Preparation method of convenient edible heat-soluble food packaging film

Abstract

The invention discloses a preparation method of a convenient edible heat-soluble food packaging film, and belongs to the field of food packaging. The preparation method comprises the following steps: mixing corn starch, nano cellulose and water to obtain a starch mixed solution; mixing hydroxymethyl cellulose, sodium alginate and water to obtain a hydroxymethyl cellulose-sodium alginate solution; adding gelatin into the starch mixed solution to obtain a gelatin-starch solution, then adding the hydroxymethyl cellulose-sodium alginate solution, and then adding the glycerol-alcohol compound solution to obtain a film forming solution; and drying the film forming liquid to obtain the edible packaging film for food. The edible packaging film disclosed by the invention is good in tensile property, can meet the requirements of storage and transportation when being used for storing soup bases, powder materials or solids, is excellent in water solubility and has no peculiar smell after being dissolved in water, so that the edible packaging film is excellent in product performance and wide in application range.

Description

Technical Field

[0001] The invention belongs to the field of food packaging, and in particular relates to a method for preparing a convenient edible heat-soluble food packaging film. Background Art

[0002] In the food industry, packaging plays a vital role in protecting food, extending shelf life, and facilitating transportation and sales. Traditional food packaging materials mainly include plastics, paper, etc. However, these traditional packaging materials have many problems. Plastic packaging is one of the most widely used food packaging materials, but it is difficult to degrade and will cause serious environmental pollution after large-scale use. Although paper packaging is relatively environmentally friendly, it has poor moisture and waterproof properties. For some foods that need to be kept dry or contain a certain amount of moisture, paper packaging cannot provide effective protection and can easily cause food to spoil. Moreover, the production process of paper packaging consumes a large amount of wood resources, which causes certain damage to the forest ecological environment. Therefore, using bio-based renewable resources (such as naturally derived proteins and polysaccharides) to produce films to replace non-renewable synthetic plastics is a promising solution.

[0003] Edible packaging films, as a new type of food packaging material, have unique advantages. They are made from edible natural substances such as polysaccharides, proteins, and lipids. After use, they can be eaten directly or naturally degrade without causing environmental pollution. In addition, edible packaging films can be eaten together with food, avoiding the trouble of separating packaging materials from food, and improving the convenience and safety of food. To achieve this goal, good sealing and sufficient sealing strength are important to prevent the failure of small bags or sachets and the leakage of packaging materials. Currently, some edible packaging films have poor mechanical properties and are easily broken and damaged, which cannot meet the requirements of food during transportation and storage. In addition, convenient and edible food packaging films must not add unpleasant flavors after dissolving in food. Therefore, it is of great significance to develop an edible packaging film with good mechanical properties, good barrier properties, excellent solubility, and no odor after dissolution.

[0004] Patent CN 115339168 B discloses a highly extensible, multi-layer edible antibacterial packaging film and its preparation method. The method involves forming a gelatin film and a corn starch film into separate films, then applying a chitosan film onto the gelatin film to form a gelatin-chitosan film. Finally, the corn starch film is laid flat on the gelatin-chitosan film to form the multi-layer edible antibacterial packaging film. However, this multi-layer edible antibacterial packaging film exhibits poor tensile properties and water solubility, making it inferior to the product of the present invention in terms of performance.

[0005] In addition, edible packaging films made with corn starch and gelatin as the main raw materials have some other problems, such as insufficient flexibility and ductility of the film, which is prone to cracking; the film has poor water resistance and is easy to soften and dissolve in a humid environment; the preservation effect of the film needs to be further improved, etc. Summary of the Invention

[0006] Technical issues

[0007] Currently, the mechanical properties of edible packaging films are poor and cannot meet the requirements of transportation and storage. In addition, they will add unpleasant flavors when directly dissolved in food. Therefore, an edible packaging film with good mechanical properties, good barrier properties, excellent solubility and no odor after dissolution is developed.

[0008] Technical Solution

[0009] To address the aforementioned technical issues, the present invention provides a method for preparing an edible food packaging film. This method uses corn starch and gelatin as primary raw materials. Through rational process steps and parameter control, it produces an edible packaging film with excellent mechanical properties, barrier properties, and heat-soluble properties. This method effectively addresses the problems of poor flexibility, insufficient water resistance, and inconvenience associated with existing edible packaging films. The film also achieves controllable heat-soluble properties through cross-linking modification and composite processing techniques, allowing it to directly heat-dissolve with food. It is suitable for disposable food packaging, seasoning encapsulation, or ready-to-eat food packaging. This method aims to address the environmental pollution issues associated with traditional plastic packaging and enhance the functionality and safety of food packaging.

