High-toughness and high-barrier fresh-keeping packaging bag and preparation method and application thereof

Abstract

The application relates to the technical field of packaging bags, in particular to a high-toughness and high-barrier fresh-keeping packaging bag and a preparation method and application thereof, which is made of a composite biological film, and raw materials are as follows in weight parts: 45-58 parts of a composite biological base material, 6-15 parts of nano montmorillonite-layered double hydroxide composite particles, 4-9 parts of bamboo fiber-based nanocellulose, 3-7 parts of a composite crosslinking agent, 5-9 parts of glycerol, 0.6-2 parts of an antioxidant, and 1-4 parts of a functional additive; the modified starch is composite esterified corn starch, the weight-average molecular weight of polylactic acid is 80000-120000, and the substitution degree of carboxymethyl chitosan is 0.6-0.8; the crystallinity of the bamboo fiber-based nanocellulose is greater than or equal to 75%, and the molecular weight of epsilon-polylysine is 3000-4000. Through material process synergy, the application improves the packaging mechanics and barrier property, is antibacterial and antioxidant, and is degradable and safe, and solves the problems of easy damage and short fresh-keeping period of the existing packaging.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of packaging bags, in particular to a high-toughness and high-barrier fresh-keeping packaging bag and a preparation method and application thereof. BACKGROUND

[0002] Food preservation is a key link to ensure food quality and extend shelf life, and the performance of packaging materials directly determines the preservation effect. With the increasing demand of consumers for food safety and quality, and the tightening of environmental protection policies, traditional petroleum-based plastic packaging is gradually facing challenges due to its non-degradability and limited barrier performance, and biobased degradable packaging materials have become a research hotspot.

[0003] At present, biobased packaging materials are mostly based on starch, polylactic acid, chitosan, etc. Starch has a wide source and low cost, but its mechanical properties are poor and it is easily hygroscopic, so it is difficult to meet the packaging requirements when used alone; polylactic acid has high mechanical strength, but it is brittle and lacks flexibility, and its oxygen barrier performance is limited; chitosan has certain antibacterial properties, but it is highly water-soluble and its barrier performance decreases significantly in a high-humidity environment. In order to improve these defects, existing technologies mostly use composite modification methods, such as blending multiple biopolymers or adding nano fillers to improve performance.

[0004] However, the existing composite modification still has obvious bottlenecks: first, the compatibility between biopolymers is poor, and simple blending can easily lead to phase separation, which not only fails to improve the performance synergistically, but also may reduce the strength and toughness of the material due to interface defects; second, nano fillers are not uniformly dispersed and tend to agglomerate, making it difficult to form a continuous barrier network, and the improvement of oxygen and moisture barrier is limited; third, cross-linking modification mostly uses a single cross-linking agent, which is difficult to balance the flexibility and density of the material, and often leads to problems such as material brittleness due to excessive cross-linking or unstable barrier and mechanical properties due to insufficient cross-linking; fourth, existing materials lack functional synergy, and only relying on physical barrier is difficult to inhibit the reproduction of microorganisms and oxidation during food storage, especially for perishable foods such as chilled meat and fresh fruits and vegetables, the preservation period is still short.

[0005] In addition, in the existing preparation process, problems such as insufficient pretreatment of raw materials and uneven mixing and dispersion further exacerbate the fluctuation of material performance. Therefore, developing a fresh-keeping packaging material with high toughness, high barrier, functionality, and environmental friendliness has become the key to solving the current food preservation problem. SUMMARY

[0006] (I) Technical problems solved

[0007] In view of the deficiencies of the prior art, the present application provides a high-toughness and high-barrier fresh-keeping packaging bag and a preparation method and application thereof.

[0008] (II) Technical solutions

[0009] A high-toughness and high-barrier fresh-keeping packaging bag made of a composite biological film, raw materials of the composite biological film include, by weight fraction: a composite biological base material 45-58 parts, nano-montmorillonite-layered double hydroxide composite particles 6-15 parts, bamboo fiber-based nanocellulose 4-9 parts, a composite crosslinking agent 3-7 parts, glycerol 5-9 parts, an antioxidant 0.6-2 parts, and a functional additive 1-4 parts.

[0010] The composite biological base material is a mixture of modified starch, polylactic acid and carboxymethyl chitosan, wherein the weight ratio of the modified starch, the polylactic acid and the carboxymethyl chitosan is 1:1.3-2:0.5-0.8, the modified starch is corn starch modified by composite esterification of acetic anhydride and octenyl succinic anhydride; the nano-montmorillonite-layered double hydroxide composite particles are formed by blending and intercalation of nano-montmorillonite and magnesium-aluminum type layered double hydroxide, the weight ratio of the two is 1:0.4-0.6, the nano-montmorillonite is first modified by stirring with cetyltrimethylammonium bromide at 60-70°C for 2-3 hours, the layered double hydroxide is prepared by a coprecipitation method and the particle size is controlled to be 50-100 nm; the bamboo fiber-based nanocellulose is prepared by sulfuric acid hydrolysis and high-pressure homogenization treatment of bamboo pulp fibers, and the surface is treated with γ-aminopropyl triethoxysilane in an ethanol aqueous solution at 65-75°C for 1.5-2 hours; the composite crosslinking agent is a complex of polyethylene glycol diglycidyl ether, citric acid and gallic acid, the weight ratio of the three is 2:1:0.5-1; the functional additive is a mixture of N-acetyl-L-cysteine and ε-polylysine, the weight ratio is 1:0.8-1.2; and the antioxidant is a complex of tea polyphenols, vitamin E and rosemary extract, the weight ratio is 3:1:0.5.

[0011] Preferably, the raw materials of the composite biological film include, by weight fraction: a composite biological base material 50-55 parts, nano-montmorillonite-layered double hydroxide composite particles 8-12 parts, bamboo fiber-based nanocellulose 5-7 parts, a composite crosslinking agent 4-6 parts, glycerol 6-8 parts, an antioxidant 0.8-1.5 parts, and a functional additive 2-3 parts; the weight ratio of the modified starch, the polylactic acid and the carboxymethyl chitosan in the composite biological base material is 1:1.5-1.8:0.6-0.7, and the weight average molecular weight of the polylactic acid is 90000-120000.

