Preparation and application of betalain-loaded peanut globulin amyloid fibril / chitosan supermolecular composite coating solution
By preparing a peanut globulin amyloid fiber/chitosan supramolecular composite coating liquid loaded with betalain, the problems of insufficient safety, antioxidant and antibacterial capabilities of coating solution materials in fruit preservation were solved, achieving a green, economical and efficient fruit preservation effect.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-06-07
- Publication Date
- 2026-04-14
AI Technical Summary
In existing fruit preservation technologies, the material safety and antioxidant and antibacterial capabilities of coating solutions are poor. Traditional synthetic waxes or chemical agents affect the quality of fruits and vegetables and are costly, making it difficult to meet the demand for green, economical and efficient preservation.
A supramolecular composite coating liquid of peanut globulin amyloid fiber/chitosan loaded with betalain is used. The peanut globulin amyloid fiber is formed by acid heating and ultrasonic treatment. It is combined with chitosan and loaded with betalain to form a supramolecular complex with antibacterial and antioxidant properties, which is applied to fruit preservation.
This method enables the preparation of readily available and safe supramolecular composite coating liquids without the introduction of organic crosslinking agents. These liquids possess antioxidant and antibacterial properties, extend the shelf life of fruits, and are easy to operate and scale up.
Smart Images
Figure CN118402552B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food preservation technology, specifically relating to the preparation of a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalain and its application in fruit preservation. Background Technology
[0002] Fresh fruits and vegetables are easily spoiled and rotten during harvesting, transportation, and storage due to environmental conditions and human factors.
[0003] Moisture loss, texture deterioration, cellular respiration, aging processes, and microbial infection are key factors affecting fruit quality and shelf life. Based on these influencing factors, researchers have developed various physical, chemical, and biological preservation technologies, including artificial waxing, refrigeration, irradiation, ethylene and plant growth regulator treatment, modified atmosphere storage, and coating preservation. However, morpholine and texture enhancers in fruit waxes may affect fruit flavor and are harmful to human health; refrigeration, irradiation, and modified atmosphere storage are costly, time-consuming, and can even alter the appearance of fruit, affecting its flavor and quality. In contrast, coating preservation is considered a convenient, economical, and effective fruit preservation technology. Preservative coating solutions form a semi-permeable membrane on the fruit surface, creating a multifunctional barrier to reduce mechanical damage during transportation and storage, inhibit gas exchange, and prevent microbial infection, extending the shelf life of fresh fruits and vegetables without altering their biological, physicochemical, and physiological characteristics. However, traditional coatings are mostly based on synthetic waxes or chemical antibacterial agents, making them difficult to wash off and affecting the quality of fruits and vegetables, potentially harming consumer health. Therefore, developing a green, safe, economical, and efficient preservation coating solution is crucial for extending the shelf life of perishable fruits.
[0004] In recent years, natural polymers derived from renewable resources, such as polysaccharides, proteins, and lipids, have been widely studied and used in the preparation of preservation coatings due to their non-toxicity, biodegradability, and good film-forming ability. Proteins and their derivatives extracted from processing byproducts such as corn, wheat, soybeans, peanuts, milk, or gelatin can all be used to prepare preservation coatings or packaging films. Compared to packaging materials formed from polysaccharides, protein-based packaging materials have higher mechanical properties and stronger barrier properties against carbon dioxide and oxygen. However, most protein films or coatings have poor water vapor barrier properties due to their good hydrophilicity. Preservation coatings or packaging materials with good application prospects should possess strong antioxidant and antibacterial activity, good mechanical strength and gas permeability, and strong adhesion. Single protein coatings or packaging materials are difficult to meet these multifaceted requirements; therefore, researchers have proposed developing protein-based composite preservation coatings that combine the advantages of various components to improve the preservation performance of protein-based coatings.
