Antibacterial precious marine product packaging material and preparation method thereof

Abstract

The invention discloses an antibacterial precious marine product packaging material and a preparation method thereof, and belongs to the technical field of packaging materials. The invention provides an antibacterial precious marine product packaging material. The antibacterial precious marine product packaging material is prepared from the following components in parts by weight: 130-150 parts of polylactic acid, 40-50 parts of a polylactic acid modifier, 0.1-10 parts of a quaternary ammonium salt antibacterial agent, 0.01-0.5 part of a cross-linking agent and 0.01-1 part of an initiator. The antibacterial precious marine product packaging material can meet the packaging requirements of different precious marine products in the market, and the technical effects of being antibacterial, damp-proof, fog-proof, oil-stain-resistant, capable of covering odor, easy to degrade and the like can be achieved.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, in particular to an antibacterial seafood packaging material and a preparation method thereof. Background Art

[0002] As global marine resource development deepens, the need for fresh-keeping of seafood products (such as abalone, sea cucumbers, and fish) is becoming increasingly prominent. These products are rich in protein and unsaturated fatty acids, making them susceptible to microbial contamination and enzymatic degradation during storage, leading to spoilage.

[0003] The spoilage of seafood is mainly caused by specific spoilage organisms (SSO) and endogenous enzyme activity. Psychrophilic bacteria such as Pseudomonas, Shewanella, and Vibrio can still reproduce under refrigerated conditions, secreting proteases to decompose fish protein to produce biogenic amines and sulfides; at the same time, polyphenol oxidase (PPO) causes shrimp to turn black, and fat oxidation produces an unpleasant odor. Studies have shown that relying solely on low-temperature preservation can extend the shelf life of Pacific white shrimp to about 7 days, but it cannot inhibit the growth of psychrophilic bacteria and enzymatic reactions. In response to the above problems, existing technologies have also made continuous technical improvements.

[0004] Prior art CN113667156A discloses a degradable antimicrobial film and its preparation method. First, a porphyrin metal-organic framework (MOF) is synthesized by solvothermal reaction of zirconium salt and tetracarboxyphenylporphyrin. This MOF is then dissolved in N,N-dimethylformamide and mixed with polycaprolactone dissolved in N,N-dimethylformamide to produce a degradable antimicrobial food packaging film. This film achieves antimicrobial properties and prevents apples from browning. However, the material contains heavy metals, and the resulting packaging film is not easily degradable.

[0005] Prior art CN117487253A discloses an antibacterial film for shrimp flavoring and fishy removal. The film is composed of a 10-13% mixture of green pepper essential oil hydrosols, 1.5-2.5% phospholipids, 8-15% antioxidants, 52-62% film-forming material, 2% plasticizer, and the remainder as a cosolvent. While the film can mask the fishy odor of shrimp, the material is physically doped to enhance its functionality. This dopant can potentially contaminate food through contact between the film and the food.

[0006] Prior art CN110894346A discloses a controlled-release antioxidant-active polylactic acid packaging film. Tea polyphenols, grape seed extract, and other antioxidant substances are added to the polylactic acid to enhance the antioxidant properties of the packaged product. Although these added substances are natural extracts or compounds permitted in the food industry, as components of the packaging film, they can still contaminate food.

[0007] Clearly, existing technologies still face some technical challenges that urgently need to be addressed. For example, the different storage methods for seafood products place diverse demands on packaging materials. However, existing packaging films still have relatively single functions and cannot meet the packaging needs of different seafood products. For example, the preservation of dried seafood requires packaging materials with sealing, moisture-proofing, antibacterial, and oil-resistance properties. Fresh seafood products require freshness, requiring materials with sealing, leak-proofing, antibacterial properties, and the ability to prevent the release of packaging components. Some products require refrigerated storage, requiring anti-fog and antibacterial properties. Furthermore, the food industry places significant demands on packaging materials for safety and environmental protection.

