0.

[0032] Step 3: Add 8% (m / v) sodium tripolyphosphate to the solution obtained in step 2, stir at 30°C for 2 h at a speed of 150 r / min, and homogenize;

[0033] Step 4: freeze-dry the homogenized solution in step 3 to obtain antioxidant bean protein powder.

[0034] Embodiment 3:

[0035] An antioxidant bean protein powder, the preparation method is as follows:

[0036] Step 1: Weigh soybean globulin and β-conglycinin powders in a mass ratio of 1.2:1;

[0037] Step 2: Dissolve the soybean globulin and β-conglycinin powders in PBS buffer. The final protein concentration in the buffer is 4 mg / mL and the pH is adjusted to 8.0.

[0038] Step 3: Add 8% (m / v) sodium tripolyphosphate to the solution obtained in step 2, stir at 30°C for 2 h at a speed of 150 r / min, and homogenize;

[0039] Step 4: freeze-dry the homogenized solution in step 3 to obtain antioxidant bean protein powder.

[0040] 1. Performing protein oxidation reaction on the antioxidant bean protein powder obtained in Examples 1, 2 and 3:

[0041] The protein was oxidized under 10mmol / L malondialdehyde and its color changed as shown in Figure 1 It can be seen that the color of Example 2 is obviously lighter than that of Example 1 and Example 3, reflecting that the antioxidant bean protein powder obtained in Example 2 has the lightest oxidation degree and stronger antioxidant capacity.

[0042] 2. Electron microscope photography was performed on the antioxidant bean protein powder obtained in Examples 1, 2 and 3:

[0043] The morphology and structure of the samples were determined by scanning electron microscopy. Figure 2 It can be seen that the electron microscope photo of Example 1 shows that the protein size distribution is uneven and dense, which may be due to the overlapping aggregation of the protein after oxidation. The structure of Example 2 is relatively loose, the surface becomes rough and gaps appear, which may be because when 11S / 7S is 0.8, the phosphation reaction destroys the non-covalent interaction between molecules, resulting in irregular protein structure breakage, loose protein structure, and internal aggregation structure transformation into a mesh structure. These morphological characteristics indicate that the protein has antioxidant function and has undergone steric modification. Example 3 shows a certain amount of aggregation, which may be related to the 11S / 7S ratio.

[0044] 3. Antioxidant capacity test of the antioxidant bean protein powder obtained in Examples 1, 2 and 3:

[0045] The antioxidant bean protein powders obtained in Examples 1, 2 and 3 were tested for three antioxidant activity indicators: ABTS cation radical scavenging rate, DPPH radical scavenging rate and hydroxyl radical scavenging capacity. Figure 3 It can be seen that the product obtained in Example 2 has strong ABTS cation free radical scavenging rate, DPPH free radical scavenging rate and hydroxyl free radical scavenging ability.

Claims

1. A method for preparing an antioxidant bean protein powder, characterized in that: The following steps are involved: Step 1: Weigh soybean globulin and β-conglycinin powders according to a certain mass ratio; Step 2: Dissolve the soybean globulin and β-conglycinin powders in a buffer solution and adjust the pH to 8.0; Step 3: Add sodium tripolyphosphate to the solution obtained in step 2, stir and homogenize; Step 4: freeze-dry the homogenized solution in step 3 to obtain antioxidant bean protein powder.

2. The method for preparing the antioxidant bean protein powder according to claim 1, characterized in that: In the step 1, the mass ratio of glycinin to β-conglycinin is 0.5-1.8:

1.

3. The method for preparing the antioxidant bean protein powder according to claim 1, characterized in that: In step 2, the buffer is PBS buffer, and the final protein concentration in the buffer is 4 mg / mL.

4. The method for preparing the antioxidant bean protein powder according to claim 1, characterized in that: In step 3, the addition amount of sodium tripolyphosphate is 5-8% (m / v).

5. The method for preparing the antioxidant bean protein powder according to claim 1, characterized in that: In the step 3, after adding sodium tripolyphosphate, the stirring conditions are: stirring speed 100-500 r / min, stirring time 60-120 min, stirring temperature 25-50°C.

6. An antioxidant bean protein powder, characterized in that: It is prepared based on the method described in any one of claims 1 to 5.

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