[0010] The present invention provides a method for preparing an edible food packaging film, comprising the following steps:

[0011] (1) mixing corn starch, nanocellulose and water, heating and stirring to obtain a starch mixed solution;

[0012] (2) mixing hydroxymethyl cellulose, sodium alginate and water, heating and stirring to obtain a hydroxymethyl cellulose-sodium alginate solution;

[0013] (3) adding gelatin to the starch mixed solution, heating and stirring to uniformly disperse the gelatin to obtain a gelatin-starch solution, then adding the hydroxymethyl cellulose-sodium alginate solution to the gelatin-starch solution, continuing to heat and stir to obtain a gelatin-corn starch mixed solution;

[0014] (4) adding a glycerol-alcohol compound solution to the gelatin-corn starch mixed solution, heating and stirring to uniformly disperse the mixture to obtain a film-forming solution;

[0015] (5) Pour the film-forming liquid into a mold and dry it to obtain an edible food packaging film.

[0016] Furthermore, the preparation method of nanocellulose in step (1) is as follows: putting the Sargassum that has been soaked in water for 20 to 40 hours into a NaOH solution, placing it at 70 to 80° C. for 10 to 15 hours, then filtering it, washing the Sargassum, mixing it with water, adding cellulase, and enzymolyzing it at 40-55° C. for 1 to 3 hours. After enzyme inactivation treatment, suspending the Sargassum cellulose in water, nanofibrillating it through high-pressure homogenization, and filtering it to obtain nanocellulose.

[0017] Furthermore, the concentration of the NaOH solution is 5-10 mg / mL; and the mass ratio of Sargassum and NaOH is 3-5:1.

[0018] Furthermore, the mass ratio of Sargassum and cellulase is 8-12:1; and the enzymatic activity of the cellulase is 8000-12000 U / g.

[0019] Furthermore, the pressure of the high-pressure homogenization is 40-50 MPa.

[0020] Furthermore, the enzyme inactivation condition is to treat at 100-110° C. for 5-10 min.

[0021] Furthermore, in step (1), the mass ratio of corn starch, nanocellulose and water is 5:1:75-125.

[0022] Preferably, in step (1), the mass ratio of corn starch, nanocellulose and water is 5:1:95-105.

[0023] Furthermore, the heating and stirring conditions in step (1) are: stirring at 35-45° C. for 45-60 min.

[0024] Furthermore, in step (2), the mass ratio of hydroxymethyl cellulose, sodium alginate and water is 3:3:1800-2200.

[0025] Furthermore, the heating and stirring conditions in step (2) are: stirring at 50-60° C. for 45-60 min.

[0026] Furthermore, the gelatin in step (3) is food-grade gelatin; and the amount of gelatin added is 4-5% of the mass of the starch mixed solution.

[0027] Furthermore, the heating and stirring conditions in step (3) are: stirring at 70-80° C. for 0.5-2 h.

[0028] Furthermore, in step (3), the volume ratio of the gelatin-starch solution to the hydroxymethyl cellulose-sodium alginate solution is 4 to 6:1.

[0029] Furthermore, in step (4), the glycerol-alcohol compound solution consists of glycerol, xylitol and erythritol; the mass ratio of glycerol to xylitol is 4:0.5-1.5; the mass ratio of glycerol to erythritol is 4:0.5-1.5.

[0030] Furthermore, in step (4), the amount of the glycerol-alcohol compound solution added is 10-15% of the mass of the gelatin-corn starch mixed solution.

[0031] Furthermore, the heating and stirring conditions in step (4) are: stirring at 70-80° C. for 0.5-2 h.

[0032] Furthermore, in step (5), bubbles can be removed before pouring the film-forming liquid into the mold; the operation of removing bubbles includes standing or ultrasonication.

[0033] Furthermore, the drying conditions in step (5) are: drying at 40-60°C for 20-30 hours, and then standing at 20-25°C for 10-15 hours.

[0034] The present invention provides an edible food packaging film prepared according to the method.

[0035] Application of the edible food packaging film provided by the present invention in the food field.