[0008] Therefore, there is an urgent need to develop an antibacterial seafood packaging material that can meet the packaging needs of different seafood in the market. Summary of the Invention

[0009] In order to overcome the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide an antibacterial seafood packaging material and a preparation method thereof, wherein the packaging material has technical effects such as antibacterial, moisture-proof, fog-proof, oil-resistant, odor-masking, and easy degradation.

[0010] In a first aspect, the present invention provides an antibacterial seafood packaging material, characterized in that, calculated by weight, the raw materials for its preparation include the following components: 130-150 parts of polylactic acid, 40-50 parts of polylactic acid modifier, 0.1-10 parts of quaternary ammonium salt antibacterial agent, 0.01-0.5 parts of cross-linking agent, and 0.01-1 parts of initiator.

[0011] The quaternary ammonium antibacterial agent has the structural formula (I):

[0012]

[0013] The polylactic acid modifier has the structural formula (II):

[0014]

[0015] The cross-linking agent is selected from at least one of diallyl thiosulfinate, diallyl disulfide, diallyl trisulfide, and diallyl sulfoxide.

[0016] The initiator is selected from at least one of dibenzoyl peroxide (BPO), tert-butyl formyl peroxide, di-tert-butyl diisopropylbenzene peroxide (BIPB), and diisopropylbenzene peroxide.

[0017] The preparation method of the quaternary ammonium salt antibacterial agent of formula (I) is as follows:

[0018] Dissolve tris(4-dimethylaminophenyl)methane in xylene solvent, add 4-cyanobenzyl chloride under nitrogen atmosphere, heat under reflux at 60-90°C for 2-10 hours, add 10-chloro-1-decene, heat under reflux at 60-90°C for 3-10 hours, stop the reaction, and purify to obtain a quaternary ammonium salt antibacterial agent of formula (I).

[0019] The molar ratio of tris(4-dimethylaminophenyl)methane, 4-cyanobenzyl chloride and 10-chloro-1-decene is 1:(2-2.3):(0.8-1.2), preferably 1:(2.1-2.2):(0.9-1).

[0020] The preparation method of the polylactic acid modifier of formula (II) is as follows:

[0021] N-hydroxysuccinimide (NHS) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) were added to the 3-maleimidopropionic acid solution, stirred for reaction, and then 12-tricosanamine was added, stirred for reaction, and purified to obtain.

[0022] The molar ratio of the 3-maleimidopropionic acid, NHS, and EDC is 1:(1-1.3):(1-1.3); the molar ratio of 3-maleimidopropionic acid to 12-tricosanamine is 1:(0.9-1.1).

[0023] In a second aspect, the present invention provides a method for preparing an antibacterial seafood packaging material, the specific preparation steps being as follows:

[0024] S1: adding polylactic acid, polylactic acid modifier of formula (II) and initiator into a high-speed mixer and stirring and mixing; then injecting the mixture into a twin-screw extruder, granulating, drying and setting aside to obtain modified polylactic acid.

[0025] S2: adding modified polylactic acid, quaternary ammonium salt antibacterial agent, crosslinking agent and initiator into a high-speed mixer and stirring and mixing; then injecting the mixture into a twin-screw extruder and extruding to obtain antibacterial seafood packaging material.

[0026] Furthermore, the antibacterial seafood packaging material can be prepared into packaging films and packaging bags.

[0027] Beneficial effects

[0028] The antibacterial seafood packaging material provided by the present invention has the technical effects of being antibacterial, moisture-proof, fog-proof, oil-proof, and easy to degrade.

[0029] The antibacterial seafood packaging material comprises polylactic acid modified with a polylactic acid modifier of formula (II), thereby enhancing its hydrophobicity. Combined with the cross-linking effect of the quaternary ammonium salt antibacterial agent and the cross-linking agent, the prepared packaging material not only has good light transmittance but also has improved air tightness and tensile strength. A molecule of the quaternary ammonium salt antibacterial agent of formula (I) has three quaternary ammonium salt structures similar to benzalkonium chloride. Furthermore, the nitrogen atom of the quaternary ammonium salt of formula (I) is linked to a benzene ring. The π-π electron effect of the benzene ring can increase the positive charge on the nitrogen atom. Furthermore, the highly polar cyano group can improve adhesion to bacterial surfaces, thereby enhancing the antibacterial effect. Furthermore, the quaternary ammonium salt antibacterial agent of formula (I) has a long carbon chain containing double bonds. Under the action of an initiator, it can undergo polymerization or cross-linking reactions, and is fixed in the prepared packaging material without contaminating the packaged seafood.

