Oyster-soy composite protein gel based on low-temperature synergistic construction and preparation method and application thereof

Abstract

The application discloses an oyster-soybean composite protein gel based on low-temperature cooperation construction and a preparation method and application thereof, and belongs to the technical field of functional food. The composite gel is formed by oyster protein and soybean protein isolate through low-temperature stabilization, medium-temperature construction and heat induction treatment, and the preparation method comprises the following steps: preparing an oyster protein suspension; preparing a soybean protein isolate suspension; mixing the oyster protein suspension and the soybean protein isolate suspension, stirring, standing, preliminarily constructing a gel structure, and then performing heat induction solidification treatment, and finally storing at low temperature to form the oyster-soybean composite protein gel, which can be used in the field of food processing. The oyster protein and the soybean protein isolate are combined, so that the composite gel has excellent gel strength, smooth texture and long-term storage stability, no organic chemical reagent and food additive is used in the preparation process, the formula safety is ensured, the process is simple, and great application value and industrialization prospect are shown.

Description

Technical Field

[0001] This invention relates to the field of functional food technology, and in particular to an oyster-soybean composite protein gel based on low-temperature synergistic construction, its preparation method, and its application. Background Technology

[0002] As global dietary concepts shift towards a balance between nutrition and health, developing novel protein products with both complete amino acid composition and excellent functional properties has become an important direction for the food industry. Animal proteins have high nutritional value and excellent gelling properties, but their production often involves high environmental impact; plant proteins have advantages in terms of resource sustainability, but their nutritional value and gelling properties are often lower than those of animal proteins, limiting their application in high-quality products.

[0003] The gelling properties of proteins are fundamental to the processing of foods such as sausages, surimi, and tofu. Soy protein isolate, as the most widely used plant protein, can form an irreversible gel upon heating, but its single gel has drawbacks such as a hard texture and coarse structure. More importantly, to achieve ideal gel strength, soy protein typically requires high concentrations (>10%) or relies on coagulants (such as gypsum, GDL, and TG enzymes) to form a stable three-dimensional network structure. This leads to increased raw material costs, becoming a key bottleneck restricting its high-value applications. Meanwhile, exploring the value of marine protein resources is gradually becoming a research hotspot. Oysters are the most produced economic shellfish in my country, rich in high-quality protein, but currently, their processing and utilization still rely on primary processing methods such as fresh consumption and drying; the level of intensive processing and comprehensive utilization urgently needs to be improved.

[0004] Generally, combining animal and plant proteins is an ideal way to achieve amino acid complementarity and improve the gel properties of products. However, a core challenge in this field has long been the introduction of plant proteins, which often disrupts the original gel network structure of animal proteins. Extensive research and practice have shown that partial replacement of animal proteins with plant proteins leads to a decline in the gel performance of composite protein gels. Specifically, plant proteins dispersed in the protein gel network replace gel components, weakening effective cross-linking between proteins, disrupting the formation of tight structures within the proteins, and ultimately diminishing the quality of the composite gel. It is noteworthy that this "performance degradation" effect caused by protein incompatibility is sharply amplified at low total protein concentrations, making "low concentration" and "high performance" a contradiction. This has led to the widespread technical bias that "high-performance composite gels cannot be prepared without relying on high concentrations or external additives."

[0005] In existing technologies, the preparation of composite protein gels is trapped by conventional technical constraints that are difficult to overcome. To overcome the compatibility barriers between proteins and ensure product texture, it is necessary to rely on one or more combined strategies among "high protein concentration (>10%)", "addition of cross-linking agents such as TG enzymes", "use of modified plant proteins", and "pH adjustment" as necessary compensatory measures. For example, published patents CN120419630A and CN117413927A prepare composite gels by using high protein concentration and pH adjustment; CN118846203B prepares composite gels by adding TG enzymes; and CN109700035A and CN118383450B even prepare composite protein gels using hydrolyzed or pH-modified plant proteins. However, this "high concentration, enzyme addition, pH adjustment" technical model increases process complexity and production costs, and also introduces exogenous additives, which deviates from the current market's pursuit of clean labels, simplified processes, and low-cost health foods.