[0005] Peanut meal, a byproduct of peanut oil extraction, is rich in protein. Peanut globulin, comprising 70% of the total peanut protein, can be extracted using ammonium sulfate precipitation and is an excellent raw material for preparing protein-based films. Simultaneously, protein fibrillation modification can induce globular protein molecules to self-assemble into fibrous structures under acid-heat treatment. These linear protein molecules react positively with iodine and are thus called amyloid fibers. Compared to natural proteins, amyloid fibers have a high aspect ratio and high stiffness, which is beneficial for enhancing the mechanical properties of protein-based coatings and packaging materials. Furthermore, their linear surface exposes numerous active groups, allowing them to bind with other biomolecules or small molecules through intermolecular forces. Polysaccharides can form transparent, barrier-like preservative coatings through intermolecular or intramolecular hydrogen bonds, and the addition of polysaccharides can improve the extensibility of protein-based packaging materials. Chitosan, a natural cationic polysaccharide, is biodegradable, antibacterial, and abundant, and is widely used in the food, pharmaceutical, and cosmetic industries. Combining chitosan with protein molecules can improve the preservation performance of composite coatings or packaging materials. It has been reported that chitosan, when combined with amyloid fibers, can improve the structural stability of amyloid fibers in acidic (pH 2) and weakly alkaline (pH 8) environments. Furthermore, the resulting complex can act as a carrier for bioactive substances such as polyphenols, forming supramolecular complexes with polyphenol molecules through molecular self-assembly, significantly enhancing the physicochemical stability of polyphenols. Typically, adding small amounts of polyphenols to coating and packaging substrates can significantly improve the antioxidant and antibacterial properties of the coating solution and packaging materials. Beetroot red pigments, derived from beet roots, possess antioxidant, anticancer, lipid-lowering, and antibacterial activities, and increasing research demonstrates their potential application value in the food packaging field.
[0006] Therefore, given the diverse preservation requirements of coating solutions for fruit storage, developing a simple, green, biodegradable bio-based coating solution with both antioxidant and antibacterial properties is of great significance for fruit preservation and storage, and can promote the development of related industries. Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalains, which will be applied to fruit preservation, in order to solve the problems of material safety and poor antioxidant and antibacterial capabilities of existing preservation technologies.
[0008] This invention provides a method for preparing a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine. First, peanut globulin is induced to fibrose and form amyloid fibers by acid heating and ultrasonic treatment. Then, it is combined with chitosan to form a complex. A betaine solution is added to the complex, the pH value is adjusted and the mixture is stirred. The peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine is obtained through molecular self-assembly.
[0009] This invention provides a method for preparing a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine, comprising the following steps:
[0010] Step 1: Dissolve peanut globulin powder in deionized water and stir magnetically until homogeneous to obtain a peanut globulin solution with a concentration of 20-40 mg / mL. Let it stand overnight at 4℃ to fully hydrate. Adjust the pH of the protein solution to 2.0 with 6 mol / L hydrochloric acid solution. Heat in a 90℃ oil bath for 2 h, then treat under 260 W sonication for 0-40 min. Continue heating at 90℃ for 24 h to obtain a peanut globulin amyloid cellulose solution.
[0011] Step 2: Mix chitosan with a 2% (v / v) acetic acid solution and stir until homogeneous under magnetic stirring at 200 rpm to obtain a chitosan solution with a mass concentration of 30 mg / mL.
[0012] Step 3: Dissolve betalain powder in deionized water to obtain a 200 mg / mL betalain solution.
[0013] Step 4: Slowly add the chitosan solution to the peanut globulin amyloid cellulose solution (20-40 mg / mL) obtained in Step 1 at a volume ratio of 1:1-4. After magnetic stirring, a complex is formed. Slowly add the betaine solution obtained in Step 3 to the complex. The betaine concentration in the system is 5 mg / mL (which has little effect on the apparent color of the fruit). Then adjust the pH of the system to 2-5. After magnetic stirring for 2 h, a peanut globulin amyloid cellulose / chitosan supramolecular composite coating liquid loaded with betaine is obtained.
[0014] A supramolecular composite coating liquid containing betalain-loaded peanut globulin amyloid cellulose / chitosan was applied to fruit preservation. Specifically, the fruit was immersed in the coating liquid, removed after one second, and then air-dried; the process is simple.
[0015] The preferred fruit is strawberry or grape.
[0016] Compared with existing technologies, the beneficial effects of this invention are reflected in:
[0017] 1. This invention uses peanut globulin, a byproduct of peanut processing, as raw material. Peanut globulin amyloid fibers are formed by heating and ultrasonic treatment under acidic conditions. The prepared amyloid fibers have a high aspect ratio, which is conducive to the binding of protein molecules with active substances such as polyphenols, thereby increasing the added value of peanut globulin.