[0030] The quaternary ammonium salt antibacterial agent of formula (I) has a strongly hydrophilic nitrogen atom end and a strongly hydrophobic long carbon chain, which makes it have the effect of a strong surfactant; the modified polylactic acid has strong hydrophobicity due to the grafting modifier, so in the process of preparing the packaging material, the long carbon chain hydrophobic segment of the quaternary ammonium salt antibacterial agent of formula (I) is more likely to be close to the modified polylactic acid, while the hydrophilic end is more likely to be away from the modified polylactic acid; therefore, in the packaging material prepared with modified polylactic acid as the main raw material, the hydrophilic end of the quaternary ammonium salt antibacterial agent of formula (I) is more likely to be distributed on the surface of the material as a whole, resulting in the film surface having strong polarity, good oleophobicity and anti-fog properties, and can improve the display aesthetics of marine delicacies.

[0031] The cross-linking agents used in the present invention all have two double bonds and can undergo cross-linking under the action of an initiator, thereby further improving the tensile strength and air tightness of the prepared packaging material and avoiding contamination of seafood caused by migration; at the same time, the cross-linking agents are all compounds with a spice smell, which can mask the unpleasant odor of seafood and improve the display effect of seafood. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is the structural formula (Ⅰ) of a quaternary ammonium salt antibacterial agent.

[0033] Figure 2 This is a synthetic flow chart of quaternary ammonium antibacterial agents.

[0034] Figure 3 This is the synthesis flow chart of polylactic acid modifier.

[0035] Figure 4 It is a schematic diagram of the chemical structure of modified polylactic acid.

[0036] Figure 5 It is the infrared spectrum of the quaternary ammonium salt antibacterial agent of formula (Ⅰ). DETAILED DESCRIPTION

[0037] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. The described embodiments are only some preferred embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] In the examples, the experimental methods used are conventional or common methods in the art unless otherwise specified, and the materials, reagents, etc. used are all commercially available unless otherwise specified.

[0039] The raw materials used in the embodiments and comparative examples are now described as follows:

[0040] Polylactic acid: Shanghai Yuanye Biotechnology Co., Ltd. (50 kDa);

[0041] 12-Tricosylamine: purchased from Henan Weitixi Chemical Technology Co., Ltd.

[0042] N-Hydroxysuccinimide (NHS): purchased from Shanghai Lingkai Technology Co., Ltd.;

[0043] 1-Ethyl-(3-dimethylaminopropyl)carbodiimide (EDC): purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.;

[0044] Diallylthiosulfinate: purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.

[0045] Diallyl disulfide: purchased from Shanghai Jizhi Biochemical Technology Co., Ltd.

[0046] Diallyl trisulfide: Shanghai Yuanye Biotechnology Co., Ltd.;

[0047] Diisopropylbenzene ditert-butylperoxide (BIPB) was purchased from Tiancheng Chemical (Jiangsu) Co., Ltd.

[0048] 4-Cyanobenzyl chloride: purchased from Nanjing Dongke Chemical Co., Ltd.

[0049] Tris(4-dimethylaminophenyl)methane: purchased from Taicang Yuntong Biochemical Co., Ltd.;

[0050] Benzalkonium chloride: purchased from Shanghai Yien Chemical Technology Co., Ltd.

[0051] Pseudomonas fluorescens (ATCC13525): purchased from Shanghai Guchen Biotechnology Co., Ltd.;

[0052] Staphylococcus aureus (ATCC6538) was purchased from Shanghai Yubo Biotechnology Co., Ltd.

[0053] Escherichia coli (ATCC8739): purchased from Guangzhou Bailanxin Scientific Instrument Co., Ltd.