[0012] Preferably, the modified starch is a complex of acetic acid ester starch and octenyl succinic acid starch ester, the weight ratio is 1:0.6-0.9, and the degree of substitution of both is 0.25-0.35; wherein the acetic acid ester starch is prepared by reacting corn starch with acetic anhydride at pH 4.5-5.5 and a temperature of 40-50°C for 2-3 hours, and the octenyl succinic acid starch ester is prepared by reacting corn starch with octenyl succinic anhydride at pH 8.0-8.5 and a temperature of 35-45°C for 3-4 hours.

[0013] Preferably, the preparation process of the nano-montmorillonite-layered double hydroxide composite particles is as follows: the nano-montmorillonite modified by cetyltrimethylammonium bromide is dispersed in deionized water, and after ultrasonic treatment for 30 minutes, magnesium-aluminum layered double hydroxide is added, and stirred at 70-80℃ for 1.5-2 hours, and after centrifugal separation, vacuum drying at 60-70℃ for 5-6 hours; the particle size of the nano-montmorillonite is 80-150nm, and the molar ratio of magnesium to aluminum in the layered double hydroxide is 3:1.

[0014] Preferably, the sulfuric acid hydrolysis conditions of the bamboo fiber-based nanocellulose are as follows: the bamboo pulp fiber is mixed with 45-50% sulfuric acid in solid-liquid ratio of 1:10-12, and stirred at 40-45℃ for 2-3 hours, and after hydrolysis, centrifugation, dialysis to neutral, and then homogenized 3-4 times by a high-pressure homogenizer at a pressure of 80-100MPa; the surface is treated with γ-aminopropyltriethoxysilane in an ethanol aqueous solution at 65-75℃ for 1.5-2 hours, and the volume fraction of ethanol in the used ethanol aqueous solution is 60-70%, and the addition amount of γ-aminopropyltriethoxysilane is 3-5% of the weight of the bamboo fiber-based nanocellulose.

[0015] Preferably, the thickness of the composite biological film is 25-45μm, the oxygen permeability is ≤2.5cm³ / (m²・d・atm) under the conditions of temperature 23℃ and relative humidity 50%, the tensile strength is ≥35MPa under the conditions of temperature 25℃ and tensile rate 50mm / min, the elongation at break is ≥300%, and the water vapor permeability is ≤15g / (m²・d) under the conditions of temperature 38℃ and relative humidity 90%.

[0016] Preferably, the preparation method of the high-toughness and high-barrier fresh-keeping packaging bag comprises the following steps:

[0017] S1. Raw material pretreatment: place the composite biological substrate in a vacuum drying oven and dry at 70-85℃ for 5-7 hours, control the moisture content to ≤2%; disperse the nano-montmorillonite-layered double hydroxide composite particles in anhydrous ethanol, ultrasonic treatment for 30-50 minutes, ultrasonic power 300-400W, and then rotary evaporation to remove ethanol at 65-75℃, and dry for standby; place the bamboo fiber-based nanocellulose in a vacuum drying oven and dry at 65-75℃ for 4-6 hours;

[0018] S2. Mixing pulping: the dried composite bio-based material is added to deionized water with a solid-liquid ratio of 1:4-6, the deionized water is sterile water filtered through a 0.22 μm filter membrane, and stirring is carried out at 60-70℃ and a stirring rate of 400-600 r / min for 1.5-2.5 hours until complete dissolution to obtain a base material solution; the pretreated nano-montmorillonite-lamellar double hydroxide composite particles and the bamboo fiber-based nanocellulose are sequentially added to the base material solution, ultrasonic dispersion is carried out for 20-30 minutes at an ultrasonic power of 250-350 W, and then the composite crosslinking agent, glycerol, antioxidant, and functional additive are added, and stirring is carried out at 65-75℃ and a stirring rate of 600-900 r / min for 2.5-3.5 hours to obtain a uniform composite slurry;

[0019] S3. Casting film: the composite slurry is degassed at a vacuum degree of -0.09 to -0.08 MPa for 30-40 minutes, and then poured into the trough of a casting machine, the knife gap is controlled at 60-120 μm, and the casting speed is controlled at 0.8-1.2 m / min; the drying process is divided into three stages, the first stage temperature is 85-90℃, the second stage temperature is 95-100℃, and the third stage temperature is 100-105℃, and the total drying time is 30-40 minutes, and the moisture content is ≤5% after drying to obtain a preliminary film;

[0020] S4. Crosslinking treatment: the preliminary film is placed in an oven, heated to 130-150℃ at a rate of 2℃ / min, and heat crosslinked at this temperature for 1.2-1.8 hours, while nitrogen gas is introduced into the oven at a flow rate of 0.5-1 L / min;

[0021] S5. Post-treatment: the crosslinked film is naturally cooled to room temperature, sterilized by irradiation with a wavelength of 254 nm ultraviolet lamp, the ultraviolet lamp power is 10-20 W, the irradiation distance is 20-30 cm, and the irradiation time is 5-10 minutes, and then cut according to the preset size, and heat sealed on a heat sealing machine, the heat sealing temperature is 160-180℃, the heat sealing pressure is 0.3-0.5 MPa, and the heat sealing time is 2-3 seconds to obtain a high-toughness and high-barrier preservative packaging bag.

[0022] Preferably, in step S2, the conductivity of the sterile deionized water is ≤10 μS / cm, and after high-pressure steam sterilization at 121℃ for 20 minutes, it is cooled for use.

[0023] Preferably, in step S4, the oxygen content in the oven is controlled to be ≤1%, and after heat crosslinking, the heating is stopped first, and the nitrogen gas is continued to be introduced until the oven temperature is reduced to below 60℃, and then the crosslinked film is taken out.

[0024] Preferably, the high-toughness and high-barrier fresh-keeping packaging bag is applied to fresh-keeping packaging of chilled fresh meat, the chilled fresh meat is pork tenderloin, beef brisket or chicken breast, the chilled fresh meat is pre-cooled at 0-4 DEG C for 2-3 hours before packaging, the chilled fresh meat is cut into meat blocks with a thickness of 2-3 cm after removing surface blood water, the chilled fresh meat is packaged by using a vacuum packaging machine, a vacuum degree is controlled to be -0.09 to -0.08 MPa, and a sealing time is 1-2 seconds; the chilled fresh meat after packaging is stored at 0-4 DEG C, and a fresh-keeping period can reach 15-20 days; during storage, a TVB-N value of the chilled fresh meat is less than or equal to 15 mg / 100 g, a total bacterial count is less than or equal to 5*10 5 CFU / g, and a pH value is maintained at 5.8-6.4.