[0006] Furthermore, the applicant's prior patent (application number: CN202510536474.6) demonstrates that oyster protein can form a high-strength gel under relatively mild, low-concentration (1.5%), and coagulant-free conditions. The significant differences in gelation behavior between oyster protein and soybean protein have led to a common technical bias among those skilled in the art: in low total protein concentration systems, without relying on compensatory methods such as "high concentration, enzyme addition, and pH adjustment," it is impossible to construct a homogeneous, high-performance composite system. Therefore, although successful methods for producing pure oyster protein gels already exist, overcoming inherent protein incompatibility and preparing composite protein gels with gel strength comparable to pure oyster protein gels using an extremely simplified process without relying on high concentrations, the addition of exogenous coagulants, or precise pH control remains a pressing technical challenge in this field.

[0007] Therefore, there is an urgent need in this field for an innovative technical solution to break the technological shackles that make it impossible to achieve both "low concentration" and "high performance". Without relying on traditional compensatory strategies, a new technical path should be used to prepare high-performance oyster-soybean composite protein gel under simplified conditions of low total protein concentration (<5%), no exogenous coagulant, and no need for precise pH control. This would meet the market's demand for diversified health foods and open up a new path for the high-value intensive processing of oysters and soybeans. Summary of the Invention

[0008] The purpose of this invention is to provide a low-temperature synergistic construction of an oyster-soybean composite protein gel, its preparation method, and its applications, thereby addressing the problems existing in the prior art. Based on a specific protein ratio, this invention combines oyster protein and soy protein isolate under coagulant-free conditions to construct a gel system with gel strength comparable to pure oyster protein gel, controllable texture, and the nutritional advantages of both proteins. This invention aims to meet market demands for diversified textures and balanced nutrition, and to provide an innovative approach to promoting the high-value utilization of oysters and soybeans.

[0009] To achieve the above objectives, the present invention provides the following solution:

[0010] In a first aspect, the present invention provides an oyster-soybean composite protein gel based on low-temperature co-construction, wherein the composite gel is formed by preliminary gel structure construction of oyster protein and soybean protein isolate followed by heat-induced treatment.

[0011] Preferably, the volume ratio of oyster protein to soy protein isolate is 90-99:1-10.

[0012] Preferably, the method for initially constructing the gel structure is as follows: the gel structure is initially constructed at 25-40℃ for a processing time of ≥20h.

[0013] Preferably, the conditions for the heat-induced treatment are: 80-90℃ water bath for 20-30 minutes.

[0014] Secondly, the present invention also provides a method for preparing the oyster-soybean composite protein gel, comprising the following steps:

[0015] Prepare oyster protein suspension;

[0016] Prepare a soy protein isolate suspension;

[0017] Oyster protein suspension and soy protein isolate suspension were mixed, stirred, and allowed to stand to initially construct a gel structure. After heat induction treatment, the mixture was stored at low temperature to form the oyster-soybean composite protein gel.

[0018] Preferably, the concentration of the oyster protein suspension is 1.5%-2.0%.

[0019] Preferably, the concentration of the soy protein isolate suspension is 1.5%-2.0%.

[0020] Preferably, the conditions for low-temperature storage after the heat-induced treatment are 4-6℃ for 12-24 hours.

[0021] Thirdly, the present invention also provides an application of the oyster-soybean composite protein gel in the preparation of protein gel foods.

[0022] Fourthly, the present invention also provides a protein gel food, including the oyster-soybean composite protein gel.

[0023] The core inventive concept of this invention lies in the first discovery that by precisely controlling the mass percentage of soy protein isolate in the total protein to within the range of 1% to 10%, and utilizing a specific low-temperature synergistic construction process (i.e., a three-stage procedure combining low-temperature static stabilization, medium-temperature construction, and high-temperature thermal induction curing), a composite protein gel with gel strength, water-holding capacity, and microstructure comparable to pure oyster protein gel can be successfully prepared under harsh conditions of low total protein concentration (0.5% to 4%) without pH adjustment or any exogenous coagulants. This breakthrough overturns the industry's traditional understanding that high-performance composite gels at low concentrations must rely on additives. Based on the above concept, this invention aims to break the traditional technical shackles of "high concentration, enzyme addition, and pH adjustment," with specific objectives including: 1. Process innovation: providing a clean and simplified preparation path that completely does not rely on complex pH adjustment steps and exogenous additives; 2. Performance breakthrough: effectively overcoming the core technical challenge of gel performance degradation caused by the inherent incompatibility of animal and plant proteins under low protein concentration conditions.