[0054] Unless otherwise specified, the components and raw materials used in the examples and comparative examples of the present invention are all commercially available raw materials, and the components and raw materials used in each parallel experiment are all of the same kind.

[0055] The preparation method of the quaternary ammonium salt antibacterial agent of formula (I) is as follows:

[0056] Dissolve tris(4-dimethylaminophenyl)methane in xylene solvent, slowly adjust the system pH to 8 using 1 mol / L sodium hydroxide solution, add 4-cyanobenzyl chloride three times under nitrogen atmosphere, add 40% for the first time, add 40% after 2 hours, and add 20% after 4 hours, heat and reflux at 80°C for 8 hours; add 10-chloro-1-decene, heat and reflux at 85°C for 10 hours, stop the reaction, and purify by chromatography to obtain the quaternary ammonium salt antibacterial agent of formula (I). The infrared spectrum of the quaternary ammonium salt antibacterial agent is shown in FIG. Figure 5 .

[0057] The molar ratio of tris(4-dimethylaminophenyl)methane, 4-cyanobenzyl chloride and 10-chloro-1-decene is 1:2.1:0.9.

[0058] The preparation method of the polylactic acid modifier of formula (II) is as follows:

[0059] N-hydroxysuccinimide (NHS) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) were added to the DMSO solution of 3-maleimidopropionic acid, and the mixture was stirred for 2 h. Subsequently, 12-tricosanamine was added, and the mixture was stirred for 4 h. The polylactic acid modifier was obtained by column purification.

[0060] The molar ratio of the 3-maleimidopropionic acid, NHS, and EDC is 1:1.2:1; the molar ratio of 3-maleimidopropionic acid to 12-tricosanamine is 1:1.05.

[0061] Example 1

[0062] A method for preparing an antibacterial seafood packaging material, the specific preparation steps are as follows:

[0063] S1: 140 parts of polylactic acid, 45 parts of a polylactic acid modifier of formula (II) and 0.15 parts of an initiator BIBP were added to a high-speed mixer, stirred at 1500 rpm for 5 min, and mixed to obtain a mixture; the mixture was then injected into a twin-screw extruder, and the parameters were set as follows: the temperatures of the extruder barrel zones were 170°C, 180°C, 200°C, 200°C, 200°C, 200°C, 200°C, and 190°C (die temperature), the main engine speed was 240 r / min, the feed speed was 30 r / min, and the vacuum degree of the vacuum section was 0.03-0.07 MPa; granulation was carried out, and the mixture was vacuum-dried at 60°C for 10 h for standby use to obtain modified polylactic acid.

[0064] S2: Add the modified polylactic acid obtained in step S1, 0.2 parts of the quaternary ammonium antibacterial agent of formula (I), 0.2 parts of diallyl disulfide (cross-linking agent) and 0.05 parts of the initiator BIBP into a high-speed mixer, stir at 1500 rpm for 5 minutes, and mix to obtain a mixture; then inject the mixture into a twin-screw extruder, and set the parameters as follows: the temperatures of each zone of the extruder barrel are 170°C, 180°C, 180°C, 180°C, 180°C, 180°C, 180°C, 170°C (die temperature), the main engine speed is 240r / min, the feeding speed is 30r / min, and the vacuum degree of the vacuum section is 0.03-0.07MPa; extrude to obtain an antibacterial seafood packaging material.

[0065] Examples 2 and 3

[0066] The preparation steps of Examples 2 and 3 are the same as those of Example 1, except that the amounts of the raw materials are adjusted.

[0067] Comparative Example 1

[0068] A method for preparing a packaging material comprises the following steps: adding 140 parts of polylactic acid, 45 parts of a polylactic acid modifier of formula (II), 0.2 parts of an initiator BIBP, 0.2 parts of a quaternary ammonium salt antibacterial agent of formula (I), and 0.2 parts of diallyl disulfide (crosslinking agent) into a high-speed mixer, stirring at 1500 rpm for 5 minutes, and uniformly mixing to obtain a mixture; then injecting the mixture into a twin-screw extruder, and setting parameters as follows: the temperatures of various zones of the extruder barrel are 170° C., 180° C., 200° C., 200° C., 200° C., 200° C., 200° C., and 190° C. (die head temperature); the main engine speed is 240 r / min; the feed speed is 30 r / min; and the vacuum degree of the vacuum section is 0.03-0.07 MPa; granulation is performed, and vacuum drying is performed at 60° C. for 10 hours for standby use to obtain the packaging material.