[0025] (Three) beneficial technical effects

[0026] Compared with the prior art, the beneficial effects of the present application are:

[0027] 1. The composite biological substrate is compounded by modified starch, polylactic acid and carboxymethyl chitosan, and the three components are complementary in molecular structure, that is, the modified starch improves the plasticity of the material, the polylactic acid ensures the basic strength, and the carboxymethyl chitosan enhances the hydrophilic regulation ability and antibacterial basis, so that the performance short board of single biological macromolecule is improved, and the comprehensive mechanical properties of the material are greatly improved.

[0028] 2. The introduction of nano-montmorillonite-layer double hydroxide composite particles and bamboo fiber-based nanocellulose forms a multi-dimensional reinforcing and barrier network through synergistic effect. Among them, the nano-composite particles form a dense barrier through interlayer stacking, which significantly improves the barrier ability to oxygen and moisture; the bamboo fiber-based nanocellulose is uniformly dispersed in the system after surface modification to form a "skeleton" structure, effectively enhancing the toughness and impact resistance of the material, and solving the problem of easy breakage of traditional biological base materials.

[0029] 3. The composite crosslinking agent is compounded by multiple components, which overcomes the limitations of single crosslinking agent, and at the same time, the flexibility and density of the material are considered, avoiding the brittleness caused by excessive crosslinking or the performance fluctuation caused by insufficient crosslinking. The addition of functional additives gives the material the functions of antioxidant and antibacterial, which can delay the oxidation and deterioration of food and inhibit the reproduction of microorganisms, and cooperates with the physical barrier effect to significantly improve the fresh-keeping effect.

[0030] 4. The material system is mainly composed of biological components, which can be naturally degraded and reduce environmental pollution; all raw materials used are food contact grade, without harmful residues, meeting the requirements of food safety. The preparation process is through step-by-step pretreatment and precise control to ensure uniform dispersion and sufficient reaction of each component, and to ensure the stability of the material performance. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1is a flow chart of a preparation method of a high-toughness and high-barrier fresh-keeping packaging bag according to the present application;

[0032] Figure 2 is a columnar broken line comparison chart of oxygen transmission rates and tensile strengths of the examples and the comparative examples;

[0033] Figure 3 is a columnar broken line comparison chart of water vapor transmission rates and fresh-keeping periods of chilled meat of the examples and the comparative examples;

[0034] Figure 4 is a radar comparison chart of performance comparison data of the examples and the comparative examples after being unified in dimension. DETAILED DESCRIPTION

[0035] According to Figures 1 to 4 , the specific embodiments of the present application are as follows:

[0036] The technical solutions of the present application are further described in detail below in combination with specific embodiments and comparative examples. It should be noted that the embodiments are only used to explain the present application, and do not limit the protection scope of the present application. The raw materials used are all food contact grade. Among them, the modified starch is corn starch modified by esterification of acetic anhydride and octenyl succinic anhydride, with a degree of substitution of 0.25-0.35; the poly-lactic acid has a weight average molecular weight of 80000-120000; the carboxymethyl chitosan has a degree of substitution of 0.6-0.8; the nano-montmorillonite is modified by cetyltrimethylammonium bromide, with a particle size of 80-150 nm; the magnesium-aluminum layered double hydroxide has a magnesium-aluminum molar ratio of 3:1, with a particle size of 50-100 nm; the bamboo fiber-based nanocellulose is modified by sulfuric acid hydrolysis and γ-aminopropyl triethoxysilane, with a sulfuric acid hydrolysis condition of 45-50% sulfuric acid, a solid-liquid ratio of 1:10-12, a reaction temperature of 40-45°C, and a reaction time of 2-3 hours, a surface modification condition of an ethanol volume fraction of 60-70%, a γ-aminopropyl triethoxysilane amount of 3-5% of the weight of the nanocellulose, a reaction temperature of 65-75°C, and a reaction time of 1.5-2 hours, and a crystallinity of ≥75%; the composite crosslinking agent is composed of polyethylene glycol diglycidyl ether, citric acid, and gallic acid at a weight ratio of 2:1:0.5-1; the antioxidant is composed of tea polyphenols with a purity of ≥98%, vitamin E, and rosemary extract with a content of salvia acid of ≥60% at a weight ratio of 3:1:0.5; and the functional additive is composed of N-acetyl-L-cysteine and ε-polylysine at a weight ratio of 1:0.8-1.2, with a molecular weight of the ε-polylysine of 3000-4000.

[0037] Raw material ratio

[0038] The raw material ratios of the composite biological membranes of the examples and the comparative examples are shown in Table 1 below (in weight parts):

[0039] Table 1

[0040] Raw material components Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Composite bio-based material 50 55 48 50 50 Modified starch 15 16 14 15 15 Polylactic acid 22.5 28.8 21 22.5 22.5 Carboxymethyl chitosan 12.5 10.2 13 12.5 12.5 Nano-montmorillonite-lamellar double hydroxide composite particles 8 12 10 8 8 (replaced with single nano-montmorillonite) Bamboo fiber-based nanocellulose 5 7 6 5 5 Composite crosslinking agent 4 6 5 4 (replaced with single citric acid) 4 Polyethylene glycol diglycidyl ether 1.6 2.4 2 0 1.6 Citric acid 0.8 1.2 1 4 0.8 Gallic acid 1.6 2.4 2 0 1.6 Glycerol 6 8 7 6 6 Antioxidant 0.8 1.5 1.2 0.8 0.8 Functional aid 2 3 2.5 2 2

[0041] Preparation step

[0042] Example 1

[0043] S1. Raw material pretreatment: composite bio-based materials (consisting of modified starch 15 parts, polylactic acid 22.5 parts, carboxymethyl chitosan 12.5 parts) were placed in a vacuum drying oven and dried at a temperature of 75°C for 6 hours, and the moisture content of the raw materials was controlled to be ≤2% during the drying process; the nano-montmorillonite-layered double hydroxide composite particles 8 parts were pretreated, the composite particles were prepared by blending intercalation at a weight ratio of 1:0.5, the preparation process was as follows: the modified nano-montmorillonite was dispersed in deionized water, after ultrasonic treatment for 30 minutes, the layered double hydroxide was added, and stirred at a temperature of 75°C for 1.8 hours, then centrifuged at a speed of 4000 r / min for 15 minutes, and then placed in a vacuum drying oven at a temperature of 65°C for 5.5 hours; the prepared nano-montmorillonite-layered double hydroxide composite particles were dispersed in anhydrous ethanol, and treated with an ultrasonic cleaner at a power of 300W for 35 minutes, then rotary evaporated to remove ethanol at a temperature of 65°C, and standby; the bamboo fiber-based nanocellulose 5 parts were placed in a vacuum drying oven and dried at a temperature of 70°C for 5 hours, and standby.

