A method for preparing high anti-deformation soybean protein composite gel by synergistic enzyme method of sesbania gum

Abstract

A method for preparing high anti-deformation soybean protein composite gel by synergistic enzyme method of sesbania gum belongs to the technical field of plant protein gel food processing. The method comprises the following steps: (1) preparing a soybean protein-sesbania gum mixed dispersion liquid; (2) adjusting the pH of the system and then adding transglutaminase; and (3) performing transglutaminase-induced gelation at a suitable temperature. The method utilizes the hydration thickening and molecular chain entanglement of sesbania gum, and combines the transglutaminase-induced intermolecular cross-linking of soybean protein to construct a soybean protein-sesbania gum composite gel network. The obtained composite gel has improved flow resistance, anti-yield performance and anti-compression deformation capacity, the network structure is more continuous, and the pore wall connection is more obvious, and can be used for plant protein gel food, structured food, plant-based food and related food processing systems. The method is simple in operation, mild in conditions and has strong practicability.

Description

Technical Field

[0001] This invention belongs to the field of plant protein gel food processing technology, and mainly relates to a method for preparing high-deformation-resistant soybean protein composite gel by guar gum synergistic enzymatic method. Background Technology

[0002] With the development of plant-based foods, structured foods, gelled foods, and high-protein foods, plant protein gels are increasingly widely used in food processing. Soy protein isolate is abundant, has high nutritional value, and possesses excellent emulsifying, water-holding, and gel-forming abilities, making it a crucial raw material for constructing plant protein gelled foods. Gel systems prepared using soy protein isolate can improve the texture, support, chewiness, and stability of foods, thus demonstrating high application value in plant-based meat products, recombinant protein foods, gelled foods, and structured foods.

[0003] In actual food processing and consumption, protein gel systems often need to withstand various external forces such as stirring, shearing, extrusion, compression, cutting, transportation, and chewing. If the gel network structure is weak or its resistance to deformation is insufficient, problems such as collapse, breakage, water leakage, flow deformation, loose texture, or poor shape retention can easily occur. These problems not only affect the appearance and taste of the product but also limit the further application of soy protein gels in extrusion molding, 3D printing, plant-based structured foods, and high-protein gel foods. Therefore, improving the compression set resistance, yield strength, and structural stability of soy protein gels is a crucial technical problem that needs to be solved in the processing of plant protein foods.

[0004] Currently, methods for regulating the structure of soybean protein gels mainly include heat induction, salt ion induction, enzymatic cross-linking, polysaccharide compounding, and physical modification. Among these, transglutaminase (TGlutaminase) is a commonly used enzyme preparation for modifying food proteins. It can promote cross-linking reactions between protein molecules, thereby enhancing the protein gel network structure. TGlutaminase-induced soybean protein gels typically possess a certain degree of elasticity and structural integrity; however, under significant external forces or complex processing conditions, problems such as network disruption, localized flow, irreversible deformation, or insufficient compression support may still occur. Therefore, relying solely on enzymatic cross-linking is sometimes insufficient to meet the requirements of structured foods for high resistance to deformation and processing stability.

[0005] Polysaccharide blending is another important method for improving the texture and stability of protein gels. Polysaccharides can regulate the gel network structure through thickening, hydration, filling, entanglement, or interaction with proteins. However, different polysaccharides have different effects on the protein gel structure. Ordinary polysaccharide blends may only increase the viscosity of the system, making it difficult to form a stable composite gel with both structural continuity and mechanical support. Therefore, selecting appropriate polysaccharides and synergistically cooperating with protein cross-linking methods is key to improving the deformation resistance of soybean protein gels.

[0006] Guise gum, a galactomannan polysaccharide, possesses strong hydration, thickening, and molecular chain entanglement capabilities, which can increase the viscosity of food systems and regulate gel network structure. Introducing guise gum into soybean protein systems helps increase the system's flow resistance and network continuity; simultaneously, transglutaminase can promote intermolecular cross-linking of soybean protein. The synergistic effect of these two factors holds promise for constructing soybean protein composite gels that combine protein cross-linking networks and polysaccharide entanglement support, thereby improving the gel's resistance to compression deformation, yield strength, and shape retention.