[0024] The core of the method described in this invention lies in the fact that it is not simply a mixture of two proteins, but rather a three-step physical process of "low-temperature stabilization, medium-temperature construction, and high-temperature curing," which works synergistically with a specific critical range of 1% to 10% soy protein isolate in the total protein. This allows for the successful construction of a unique dual-protein composite gel with performance comparable to pure oyster protein gel at a low total protein concentration (0.5% to 4%) using a clean-label process without the use of any chemical additives, enzymes, or pH adjusters. The 1% to 10% protein ratio is the critical range for effective composite formation; exceeding this range will lead to phase separation and significant performance degradation.

[0025] The present invention discloses the following technical effects:

[0026] This invention utilizes oyster protein obtained through an alkali-dissolution and acid-precipitation method and commercial soy protein isolate as raw materials. Through a low-temperature synergistic construction process with a specific ratio, comprising three key stages—low-temperature stabilization, medium-temperature construction, and thermally induced solidification—a rigid and stable dual-protein composite gel was successfully constructed under conditions of low protein concentration and no coagulant addition. This gel exhibits excellent gel strength, a smooth texture, and long-term storage stability. The key to this invention lies in the ability to precisely control the phase separation behavior of the gel simply by adjusting the protein ratio, thereby achieving flexible customization of the product's appearance and texture. The entire preparation process does not use any organic chemical reagents or food additives, ensuring the cleanliness and safety of the formulation. Furthermore, the process is simple and demonstrates significant application value and industrialization potential.

[0027] Compared with the prior art, the present invention has the following significant advantages: 1. Simplified process: The entire process does not require pH adjustment, avoiding the problems of process complexity, increased cost and product flavor damage caused by adding acid and alkali reagents;

[0028] 2. Mild conditions and economic efficiency: High-strength gels can be achieved at low total protein concentrations, greatly reducing raw material costs;

[0029] 3. Natural and high-quality products: The composite gel produced by the clean formula without external coagulants or pH adjustment can still maintain gel strength, water retention and smooth texture comparable to pure oyster protein gel. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 Comparative images of the macroscopic appearance of oyster protein-soy protein isolate composite gels in Examples 1-4 and Comparative Examples 1-4;

[0032] Figure 2 The graphs show a comparison of the gel strength of the oyster protein-soy protein isolate composite gels in Examples 1-4 and Comparative Examples 1-3; where different letters in the graphs indicate significant differences (P < 0.05).

[0033] Figure 3 The graph shows a comparison of the hardness of the oyster protein-soy protein isolate composite gels in Examples 1-4 and Comparative Examples 1-3; different letters in the graph indicate significant differences (P < 0.05).

[0034] Figure 4 The figures show a comparison of the water retention properties of oyster protein-soy protein isolate composite gels in Examples 1-4 and Comparative Examples 1-3; where different letters in the figures represent significant differences (P < 0.05).

[0035] Figure 5 The images show a comparison of scanning electron microscope images of oyster protein-soy protein isolate composite gels in Examples 3-4 and Comparative Examples 1-3; the upper image is magnified 300 times, and the lower image is magnified 500 times.

[0036] Figure 6The images show a laser confocal microscope comparison of the oyster protein-soy protein isolate composite gels in Examples 3-4 and Comparative Examples 1-3; where the scale bar of the upper image is 100 μm and the scale bar of the lower image is 20 μm. Detailed Implementation

[0037] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0038] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0039] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0040] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0041] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0042] The oyster protein preparation method in the embodiments and comparative examples of this invention refers to the method disclosed in the patent document with application number CN202510536474.6, and the soy protein isolate is commercially available soy protein isolate.

[0043] Example 1: A method for preparing an oyster-soybean composite protein gel

[0044] This embodiment demonstrates a specific implementation with a total protein concentration of 1.5% (w / v), which falls within the 0.5%-4% range required by this invention.

[0045] (1) Disperse oyster protein in deionized water to prepare a protein suspension with a mass fraction of 1.5%. Stir with a magnetic stirrer at 500 rpm for 10 minutes, and then let it stand at 4°C for 12 hours to ensure that the protein is fully hydrated.

[0046] (2) Prepare a 1.5% (natural) soy protein isolate suspension and let it stand at 4°C for 12 hours to hydrate it.