[0069] The difference between Comparative Example 1 and Example 1 is that the polylactic acid is not modified first, but all the raw materials of the packaging material are mixed and directly co-melt-extruded to prepare the packaging material.

[0070] Comparative Example 2

[0071] The preparation method of Comparative Example 2 is the same as that of Comparative Example 1, except that the composition and amount of the raw materials are adjusted.

[0072] Comparative Examples 3-4

[0073] The preparation steps of Comparative Examples 3-4 are the same as those of Example 1, except that the composition and amount of the raw materials are adjusted.

[0074] Table 1: Weight ratio of raw materials used in Examples 1-3 and Comparative Examples 1-4

[0075]

[0076]

[0077] Note: “ / ” means the raw material is not added.

[0078] 1) Antibacterial performance test

[0079] This test complies with the standard "GB / T31402-2023 Determination of antibacterial activity on the surface of plastics and other non-porous materials".

[0080] The test bacteria species used were Pseudomonas fluorescens (ATCC13525), Staphylococcus aureus (ATCC6538), and Escherichia coli (ATCC8739).

[0081] Table 2 Antibacterial rate

[0082]

[0083]

[0084] According to the data in Table 2, (1) the inhibition rates of Examples 1-3 against Pseudomonas fluorescens, Staphylococcus aureus, and Escherichia coli all reached over 99%, indicating that the antibacterial seafood packaging materials prepared in Examples 1-3 meet the requirements for seafood packaging. (2) In Comparative Example 1, the polylactic acid was not modified first, but all raw materials including polylactic acid were mixed and co-melted and extruded to prepare the packaging material; in Comparative Example 2, no polylactic acid modifier was added, but all raw materials were mixed and co-melted and extruded to prepare the packaging material. Although Example 1 and Comparative Examples 1 and 2 all contain the same amount of the quaternary ammonium salt antibacterial agent of formula (I), the antibacterial effect of Example 1 is significantly better than that of Comparative Examples 1 and 2, which is due to the different preparation steps. Example 1 adopts co-melt extrusion method to modify polylactic acid first, and the polarity of polylactic acid after modification is significantly reduced, and then the modified polylactic acid is mixed with the remaining raw materials for a second co-melt extrusion to prepare packaging material, resulting in the non-polar end of the quaternary ammonium salt antibacterial agent molecule of formula (I) (hydrophobic end of long carbon chain) being more easily soluble in the modified polylactic acid molecule and undergoing chemical reaction, resulting in the strong polar end (hydrophilic end) of the quaternary ammonium salt antibacterial agent of formula (I) having antibacterial efficacy being more easily distributed on the surface of the prepared packaging material, thereby improving the antibacterial effect. During the preparation process of Comparative Examples 1 and 2, the strong polar end of the quaternary ammonium salt antibacterial agent of formula (I) is more easily close to the polylactic acid through the carbonyl or hydroxyl group on the polylactic acid, and the cross-linking reaction process easily causes the quaternary ammonium salt antibacterial agent of formula (I) to be embedded in the polylactic acid, and then the antibacterial effect is significantly reduced compared with Example 1. (3) The only difference between Example 1 and Comparative Example 3 is the different quaternary ammonium salt antibacterial agents. The inhibition rates of Example 1 against Pseudomonas fluorescens, Staphylococcus aureus, and Escherichia coli were all higher than those of Comparative Example 3, indicating that the antibacterial effect of the quaternary ammonium salt antibacterial agent of formula (I) in Example 1 is superior to that of the commercially available antibacterial agent benzalkonium chloride. (4) The antibacterial effect of Comparative Example 4 is comparable to that of Example 1, indicating that diallyl disulfide (cross-linking agent) has no effect on the antibacterial effect.

