An edible double network crosslinked film, preparation and use thereof

Abstract

The application provides a kind of edible double-network crosslinked membrane, preparation and application thereof.The preparation method of the double-network crosslinked membrane comprises: adding hydrochloric acid to pea protein insoluble to carry out deamidation treatment, to obtain deamidation product;Mixing sodium alginate solution with the deamidation product, adding glycerol to the obtained mixed solution to carry out hydration reaction, and preparing film-forming liquid after the reaction is completed;After the film-forming liquid is coated and dried, crosslinking is carried out by dropping calcium chloride solution, and then drying is carried out to obtain the double-network crosslinked membrane;The pea protein insoluble is extracted by the following method: pea protein is dispersed in water to obtain pea protein aqueous solution, centrifuged, filtered, and pea protein insoluble is obtained.The preparation method is simple in operation, mild in reaction condition, and the double-network crosslinked membrane obtained has good tensile strength, transparency and water resistance, which effectively improves the comprehensive performance of traditional pea protein membrane.

Description

Technical Field

[0001] This invention belongs to the field of edible protein membrane preparation technology, specifically including an edible double-network cross-linked membrane, its preparation and application. Background Technology

[0002] Food protein films are thin layers that can be applied to the surface of food by using natural edible proteins as raw materials and adding edible plasticizers, cross-linking agents, etc., through the interaction between different molecules. The covering forms include wrapping, coating, microcapsules, etc. The resulting food protein films can be used to preserve and protect food, playing a role in blocking gas and moisture, and preventing food from oxidation and microbial corrosion. In addition, they can be developed into functional edible protein film foods to enhance the advantages of food in terms of appearance, taste, and nutritional value.

[0003] Based on the protein source, edible protein films can be categorized into animal protein films, plant protein films, and composite protein films. Commonly used plant protein films include soy protein isolate films, and research on their applications is increasing, yielding a series of results. However, their poor mechanical strength, heat-sealing properties, and susceptibility to water solubility or high water permeability still restrict their industrial production and everyday applications. Furthermore, in certain foods such as rice noodle rolls and spring rolls, the presence of liquid during preparation causes soluble food protein films to dissolve to some extent, making them unsuitable. Therefore, the preparation of insoluble edible protein films has application value for food packaging and the development of diverse food products.

[0004] Pea protein possesses a wealth of functional properties, such as solubility, gelling properties, foaming properties, emulsifying properties, and film-forming properties. Pea protein is inexpensive, widely available, and exhibits low toxicity and low allergenicity, making it a promising low-fat, low-calorie plant protein that can be used in the preparation of insoluble edible protein films. Furthermore, pea protein has a well-balanced amino acid profile; the content of the seven essential amino acids (except methionine) is close to the FAO / WHO recommended levels, resulting in protein films with high nutritional value. However, pea protein also presents certain challenges in membrane fabrication. Due to its strong hydrophobicity and low charge, pea protein exhibits low solubility, making membrane formation difficult. Typically, the insoluble portion of pea protein needs to be separated, leaving only the soluble portion (albumin) for membrane preparation. This is because the insoluble portion exists within the polymer chain due to intermolecular and intramolecular interactions, exhibiting relatively low mechanical strength, high brittleness, low heat distortion temperature, and poor water vapor barrier properties, making membrane formation challenging. These insoluble components primarily include three types of pea globular proteins: legumin, vicilin, and convicilin. These three pea globular proteins account for over 70% of the total protein in pea protein. If discarded directly, these pea globular proteins become waste or animal feed, inevitably leading to significant resource waste. Furthermore, this restricts the raw material sources for pea protein membrane products, limiting their application areas. Therefore, in recent years, researchers have tried to use pea protein directly as a raw material to make films by adjusting the solubility of pea globular protein or by directly modifying pea protein. However, they have found that the obtained protein films still have many problems in terms of transparency, uniformity, and flexibility, and have not solved the problem that the insoluble components in pea protein are difficult to form films.

[0005] Therefore, developing a method for preparing an edible film using pea protein insolubles as raw material is of great significance to the development of edible protein film preparation. Summary of the Invention

[0006] To address the aforementioned problems in the existing technology, the first objective of this invention is to provide a method for preparing an edible double-network cross-linked membrane. This preparation method is simple to operate and uses mild reaction conditions. The method uses pea protein insolubles as raw material, and through acid deamidation treatment and cross-linking with sodium alginate and calcium chloride, an edible double-network cross-linked membrane with high transparency, good air permeability, high mechanical strength, and good water resistance is obtained, overcoming the problem of difficulty in forming films with pea protein insolubles in the existing technology.