[0047] (3) Mix the hydrated oyster protein solution with the soy protein isolate solution at a volume ratio of 99:1 (at this ratio, the mass percentage of soy protein isolate in the total protein is about 1%), stir with a magnetic stirrer at 500 rpm for 5 minutes in an ice bath at 2-10℃, and then let it stand at 4℃ for 1 hour to stabilize the system.

[0048] (4) Preliminary construction of gel structure: Dispense the well-mixed protein suspension into molds and seal them, and let it stand at 25°C for no less than 20 hours.

[0049] (5) Thermal induction treatment: The static sample was heated in an 80°C water bath for 20 min to induce gelation and solidify the network structure. Then it was cooled with flowing cold water and stored at 4°C for 12 h.

[0050] (6) After the prepared composite gel was restored to room temperature, the oyster-soybean composite protein gel was obtained and its performance was characterized.

[0051] Example 2: A method for preparing an oyster-soybean composite protein gel

[0052] The steps are exactly the same as in Example 1, except that in step (3), the volume mixing ratio of oyster protein solution and soy protein isolate solution is 95:5 (at this ratio, the mass percentage of soy protein isolate in the total protein is approximately 5%). After the prepared gel is brought to room temperature, its performance is characterized.

[0053] Example 3: A method for preparing an oyster-soybean composite protein gel

[0054] The steps are exactly the same as in Example 1, except that in step (3), the volume mixing ratio of oyster protein solution and soy protein isolate solution is 90:10 (at this ratio, the mass percentage of soy protein isolate in the total protein is approximately 10%). After the prepared gel is brought to room temperature, its performance is characterized.

[0055] Example 4: A method for preparing an oyster-soybean composite protein gel

[0056] The steps are exactly the same as in Example 3, except that in step (2), a protein suspension is prepared using preheated soy protein isolate. After the prepared gel is brought back to room temperature, its performance is characterized.

[0057] Comparative Example 1

[0058] To provide a performance benchmark, pure oyster protein gel was prepared in this embodiment. It was prepared according to the preferred method disclosed in application number CN202510536474.6: oyster protein was formulated into a 1.5% suspension, and after hydration, pre-coagulation, and thermal induction, pure oyster protein gel was obtained. This gel will serve as the performance reference benchmark for subsequent embodiments and comparative examples.

[0059] Comparative Example 2

[0060] The difference between this comparative example and Example 3 is that in step (3), the volume mixing ratio of oyster protein solution and soy protein isolate solution is 80:20 (at this ratio, the mass percentage of soy protein isolate in the total protein is about 20%), and the remaining steps and conditions are the same as in Example 3.

[0061] Comparative Example 3

[0062] The difference between this comparative example and Example 3 is that in step (3), the volume mixing ratio of oyster protein solution and soy protein isolate solution is 70:30 (at this ratio, the mass percentage of soy protein isolate in the total protein is about 30%), and the remaining steps and conditions are the same as in Example 3.

[0063] Comparative Example 4

[0064] This comparative example aims to illustrate the gel-forming properties of soy protein isolate in this system. The preparation method differs from Comparative Example 1 in that oyster protein is not added; a 1.5% (w / w) suspension is prepared using only soy protein isolate, and an attempt is made to form a gel following the same steps.

[0065] The gel materials prepared in Examples 1-4 and Comparative Examples 1-4 were comprehensively characterized and analyzed. The results are as follows:

[0066] 1. Appearance Analysis

[0067] Figure 1 The images show a comparison of the appearance of the composite protein gels in Examples 1-4 and Comparative Examples 1-4.

[0068] The results showed that the composite gels with less than 10% natural soy protein isolate (Examples 1-3) or 10% preheated soy protein isolate (Example 4) had an appearance comparable to pure oyster protein gel (Comparative Example 1), exhibiting a stable and smooth state, demonstrating the feasibility of the technical solution of the present invention and its inclusiveness of heat treatment of soy protein isolate. When the proportion of soy protein isolate was 20% and 30% (Comparative Examples 2-3), the composite gels exhibited stratification, with transparent edges, indicating that the composite protein gels became unstable and their appearance quality deteriorated. This result intuitively revealed the incompatibility between proteins beyond a specific proportion. Furthermore, the results of Comparative Example 4 showed that under exactly the same process conditions, a single soy protein isolate solution could not form a self-supporting gel and remained in a liquid state. This indicates that in the low-temperature co-construction process of the present invention, oyster protein is an indispensable gel matrix, while soy protein can only be effectively contained as a functional excipient at a specific proportion (≤10%), demonstrating the necessity of the dual-protein composite system.