[0007] Existing technologies for the synergistic construction of soybean protein composite gels using guar gum and transglutaminase, particularly for improving the deformation resistance, yield strength, and structural stability of soybean protein gels, still require further improvement. Therefore, developing a simple, mild, and food-grade soybean protein composite gel preparation method is of practical significance for enhancing the processing adaptability and structural stability of plant protein gel foods. Summary of the Invention

[0008] This invention provides a method for preparing highly deformable soybean protein composite gel using guar gum and synergistic enzymatic method. The method is simple to operate, has good gel structure stability, and effectively improves the deformability and textural support performance of soybean protein gel.

[0009] The technical problem to be solved by the present invention is achieved through the following technical solution: A method for preparing a high-deformation-resistant soybean protein composite gel using guar gum synergistic enzymatic method is characterized by the following steps: (1) Preparation of soybean protein-guar gum mixed dispersion: Guar gum is dispersed in deionized water, and soybean protein isolate is added to make the final concentration of soybean protein isolate 3-8% (w / v) and the final concentration of guar gum 0.05-0.80% (w / v). After stirring until uniform dispersion, the mixture is allowed to stand at 2-8 ℃ for hydration to obtain soybean protein-guar gum mixed dispersion; (2) pH adjustment: The pH of the soybean protein-guar gum mixed dispersion obtained in step (1) is adjusted to 6.0-8.0; (3) Transglutaminase-induced gelation: Transglutaminase is added to the soybean protein-guar gum mixed dispersion obtained in step (2), and the amount of transglutaminase added is 5-25 U / g protein. After uniform mixing, the mixture is treated at 45-55 ℃ for 1-4 h to prepare soybean protein-guar gum composite gel.

[0010] The preparation process of the soybean protein-guar gum mixed dispersion is as follows: Guar gum is dispersed in deionized water, soybean protein isolate is added to make the final concentration of soybean protein isolate 5% (w / v) and the final concentration of guar gum 0.15-0.50% (w / v), and the mixture is stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8-16 h.

[0011] The final concentration of the guar gum is 0.30-0.50% (w / v).

[0012] The pH adjustment conditions are as follows: the pH of the soybean protein-guar gum mixture is adjusted to 7.0 using NaOH solution.

[0013] The transglutaminase-induced gelation process is as follows: transglutaminase is added to the pH-adjusted soybean protein-guar gum mixed dispersion at a concentration of 10 U / g protein. After mixing evenly, the mixture is treated at 50 °C for 2 h to prepare the soybean protein-guar gum composite gel.

[0014] The soy protein isolate is food-grade soy protein isolate, or it is prepared from defatted soy flour by alkali dissolution and acid precipitation followed by freeze drying; the guar gum is food-grade guar gum, and the transglutaminase is food-grade transglutaminase.

[0015] This invention introduces guar gum into a soybean protein isolate system and combines this with transglutaminase-induced intermolecular cross-linking of soybean protein to construct a soybean protein-guar gum composite gel network. The hydration thickening and molecular chain entanglement effects of guar gum improve the flow resistance and network support of the gel system, while the transglutaminase-induced protein cross-linking enhances the integrity of the gel structure. The synergistic effect of these two factors results in a composite gel exhibiting high resistance to flow, yielding, and compression deformation. Under preferred conditions, compared to the control group without guar gum, the consistency coefficient of the composite gel prepared by this method is 25.37 Pa·s. n Increased to 95.94 Pa·s for the 0.50% guar gum group. n The static yield stress increased from 24.8 Pa to 62.8 Pa, the elastic bifurcation stress obtained from large-amplitude oscillatory shear analysis increased from 12.2 Pa to 48.8 Pa, and the Young's modulus increased from 0.45 kPa to 1.56 kPa. Microstructural observation showed that the gel network structure was more continuous, the pore wall boundaries were clearer, and the connections between pore walls were more obvious after the addition of guar gum. The above results indicate that the soybean protein-guar gum composite gel prepared by this invention has good structural integrity, yield strength, and resistance to compression deformation, and can be used in plant protein gel foods, structured foods, plant-based foods, and related food processing systems, demonstrating strong practicality. Attached Figure Description

[0016] Figure 1 This is the overall process flow diagram of the present invention.

[0017] Figure 2 The rheological test of Example 1 was used to evaluate the flow resistance and linear viscoelastic properties of the composite gel.

[0018] Figure 3 Example 2: Yield stress determination to analyze the yield resistance of the composite gel.