[0044] S2. Mixing and pulping: take 200 parts of sterile deionized water, the conductivity of the sterile deionized water is ≤10 μS / cm, after high-pressure steam sterilization at 121°C for 20 minutes, cool to room temperature; add the dried composite bio-based materials into the sterile deionized water, stir at a temperature of 65°C and a stirring rate of 500 r / min for 2 hours, until the composite bio-based materials are completely dissolved, to obtain a base material solution; add the pretreated nano-montmorillonite-layered double hydroxide composite particles and bamboo fiber-based nanocellulose into the base material solution in turn, and treat with an ultrasonic cleaner at a power of 280W for 25 minutes; after ultrasonic treatment, add composite crosslinking agent 4 parts, glycerol 6 parts, antioxidant 0.8 parts, and functional additives 2 parts into the system, and stir at a temperature of 70°C and a stirring rate of 750 r / min for 3 hours, to obtain a uniform composite slurry.

[0045] S3. Casting film: place the composite slurry in a vacuum environment, and degas at a vacuum degree of -0.085 MPa for 35 minutes; pour the degassed composite slurry into the trough of the casting machine, adjust the gap between the casting machine knives to 80 μm, and control the casting speed to be 1.0 m / min; during the casting process, adopt three-stage drying, the first-stage drying temperature is 88°C, the second-stage drying temperature is 98°C, and the third-stage drying temperature is 102°C, the total drying time is 35 minutes, and the moisture content of the primary film is controlled to be ≤5% during the drying process, to obtain a primary film.

[0046] S4. Crosslinking treatment: the primary film is placed in an oven, and heated to 140°C at a heating rate of 2°C / min, and heat crosslinking is performed at 140°C for 1.5 hours; nitrogen is introduced into the oven during the heat preservation process, the nitrogen flow is controlled to be 0.8 L / min, and the oxygen content in the oven is controlled to be ≤1%; after the heat crosslinking is completed, the heating is stopped, and the nitrogen is continuously introduced into the oven until the temperature of the oven is reduced to below 60°C, and the crosslinked film is taken out.

[0047] S5. Post-treatment: the crosslinked film is naturally cooled to room temperature, and the crosslinked film is sterilized by irradiation with a UV lamp, the wavelength of the UV lamp is 254 nm, the power is 15 W, the irradiation distance is 25 cm, and the irradiation time is 8 minutes; the crosslinked film after sterilization is cut according to the size of 20 cm x 30 cm; the cut film is placed on a heat sealing machine for heat sealing, the heat sealing temperature is 170°C, the heat sealing pressure is 0.4 MPa, and the heat sealing time is 2.5 seconds, and a high-toughness and high-barrier fresh-keeping packaging bag is obtained.

[0048] Example 2

[0049] S1. Raw material pretreatment: the composite biological substrate (composed of modified starch 16 parts, polylactic acid 28.8 parts, and carboxymethyl chitosan 10.2 parts) is placed in a vacuum drying oven and dried at 80°C for 5.5 hours, and the water content of the raw material is controlled to be ≤2% during the drying process; the nano-montmorillonite-layer double hydroxide composite particles 12 parts are pretreated, the composite particles are prepared by blending intercalation at a weight ratio of 1:0.6, and the preparation process is as follows: the modified nano-montmorillonite is dispersed in deionized water, ultrasonic treatment is performed for 30 minutes, then the layered double hydroxide is added, stirring is performed at 78°C for 2 hours, then centrifugation is performed at a speed of 4500 r / min for 12 minutes, and then it is placed in a 70°C vacuum drying oven for drying for 5 hours; the prepared nano-montmorillonite-layer double hydroxide composite particles are dispersed in anhydrous ethanol, and ultrasonic cleaning is performed for 30 minutes at a power of 350 W using an ultrasonic cleaner, and then ethanol is removed by rotary evaporation at a temperature of 70°C; 7 parts of bamboo fiber-based nanocellulose are placed in a vacuum drying oven and dried at 75°C for 4.5 hours.

[0050] S2. Mixing pulp preparation: 275 parts of sterile deionized water with conductivity ≤10 μS / cm was taken, which was sterilized by 121 ℃ high pressure steam for 20 minutes and then cooled to room temperature; the dried composite biological substrate was added into the sterile deionized water, and stirred at 68 ℃ temperature and 550 r / min stirring rate for 2.2 hours until the composite biological substrate was completely dissolved to obtain a substrate solution; the pretreated nano-montmorillonite-layer double hydroxide composite particles and bamboo fiber-based nanocellulose were sequentially added into the substrate solution, and ultrasonic cleaning was performed with an ultrasonic cleaner at a power of 320 W for 22 minutes; after ultrasonic cleaning, 6 parts of a composite crosslinking agent, 8 parts of glycerol, 1.5 parts of an antioxidant, and 3 parts of a functional additive were added into the system, and stirred at 72 ℃ temperature and 850 r / min stirring rate for 3.2 hours to obtain a uniform composite slurry.

[0051] S3. Casting film preparation: the composite slurry was placed in a vacuum environment and degassed at a vacuum degree of -0.09 MPa for 30 minutes; the degassed composite slurry was poured into the trough of the casting machine, the gap between the casting knife of the casting machine was adjusted to 100 μm, and the casting speed was controlled to be 1.2 m / min; a three-stage drying was adopted during the casting process, the first-stage drying temperature was 90 ℃, the second-stage drying temperature was 100 ℃, the third-stage drying temperature was 105 ℃, the total drying time was 32 minutes, and the moisture content of the primary film was controlled to be ≤5% during the drying process to obtain a primary film.

[0052] S4. Crosslinking treatment: the primary film was placed in an oven, and heated to 145 ℃ at a heating rate of 2 ℃ / min, and then heat-crosslinked at 145 ℃ for 1.2 hours; nitrogen was introduced into the oven during the heat-crosslinking process, the nitrogen flow was controlled to be 0.9 L / min, and the oxygen content in the oven was controlled to be ≤1%; after the heat-crosslinking was completed, the heating was stopped, and the nitrogen was continuously introduced into the oven until the temperature of the oven was reduced to below 60 ℃, and then the crosslinked film was taken out.