[0085] 2) Anti-fog performance and anti-oil pollution test

[0086] (A) The anti-fog performance of polypropylene heat-sealing film was evaluated using the cold mist method specified in the national standard GB / T31726-2015, which specifically includes the following steps: (a) the sample was placed in a constant temperature and humidity environment for 24 hours; (b) a cold plate was set at a temperature of 50±1°C in a sealed test chamber; (c) the sample was placed on the opening of a container filled with 23°C distilled water, with a distance of 10±0.5 mm between the film surface and the cold plate; (d) the sample was removed from the container after being kept at a constant temperature for 30 minutes and the film was immediately observed under standard lighting conditions. Surface water mist state; (e) Determine the anti-fog grade according to the following grading standards: Level 1: The film surface is completely transparent, with no visible water droplets; Level 2: The film surface has good transparency, with a small number of discrete large water droplets (diameter>1mm), and the area of ​​the light-transmitting area accounts for ≥50%; Level 3: The film surface is translucent, with densely attached small water droplets (diameter 0.2-1mm), and the area of ​​the light-transmitting area accounts for <50%; Level 4: A continuous water film is formed on the film surface, appearing milky white and misty; Level 5: The film surface is completely opaque and appears white and opaque.

[0087] Among them, the standard for determining the light-transmitting area is that the ISO2859 standard eye chart E sight mark placed on the back side can be clearly identified through the film layer.

[0088] (B) Anti-oil stain test: edible soybean oil was used and the contact angle was measured using a contact angle meter to evaluate the anti-oil stain performance.

[0089] Table 3 Anti-fog grade and contact angle record

[0090]

[0091] According to the data in Table 3, Examples 1-3 exhibit excellent anti-fog and oil-resistance. Comparative Example 1 exhibits reduced anti-fog and oil-resistance compared to Example 1. This is due to differences in the distribution of the quaternary ammonium salt antimicrobial agent (Formula (I)) on the packaging material surface, resulting from different preparation methods. The strong polarity of the hydrophilic end of the quaternary ammonium salt antimicrobial agent (Formula (I)) significantly enhances the hydrophilicity of the packaging material surface and reduces the surface tension of water through the action of a surfactant, facilitating the uniform distribution of water on the packaging material surface, thereby preventing the formation of small droplet mist. This enhanced hydrophilicity of the packaging material surface also indicates enhanced oil-resistance. The packaging material prepared in Comparative Example 2 does not contain a surfactant, resulting in the easy condensation of small droplets on the surface to form water mist. The contact angle of Comparative Example 2 with soybean oil is smaller, which is determined by the properties of the polylactic acid material. The packaging material prepared in Comparative Example 3 is highly hydrophobic. Although benzalkonium chloride acts as a surfactant, its polar end is weaker than that of the quaternary ammonium salt antimicrobial agent of formula (I) and does not significantly alter the surface hydrophobicity of the packaging material in Comparative Example 3. Consequently, the anti-fog and anti-oil performance of Comparative Example 3 is poor. In summary, the packaging materials prepared in Examples 1-3 are effective in preventing fog and resisting oil, meeting the requirements for displaying seafood.

[0092] 3) Air tightness, tensile strength test and packaging material odor evaluation

[0093] According to GB / T1038-2000 "Plastic Film and Sheeting Gas Permeability Test Method - Pressure Difference Method", the air permeability performance of the film is tested at 25°C using a Lyssy L100-5000 permeability meter. The gas permeation rate is calculated to evaluate the air tightness and moisture resistance of the packaging material.

[0094] The test was carried out in accordance with the provisions of GB / T1040.1-2018 "Determination of Tensile Properties of Plastics" to determine the elongation at break.

[0095] Evaluation of packaging material odor: Use direct human sensory evaluation method to record the odor of packaging materials.