[0018] 2. This invention is the first to propose using peanut globulin amyloid fibers and chitosan to form a complex to load betalains, and to form a supramolecular complex with antibacterial and antioxidant properties through molecular self-assembly, which can be applied to fruit preservation.
[0019] 3. This invention combines peanut globulin amyloid fibers with chitosan and loads betaine to form a supramolecular complex without introducing any organic cross-linking agents, thereby achieving the loading of betaine. Furthermore, the supramolecular composite coating liquid prepared by this invention uses readily available materials, requires simple equipment operation, is easy to prepare on a large scale, and has excellent product safety performance. It also has antioxidant and antibacterial properties, which can extend the shelf life of fruits and is expected to be widely used in the field of fruit preservation. Attached Figure Description
[0020] Figure 1 The results show the DPPH anion free radical scavenging ability of the supramolecular composite coating liquids prepared in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3.
[0021] Figure 2 The results show the ABTS cationic free radical scavenging ability of the supramolecular composite coating liquids prepared in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3.
[0022] Figure 3 The results show the antibacterial effects of the supramolecular composite coating liquids prepared in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3 against Escherichia coli and Staphylococcus aureus.
[0023] Figure 4 The antibacterial results of the supramolecular composite coating liquids prepared in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3 against Botrytis cinerea are presented.
[0024] Figure 5 The results show the cytotoxicity of the supramolecular composite coating liquids prepared in Examples 1, 2, 3, 4, 5, Comparative Examples 1, 2, and 3.
[0025] Figure 6 The graph shows the changes in hardness and weight loss of strawberries and grapes during storage, using the coating treatment and the uncoated treatment of Example 2.
[0026] Figure 7 An atomic force microscope image of peanut globulin amyloid fibers and supramolecular complexes. Detailed Implementation
[0027] The non-limiting implementation method is described below: Example 1
[0028] Peanut globulin powder was dissolved in deionized water and magnetically stirred until homogeneous, yielding a 20 mg / mL peanut globulin solution. This solution was left at 4°C overnight for full hydration. The pH of the protein solution was adjusted to 2.0 with 6 mol / L hydrochloric acid, and then heated in a 90°C oil bath for 24 h to obtain a peanut globulin amyloid cellulose solution. Chitosan was mixed with a 2% (v / v) acetic acid solution and continuously stirred at 400 rpm until homogeneous, yielding a 30 mg / mL chitosan solution. Betaine powder was dissolved in deionized water to obtain a 200 mg / mL betaine solution. The chitosan solution was slowly added to the peanut globulin amyloid cellulose solution at a 1:4 volume ratio and magnetically stirred until homogeneous, forming a complex. The betaine solution was then slowly added to the complex solution to a concentration of 5 mg / mL, forming a supramolecular complex through intermolecular interactions. The pH of the complex solution was then adjusted to 2, and the mixture was magnetically stirred for 2 hours. After h, a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalain was obtained. Example 2
[0029] Peanut globulin powder was dissolved in deionized water and magnetically stirred until homogeneous, yielding a 30 mg / mL peanut globulin solution. This solution was left at 4°C overnight for full hydration. The pH of the protein solution was adjusted to 2.0 with 6 mol / L hydrochloric acid, heated in a 90°C oil bath for 2 h, and then sonicated at 260 W for 20 min. Heating continued for 24 h to obtain a peanut globulin amyloid cellulose solution. Chitosan was mixed with a 2% (v / v) acetic acid solution and continuously stirred at 400 rpm until homogeneous, yielding a 30 mg / mL chitosan solution. Betaine powder was dissolved in deionized water to obtain a 200 mg / mL betaine solution. The chitosan solution was slowly added to the peanut globulin amyloid cellulose solution at a 1:2 volume ratio and magnetically stirred until homogeneous to form a complex. The betaine solution was then slowly added to the complex solution to a concentration of 5%. mg / mL, forming a supramolecular complex through intermolecular interactions; then adjusting the pH of the composite solution to 3.5, and after magnetic stirring for 2 h, a peanut globulin amyloid fiber / chitosan supramolecular composite coating solution loaded with betalains was obtained. Example 3