[0019] Figure 4 Example 2 uses a compression test to detect the composite gel's resistance to compression deformation.

[0020] Figure 5 Example 3: Scanning electron microscopy was used to observe the microstructure of the composite gel network. Detailed Implementation

[0021] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] A method for preparing a high-deformation-resistant soybean protein composite gel using guar gum synergistic enzymatic method is characterized by the following steps: (1) Preparation of soybean protein-guar gum mixed dispersion: Guar gum is dispersed in deionized water, and soybean protein isolate is added to make the final concentration of soybean protein isolate 3-8% (w / v) and the final concentration of guar gum 0.05-0.80% (w / v). After stirring until uniform dispersion, the mixture is allowed to stand at 2-8 ℃ for hydration to obtain soybean protein-guar gum mixed dispersion; (2) pH adjustment: The pH of the soybean protein-guar gum mixed dispersion obtained in step (1) is adjusted to 6.0-8.0; (3) Transglutaminase-induced gelation: Transglutaminase is added to the soybean protein-guar gum mixed dispersion obtained in step (2), and the amount of transglutaminase added is 5-25 U / g protein. After uniform mixing, the mixture is treated at 45-55 ℃ for 1-4 h to prepare soybean protein-guar gum composite gel.

[0023] The preparation process of the soybean protein-guar gum mixed dispersion is as follows: Guar gum is dispersed in deionized water, soybean protein isolate is added to make the final concentration of soybean protein isolate 5% (w / v) and the final concentration of guar gum 0.15-0.50% (w / v), and the mixture is stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8-16 h.

[0024] The final concentration of the guar gum is 0.30-0.50% (w / v).

[0025] The pH adjustment conditions are as follows: the pH of the soybean protein-guar gum mixture is adjusted to 7.0 using NaOH solution.

[0026] The transglutaminase-induced gelation process is as follows: transglutaminase is added to the pH-adjusted soybean protein-guar gum mixed dispersion at a concentration of 10 U / g protein. After mixing evenly, the mixture is treated at 50 °C for 2 h to prepare the soybean protein-guar gum composite gel.

[0027] The soy protein isolate is food-grade soy protein isolate, or it is prepared from defatted soy flour by alkali dissolution and acid precipitation followed by freeze drying; the guar gum is food-grade guar gum, and the transglutaminase is food-grade transglutaminase.

[0028] Example 1: To evaluate the effect of guar gum addition on the flow resistance and linear viscoelastic properties of composite gels, guar gum was dispersed in deionized water and stirred until uniformly dispersed to prepare dispersions with final guar gum concentrations of 0%, 0.15%, 0.20%, 0.30%, and 0.50% (w / v). Soy protein isolate was added to each dispersion to a final concentration of 5% (w / v), and the mixture was stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8–16 h. The pH of the mixed dispersion was adjusted to 7.0 using NaOH solution, and transglutaminase was added at a concentration of 10 U / g protein. After thorough mixing, the mixture was treated at 50 ℃ for 2 h to prepare soybean protein-guar gum composite gels with different guar gum addition amounts. The flow behavior and linear viscoelastic properties of the composite gels were detected using a rheometer. The results showed that the addition of guar gum enhanced both the flow resistance and linear viscoelastic properties of the composite gel, increasing the consistency coefficient from 25.37 Pa·sⁿ in the group without guar gum to 95.94 Pa·sⁿ in the group with 0.50% guar gum. (See attached figures). Figure 2 .

[0029] Example 2: To analyze the effect of guar gum addition on the yield strength and compressive strength of the composite gel, guar gum was dispersed in deionized water and stirred until uniformly dispersed to prepare dispersions with final guar gum concentrations of 0%, 0.15%, 0.20%, 0.30%, and 0.50% (w / v). Soy protein isolate was added to each dispersion to a final concentration of 5% (w / v), and the mixture was stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8–16 h. The pH of the mixed dispersion was adjusted to 7.0 using NaOH solution, and transglutaminase (TGlutaminase) was added at a concentration of 10 U / g protein. After thorough mixing, the mixture was treated at 50 ℃ for 2 h to prepare soybean protein-guar gum composite gels with different guar gum addition amounts. The yield strength and compressive strength of the composite gels were determined using yield stress measurement and compression testing, respectively. The results showed that the addition of guar gum enhanced the yield strength of the composite gel. Specifically, the static yield stress increased from 24.8 Pa in the group without guar gum to 62.8 Pa in the group with 0.50% guar gum, and the elastic bifurcation stress increased from 12.2 Pa to 48.8 Pa. (See attached figures). Figure 3 Compression test results showed that the composite gel with added guar gum exhibited enhanced resistance to compression deformation, with the Young's modulus increasing from 0.45 kPa in the group without guar gum to 1.56 kPa in the group with 0.50% guar gum. (See attached figures). Figure 4 .