[0053] S5. Post-treatment: the crosslinked film was naturally cooled to room temperature, and then sterilized by irradiation with a UV lamp, the wavelength of the UV lamp was 254 nm, the power was 18 W, the irradiation distance was 25 cm, and the irradiation time was 6 minutes; the sterilized crosslinked film was cut into a size of 20 cm×30 cm; the cut film was placed on a heat sealing machine for heat sealing, the heat sealing temperature was 175 ℃, the heat sealing pressure was 0.45 MPa, and the heat sealing time was 2.2 seconds to obtain a high-toughness and high-barrier preservative packaging bag.

[0054] Example 3

[0055] S1. Raw material pretreatment: the composite bio-based material (consisting of modified starch 14 parts, polylactic acid 21 parts, carboxymethyl chitosan 13 parts) is placed in a vacuum drying oven, dried at a temperature of 72°C for 6.5 hours, and the moisture content of the raw material is controlled to be ≤2% during the drying process; the nano-montmorillonite-layered double hydroxide composite particles 10 parts are pretreated, the composite particles are prepared by blending intercalation at a weight ratio of 1:0.4, the preparation process is as follows: the modified nano-montmorillonite is dispersed in deionized water, after ultrasonic treatment for 30 minutes, the layered double hydroxide is added, stirred at a temperature of 72°C for 1.6 hours, then centrifuged at a speed of 3800r / min for 18 minutes, and then placed in a vacuum drying oven at a temperature of 62°C for 6 hours; the prepared nano-montmorillonite-layered double hydroxide composite particles are dispersed in anhydrous ethanol, and then treated with an ultrasonic cleaner at a power of 320W for 40 minutes, and then rotary evaporated at a temperature of 68°C to remove ethanol, ready for use; the bamboo fiber-based nanocellulose 6 parts is placed in a vacuum drying oven, dried at a temperature of 68°C for 5.5 hours, ready for use.

[0056] S2. Mixing and pulping: take 240 parts of sterile deionized water, the conductivity of the sterile deionized water is ≤10μS / cm, after high-pressure steam sterilization at 121°C for 20 minutes, cool to room temperature; add the dried composite bio-based material into the sterile deionized water, stir at a temperature of 62°C and a stirring rate of 480r / min for 2.4 hours, until the composite bio-based material is completely dissolved, to obtain a base solution; add the pretreated nano-montmorillonite-layered double hydroxide composite particles and bamboo fiber-based nanocellulose into the base solution in turn, and then treat with an ultrasonic cleaner at a power of 260W for 28 minutes; after ultrasonic treatment, add composite crosslinking agent 5 parts, glycerol 7 parts, antioxidant 1.2 parts, and functional additives 2.5 parts into the system, and stir at a temperature of 68°C and a stirring rate of 700r / min for 3.4 hours, to obtain a uniform composite slurry.

[0057] S3. Casting film: the composite slurry is placed in a vacuum environment, and degassed at a vacuum degree of -0.08MPa for 38 minutes; pour the degassed composite slurry into the trough of the casting machine, adjust the gap between the casting knife to 70μm, and control the casting speed to be 0.9m / min; during the casting process, adopt three-stage drying, the first-stage drying temperature is 86°C, the second-stage drying temperature is 96°C, and the third-stage drying temperature is 101°C, the total drying time is 38 minutes, and the moisture content of the primary film is controlled to be ≤5% during the drying process, to obtain a primary film.

[0058] S4. Crosslinking treatment: the primary film is placed in an oven, and heated to 135°C at a heating rate of 2°C / min, and heat crosslinking is performed at 135°C for 1.7 hours; nitrogen is introduced into the oven during the heat preservation process, the nitrogen flow is controlled to be 0.6 L / min, and the oxygen content in the oven is controlled to be ≤1% at the same time; after the heat crosslinking is completed, the heating is stopped, and the nitrogen is continuously introduced into the oven until the temperature of the oven is reduced to below 60°C, and the crosslinked film is taken out.

[0059] S5. Post-treatment: the crosslinked film is naturally cooled to room temperature, and the crosslinked film is sterilized by irradiation with a UV lamp, the wavelength of the UV lamp is 254 nm, the power is 12 W, the irradiation distance is 25 cm, and the irradiation time is 9 minutes; the crosslinked film after sterilization is cut according to the size of 20 cm x 30 cm; the cut film is placed on a heat sealing machine for heat sealing, the heat sealing temperature is 165°C, the heat sealing pressure is 0.35 MPa, and the heat sealing time is 2.8 seconds, and a high-toughness and high-barrier fresh-keeping packaging bag is obtained.

[0060] Comparative Example 1

[0061] S1. Raw material pretreatment: the composite biological substrate (composed of modified starch 15 parts, polylactic acid 22.5 parts, and carboxymethyl chitosan 12.5 parts) is placed in a vacuum drying oven and dried at 75°C for 6 hours, and the water content of the raw material is controlled to be ≤2% during the drying process; the nano-montmorillonite-layer double hydroxide composite particles 8 parts are pretreated, the composite particles are prepared by blending intercalation at a weight ratio of 1:0.5, and the preparation process is as follows: the modified nano-montmorillonite is dispersed in deionized water, ultrasonic treatment is performed for 30 minutes, then the layered double hydroxide is added, stirring is performed at 75°C for 1.8 hours, then centrifugation is performed at a speed of 4000 r / min for 15 minutes, and then it is placed in a vacuum drying oven at 65°C for drying for 5.5 hours; the prepared nano-montmorillonite-layer double hydroxide composite particles are dispersed in anhydrous ethanol, and ultrasonic treatment is performed for 35 minutes by using an ultrasonic cleaner at a power of 300 W, then ethanol is removed by rotary evaporation at a temperature of 65°C, and then it is ready for use; the bamboo fiber-based nanocellulose 5 parts is placed in a vacuum drying oven and dried at 70°C for 5 hours.