[0007] A second objective of this invention is to provide an edible dual-network cross-linked membrane.

[0008] A third objective of this invention is to provide an application of the dual-network crosslinked membrane described above in the preparation of edible protein membrane foods.

[0009] To achieve the first objective mentioned above, the technical solution adopted by this invention includes:

[0010] This invention discloses a method for preparing a dual-network crosslinked membrane as described above, comprising the following steps:

[0011] Hydrochloric acid was added to the pea protein insolubles to perform deamidation treatment, yielding the deamidated product;

[0012] Sodium alginate solution was mixed with the deamidation product, and glycerol was added to the mixture for hydration reaction. After the reaction was completed, the film-forming solution was obtained.

[0013] After coating the film-forming solution onto a plate and drying it, cross-linking is achieved by dripping calcium chloride solution onto the plate. After drying, the film is obtained.

[0014] The pea protein insolubles were extracted using the following method:

[0015] Pea protein was dispersed in water to obtain a pea protein aqueous solution, which was then centrifuged and filtered to obtain pea protein insolubles.

[0016] To address the problem of pea protein insolubles being difficult to form films and thus discarded, this invention provides a method for preparing a double-network cross-linked membrane using pea protein insolubles as raw material. In this method, considering that pea protein insolubles contain a high proportion of pea globulin, this invention utilizes both modification and cross-linking to induce interactions between pea globulin proteins, and between pea globulin proteins and sodium alginate and calcium chloride, thereby forming a double-network cross-linked membrane with excellent overall performance. Specifically, pea globulin proteins are linked to each other through disulfide bonds. Furthermore, amino acid residues on pea globulin proteins are further linked to sodium alginate through hydrogen bonds and ionic bonds. Later, it was discovered that... 2+ The chelation effect makes the molecular chains of sodium alginate more tightly bound, and through the above-mentioned interconnection, it is beneficial to the film-forming process of pea protein insolubles.

[0017] In this invention, the double-network cross-linked membrane refers to the existence of a double-network structure between protein membranes, specifically: 1) the network structure between various pea globulins in the pea protein insolubles after deamidation; 2) the network structure formed by the interaction between sodium alginate and pea protein insolubles after the addition of sodium alginate and calcium chloride.

[0018] The preparation method employs a two-step crosslinking technique. First, hydrochloric acid is used to deamidulate the pea protein insolubles under heating conditions, exposing crosslinking sites in the pea protein insolubles that originally lacked film-forming properties, thus giving them some film-forming ability. Then, the deamidated product undergoes a crosslinking reaction between sodium alginate and calcium chloride, forming a film-forming layer within the Ca... 2+ The chelation effect makes the molecular chains of sodium alginate more tightly bound, and the synergistic effect of pea globulin on film formation is stronger. The interaction between the chains ultimately leads to the formation of a three-dimensional network structure, i.e., a gel state, which improves the tensile strength, transparency and water resistance of the protein membrane, thereby greatly improving the overall performance of the protein membrane.

[0019] The principle of the two-step cross-linking technology lies in the fact that, firstly, in the first stage, the side chain amino groups of glutamine and asparagine residues in pea globulin are removed by hydrochloric acid deamidation, converting them into glutamic acid and aspartic acid. Under acidic conditions, the carbonyl oxygen of the amide is first protonated by the acid, and the conjugate base (A... - or OH - The amino group attacks the tetrahedron as a nucleophile or activates another nucleophile to attack it by binding a proton, forming an unstable tetrahedral intermediate. After proton transfer, the amino group leaves the tetrahedral intermediate, completing the hydrolysis reaction. In addition, amino-terminal glutamine and carboxyl-terminal asparagine exhibit two special deamidation mechanisms. Terminal glutamine readily cyclizes with its terminal amino group to form pyrrolidone carboxylic acid, releasing ammonia. Terminal asparagine can cyclize with its terminal carboxyl group to form an anhydride, releasing ammonia. The reaction equations are as follows:

[0020]

[0021] Secondly, in the second stage, after the addition of sodium alginate, its hydroxyl and carboxyl groups exist in a free state. Upon contact with anhydrous calcium chloride, Ca... 2+ It forms a completely compatible and stable cross-linked network structure with sodium alginate, which significantly improves the barrier properties of the membrane. The reaction equation is as follows:

[0022] NaAlg + CaCl2 → CaAlg + NaCl

[0023] This method solves the problem of limited applications of pea protein, such as the insoluble portion being used as waste and animal feed, and provides technical guidance for fields such as food packaging and edible films.