[0030] Example 3: To observe the effect of guar gum addition on the microstructure of the composite gel, guar gum was dispersed in deionized water and stirred until uniformly dispersed to prepare dispersions with final concentrations of 0%, 0.15%, 0.20%, 0.30%, and 0.50% (w / v). Soy protein isolate was added to each dispersion to achieve a final concentration of 5% (w / v), and the mixture was stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8–16 h. The pH of the mixed dispersion was adjusted to 7.0 using NaOH solution, and transglutaminase (TGlutaminase) was added at a concentration of 10 U / g protein. After thorough mixing, the mixture was treated at 50 ℃ for 2 h to prepare soybean protein-guar gum composite gels with different guar gum addition amounts. The gel samples were cut into small pieces, fixed, washed, dehydrated, dried, and sputter-coated with gold. The microstructure of the composite gel was then observed using scanning electron microscopy. The results showed that the composite gel network structure was more continuous, the pore wall boundaries were clearer, and the connections between the pore walls were more obvious after the addition of guar gum. (See attached figures.) Figure 5 .

Claims

1. A method for preparing a high-density soybean protein composite gel using guar gum and synergistic enzymatic method, characterized in that, The method includes the following steps: (1) Preparation of soybean protein-guar gum mixed dispersion: Guar gum is dispersed in deionized water, soybean protein isolate is added, so that the final concentration of soybean protein isolate is 3-8% (w / v) and the final concentration of guar gum is 0.05-0.80% (w / v), and after stirring until uniform dispersion, it is allowed to stand at 2-8 ℃ for hydration to obtain soybean protein-guar gum mixed dispersion; (2) pH adjustment: The pH of the soybean protein-guar gum mixed dispersion obtained in step (1) is adjusted to 6.0-8.0; (3) Transglutaminase-induced gelation: Transglutaminase is added to the soybean protein-guar gum mixed dispersion obtained in step (2), the amount of transglutaminase added is 5-25 U / g protein, and after uniform mixing, it is treated at 45-55 ℃ for 1-4 h to prepare soybean protein-guar gum composite gel.

2. The method for preparing high-density soybean protein composite gel using guar gum synergistic enzymatic method according to claim 1, characterized in that, The preparation process of the soybean protein-guar gum mixed dispersion is as follows: Guar gum is dispersed in deionized water, soybean protein isolate is added to make the final concentration of soybean protein isolate 5% (w / v) and the final concentration of guar gum 0.15-0.50% (w / v), and the mixture is stirred continuously at room temperature for 5 h, followed by hydration at 4 ℃ for 8-16 h.

3. The method for preparing high-density soybean protein composite gel using guar gum synergistic enzymatic method according to claim 1 or 2, characterized in that, The final concentration of the guar gum is 0.30-0.50% (w / v).

4. The method for preparing high-density soybean protein composite gel using guar gum synergistic enzymatic method according to claim 1, characterized in that, The pH adjustment conditions are as follows: the pH of the soybean protein-guar gum mixture is adjusted to 7.0 using NaOH solution.

5. The method for preparing high-density soybean protein composite gel using guar gum synergistic enzymatic method according to claim 1, characterized in that, The transglutaminase-induced gelation process is as follows: transglutaminase is added to the pH-adjusted soybean protein-guar gum mixed dispersion at a concentration of 10 U / g protein. After mixing evenly, the mixture is treated at 50 °C for 2 h to prepare the soybean protein-guar gum composite gel.

6. The method for preparing high-density soybean protein composite gel using guar gum synergistic enzymatic method according to claim 1, characterized in that, The soy protein isolate is food-grade soy protein isolate, or it is prepared from defatted soy flour by alkali dissolution and acid precipitation followed by freeze drying; the guar gum is food-grade guar gum, and the transglutaminase is food-grade transglutaminase.

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