[0062] S2. Mixing pulp preparation: 200 parts of sterile deionized water with conductivity ≤10 μS / cm was taken, which was sterilized by 121 ℃ high pressure steam for 20 minutes and then cooled to room temperature; the dried composite biological substrate was added into the sterile deionized water, and stirred at 65 ℃ and 500 r / min for 2 hours until the composite biological substrate was completely dissolved to obtain a substrate solution; the pretreated nano-montmorillonite-layer double hydroxide composite particles and bamboo fiber-based nanocellulose were sequentially added into the substrate solution, and ultrasonic cleaning was performed at 280 W for 25 minutes; after ultrasonic cleaning, 4 parts of single citric acid, 6 parts of glycerol, 0.8 parts of antioxidant and 2 parts of functional additives were added into the system, and stirred at 70 ℃ and 750 r / min for 3 hours to obtain a uniform composite slurry.

[0063] S3. Casting film preparation: the composite slurry was placed in a vacuum environment and degassed at a vacuum degree of -0.085 MPa for 35 minutes; the degassed composite slurry was poured into the trough of the casting machine, the gap between the casting knife was adjusted to 80 μm, and the casting speed was controlled to be 1.0 m / min; three-stage drying was adopted during the casting process, the first-stage drying temperature was 88 ℃, the second-stage drying temperature was 98 ℃, the third-stage drying temperature was 102 ℃, the total drying time was 35 minutes, and the moisture content of the primary film was controlled to be ≤5% during the drying process to obtain a primary film.

[0064] S4. Crosslinking treatment: the primary film was placed in an oven, and heated to 140 ℃ at a heating rate of 2 ℃ / min, and then heat-crosslinked at 140 ℃ for 1.5 hours; nitrogen was introduced into the oven during the heat-crosslinking process, and the nitrogen flow was controlled to be 0.8 L / min, and the oxygen content in the oven was controlled to be ≤1%; after the heat-crosslinking was completed, the heating was stopped, and the nitrogen was continuously introduced into the oven until the temperature of the oven was reduced to below 60 ℃, and then the crosslinked film was taken out.

[0065] S5. Post-treatment: the crosslinked film was naturally cooled to room temperature, and then sterilized by irradiation of an ultraviolet lamp, the wavelength of the ultraviolet lamp was 254 nm, the power was 15 W, the irradiation distance was 25 cm, and the irradiation time was 8 minutes; the sterilized crosslinked film was cut into a size of 20 cm×30 cm; the cut film was placed on a heat sealing machine for heat sealing, the heat sealing temperature was 170 ℃, the heat sealing pressure was 0.4 MPa, and the heat sealing time was 2.5 seconds to obtain a fresh-keeping packaging bag.

[0066] Comparative Example 2

[0067] S1. Raw material pretreatment: the composite bio-based material (consisting of modified starch 15 parts, polylactic acid 22.5 parts, carboxymethyl chitosan 12.5 parts) is placed in a vacuum drying oven and dried at a temperature of 75°C for 6 hours, and the moisture content of the raw material is controlled to be ≤2% during the drying process; 8 parts of single modified nano-montmorillonite are dispersed in anhydrous ethanol, and then treated with an ultrasonic cleaner at a power of 300W for 35 minutes, and then rotary evaporation is performed at a temperature of 65°C to remove ethanol, and then standby; 5 parts of bamboo fiber-based nanocellulose are placed in a vacuum drying oven and dried at a temperature of 70°C for 5 hours, and then standby.

[0068] S2. Mixing and pulping: 200 parts of sterile deionized water with an electrical conductivity of ≤10 μS / cm is taken, which is sterilized by high-pressure steam at 121°C for 20 minutes and then cooled to room temperature; the dried composite bio-based material is added to the sterile deionized water, and stirred at a temperature of 65°C and a stirring rate of 500 r / min for 2 hours until the composite bio-based material is completely dissolved, to obtain a base solution; the pretreated single modified nano-montmorillonite and bamboo fiber-based nanocellulose are sequentially added to the base solution, and treated with an ultrasonic cleaner at a power of 280W for 25 minutes; after ultrasonic treatment, 4 parts of a composite crosslinking agent, 6 parts of glycerol, 0.8 parts of an antioxidant, and 2 parts of a functional additive are added to the system, and stirred at a temperature of 70°C and a stirring rate of 750 r / min for 3 hours to obtain a uniform composite slurry.

[0069] S3. Casting film: the composite slurry is placed in a vacuum environment and degassed at a vacuum degree of -0.085 MPa for 35 minutes; the degassed composite slurry is poured into the trough of the casting machine, the gap between the casting knife is adjusted to 80 μm, and the casting speed is controlled to be 1.0 m / min; during the casting process, three-stage drying is adopted, the first-stage drying temperature is 88°C, the second-stage drying temperature is 98°C, and the third-stage drying temperature is 102°C, the total drying time is 35 minutes, and the moisture content of the primary film is controlled to be ≤5% during the drying process, to obtain a primary film.

[0070] S4. Crosslinking treatment: the primary film is placed in an oven, heated to 140°C at a heating rate of 2°C / min, and heat-crosslinked at 140°C for 1.5 hours; during the heat-crosslinking process, nitrogen gas is introduced into the oven at a flow rate of 0.8 L / min, and the oxygen content in the oven is controlled to be ≤1%; after heat-crosslinking, the heating is stopped, and the nitrogen gas is continuously introduced into the oven until the temperature of the oven is reduced to below 60°C, and then the crosslinked film is taken out.

[0071] S5. Post-processing: The crosslinked film is naturally cooled to room temperature, and the crosslinked film is sterilized by irradiation with a UV lamp, the wavelength of the UV lamp is 254 nm, the power is 15 W, the irradiation distance is 25 cm, and the irradiation time is 8 minutes; the crosslinked film after sterilization is cut according to the size of 20 cm x 30 cm; the cut film is placed on a heat sealing machine for heat sealing, the heat sealing temperature is 170℃, the heat sealing pressure is 0.4 MPa, and the heat sealing time is 2.5 seconds, to obtain a fresh-keeping packaging bag.

