Method for preparing soybean protein isolate-polyphenol compound based on microwave synergistic pH migration treatment
Through microwave synergistic pH offset treatment and quercetin addition, the soy protein isolate-polyphenol complex is formed, which solves the problem of insufficient emulsification characteristics of soy protein isolate, significantly improves its emulsification activity and stability, and broadens its application in the food field.
Patent Information
- Application Number
- CN202510328905.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-20
- Publication Date
- 2025-05-16
AI Technical Summary
The prior art is difficult to effectively improve the emulsification characteristics of soy protein isolate, which limits its application in the food field.
Soy protein isolate is treated with microwave synergistic pH offset and assist in the addition of quercetin, thereby forming a soy protein isolate-polyphenol complex, significantly improving its emulsification characteristics.
Through microwave synergistic pH offset treatment and quercetin addition, the emulsification activity and emulsification stability of soy protein isolate-polyphenol complexes have been significantly improved, broadening their application potential in the food field.
Smart Images
Figure HDA0005319704620000011
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of food processing and manufacturing, and particularly relates to a method for preparing a soy protein isolate-polyphenol complex based on microwave-assisted pH shift treatment. Background Art
[0002] Soy protein isolate is rich in a variety of essential amino acids. Its composition is close to that of the human body and is easily absorbed and utilized by the human body. It is a natural surfactant with rich nutritional value and does not contain cholesterol. It is one of the few varieties of plant protein that can replace animal protein. It is separated from soybeans by alkali dissolution and acid precipitation, and its protein content is as high as more than 90%. In addition, soy protein isolate removes the original nutritional inhibitor trypsin inhibitor in soybeans, effectively reducing problems such as indigestion. As one of the most common plant protein raw materials, soy protein isolate is widely used in the field of food processing because of its excellent functional properties, such as good emulsification, gelling properties, and foaming properties.
[0003] Protein modification through the interaction of protein molecules with other chemical components of food (such as polyphenolic compounds) has been identified as a promising approach to create novel protein conjugates with enhanced antioxidant activity. The interaction between protein and polyphenols is mainly achieved through non-covalent interactions (hydrogen bonds, electrostatic interactions, and hydrophobic interactions, etc.) and covalent interactions. These interactions can not only change the structure of proteins and thus affect their functional properties, but also affect the biological activities of polyphenols, such as the antioxidant and antibacterial properties of polyphenols. Protein-polyphenol complexes have important application value in food processing, broadening their application range in food, pharmaceuticals and other fields.
[0004] There are many ways to modify soy protein, including microwave treatment, pH shift treatment, ultrasonic treatment, heat treatment, covalent bonding, enzymatic modification, etc. Among them, microwave treatment mainly uses microwave energy to destroy the non-covalent bonds that maintain the spatial structure of soy protein, unfold the protein molecular structure, and thus change its functional properties. Microwave treatment has received widespread attention in recent years as a fast, efficient modification method that does not require the addition of chemical reagents. In addition, many studies have shown that microwave treatment of soy protein and protein-polyphenol composites can significantly improve the emulsification properties of protein-based products. pH shift treatment is also a method commonly used to modify soy protein. By adjusting the pH value of the protein solution to an acidic or alkaline range far away from its isoelectric point, the protein is denatured, thereby changing its structural and functional properties.
[0005] Quercetin is a natural flavonoid compound that is widely distributed in the plant kingdom. It mostly exists in the form of glycosides and can be obtained by acid hydrolysis. Quercetin has multiple pharmacological effects such as antioxidant, anti-inflammatory, antiviral, anti-tumor, hypoglycemic, lipid-lowering, and immunomodulatory. In the food industry, quercetin is used as an antioxidant and food additive to improve the stability and nutritional value of food. In the medical field, it can be used to prevent and treat a variety of diseases.
[0006] Therefore, the present invention will use microwaves to coordinate pH shift to treat soy protein isolate, and at the same time assist in adding quercetin, thereby giving soy protein excellent emulsifying properties. This will further broaden the application of protein-polyphenol complexes in the food field, in line with the general trend of "Healthy China 2030", and is expected to further improve the development and application of soy protein in the food field. Summary of the invention
[0007] The purpose of the present invention is to provide a method for preparing a soy protein isolate-polyphenol complex based on microwave synergistic pH shift treatment, which utilizes microwave synergistic pH shift to treat soy protein isolate and simultaneously assists in adding quercetin to achieve the modification of soy protein and give soy protein excellent emulsifying properties, thereby providing a theoretical basis for preparing protein-based foods with excellent emulsifying properties.