[0036] Compared with the prior art, the present invention has the following beneficial effects:

[0037] 1. The edible packaging film of the present invention has excellent tensile properties, with an elongation at break exceeding 200% and a toughness exceeding 380 MPa. Whether storing soups, powders, or solids, it is not easily broken during storage and transportation. The breaking strength is approximately 2.5 MPa, which can meet the needs of consumers who need to tear the packaging film. Furthermore, the edible packaging film has excellent water solubility and no odor after dissolving in water, allowing consumers to directly use the edible packaging film in food processing, making it more convenient to use. Therefore, the present invention produces an edible packaging film with excellent product performance and a wide range of applications.

[0038] 2. The present invention uses corn starch and gelatin as the main base materials to prepare heat-soluble edible food packaging film. It is prepared using non-toxic and harmless raw materials, and the overall process is simple, the reaction conditions are relatively mild, the equipment requirements are not high, the raw materials are cheap to obtain, and it is easy to achieve large-scale industrial production, with high economic, social and ecological value. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 These are the thermal dissolution temperature test results of Examples 1-9 and Comparative Examples 1-6.

[0040] Figure 2 The sensory evaluation results of Example 1 are shown.

[0041] Figure 3 This is the appearance of the edible film for sauce packaging prepared in Example 1.

[0042] Figure 4 This is the appearance of the edible film prepared in Example 1 for packaging soup products such as fish soup and concentrated soup.

[0043] Figure 5 This is the appearance of the solution of Example 1 after being dissolved in 80°C hot water for 30 to 40 seconds. DETAILED DESCRIPTION

[0044] The present invention will be further described below in conjunction with the accompanying drawings and specific examples, but the examples do not limit the present invention in any form. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0045] Source of raw materials

[0046] Cellulase with an activity of 10,000 U / g was purchased from Macklin.

[0047] Example 1

[0048] (1) Preparation of nanocellulose:

[0049] After soaking 5.0 g of Sargassum in deionized water for 24 hours, the mixture was taken out and placed in 250 mL of 6 mg / mL NaOH aqueous solution, and then allowed to stand at 80°C for 12 hours. After that, the mixture was filtered and washed with deionized water. The Sargassum was then mixed with 0.5 g of cellulase and 100 mL of water and enzymatically hydrolyzed at 50°C for 2 hours. After enzyme inactivation, the precipitate was centrifuged to obtain Sargassum cellulose. The Sargassum cellulose was suspended in deionized water and nanofibrillated by 40 MPa high-pressure homogenization to obtain nanocellulose.

[0050] (2) Preparation of starch mixed solution:

[0051] Corn starch, nanocellulose and deionized water were mixed in a mass ratio of 5:1:100, and stirred at 40°C for 50 minutes to obtain a starch mixed solution;

[0052] (3) Preparation of hydroxymethyl cellulose-sodium alginate solution:

[0053] Mixing hydroxymethyl cellulose, sodium alginate and deionized water in a mass ratio of 3:3:2000, heating and stirring at 50-60° C. for 40 minutes to obtain a hydroxymethyl cellulose-sodium alginate solution;

[0054] (4) Preparation of gelatin-corn starch mixed solution:

[0055] The starch mixed solution in step (2) was mixed with food-grade gelatin in a mass ratio of 21:1, and stirred at 70° C. for 1 h to form a uniform mixed solution, thereby obtaining a gelatin-starch solution;

[0056] (5) Compound gelatin-starch mixed solution

[0057] The hydroxymethyl cellulose-sodium alginate solution of step (3) and the gelatin-starch solution of step (4) were mixed in a mass ratio of 1:5, and stirred at 70° C. for 30 min to obtain a composite gelatin-starch mixed solution;

[0058] (6) Adding plasticizer:

[0059] Glycerol, xylitol and erythritol are compounded in a mass ratio of 4:1:1 to obtain a glycerol-alcohol compound liquid, and then added to the compounded gelatin-starch mixed solution of step (5) under stirring, the added amount being 10% of the mass of the compounded gelatin-starch mixed solution, and the stirring is continued at 75° C. for 20 minutes, and then the solution is ultrasonicated at 40° C. for 30 minutes to remove bubbles, thereby obtaining a film-forming liquid;

[0060] (7) Film forming process

[0061] The solution obtained in (6) is poured onto a mold, dried at 40° C. for 24 h, and then placed at room temperature for 12 h. The film is then peeled off from the mold to obtain an edible packaging film.

[0062] Example 2

[0063] The ratio of corn starch, nanocellulose and deionized water in step (2) of Example 1 was adjusted to 5:1:125, and the other operations were kept consistent with Example 1 to finally prepare an edible packaging film.