[0096] Table 4 Evaluation table of tensile strength, gas permeability and odor of packaging materials

[0097]

[0098]

[0099] According to the data in Table 4, (1) the packaging materials prepared in Examples 1-3 have good tensile properties; compared with Comparative Examples 1-4, the polylactic acid modifier of formula (II) can significantly improve the tensile properties of the packaging materials prepared in Example 1; (2) the packaging materials prepared in Examples 1-3 have better air tightness than those prepared in Examples 1-4, indicating that Examples 1-3 have good moisture-proof properties; a comparison of Example 1 with Comparative Examples 1-4 shows that the preparation steps, the polylactic acid modifier of formula (II), the quaternary ammonium salt antibacterial agent of formula (I), and the crosslinking agent can all affect the air tightness of the prepared packaging materials, and can synergistically improve the air tightness of the packaging material prepared in Example 1, which is beneficial for the packaging and preservation of seafood. (3) Comparative Example 4 does not have a spice (cooked garlic) odor, which indicates that the crosslinking agent (diallyl disulfide) not only plays a crosslinking role, but also gives the packaging material a spice odor, which is beneficial for masking the odor of seafood.

[0100] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to the specific embodiments described. Obviously, many modifications and variations are possible based on the content of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. An antibacterial seafood packaging material, characterized in that: The raw materials include the following components by weight: 130-150 parts of polylactic acid, 40-50 parts of polylactic acid modifier, 0.1-10 parts of quaternary ammonium salt antibacterial agent, 0.01-0.5 parts of cross-linking agent, and 0.01-1 parts of initiator; The quaternary ammonium antibacterial agent has the structural formula (I): The polylactic acid modifier has the structural formula (II):

2. The antibacterial seafood packaging material according to claim 1, characterized in that: The cross-linking agent is selected from at least one of diallyl thiosulfinate, diallyl disulfide, diallyl trisulfide, and diallyl sulfoxide.

3. The antibacterial seafood packaging material according to claim 1, characterized in that: The initiator is at least one selected from dibenzoyl peroxide, tert-butyl formyl peroxide, di-tert-butyl dicumyl peroxide, and dicumyl peroxide.

4. The antibacterial seafood packaging material according to claim 1, characterized in that: The preparation method of the quaternary ammonium salt antibacterial agent of formula (I) is as follows: tris(4-dimethylaminophenyl)methane is dissolved in a xylene solvent, 4-cyanobenzyl chloride is added under a nitrogen atmosphere, and the mixture is heated under reflux at 60-90°C for 2-10 hours, 10-chloro-1-decene is added, and the mixture is heated under reflux at 60-90°C for 3-10 hours, the reaction is stopped, and the mixture is purified to obtain the quaternary ammonium salt antibacterial agent of formula (I).

5. The antibacterial seafood packaging material according to claim 4, characterized in that: The molar ratio of tris(4-dimethylaminophenyl)methane, 4-cyanobenzyl chloride and 10-chloro-1-decene is 1:(2-2.3):(0.8-1.2).

6. The antibacterial seafood packaging material according to claim 1, characterized in that: The preparation method of the polylactic acid modifier of formula (II) is as follows: N-hydroxysuccinimide (NHS) and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) are added to a 3-maleimide propionic acid solution, stirred for reaction, and then 12-tricosanamine is added, stirred for reaction, and purified to obtain.

7. The antibacterial seafood packaging material according to claim 6, characterized in that: The molar ratio of the 3-maleimidopropionic acid, NHS, and EDC is 1:(1-1.3):(1-1.3); the molar ratio of 3-maleimidopropionic acid to 12-tricosanamine is 1:(0.9-1.1).

8. A method for preparing the antibacterial seafood packaging material according to any one of claims 1 to 7, comprising the following steps: S1: adding polylactic acid, a polylactic acid modifier of formula (II) and an initiator into a high-speed mixer and stirring and mixing; then injecting the mixture into a twin-screw extruder, granulating, and drying for use to obtain modified polylactic acid; S2: adding modified polylactic acid, quaternary ammonium salt antibacterial agent, crosslinking agent and initiator into a high-speed mixer and stirring and mixing; then injecting the mixture into a twin-screw extruder and extruding to obtain antibacterial seafood packaging material.

9. The preparation method according to claim 8, characterized in that: The obtained antibacterial seafood packaging material can be prepared into packaging films and packaging bags.

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