[0008] The preparation method of the present invention is as follows:
[0009] (1) Defatted soybean meal was mixed with deionized water, the pH value was adjusted to 8.0, stirred with a magnetic stirrer for 2 hours, and then centrifuged. The supernatant was collected and the pH was adjusted, and hydrated at 4°C for 12 hours. The supernatant was centrifuged again to obtain a precipitate, which was washed and dialyzed for multiple times, and the pH value of the solution was adjusted to 7.5 and freeze-dried to finally obtain soy protein isolate powder;
[0010] (2) dissolving the soy protein isolate powder described in step (1) in phosphate buffer (pH 7.4, 10 mM), stirring with a magnetic stirrer at room temperature for 2 h to fully dissolve it, and hydrating at 4° C. overnight to prepare a soy protein isolate solution;
[0011] (3) adjusting the pH of the final soy protein isolate solution in step (2) to 2.0-3.0 with 2M HCl;
[0012] (4) subjecting the protein solution in step (3) to microwave treatment, and continuously stirring during the microwave treatment to ensure that the solution is evenly heated;
[0013] (5) dissolving quercetin in deionized water, stirring evenly, and slowly adding it to the microwave-treated protein solution and stirring for 2 h to form a soy protein isolate-polyphenol complex;
[0014] (6) The pH value of the soy protein isolate-polyphenol complex described in step (5) is adjusted to 6.5-7.5 using 2M NaOH for 30 minutes to further stabilize the structure of the complex, and then the sample is dialyzed and freeze-dried to obtain the soy protein isolate-polyphenol complex modified by microwave synergistic pH shift.
[0015] It is further defined that the mixing ratio of the defatted soybean meal and deionized water in step (1) is 1:10 (w / w), and the dialysis cut-off molecular weight is 10,000Da;
[0016] It is further defined that the concentration of the soy protein isolate solution in step (2) is 30-50 mg / mL;
[0017] It is further defined that the pH value in step (3) is adjusted to 2.5;
[0018] It is further defined that the microwave treatment conditions in step (4) are 500-700W, 20-30min;
[0019] It is further defined that the final concentration of quercetin in step (5) is 1.6-1.8%;
[0020] It is further defined that the pH value in step (6) is finally adjusted to 7.0 and the dialysis cut-off molecular weight is 7,000 Da.
[0021] Beneficial effects: Compared with single soy protein isolate and its products, the soy protein isolate-polyphenol complex prepared by the present invention has significantly improved emulsification properties. The present invention uses microwaves to coordinate pH shift to treat soy protein isolate, and at the same time assists in adding flavonoid compound quercetin, which can create better economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1 This is the process diagram of soy protein isolate-polyphenol complex. Specific embodiments
[0023] The defatted soybean meal used in the present invention was purchased from Heilongjiang Beidahuang Group, and other auxiliary materials were purchased from laboratory cooperative merchants. The specific embodiments of the present invention are described in detail below.
[0024] Example 1.
[0025] A method for preparing a soy protein isolate-polyphenol complex based on microwave-assisted pH shift treatment, characterized in that the preparation method is as follows:
[0026] (1) defatted soybean meal and deionized water were mixed at a ratio of 1:10 (w / w), the pH value was adjusted to 8.0, stirred with a magnetic stirrer for 2 hours, and then centrifuged. The supernatant was collected and the pH was adjusted, and hydrated at 4°C for 12 hours. The supernatant was centrifuged again to obtain a precipitate, which was washed and dialyzed for multiple times (molecular weight cutoff of 10,000 Da), the pH value of the solution was adjusted to 7.5, and freeze-dried to finally obtain soy protein isolate powder;
[0027] (2) dissolving the soy protein isolate powder described in step (1) in phosphate buffer (pH 7.4, 10 mM), stirring with a magnetic stirrer at room temperature for 2 h to fully dissolve it, and hydrating at 4° C. overnight to prepare a soy protein isolate solution with a concentration of 30 mg / mL;
[0028] (3) adjusting the pH of the final soy protein isolate solution in step (2) to 2.5 with 2M HCl;
[0029] (4) treating the protein solution in step (3) with microwaves at 500 W for 30 min. During the microwave treatment, stirring was continued to ensure that the solution was evenly heated.