[0064] Example 3

[0065] The ratio of corn starch, nanocellulose and deionized water in step (2) of Example 1 was adjusted to 5:1:75, and the other operations were kept consistent with Example 1 to finally prepare an edible packaging film.

[0066] Example 4

[0067] The ratio of the starch mixed solution to food-grade gelatin in step (4) of Example 1 was adjusted to 21:2, and the other operations were kept consistent with Example 1, and finally an edible packaging film was prepared.

[0068] Example 5

[0069] The amount of the glycerol-alcohol composite solution added in step (6) of Example 1 was adjusted to 5% of the mass of the composite gelatin-starch mixed solution. Other operations were kept consistent with Example 1, and an edible packaging film was finally prepared.

[0070] Example 6

[0071] The amount of the glycerol-alcohol composite solution added in step (6) of Example 1 was adjusted to 15% of the mass of the composite gelatin-starch mixed solution. Other operations were kept consistent with Example 1, and an edible packaging film was finally prepared.

[0072] Example 7

[0073] The nanocellulose in step (2) of Example 1 was omitted, and then corn starch and deionized water were mixed in a mass ratio of 5:100 to obtain a starch mixed solution. The other operations were consistent with Example 1, and finally an edible packaging film was prepared.

[0074] Example 8

[0075] The hydroxymethyl cellulose in step (3) of Example 1 was adjusted to be omitted, and then sodium alginate and deionized water were mixed at a mass ratio of 3:2000 to obtain a sodium alginate mixed solution. The other operations were consistent with Example 1, and finally an edible packaging film was prepared.

[0076] Example 9

[0077] Example 1 was adjusted to omit steps (3) and (5), and other operations remained consistent with Example 1, and an edible packaging film was finally prepared.

[0078] Comparative Example 1

[0079] (1) corn starch and deionized water were mixed in a mass ratio of 1:20, and stirred at 40° C. for 50 min to obtain a corn starch solution;

[0080] (2) heating the solution at 30°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0081] (3) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0082] Comparative Example 2

[0083] (1) Gelatin and deionized water were mixed in a mass ratio of 1:20, and stirred at 40°C for 50 minutes to obtain a gelatin solution;

[0084] (2) heating the solution at 30°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0085] (3) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0086] Comparative Example 3

[0087] (1) Gelatin and deionized water were mixed in a mass ratio of 1:20, and stirred at 40°C for 50 minutes to obtain a gelatin solution;

[0088] (2) Sodium alginate and deionized water were mixed in a ratio of 3:2000, and heated and stirred for 40 minutes under heating conditions to obtain a sodium alginate solution;

[0089] (3) taking the sodium alginate solution described in step (2) and the gelatin solution described in step (1) at a mass ratio of 1:5, stirring at 70° C. for 30 minutes to obtain a composite gelatin-sodium alginate mixed solution;

[0090] (4) heating the solution at 40°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0091] (5) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0092] Comparative Example 4

[0093] (1) corn starch and deionized water were mixed in a mass ratio of 1:20, and stirred at 40° C. for 50 min to obtain a corn starch solution;

[0094] (2) mixing the starch solution of step (1) with food-grade gelatin in a mass ratio of 21:1, and stirring at 70° C. for 1 h to form a uniform mixed solution, thereby obtaining a gelatin-starch solution;

[0095] (3) heating the solution at 40°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0096] (4) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0097] Comparative Example 5

[0098] (1) Sodium alginate and deionized water are mixed in a ratio of 3:2000, and heated and stirred for 40 minutes under heating conditions to obtain a sodium alginate solution;

[0099] (2) heating the solution at 40°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0100] (3) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0101] Comparative Example 6

[0102] (1) corn starch and deionized water were mixed in a mass ratio of 1:20, and stirred at 40° C. for 50 min to obtain a corn starch solution;

[0103] (2) Sodium alginate and deionized water were mixed in a ratio of 3:2000, and heated and stirred for 40 minutes under heating conditions to obtain a sodium alginate solution;

[0104] (3) mixing the sodium alginate solution of step (2) with the corn starch solution of step (1) in a mass ratio of 1:5, stirring at 70° C. for 30 min to obtain a composite corn starch-sodium alginate mixed solution;

[0105] (4) heating the solution at 40°C and ultrasonicating it for 30 min to remove bubbles and obtain a membrane-forming liquid;

[0106] (5) Pour the solution onto the mold while it is still hot, dry it in a drying oven at 40°C for 24 hours, take it out of the drying oven, place it at room temperature for 12 hours, and then peel the film from the mold to obtain an edible packaging film.