[0024] Furthermore, the pea protein is a commercially available product with a purity of 80%, and the mass concentration of the pea protein aqueous solution is 10%.

[0025] Furthermore, the centrifugation speed is 4000-8000 r / min, and the centrifugation time is 10-15 min; preferably, the centrifugation speed is 4000 r / min, and the centrifugation time is 10 min.

[0026] Furthermore, the volume ratio of the pea protein insolubles to the hydrochloric acid solution is 1:1-1.5.

[0027] Further, the concentration of the hydrochloric acid solution is 0.2-0.3 mol / L; preferably, the concentration of the hydrochloric acid solution is 0.3 mol / L.

[0028] Furthermore, the deamidation reaction temperature is 50-70℃, and the reaction time is 60-90 min.

[0029] Furthermore, the volume ratio of the deamide product to the sodium alginate solution is 1:2-2.5; preferably, the volume ratio of the deamide product to the sodium alginate solution is 1:2.

[0030] Furthermore, the mass concentration of the sodium alginate solution is 0.9-1.1%.

[0031] Furthermore, the mass concentration of glycerol in the mixture is 23-27%.

[0032] Furthermore, the hydration reaction is carried out at a temperature of 60-80°C for 30-60 minutes.

[0033] Furthermore, the drying time after coating is 20-24 hours.

[0034] Furthermore, the volume ratio of the film-forming solution to the calcium chloride solution is 1.5-2.5:1.

[0035] Furthermore, the mass concentration of the calcium chloride solution is 0.6-0.8%.

[0036] Furthermore, the crosslinking time is 10-20 seconds.

[0037] Furthermore, the deamidation treatment further includes terminating the deamidation reaction with an alkaline solution; preferably, the pH is adjusted to 9-10 with an alkaline solution to terminate the deamidation reaction.

[0038] To achieve the second objective mentioned above, the technical solution adopted by the present invention includes:

[0039] This invention discloses an edible dual-network crosslinked membrane, which is prepared by the preparation method described above.

[0040] To achieve the third objective mentioned above, the technical solution adopted by this invention includes:

[0041] This invention discloses the application of a dual-network crosslinked membrane as described above in the preparation of edible protein membrane foods.

[0042] Furthermore, the edible protein membrane foods include, but are not limited to, rice noodle rolls, rice sausages, spring rolls, spring pancakes, or crystal vegetable rolls.

[0043] Beneficial effects of this invention:

[0044] This invention provides an edible double-network cross-linked membrane, its preparation, and its application. The preparation method is simple to operate and uses mild reaction conditions. The method uses pea protein insolubles as raw material, and through acid deamidation treatment and cross-linking with sodium alginate and calcium chloride, an edible double-network cross-linked membrane with high transparency, high mechanical strength, and good water resistance is obtained, overcoming the problem of difficulty in forming films with pea protein insolubles in existing technologies.

[0045] The dual-network crosslinked membrane prepared by this invention has a tensile strength of over 8.54 MPa, a transparency of over 70.70%, a cooking loss rate of less than 12.20%, and a water solubility and dispersibility of less than 26.87%. It can maintain high integrity and toughness even after being placed in water for more than 24 hours, while retaining the rich nutritional value of the raw materials.

[0046] The dual-network cross-linked membrane prepared by this invention can be used to prepare a variety of edible protein membrane foods, such as rice noodle rolls, rice sausages, spring rolls, spring pancakes, and crystal vegetable rolls, etc., and can withstand various post-processing food preparation steps such as steaming, boiling, grilling, and frying. Attached Figure Description

[0047] The specific embodiments of the present invention will be described in further detail below with reference to the accompanying drawings.

[0048] Figure 1 The mechanical properties of the samples prepared in Example 1, Comparative Example 1, Comparative Example 2 and Comparative Example 3 are shown in the comparison graph.