[0030] Peanut globulin powder was dissolved in deionized water and magnetically stirred until homogeneous, yielding a 30 mg / mL peanut globulin solution. This solution was left at 4°C overnight for full hydration. The pH of the protein solution was adjusted to 2.0 with 6 mol / L hydrochloric acid, heated in a 90°C oil bath for 2 h, and then sonicated at 260 W for 20 min. Heating continued for 24 h to obtain a peanut globulin amyloid cellulose solution. Chitosan was mixed with a 2% (v / v) acetic acid solution and continuously stirred at 400 rpm until homogeneous, yielding a 30 mg / mL chitosan solution. Betaine powder was dissolved in deionized water to obtain a 200 mg / mL betaine solution. The chitosan solution was slowly added to the peanut globulin amyloid cellulose solution at a 1:2 volume ratio and magnetically stirred until homogeneous to form a complex. The betaine solution was then slowly added to the complex solution to a concentration of 5%. mg / mL, forming a supramolecular complex through intermolecular interaction forces; then adjusting the pH of the composite solution to 5, and after magnetic stirring for 2 h, a peanut globulin amyloid fiber / chitosan supramolecular complex coating solution loaded with betalains was obtained. Example 4
[0031] Peanut globulin powder was dissolved in deionized water and magnetically stirred until homogeneous, yielding a 40 mg / mL peanut globulin solution. This solution was left at 4°C overnight for full hydration. The pH of the protein solution was adjusted to 2.0 with 6 mol / L hydrochloric acid, heated in a 90°C oil bath for 2 h, and then sonicated at 260 W for 40 min. Heating continued for 24 h to obtain a peanut globulin amyloid cellulose solution. Chitosan was mixed with a 2% (v / v) acetic acid solution and continuously stirred at 400 rpm until homogeneous, yielding a 30 mg / mL chitosan solution. Betaine powder was dissolved in deionized water to obtain a 200 mg / mL betaine solution. The chitosan solution was slowly added to the peanut globulin amyloid cellulose solution at a 1:1 volume ratio and magnetically stirred until homogeneous to form a complex. The betaine solution was then slowly added to the complex solution to a concentration of 5%. mg / mL, forming a supramolecular complex through intermolecular interactions; then adjusting the pH of the composite solution to 3.5, and after magnetic stirring for 2 h, a peanut globulin amyloid fiber / chitosan supramolecular complex coating solution loaded with betalains was obtained. Example 5
[0032] Peanut globulin powder was dissolved in deionized water and magnetically stirred until homogeneous, yielding a 40 mg / mL peanut globulin solution. This solution was left at 4°C overnight for full hydration. The pH of the protein solution was adjusted to 2.0 with 6 mol / L hydrochloric acid, heated in a 90°C oil bath for 2 h, and then sonicated at 260 W for 40 min. Heating continued for 24 h to obtain a peanut globulin amyloid cellulose solution. Chitosan was mixed with a 2% (v / v) acetic acid solution and continuously stirred at 400 rpm until homogeneous, yielding a 30 mg / mL chitosan solution. Betaine powder was dissolved in deionized water to obtain a 200 mg / mL betaine solution. The chitosan solution was slowly added to the peanut globulin amyloid cellulose solution at a 1:2 volume ratio and magnetically stirred until homogeneous to form a complex. The betaine solution was then slowly added to the complex solution to a concentration of 5%. mg / mL, forming a supramolecular complex through intermolecular interactions; then adjusting the pH of the composite solution to 3.5, and after magnetic stirring for 2 h, a peanut globulin amyloid fiber / chitosan supramolecular composite coating solution loaded with betalains was obtained. Comparative Example 1
[0033] Comparative Example 1 provides a method for preparing a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalain. Its formulation and preparation method are basically the same as those in Example 3, except that natural peanut globulin is used instead of peanut globulin amyloid fiber, and the concentration is 30 mg / mL. Comparative Example 2
[0034] Comparative Example 2 provides a method for preparing a chitosan coating liquid loaded with betaine. Its formula and preparation method are basically the same as those in Example 2, except that deionized water is used instead of peanut globulin amyloid fibers, the volume ratio of deionized water to chitosan is 2:1, and the solution pH is 3.5. Comparative Example 3
[0035] Comparative Example 1 provides a method for preparing a peanut globulin amyloid fiber coating solution loaded with betaine. Its formula and preparation method are basically the same as those in Example 2, except that deionized water is used instead of chitosan solution, the volume ratio of peanut globulin amyloid fiber to deionized water is 2:1, and the solution pH is 3.5.