[0072] Performance test:

[0073] The fresh-keeping packaging bags prepared in each example and comparative example are subjected to performance test, and the test method is as follows:

[0074] Thickness: according to GB / T 6672-2001 standard, a thickness gauge is used to measure, and the average value of 5 measuring points is taken as the final thickness value;

[0075] Oxygen transmission rate: according to GB / T 1038-2000 standard, a gas permeation instrument is used to measure under the condition of 23℃ temperature and 50% relative humidity;

[0076] Tensile strength and elongation at break: according to GB / T 1040.3-2006 standard, a tensile testing machine is used to measure under the condition of 25℃ temperature and tensile rate of 50 mm / min;

[0077] Water vapor transmission rate: according to GB / T 1037-2021 standard, a moisture permeation instrument is used to measure under the condition of 38℃ temperature and 90% relative humidity;

[0078] Fresh-keeping test of chilled meat: take pork tenderloin, first pre-cool at 0-4℃ for 2.5 hours, then cut into meat blocks with a thickness of 2-3 cm; use a vacuum packaging machine to package the meat blocks, control the vacuum degree to-0.085 MPa and the sealing time to 1.5 seconds during packaging; store the packaged chilled meat at 0-4℃, measure the TVB-N value according to GB 5009.228-2016 standard, and measure the total bacterial count according to GB 4789.2-2016 standard; record the fresh-keeping period, which is defined as the longest storage time when the TVB-N value is ≤15 mg / 100 g and the total bacterial count is ≤5 x 10 5 CFU / g.

[0079] The performance effects of the examples and comparative examples are compared as follows:

[0080] Table 2

[0081] Performance index Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Thickness (μm) 32 42 28 31 33 Oxygen transmission rate (cm³ / (m²・d・atm)) 2.1 1.8 2.3 3.8 3.5 Tensile strength (MPa) 38 42 36 25 30 Elongation at break (%) 320 350 310 180 220 Water vapor transmission rate (g / (m²・d)) 13 11 14 22 20 Chilled fresh meat shelf life (days) 18 20 17 10 12 TVB-N value after 15 days of storage (mg / 100g) 12.5 11.8 13.2 21.3 18.6 Total colony count (x 10 5 CFU / g) after 15 days storage 3.2 2.8 3.5 8.5 6.8

[0082] Compared with the scheme of using a single crosslinking agent or a single nano barrier particle, the present application realizes all-round breakthrough in barrier property, mechanical toughness and preservation function of the preservation packaging bag through multi-dimensional optimization of "composite biological substrate synergy + nano montmorillonite-layered double hydroxide composite barrier particle + polyethylene glycol diglycidyl ether-citric acid-gallic acid composite crosslinking agent", solving the core pain points of traditional biological packaging "weak barrier, easy brittle, short preservation period".

[0083] In terms of barrier property, the embodiment relies on the blending intercalation structure of nano montmorillonite and magnesium aluminum type layered double hydroxide, and the oxygen transmission rate is as low as 1.8-2.3 cm³ / (m²・d・atm), and the water vapor transmission rate is only 11-14 g / (m²・d), effectively blocking the invasion of oxygen and moisture, and avoiding food oxidation and deterioration; the comparative example cannot form a complete barrier network due to a single barrier particle, and the barrier effect is significantly insufficient.

[0084] In terms of mechanical toughness, the embodiment uses a composite crosslinking agent, combined with the "skeleton" reinforcing effect of bamboo fiber-based nanocellulose, and the tensile strength reaches 36-42 MPa, and the elongation at break is 310-350%, which not only solves the problem of material embrittlement caused by a single crosslinking agent, but also overcomes the defect of poor mechanical properties of biological materials, ensuring the anti-breaking ability of the packaging bag.

[0085] In terms of preservation function, the embodiment relies on the synergy of "physical barrier + functional additives", and the preservation period of chilled meat reaches 17-20 days; after 15 days of storage, the TVB-N value is only 11.8-13.2 mg / 100g, and the total number of colonies is 3.2-3.5×10 5 CFU / g, effectively inhibiting microbial reproduction and lipid oxidation, and greatly extending the shelf life of perishable food.

[0086] In summary, through multi-component synergistic design, the present application realizes the functional unification of "high toughness-high barrier-long preservation", and at the same time, takes biological materials as the main body, and considers environmental protection and biodegradability and food contact safety, completely breaking through the performance bottleneck of traditional biological preservation packaging.

[0087] Although embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A high-toughness, high-barrier, fresh-keeping packaging bag, characterized in that, The composite biological film is made of raw materials including, by weight fraction, 45-58 parts of a composite biological substrate, 6-15 parts of nano-montmorillonite-layered double hydroxide composite particles, 4-9 parts of bamboo fiber-based nanocellulose, 3-7 parts of a composite crosslinking agent, 5-9 parts of glycerol, 0.6-2 parts of an antioxidant, and 1-4 parts of a functional additive; The composite biological substrate is a mixture of modified starch, polylactic acid and carboxymethyl chitosan, wherein the weight ratio of the modified starch, the polylactic acid and the carboxymethyl chitosan is 1:1.3-2:0.5-0.8, and the modified starch is corn starch modified by composite esterification of acetic anhydride and octenyl succinic anhydride; The preparation process of the nano-montmorillonite-layered double hydroxide composite particles is as follows: nano-montmorillonite modified by cetyltrimethylammonium bromide is dispersed in deionized water, ultrasonic treatment is performed for 30 minutes, then magnesium-aluminum layered double hydroxide is added, stirring is performed at 70-80℃ for 1.5-2 hours, centrifugal separation is performed, and vacuum drying is performed at 60-70℃ for 5-6 hours; the particle size of the nano-montmorillonite is 80-150nm, the molar ratio of magnesium to aluminum in the layered double hydroxide is 3:1, and the weight ratio of the nano-montmorillonite to the magnesium-aluminum layered double hydroxide is 1:0.4-0.6; the nano-montmorillonite is first modified by cetyltrimethylammonium bromide at 60-70℃ for 2-3 hours, the layered double hydroxide is prepared by a coprecipitation method and the particle size is controlled to be 50-100nm; the bamboo fiber-based nanocellulose is prepared from bamboo pulp fiber by sulfuric acid hydrolysis combined with high-pressure homogenization treatment, and the surface is treated by γ-aminopropyl triethoxysilane in an ethanol aqueous solution at 65-75℃ for 1.5-2 hours; the composite crosslinking agent is a compound of polyethylene glycol diglycidyl ether, citric acid and gallic acid, and the weight ratio of the three is 2:1:0.5-1; the functional additive is a mixture of N-acetyl-L-cysteine and ε-polylysine, and the weight ratio is 1:0.8-1.2; and the antioxidant is a compound of tea polyphenols, vitamin E and rosemary extract, and the weight ratio is 3:1:0.

5.