[0049] Figure 2 The images show the state of samples prepared in Comparative Examples 1(A), 2(B), 3(C), and 1(D) after being dispersed in water for 0 hours, and the state of samples prepared in Comparative Examples 1(a), 2(b), 3(c), and 1(d) after being dispersed in water for 24 hours. Detailed Implementation

[0050] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments and accompanying drawings, further clarifies the invention. It should be understood that the described embodiments are merely some, not all, of the embodiments of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0051] Example 1

[0052] This embodiment provides a method for preparing an edible dual-network crosslinked membrane, as detailed below:

[0053] Pea protein was added to water to prepare a 10wt% pea protein aqueous solution. The 10wt% pea protein aqueous solution was magnetically stirred for 30 minutes to fully disperse it. After centrifugation at 4000 r / min for 10 minutes, the precipitate was collected to obtain the pea protein insoluble matter.

[0054] Add 30 mL of 0.3 mol / L hydrochloric acid solution to 30 mL of pea protein insolubles, stir magnetically for 10 min, and then heat in a water bath at 60 °C for 90 min to perform deamidation. Then, adjust the pH to 9-10 with 3 mol / L NaOH solution to terminate the deamidation reaction and obtain the deamidated product.

[0055] The deamidation product was mixed with a 1 wt% sodium alginate solution at a volume ratio of 1:2. Glycerol was added to the mixture to control the concentration of glycerol in the mixture at 27 wt%. Then, the mixture was fully hydrated. The hydration reaction was carried out at a temperature of 80°C for 30 min. After the hydration reaction was completed, a film-forming solution was obtained.

[0056] Pour 40 mL of film-forming solution into a 200×100×5 mm immersion tank. 3 The film is placed in an acrylic container and ventilated at room temperature for 24 hours. Then, 20 mL of 0.7 wt% calcium chloride solution is dropped onto the formed film for cross-linking. The cross-linking time is 15 seconds. The cross-linked film is then placed in a cool, ventilated place at room temperature for 12 hours to dry.

[0057] Comparative Example 1

[0058] Pea protein was added to water to prepare a 10wt% pea protein aqueous solution. The 10wt% pea protein aqueous solution was magnetically stirred for 30 minutes to fully disperse it. After centrifugation at 4000 r / min for 10 minutes, the precipitate was collected to obtain the pea protein insoluble matter.

[0059] Pea protein insolubles were mixed with water at a volume ratio of 1:2. Glycerin was then added to the mixture to control the concentration of glycerin in the mixture at 27 wt%. The mixture was then fully hydrated at a temperature of 80°C for 30 min. After the hydration reaction was completed, a film-forming solution was obtained.

[0060] Pour 40 mL of film-forming solution into a 200×100×5 mm immersion tank. 3The product is obtained by placing it in an acrylic container at room temperature with ventilation for 24 hours.

[0061] Comparative Example 2

[0062] Pea protein was added to water to prepare a 10wt% pea protein aqueous solution. The 10wt% pea protein aqueous solution was magnetically stirred for 30 minutes to fully disperse it. After centrifugation at 4000 r / min for 10 minutes, the precipitate was collected to obtain the pea protein insoluble matter.

[0063] Pea protein insolubles were mixed with a 1 wt% sodium alginate solution at a volume ratio of 1:2. Glycerin was then added to the mixture to control the concentration of glycerin at 27 wt%. The mixture was then fully hydrated at a temperature of 80°C for 30 minutes. After the hydration reaction was completed, a film-forming solution was obtained.

[0064] Pour 40 mL of film-forming solution into a 200×100×5 mm immersion tank. 3 The product is obtained by placing it in an acrylic container at room temperature with ventilation for 24 hours.

[0065] Comparative Example 3

[0066] Pea protein was added to water to prepare a 10wt% pea protein aqueous solution. The 10wt% pea protein aqueous solution was magnetically stirred for 30 minutes to fully disperse it. After centrifugation at 4000 r / min for 10 minutes, the precipitate was collected to obtain the pea protein insoluble matter.

[0067] Add 30 mL of 0.3 mol / L hydrochloric acid solution to 30 mL of pea protein insolubles, stir magnetically for 10 min, and then heat in a water bath at 60 °C for 90 min to perform deamidation. Then, adjust the pH to 9-10 with 3 mol / L NaOH solution to terminate the deamidation reaction and obtain the deamidated product.