[0069] 2. Gel strength analysis

[0070] The gel strength of the composite gel was determined using a texture analyzer. The test parameters were: trigger force 5g, test speed 2.0mm / s, and pressing distance 5mm.

[0071] Figure 2 The graph shows a comparison of the gel strength of the composite protein gels in Examples 1-4 and Comparative Examples 1-3.

[0072] The results showed that when the proportion of soy protein isolate added was within the range of 1% to 10% as described in this invention (Examples 1-3), the strength of the composite gel could be maintained at around 200g, with no significant difference compared to pure oyster protein gel (Comparative Example 1). This result indicates that within this specific proportion range, the composite system successfully formed a gel strength comparable to that of high-strength pure oyster protein gel. This proves that this invention successfully reduced the total protein concentration of the high-performance gel from >10% in traditional techniques to 0.5%-4%, achieving high strength construction at extremely low concentrations and overcoming the bottleneck of raw material cost. Furthermore, even when using preheated soy protein isolate (Example 4), a considerably high gel strength was maintained at an addition proportion of 10%, indicating that this invention is insensitive to the heat treatment of soy protein isolate and has good industrial adaptability. However, when the addition ratio increased to 30% (Comparative Example 3), the gel strength decreased significantly to 155.02g, proving that "1%-10%" is not an arbitrary ratio range, but a precise critical range for achieving synergistic effects between the two proteins and avoiding phase separation. This clearly defines the effective ratio boundary for achieving high-strength composite protein gels.

[0073] 3. Hardness Analysis

[0074] The hardness of the composite gel was determined using the full texture mode with the following parameters: compression ratio 30% and test speed 2.0 mm / s.

[0075] Figure 3 The figures show a comparison of the hardness of the composite protein gels in Examples 1-4 and Comparative Examples 1-3. The results demonstrate that the hardness test further validates the effectiveness of the invention: when the proportion of soy protein isolate added was 1% to 10% (Examples 1-3), the hardness of the composite gel remained at a high level of over 131.72 g, comparable to Comparative Example 1. Furthermore, Example 4, which added 10% preheated soy protein isolate, also achieved this hardness level. This indicates that under the formulation protected by this invention, the composite gel also possesses excellent textural properties. However, when the addition proportion reached 20% (Comparative Example 2) or higher, the hardness decreased significantly, further confirming that 10% is the upper limit for high hardness achievable by this invention.

[0076] 4. Water retention analysis

[0077] Accurately weigh a certain mass (W0) of gel sample and centrifuge at 3000 r / min for 10 min. After removing it, wipe off the surface water and weigh it again (W1). The water-holding capacity (WHC) is calculated according to the following formula: WHC(%) = (W1 / W0) × 100%.

[0078] Figure 4 The figures show a comparison of the water retention properties of the composite protein gels in Examples 1-4 and Comparative Examples 1-3. The results are highly consistent with the strength and hardness results: at addition ratios of 1% to 10% (Examples 1-3), the water retention properties of the composite gels were all above 68.91%, comparable to pure oyster protein gel (Comparative Example 1). Furthermore, even with preheated soy protein isolate (Example 4), the water retention properties were not negatively affected. This demonstrates that the gel network structure formed within this range also possesses excellent water-holding capacity. However, when the proportion of soy protein isolate exceeded 10% (Comparative Examples 2-3), the water retention properties decreased significantly, indicating that the gel network structure had been damaged, a stark contrast to the technical effects of this invention. This further illustrates that exceeding the critical ratio leads not only to macroscopic phase separation but also to a fundamental deterioration of the microscopic network structure.

[0079] 5. Scanning electron microscope image

[0080] The microstructure of the composite gel was observed using scanning electron microscopy. The sample was fixed with 2.5% glutaraldehyde solution, followed by gradient dehydration with ethanol, freeze-drying, and gold sputtering before being observed and photographed under an electron microscope.