[0107] Testing process

[0108] 1. Thermal Dissolution Temperature: The hot water dissolution temperature of the edible packaging films prepared in Examples 1 to 9 and Comparative Examples 1 to 6 was measured. The specific process is as follows: the edible packaging films were dissolved in water at different temperatures, and the hot water temperature at which the films were completely dissolved was measured.

[0109] The requirements for edible heat-soluble food packaging films are that they can be stored stably at room temperature and can be completely dissolved at 70-90°C, because 70-90°C is a common heating temperature in home cooking and food processing. Figure 1 As shown, it can be seen from the results that Example 1 meets the above requirements.

[0110] 2. Sensory Evaluation: The edible packaging film prepared in Example 1 was completely dissolved in 80°C hot water in the test group, while the control group was treated with 80°C hot water. A sensory test was conducted to evaluate the odor changes caused by the complete dissolution of the edible film in hot water. Fifteen professional food sensory panelists conducted the sensory evaluation, with a score of 1 to 5 indicating the severity of the odor, with higher scores indicating a stronger odor.

[0111] Test results such as Figure 2 As shown, it can be seen that the edible heat-soluble film in Example 1 can be completely dissolved in 80°C hot water without adding any peculiar smell.

[0112] 3. Mechanical Property Testing: The edible packaging films prepared in Examples 1-9 and Comparative Examples 1-6 were subjected to tensile property testing using a texture analyzer. Film materials with high elongation at break are less likely to break when subjected to tensile force and can adapt to larger deformations (such as bending and folding). Film materials with high toughness have strong tensile resistance and elastic recovery capabilities. The ideal breaking force value needs to be balanced according to the specific packaging type and usage requirements. It should not be too high, resulting in inconvenience, nor too low, affecting the integrity of the packaging.

[0113] The test results are shown in Table 1 below, which shows that the elongation at break and toughness of Example 1 are both high, indicating that it is not easy to break during storage and transportation, causing leakage of the contents. At the same time, the breaking force of the packaging film of Example 1 is moderate, making it convenient for consumers to disassemble the packaging film by themselves. Therefore, the tensile properties of Example 1 are more in line with the requirements of edible heat-soluble food packaging films.

[0114] Table 1 Tensile performance test results of Examples 1-9 and Comparative Examples 1-6

[0115] Example / Comparative Example Elongation at break (%) Toughness (MPa) Breaking force (MPa) Example 1 202.425±24.27686 381.47333±14.101356 2.64533±0.2035 Example 2 1.12667±0.025166 26.49767±2.993047 37.15733±2.1107 Example 3 0.37167±0.055788 8.96333±2.280884 31.39867±1.636967 Example 4 0.46567±0.114001 9.63333±1.60051 35.55933±2.577196 Example 5 110.93333±6.053368 467.533±36.787354 5.82067±0.25987 Example 6 14.23667±0.802719 1.45±0.256689 0.18533±0.034298 Example 7 38.82±2.93869 16.20333±1.556278 0.76967±0.123087 Example 8 44.65833±10.117846 17.237±1.280436 0.65833±0.045325 Example 9 185.39833±37.56642 345.75633±53.441918 2.677±0.111014 Comparative Example 1 0.513±0.059093 16.942±1.572438 26.80267±2.438205 Comparative Example 2 0.96333±0.120035 18.68167±0.878506 31.769±1.728684 Comparative Example 3 0.74633±0.033546 14.12±0.780374 26.54067±3.581871 Comparative Example 4 0.466±0.158187 4.45333±2.043737 15.619±3.925097 Comparative Example 5 1.15767±0.3075 0.742±0.088 1.76633±0.6855 Comparative Example 6 0.33367±0.023029 0.35467±0.077022 1.66033±0.069097

[0116] 4. Solubility test: 5 g of each of the edible packaging films prepared in Examples 1 to 9 and Comparative Examples 1 to 6 was added to 85° C. water and stirred for 30 seconds before dissolving. The soluble solids in the films were then tested.

[0117] The test results are shown in Table 2 below, wherein Example 1 has good solubility and does not cause insoluble residues, and therefore better meets the requirements of edible heat-soluble food packaging films.