[0068] The deamidation product was mixed with a 1 wt% sodium alginate solution at a volume ratio of 1:2. Glycerol was then added to the mixture to control the concentration of glycerol in the mixture at 27 wt%. The mixture was then fully hydrated at a temperature of 80°C for 30 min. After the hydration reaction was completed, a film-forming solution was obtained.

[0069] Pour 40 mL of film-forming solution into a 200×100×5 mm immersion tank. 3 The product is obtained by placing it in an acrylic container at room temperature with ventilation for 24 hours.

[0070] Experimental Example 1

[0071] The samples prepared in each of the following groups (Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3) were subjected to performance tests. The specific results are shown in Table 1.

[0072] The testing methods are summarized below:

[0073] Transparency: Cut the sample film to be tested into strips according to the size of the cuvette, attach them to the surface of the cuvette, and measure its transparency at a wavelength of 600 nm, using a blank cuvette as a control.

[0074] Water solubility: After placing the sample membrane in a desiccator for one week, record the initial mass W1. Place the sample in 50 mL of distilled water, remove it after 24 hours, and dry it in an oven at 105℃ until constant weight. Weigh the sample as W2. Calculate the water solubility of the membrane using the following equation: Solubility = (W1 - W2) / W1 × 100%.

[0075] Cooking loss rate: After placing the sample membrane in a desiccator for one week, record the initial mass W1. Immerse the sample membrane in boiling water for 3 minutes, then remove it and dry it in an oven at 105℃ until constant weight, and weigh it as W2. Calculate the cooking loss rate of the membrane using the following equation: Cooking loss rate = (W1 - W2) / W1 × 100%.

[0076] Water vapor transmission rate: According to GB 1037-1988, the pseudo-cup method was adopted. The sample film to be tested was cut into a circular piece with a diameter of 25 mm, the film thickness was measured, and then sealed with sealing film at the mouth of a conical flask. 4 g of anhydrous calcium chloride was placed in the conical flask and placed in a desiccator with a relative humidity of 80% and a temperature of 25℃. The mass in the cup was tested every 24 hours.

[0077] The calculation formula is as follows: WVP=△m×L×t×△P / A.

[0078] Where: WVP - Water vapor transmission coefficient (G·mm) / (m) 2 ·d·kPa); Δm - water vapor migration (g); A - membrane area (mm²) 2 ); t - measurement time (h); L - film thickness (mm); ΔP - water vapor pressure difference across the film (kPa).

[0079] Note: The saturated vapor pressure of pure water at 25℃ is 3.1671 kPa.

[0080] Tensile strength: The sample film to be tested is cut into standard specimens of 10×50mm, and a tensile test is performed on the instrument. Three parallel samples are made for each test, and the arithmetic mean is taken. Before the test, the specimens are equilibrated at room temperature (25℃) and relative humidity (50%) for 48 hours. Tensile strength is expressed as TS, and the calculation formula is as follows: TS=P / (b×d), where: TS-tensile strength (MPa); P-maximum load (mm); b-specimen width (mm); d-specimen thickness (mm).

[0081] Table 1

[0082]

[0083] As shown in the table above, water solubility decreased from 56.82% to 26.87%; transparency increased from 59.90% to 70.70%; cooking loss decreased from 22.60% to 12.20%; and tensile strength increased from 5.37 MPa to 8.54 MPa. It can be seen that the double-network crosslinked membrane prepared by the method of this invention has significant improvements in transparency, water solubility, cooking loss, water vapor permeability, and tensile strength, indicating that the Ca... 2+ Under the chelation effect, the molecular chains of sodium alginate are more tightly bound, and the synergistic effect of pea globulin on film formation is stronger. The interaction between the chains ultimately leads to the formation of a three-dimensional network structure, i.e., a gel state, which greatly improves the overall performance of the protein membrane.

[0084] Experimental Example 2

[0085] The samples prepared in each of the following groups (Example 1, Comparative Example 1, Comparative Example 2, and Comparative Example 3) were placed in water for 24 hours. See [link to relevant documentation]. Figure 2 It was found that only Example 1 could maintain good transparency and integrity, indicating that the dual-network crosslinked membrane prepared by the present invention can be stably maintained in water for more than 24 hours. The samples prepared by Comparative Examples 1 and 2 showed different degrees of breakage and decomposition, and the integrity decreased significantly. The sample of Comparative Example 3 had low transparency. Therefore, the samples of Comparative Examples 1-3 could not meet the requirements for use as edible membranes.