[0081] Figure 5The images show a comparison of scanning electron microscopy (SEM) images of the composite protein gels in Examples 3-4 and Comparative Examples 1-3. The results show that, regardless of whether 10% natural soy protein isolate (Example 3) or 10% preheated soy protein isolate (Example 4) is added, the composite gel exhibits a similar microstructure to the pure oyster protein gel (Comparative Example 1), displaying a continuous and uniform three-dimensional network structure. This result explains the high gel strength exhibited macroscopically at the microscopic level. More importantly, the results of Example 4 demonstrate that even after preheating, the dispersion and network structure of the soy protein isolate remain excellent, indicating that the core process of this invention is insensitive to the heat treatment of raw materials, demonstrating strong industrial adaptability and universality. Conversely, the microscopic images of Comparative Examples 2-3 clearly show that when the proportion of soy protein isolate exceeds 10%, the gel microstructure becomes disordered, coarse, and uneven, intuitively explaining the fundamental reason for the deterioration of its macroscopic performance.

[0082] 6. Laser confocal microscope image

[0083] The microstructure of the composite gel was observed using laser confocal microscopy. After staining with Rhodamine B, the samples were placed under a laser confocal microscope and observed and images were acquired under 561 nm excitation light.

[0084] Figure 6 The images show a laser confocal microscope comparison of the composite protein gels in Examples 3-4 and Comparative Examples 1-3. The results show that with a 10% addition of soy protein isolate, the composite protein formed a uniform and continuous network structure. In Example 3 (natural soy protein isolate), the soy protein isolate was uniformly dispersed in the oyster protein network as small particles. However, in Example 4, despite preheating, the distribution of the soy protein isolate in the gel network was similar to that in Example 3, with no obvious large-size aggregates. This demonstrates that under the specific proportions and processes of this invention, the gelation behavior of the composite protein is insensitive to the preheating treatment of the soy protein isolate, further confirming the universality and stability of the technical solution of this invention. Conversely, in Comparative Examples 2 (20% soy protein isolate added) and 3 (30% soy protein isolate added), the soy protein isolate aggregated to form large aggregates, severely disrupting the uniformity and continuity of the composite gel network.

[0085] Based on the analysis of all the above data and compared with existing technologies that rely on "high concentration, enzyme addition, and pH adjustment", this invention has achieved unexpected technological progress: under the conditions of lower total protein concentration (0.5%-4% vs >10%) and simpler process (no pH adjustment, no exogenous coagulant), a product with gel strength, water retention and microstructure comparable to pure oyster protein gel or high-concentration traditional composite gel has been successfully prepared.

[0086] This invention, by discovering a specific critical range of protein ratios between 1% and 10%, and synergizing it with a temperature program of "low-temperature stability, medium-temperature construction, and high-temperature curing," successfully overcomes the technical prejudice that "high-performance animal and plant composite protein gels cannot be constructed at such low protein concentrations without relying on pH adjustment or exogenous cross-linking agents." This not only achieves high-performance construction at low concentrations but also establishes a novel, clean-label composite protein gel preparation mode.

[0087] The above embodiments and comparative examples specifically demonstrate the implementation effect under the preferred condition of a total protein concentration of 1.5%, and the results fully support the general feasibility of the present invention in the concentration range of 0.5%-4%.

[0088] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for preparing an oyster-soybean composite protein gel, characterized in that, Includes the following steps: Prepare oyster protein suspension; Prepare a soy protein isolate suspension; Oyster protein suspension and soy protein isolate suspension were mixed, stirred, and allowed to stand. After preliminary gel structure construction, thermal induction treatment was performed. After the treatment, the mixture was stored at low temperature to form the oyster-soybean composite protein gel. The concentration of the oyster protein suspension is 1.5%; The concentration of the soy protein isolate suspension is 1.5%; The volume ratio of the oyster protein suspension to the soy protein isolate suspension is 90-99:1-10; The stirring and settling conditions are as follows: stir for 5 minutes at 500 rpm using a magnetic stirrer in an ice bath environment at 2-10℃, and then settling for 1 hour at 4℃. The method for initially constructing the gel structure is as follows: the gel structure is initially constructed at 25-40℃ for a processing time of ≥20h. The conditions for the heat-induced treatment are: 80-90℃ water bath for 20-30 minutes.

2. The preparation method according to claim 1, characterized in that, The conditions for low-temperature storage after heat-induced treatment are 4-6℃ for 12-24 hours.

3. An oyster-soybean composite protein gel prepared by the preparation method according to any one of claims 1-2.

4. The application of the oyster-soybean composite protein gel according to claim 3 in the preparation of protein gel foods.

5. A protein gel food product, characterized in that, Includes the oyster-soybean composite protein gel as described in claim 3.

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