[0030] (5) dissolving quercetin in deionized water, stirring evenly, and slowly adding it into the microwave-treated protein solution and stirring for 2 h to form a soy protein isolate-polyphenol complex;
[0031] (6) The pH value of the soy protein isolate-polyphenol complex described in step (5) is adjusted back to 7.0 using 2M NaOH for 30 minutes to further stabilize the structure of the complex, and then the sample is dialyzed and freeze-dried (dialysis molecular weight cutoff is 7,000Da) to obtain a soy protein isolate-polyphenol complex modified by microwave synergistic pH shift.
[0032] Example 2.
[0033] A method for preparing a soy protein isolate-polyphenol complex based on microwave-assisted pH shift treatment, characterized in that the preparation method is as follows:
[0034] (1) defatted soybean meal and deionized water were mixed at a ratio of 1:10 (w / w), the pH value was adjusted to 8.0, stirred with a magnetic stirrer for 2 hours, and then centrifuged. The supernatant was collected and the pH was adjusted, and hydrated at 4°C for 12 hours. The supernatant was centrifuged again to obtain a precipitate, which was washed and dialyzed for multiple times (molecular weight cutoff was 10,000 Da), the pH value of the solution was adjusted to 7.5, and freeze-dried to finally obtain soy protein isolate powder;
[0035] (2) dissolving the soy protein isolate powder described in step (1) in phosphate buffer (pH 7.4, 10 mM), stirring with a magnetic stirrer at room temperature for 2 h to fully dissolve it, and hydrating at 4° C. overnight to prepare a soy protein isolate solution with a concentration of 50 mg / mL;
[0036] (3) adjusting the pH of the final soy protein isolate solution in step (2) to 2.5 with 2M HCl;
[0037] (4) subjecting the protein solution in step (3) to microwave treatment at 600 W for 25 min. During the microwave treatment, continuous stirring was performed to ensure that the solution was evenly heated.
[0038] (5) dissolving quercetin in deionized water, stirring evenly, and slowly adding it into the microwave-treated protein solution and stirring for 2 h to form a soy protein isolate-polyphenol complex;
[0039] (6) The pH value of the soy protein isolate-polyphenol complex described in step (5) was adjusted back to 7.0 using 2M NaOH for 30 minutes to further stabilize the structure of the complex, and then the sample was dialyzed and freeze-dried (dialysis molecular weight cutoff was 7,000Da) to obtain the soy protein isolate-polyphenol complex modified by microwave synergistic pH shift.
[0040] Example 3.
[0041] A method for preparing a soy protein isolate-polyphenol complex based on microwave-assisted pH shift treatment, characterized in that the preparation method is as follows:
[0042] (1) defatted soybean meal and deionized water were mixed at a ratio of 1:10 (w / w), the pH value was adjusted to 8.0, stirred with a magnetic stirrer for 2 hours, and then centrifuged. The supernatant was collected and the pH was adjusted, and hydrated at 4°C for 12 hours. The supernatant was centrifuged again to obtain a precipitate, which was washed and dialyzed for multiple times (molecular weight cutoff of 10,000 Da), the pH value of the solution was adjusted to 7.5, and freeze-dried to finally obtain soy protein isolate powder;
[0043] (2) dissolving the soy protein isolate powder described in step (1) in phosphate buffer (pH 7.4, 10 mM), stirring with a magnetic stirrer at room temperature for 2 h to fully dissolve it, and hydrating at 4° C. overnight to prepare a soy protein isolate solution with a concentration of 40 mg / mL;
[0044] (3) adjusting the pH of the final soy protein isolate solution in step (2) to 2.5 with 2M HCl;
[0045] (4) treating the protein solution in step (3) with microwaves at 700 W for 20 min. During the microwave treatment, stirring was continued to ensure that the solution was evenly heated.