[0086] Experimental Example 3

[0087] The amino acid content of the pea protein insolubles and deamide products from Example 1 was analyzed, and the results are shown in Table 2. It is easy to see that the deamide treatment retained the 15 amino acids contained in the original pea protein insolubles. The content of eight amino acids, namely aspartic acid, threonine, methionine, isoleucine, phenylalanine, histidine, leucine, and glycine, was increased to varying degrees, especially glycine, which increased by 85.4%. Furthermore, the ratio of essential amino acids to total amino acids was slightly increased, indicating that the product prepared after deamide treatment has improved nutritional value.

[0088] Table 2

[0089] Aspartic acid (Asp) 9.91 10.32 Threonine*(Thr) 3.42 3.67 Serine 4.92 4.91 Glutamic acid (Glu) 14.58 14.20 Valine* 6.63 6.01 Methionine* (Met) 3.03 3.27 Isoleucine* (Ile) 6.37 6.76 Tyrosine (Tyr) 7.68 7.49 Phenylalanine* (Phe) 5.34 5.45 Histidine*(His) 2.18 2.43 Lysine* (Lys) 7.58 7.46 Leucine* 9.79 10.02 Cysteine ​​(Cys) 0.37 0.28 Glycine (Gly) 3.78 7.01 Arginine (Arg) 7.45 6.88 Essential amino acids / Total amino acids 44.59 45.08

[0090] Note: Amino acids marked with * are essential amino acids.

[0091] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing an edible double-network crosslinked membrane, characterized in that, Includes the following steps: Hydrochloric acid was added to the pea protein insolubles to perform deamidation treatment, yielding the deamidated product; Sodium alginate solution was mixed with the deamidation product, and glycerol was added to the mixture for hydration reaction. After the reaction was completed, the film-forming solution was obtained. After coating the film-forming solution onto a plate and drying it, cross-linking is achieved by dripping calcium chloride solution onto the plate, and the film is then dried to obtain the final product. The pea protein insolubles were extracted using the following method: Pea protein was dispersed in water to obtain a pea protein aqueous solution, which was then centrifuged and filtered to obtain pea protein insolubles. The volume ratio of the pea protein insolubles to hydrochloric acid is 1:1-1.5; The deamidation reaction temperature is 50-70 ℃, and the reaction time is 60-90 min; The volume ratio of the deamide product to the sodium alginate solution is 1:2-2.5; The sodium alginate solution has a mass concentration of 0.9-1.1%; The mass concentration of glycerol in the mixture is 23-27%; The hydration reaction is carried out at a temperature of 60-80 ℃ and for a time of 30-60 min. The volume ratio of the film-forming solution to the calcium chloride solution is 1.5-2.5:

1.

2. The preparation method according to claim 1, characterized in that, The centrifugation speed is 4000-8000 r / min, and the centrifugation time is 10-15 min.

3. The preparation method according to claim 1, characterized in that, The concentration of the hydrochloric acid is 0.2-0.3 mol / L.

4. The preparation method according to claim 1, characterized in that, The drying time after coating is 20-24 hours.

5. The preparation method according to claim 1, characterized in that, The mass concentration of the calcium chloride solution is 0.6-0.8%.

6. The preparation method according to claim 1, characterized in that, The crosslinking time is 10-20 s.

7. The preparation method according to claim 1, characterized in that, The deamidation process also includes terminating the deamidation reaction with an alkaline solution.

8. The preparation method according to claim 7, characterized in that, The pH of the system was adjusted to 9-10 with an alkaline solution to terminate the deamidation reaction.

9. An edible dual-network cross-linked membrane, characterized in that, The dual-network crosslinked membrane is prepared using the preparation method described in any one of claims 1-8.

10. The application of the dual-network crosslinked membrane as described in claim 9 in the preparation of edible protein membrane foods.

11. The application according to claim 10, characterized in that, The edible protein membrane foods include rice noodle rolls, rice sausages, spring rolls, spring pancakes, or crystal vegetable rolls.

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