[0036] Figure 1 , Figure 2 The comparative examples and embodiments demonstrate their scavenging abilities against DPPH anionic radicals and ABTS cationic radicals. Figure 1It can be seen that the scavenging abilities of the complexes prepared in Comparative Examples 1, 2, and 3 against DPPH anion free radicals were 40.3%, 30.7%, and 23.8%, respectively, while the scavenging abilities of the complexes prepared in Examples 1, 3, 4, and 5 against DPPH anion free radicals were 45.7%, 41.5%, 67.2%, and 54.1%, respectively. However, the peanut globulin amyloid cellulose / chitosan supramolecular composite coating liquid loaded with betaine prepared according to this invention (Example 2) can achieve a scavenging ability of 73.40% against DPPH anion free radicals. Figure 2 It can be seen that the scavenging abilities of the complexes prepared in Comparative Examples 1, 2, and 3 against ABTS cationic free radicals were 34.6%, 24.2%, and 20.2%, respectively, while the scavenging abilities of the complexes prepared in Examples 1, 3, 4, and 5 against ABTS cationic free radicals were 38.1%, 35.2%, 60.1%, and 40.1%, respectively. However, the peanut globulin amyloid fiber / chitosan supramolecular composite coating solution loaded with betaine prepared according to the present invention (Example 2) can achieve a scavenging ability of 66.4% against ABTS cationic free radicals. Therefore, the peanut globulin amyloid fiber / chitosan supramolecular composite coating solution loaded with betaine prepared according to the present invention has high antioxidant capacity.
[0037] Figure 3 The comparative examples and specific examples demonstrate the antibacterial activity against *Escherichia coli* and *Staphylococcus aureus*. Specifically, the complexes prepared in Comparative Examples 1, 2, and 3 showed antibacterial activities against *Escherichia coli* of 57.8%, 52.1%, and 20.1%, respectively; while the complexes prepared in Examples 1, 3, 4, and 5 showed antibacterial activities against *Escherichia coli* of 69.0%, 73.0%, 73.4%, and 66.2%, respectively. Similarly, the complexes prepared in Comparative Examples 1, 2, and 3 showed antibacterial activities against *Staphylococcus aureus* of 53.5%, 48.1%, and 16.7%, respectively; and the complexes prepared in Examples 1, 3, 4, and 5 showed antibacterial activities against *Staphylococcus aureus* of 49.3%, 58.8%, 59.6%, and 57.8%, respectively. The peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine prepared by the present invention (Example 2) showed antibacterial abilities of 83.6% and 65.9% against Escherichia coli and Staphylococcus aureus, respectively, indicating that the peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine prepared by the present invention has high antibacterial ability.
[0038] Figure 4The antifungal activity of the comparative examples and the embodiments against *Botrytis cinerea* was demonstrated. Specifically, the complexes prepared in Comparative Examples 1, 2, and 3 showed antifungal activity against *Escherichia coli* of 5.2%, 4.1%, and 4.2%, respectively; while the complexes prepared in Examples 1, 3, 4, and 5 showed antifungal activity against *Escherichia coli* of 12.7%, 5.3%, 15.1%, and 12.2%, respectively. In contrast, the peanut globulin-loaded amyloid fiber / chitosan supramolecular composite coating liquid prepared according to this invention (Example 2) showed an antifungal activity of 20.2% against *Botrytis cinerea*, indicating that the peanut globulin-loaded amyloid fiber / chitosan supramolecular composite coating liquid prepared according to this invention has high antifungal activity.
[0039] Figure 5 The results of the comparative and example studies on the cytotoxicity of Caco-2 cells are shown. As can be seen from the figure, after co-incubating all examples and comparative examples with Caco-2 cells for 24 hours, the cell viability in the samples was higher than 100%, indicating that the peanut globulin amyloid cellulose / chitosan supramolecular composite coating solution loaded with betaine prepared in this invention has good cell safety.
[0040] The above analysis shows that the ultrasonic time, solution concentration, mixing ratio with chitosan, and pH value of the system during the preparation of peanut globulin amyloid fibers affect the antibacterial and antioxidant capabilities of the supramolecular composite coating solution. Specifically, comparing Examples 2 and 3, the supramolecular composite coating solution at pH 3.5 (Example 2) exhibits higher antibacterial and antioxidant capabilities. Comparing Examples 4 and 5, the supramolecular composite coating solution at a higher chitosan concentration (Example 4) demonstrates higher antibacterial and antioxidant capabilities. Among all the implementation cases, Example 2, exhibiting higher antibacterial and antioxidant capabilities, was selected for fruit preservation research.