[0046] (5) dissolving quercetin in deionized water, stirring evenly, and slowly adding it into the microwave-treated protein solution and stirring for 2 h to form a soy protein isolate-polyphenol complex;
[0047] (6) The pH value of the soy protein isolate-polyphenol complex described in step (5) is adjusted back to 7.0 using 2M NaOH for 30 minutes to further stabilize the structure of the complex, and then the sample is dialyzed and freeze-dried (dialysis molecular weight cutoff is 7,000Da) to obtain a soy protein isolate-polyphenol complex modified by microwave synergistic pH shift.
[0048] The following experiment was used to verify the experimental effect: Example 2 was used to verify the experimental effect:
[0049] 1. The indicators are determined as follows:
[0050] Emulsifying activity and emulsifying stability were determined as follows: a protein-polyphenol composite sample (15 mL, 1.0 mg / mL) was mixed with soybean oil (5 mL), and the mixture was homogenized at 13600 rpm for 3 min (UltraTurrax T25, IKA, Staufen, Germany). A 50 μL aliquot was taken from the bottom of the emulsion and mixed with SDS solution (0.1 w / v%), and the absorbance was measured at 500 nm after 0 and 10 min.
[0051] 2. Results Analysis
[0052] Ordinary soy protein isolate-polyphenol complex solution: emulsifying activity is 69.91m 2 / g; emulsion stability is 20.45min;
[0053] Example 2: Emulsifying activity is 76.50m 2 / g; emulsion stability is 28.37min;
[0054] As analyzed above, the emulsifying activity and emulsifying stability of soy protein isolate-polyphenol complex can be significantly improved by microwave-assisted pH shift treatment.
Claims
1. A method for preparing a soy protein isolate-polyphenol complex based on microwave-assisted pH shift treatment, characterized in that: The preparation method is as follows: (1) Defatted soybean meal was mixed with deionized water, the pH value was adjusted to 8.0, stirred with a magnetic stirrer for 2 hours, and then centrifuged. The supernatant was collected and the pH was adjusted, and hydrated at 4°C for 12 hours. The supernatant was centrifuged again to obtain a precipitate, which was washed and dialyzed for multiple times, and the pH value of the solution was adjusted to 7.5 and freeze-dried to finally obtain soy protein isolate powder; (2) dissolving the soy protein isolate powder described in step (1) in phosphate buffer (pH 7.4, 10 mM), stirring with a magnetic stirrer at room temperature for 2 h to fully dissolve it, and hydrating at 4° C. overnight to prepare a soy protein isolate solution; (3) adjusting the pH of the final soy protein isolate solution in step (2) to 2.0-3.0 with 2M HCl; (4) subjecting the protein solution in step (3) to microwave treatment, and continuously stirring during the microwave treatment to ensure that the solution is evenly heated; (5) dissolving quercetin in deionized water, stirring evenly, and slowly adding it to the microwave-treated protein solution and stirring for 2 h to form a soy protein isolate-polyphenol complex; (6) The pH value of the soy protein isolate-polyphenol complex described in step (5) is adjusted to 6.5-7.5 using 2M NaOH for 30 minutes to further stabilize the structure of the complex, and then the sample is dialyzed and freeze-dried to obtain the soy protein isolate-polyphenol complex modified by microwave synergistic pH shift.
2. The preparation method according to claim 1, characterized in that: The defatted soybean meal and deionized water in step (1) are mixed in a ratio of 1:10 (w / w), and the dialysis cut-off molecular weight is 10,000 Da.
3. The preparation method according to claim 1, characterized in that: The concentration of the soy protein isolate solution in step (2) is 30-50 mg / mL.
4. The preparation method according to claim 1, characterized in that: The maximum pH value in step (3) is adjusted to 2.
5.
5. The preparation method according to claim 1, characterized in that: The microwave treatment conditions in step (4) are 500-700W for 20-30min.
6. The preparation method according to claim 1, characterized in that: The final concentration of quercetin in step (5) is 1.6-1.8%.
7. The preparation method according to claim 1, characterized in that: The pH value of step (6) is finally adjusted to 7.0, and the dialysis cut-off molecular weight is 7,000Da.