[0118] Table 2 Solubility test results of Examples 1-9 and Comparative Examples 1-6

[0119]

[0120]

[0121] 5. Packaging application: Cut the film of Example 1 into rectangular strips of 8.0 cm x 10.0 cm for making heat-sealed bags. Heat-sealing conditions (150 ± 1°C, 300 kPa, holding time 1.50 seconds). Transfer 10 g of sauce into a three-side sealed bag, and then heat-seal it with a heat sealer to form a completely sealed bag. Figure 3 This is the appearance of the edible film for sauce packaging prepared in Example 1.

[0122] Cut the film of Example 1 into rectangular strips of 8.0 cm x 10.0 cm for making heat-sealed bags. Heat-sealing conditions (150 ± 1°C, 300 kPa, holding time 1.50 seconds). Transfer 10 g of fish soup into a three-side sealed bag, and then heat-seal it with a heat sealer to form a completely sealed bag. Figure 4 This is the appearance of the edible film prepared in Example 1 for packaging soup products such as fish soup and concentrated soup.

[0123] Although the present invention has been disclosed above in terms of preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be based on the definition of the claims.

Claims

1. A method for preparing an edible food packaging film, characterized in that: The following steps are involved: (1) mixing corn starch, nanocellulose, and water, heating and stirring to obtain a starch mixed solution; the mass ratio of corn starch, nanocellulose, and water is 5:1:95-105; (2) mixing hydroxymethyl cellulose, sodium alginate and water, heating and stirring to obtain a hydroxymethyl cellulose-sodium alginate solution; the mass ratio of hydroxymethyl cellulose, sodium alginate and water is 3:3:1800-2200; (3) adding gelatin to the starch mixed solution, heating and stirring to uniformly disperse the gelatin to obtain a gelatin-starch solution, then adding the hydroxymethyl cellulose-sodium alginate solution to the gelatin-starch solution, continuing heating and stirring to obtain a gelatin-corn starch mixed solution; the amount of gelatin added is 4-5% of the mass of the starch mixed solution; and the volume ratio of the gelatin-starch solution to the hydroxymethyl cellulose-sodium alginate solution is 4-6:1; (4) adding a glycerol-alcohol compound liquid to the gelatin-corn starch mixed solution, heating and stirring to uniformly disperse the mixture, and obtaining a film-forming liquid; the glycerol-alcohol compound liquid comprises glycerol, xylitol, and erythritol; the mass ratio of glycerol to xylitol is 4:0.5-1.5; the mass ratio of glycerol to erythritol is 4:0.5-1.5; the amount of the glycerol-alcohol compound liquid added is 10-15% of the mass of the gelatin-corn starch mixed solution; (5) Pour the film-forming liquid into a mold and dry it to obtain an edible food packaging film.

2. The preparation method according to claim 1, characterized in that The preparation method of nanocellulose in step (1) is as follows: putting Sargassum soaked in water for 20 to 40 hours into a NaOH solution, placing it at 70 to 80° C. for 10 to 15 hours, then filtering it, washing the Sargassum, mixing it with water, adding cellulase, and performing enzymatic hydrolysis at 40-55° C. for 1 to 3 hours. After enzyme inactivation, suspending the Sargassum cellulose in water, nanofibrillating it through high-pressure homogenization, and filtering it to obtain nanocellulose; the concentration of the NaOH solution is 5 to 10 mg / mL; the mass ratio of Sargassum to NaOH is 3 to 5:1; the mass ratio of Sargassum to cellulase is 8 to 12:1; and the enzymatic activity of the cellulase is 8000 to 12000 U / g.

3. The preparation method according to claim 2, characterized in that The pressure of high-pressure homogenization is 40-50 MPa.

4. The preparation method according to claim 1, wherein The heating and stirring conditions in step (1) are: stirring at 35-45° C. for 45-60 min.

5. The preparation method according to claim 1, wherein The heating and stirring conditions in step (2) are: stirring at 50-60° C. for 45-60 min.

6. The preparation method according to claim 1, wherein The heating and stirring conditions in step (3) are: stirring at 70-80° C. for 0.5-2 h.

7. The preparation method according to claim 1, characterized in that The heating and stirring conditions in step (4) are: stirring at 70-80° C. for 0.5-2 h.

8. The preparation method according to claim 1, characterized in that The drying conditions in step (5) are: drying at 40-60° C. for 20-30 h, and then standing at 20-25° C. for 10-15 h.

9. An edible food packaging film, characterized in that: The edible food packaging film is prepared according to the preparation method according to any one of claims 1 to 8.

10. Use of the edible food packaging film according to claim 9 in the food field.

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