[0041] Figure 6 The changes in quality of strawberries and grapes during storage are shown in both uncoated (control group) and coated (Comparative Example 2) samples. Figure 5It can be seen that after 8 days of storage, the hardness of uncoated strawberries decreased from 144.3 g to 42.3 g, while the hardness of strawberries coated in Comparative Example 2 decreased from 158.2 g to 73.0 g. After 10 days of storage, the hardness of uncoated grapes decreased from 127.3 g to 22.7 g, while the hardness of grapes coated in Comparative Example 2 decreased from 131.0 g to 55.7 g. Meanwhile, after 8 days of storage, the weight loss of uncoated strawberries increased from 6.0% to 28.5%, while the weight loss of strawberries coated in Comparative Example 2 increased from 4.6% to 20.8%. After 10 days of storage, the weight loss of uncoated grapes increased from 1.1% to 12.8%, while the weight loss of grapes coated in Comparative Example 2 increased from 0.6% to 8.2%. Therefore, the peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalain prepared in this invention has an inhibitory effect on weight loss and pulp softening of strawberries and grapes, thus prolonging their shelf life.
[0042] Figure 7 This image shows the atomic force microscopy (AFM) structure of peanut globulin amyloid fibers and a peanut globulin amyloid fiber / chitosan supramolecular complex loaded with betaine. As can be seen from the image, a network structure is formed between peanut globulin amyloid fibers, chitosan, and betaine. Betaine molecules are immobilized within this network structure. This network structure of the complex helps stabilize betaine, thereby enhancing its antioxidant and antibacterial effects on fruits and extending the shelf life of strawberries and grapes.
Claims
1. A method for preparing a peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine, characterized in that: First, peanut globulin is induced to fibrose and form amyloid fibers using acid heating and ultrasonic treatment. These fibers then bind with chitosan to form a complex. A betaine solution is added to this complex, the pH is adjusted, and the mixture is stirred. Through molecular self-assembly, a peanut globulin amyloid fiber / chitosan supramolecular composite coating solution loaded with betaine is obtained. The process includes the following steps: Step 1: Dissolve peanut globulin powder in deionized water, stir evenly to obtain peanut globulin solution, let stand at 4℃ to fully hydrate, adjust the pH value to 2.0 with hydrochloric acid solution, heat and supplement with ultrasonic treatment to obtain peanut globulin amyloid cellulose solution; Step 2: Mix chitosan with acetic acid solution and stir until homogeneous to obtain chitosan solution; Step 3: Dissolve betalain powder in deionized water to obtain betalain solution; Step 4: Slowly add the chitosan solution obtained in Step 2 to the peanut globulin amyloid fiber solution obtained in Step 1, mix at different volume ratios, and form a complex after magnetic stirring; slowly add the betaine solution obtained in Step 3 to the obtained complex, then adjust the pH of the system to 2-5, and after magnetic stirring, obtain the peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betaine. In step 1, the heating and ultrasonic treatment involves first heating at 90°C for 2 hours, followed by ultrasonic treatment for 20-40 minutes, and then continuing to heat at 90°C for 24 hours to obtain a peanut globulin amyloid fiber solution. In step 4, the volume ratio of chitosan solution to peanut globulin amyloid cellulose solution is 1:1-4; In step 4, the betaine solution is added to make the betaine concentration in the system 5 mg / mL.
2. The preparation method according to claim 1, characterized in that: In step 1, the concentration of the peanut globulin solution is 20-40 mg / mL.
3. The preparation method according to claim 1, characterized in that: The ultrasonic power is 260 W.
4. The preparation method according to claim 1, characterized in that: In step 2, the volume concentration of the acetic acid solution is 2%, and the mass concentration of the chitosan solution is 30 mg / mL.
5. The preparation method according to claim 1, characterized in that: In step 3, the concentration of the betaine solution is 200 mg / mL.
6. The application of the peanut globulin amyloid fiber / chitosan supramolecular composite coating liquid loaded with betalain prepared by any one of claims 1-5 in fruit preservation.