2. The high tenacity, high barrier, fresh-keeping packaging bag according to claim 1, characterized in that, The raw materials of the composite biological film include, by weight fraction, 50-55 parts of a composite biological substrate, 8-12 parts of nano-montmorillonite-layered double hydroxide composite particles, 5-7 parts of bamboo fiber-based nanocellulose, 4-6 parts of a composite crosslinking agent, 6-8 parts of glycerol, 0.8-1.5 parts of an antioxidant, and 2-3 parts of a functional additive; the weight ratio of the modified starch, the polylactic acid and the carboxymethyl chitosan in the composite biological substrate is 1:1.5-1.8:0.6-0.7, and the weight average molecular weight of the polylactic acid is 90000-120000.

3. The high tenacity, high barrier, fresh-keeping packaging bag according to claim 1, characterized in that, The sulfuric acid hydrolysis conditions of the bamboo fiber-based nanocellulose are as follows: bamboo pulp fiber is mixed with sulfuric acid with a mass fraction of 45-50% at a solid-liquid ratio of 1:10-12, stirring is performed at 40-45℃ for 2-3 hours, after hydrolysis, centrifugal separation, dialysis to neutral, and then high-pressure homogenization is performed 3-4 times by a high-pressure homogenizer at a pressure of 80-100MPa; The surface of the bamboo fiber is treated with γ-aminopropyl triethoxysilane in an aqueous ethanol solution at 65-75℃ for 1.5-2 hours, the volume fraction of ethanol in the aqueous ethanol solution is 60-70%, and the addition amount of γ-aminopropyl triethoxysilane is 3-5% of the weight of the bamboo fiber-based nanocellulose.

4. The high tenacity, high barrier, fresh- preserving packaging bag of claim 1, wherein, The thickness of the composite biological film is 25-45μm, the oxygen permeability is ≤2.5cm³ / (m²・d・atm) under the conditions of temperature 23℃ and relative humidity 50%, the tensile strength is ≥35MPa under the conditions of temperature 25℃ and tensile rate 50mm / min, the elongation at break is ≥300%, and the water vapor permeability is ≤15g / (m²・d) under the conditions of temperature 38℃ and relative humidity 90%.

5. A process for the preparation of a high-toughness, high-barrier, fresh-keeping packaging bag as claimed in any one of claims 1-4, characterized in that, The method comprises the following steps: S1. Raw material pretreatment: place the composite biological substrate in a vacuum drying oven and dry at 70-85℃ for 5-7 hours to control the moisture content to ≤2%; disperse the nanometer montmorillonite-layer double hydroxide composite particles in anhydrous ethanol, ultrasonic treatment for 30-50 minutes at an ultrasonic power of 300-400W, and then remove the ethanol by rotary evaporation at 65-75℃; place the bamboo fiber-based nanocellulose in a vacuum drying oven and dry at 65-75℃ for 4-6 hours; S2. Mixing and pulping: add the dried composite biological substrate to deionized water, the solid-liquid ratio is 1:4-6, the deionized water is sterile water filtered through a 0.22μm filter membrane, stir at 60-70℃ and a stirring rate of 400-600r / min for 1.5-2.5 hours until completely dissolved to obtain a substrate solution; add the pretreated nanometer montmorillonite-layer double hydroxide composite particles and bamboo fiber-based nanocellulose to the substrate solution in sequence, ultrasonic dispersion for 20-30 minutes at an ultrasonic power of 250-350W, and then add a composite crosslinking agent, glycerol, an antioxidant, and a functional additive, and stir at 65-75℃ and a stirring rate of 600-900r / min for 2.5-3.5 hours to obtain a uniform composite slurry; S3. Casting film: degas the composite slurry under a vacuum of-0.09 to-0.08MPa for 30-40 minutes, and then pour it into the trough of a casting machine, control the gap between the doctor blade to be 60-120μm and the casting speed to be 0.8-1.2m / min, and perform the drying process in three stages, the first stage temperature is 85-90℃, the second stage temperature is 95-100℃, and the third stage temperature is 100-105℃, and the total drying time is 30-40 minutes, and the moisture content is ≤5% after drying to obtain a preliminary film; S4. Crosslinking treatment: place the preliminary film in an oven, first increase the temperature to 130-150℃ at a rate of 2℃ / min, and heat crosslink at this temperature for 1.2-1.8 hours, and at the same time, introduce nitrogen into the oven, and control the nitrogen flow rate to be 0.5-1L / min. S5. Post-processing: the crosslinked film is naturally cooled to room temperature, sterilized by irradiation with a UV lamp with a wavelength of 254 nm, the power of the UV lamp is 10-20 W, the irradiation distance is 20-30 cm, the irradiation time is 5-10 minutes, then cut according to the preset size, heat sealing on a heat sealing machine, the heat sealing temperature is 160-180 ℃, the heat sealing pressure is 0.3-0.5 MPa, the heat sealing time is 2-3 seconds, to obtain a high-toughness and high-barrier fresh-keeping packaging bag.

6. The method for preparing the high-toughness, high-barrier food preservation packaging bag according to claim 5, characterized in that, In step S2, the conductivity of the deionized water is ≤10 μS / cm, and after 121 ℃ high-pressure steam sterilization for 20 minutes, it is cooled for use.

7. The method for preparing the high-toughness, high-barrier preservation packaging bag according to claim 5, characterized in that, In step S4, the oxygen content in the oven is controlled to be ≤1%, and after the heat crosslinking is completed, the heating is stopped first, and nitrogen is continuously introduced until the oven temperature is reduced to below 60 ℃, and then the crosslinked film is taken out.

8. Use of the high-toughness, high-barrier, fresh-keeping packaging bag according to any one of claims 1-4, characterized in that, The fresh-keeping packaging is used for chilled meat, the chilled meat is pork tenderloin, beef brisket or chicken breast, the chilled meat is pre-cooled at 0-4 ℃ for 2-3 hours before packaging, and the surface blood is removed and cut into meat blocks with a thickness of 2-3 cm; vacuum packaging machine is used for packaging, the vacuum degree is controlled at -0.09 to -0.08 MPa, and the sealing time is 1-2 seconds; the packaged chilled meat is stored at 0-4 ℃, and the fresh-keeping period can reach 15-20 days; During storage, the TVB-N value of the chilled meat is ≤15 mg / 100 g, the total number of colonies is ≤5×10 5 CFU / g, and the pH value is maintained at 5.8-6.4.

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