A bio-based active food packaging material and a method for preparing the same

Abstract

The present application relates to the technical field of food packaging materials, and particularly relates to a bio-based active food packaging material and a preparation method thereof; the food packaging material comprises the following components in parts by weight: 70-80 parts of polylactic acid, 20-30 parts of polyhydroxybutyric acid valeric acid copolymer, 0.5 parts of chain extender ADR 43700, 3 parts of acetyl tri-butyl citrate, and 2-6 parts of halloysite nanotube powder loaded with essential oil. The preparation method comprises the following steps: (1) halloysite nanotube pretreatment; (2) preparation of mixed essential oil; (3) preparation of halloysite nanotube powder loaded with essential oil; (4) encapsulation of the halloysite nanotube powder loaded with essential oil by using polylysine solution and polyglutamic acid solution; the above-mentioned formula and preparation method can achieve intelligent control release of multi-effect natural active substances with antioxidant and antibacterial capacity, and achieve the purpose of long-term preservation.

Description

Technical Field

[0001] This invention relates to the field of food packaging materials technology, and in particular to a bio-based active food packaging material and its preparation method. Background Technology

[0002] Food packaging protects fresh foods such as fruits and vegetables from adverse factors during transportation, sales, storage, and consumption. It is a key technology for ensuring food safety, extending shelf life, and reducing food waste. It is well known that oxidation and microbial contamination are the main causes of food quality deterioration. With the frequent occurrence of food safety issues, the safety of industrially synthesized antioxidants and antibacterial agents has been questioned by the public. Effective and safe natural bioactive extracts are increasingly favored as packaging materials.

[0003] Currently, polylactic acid (PLA) is a popular choice for food packaging materials due to its cost-effectiveness and biodegradability. While PLA boasts excellent biodegradability, compatibility, and ductility, it also has limitations such as low crystallization rate, poor thermal stability, and high gas permeability. Active packaging, containing natural or synthetic antioxidants and antibacterial agents, can effectively slow down the oxidation of fresh food and inhibit the growth and activity of pathogens. Compared to traditional petroleum-based food packaging, bio-based active packaging materials not only provide an inert barrier between food and the external environment but also offer multiple functions such as antibacterial activity, antioxidant properties, moisture adsorption, biodegradability, and carbon dioxide release or adsorption, extending the shelf life of fresh food and preserving its nutritional value. *Xanthoceras sorbifolium* is a unique traditional Chinese medicinal plant. Its essential oil has excellent antioxidant properties, while honeysuckle essential oil is naturally derived, safe to use, and possesses significant broad-spectrum antibacterial and anti-inflammatory activities with low risk of drug resistance. Therefore, both *Xanthoceras sorbifolium* oil and honeysuckle essential oil can be used as natural antibacterial and antioxidant additives in active packaging. However, directly adding essential oils and other active compounds to bio-based biodegradable materials makes it difficult to control the release rate of the active essential oils, thus affecting the shelf life of food. Therefore, to address these issues, it is necessary to develop a bio-based active food packaging material and its preparation method. Summary of the Invention

[0004] The first technical problem to be solved by the present invention is to provide a bio-based active food packaging material that has good antibacterial and antioxidant activity for food, and can extend the shelf life and freshness of food, in order to address the shortcomings of the prior art.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0006] A bio-based active food packaging material, wherein the food packaging material comprises the following components by weight: 70-80 parts of polylactic acid, 20-30 parts of polyhydroxybutyrate-valerate copolyester, 0.5 parts of chain extender ADR 43700, 3 parts of tributyl acetylacetate, and 2-6 parts of halloysite nanotube powder loaded with essential oils.

[0007] As an improved technical solution, the essential oils loaded in the halloysite nanotube powder include honeysuckle essential oil and saxifrage essential oil.

[0008] The second technical problem to be solved by this invention is to provide a method for preparing bio-based active food packaging materials, which can slowly release active substances and extend the shelf life of food, in order to address the shortcomings of the prior art.

[0009] To solve the above-mentioned technical problems, the technical solution of the present invention is as follows:

[0010] A method for preparing a bio-based active food packaging material, the method comprising the following steps:

[0011] (1) Take halloysite nanotubes, add alkaline solution, then treat with ultrasonic water bath, stir magnetically, wash until neutral, centrifuge, separate and collect halloysite nanotubes, and dry them for later use.

[0012] (2) Take honeysuckle essential oil and sago palm essential oil, stir and mix them to obtain a mixed essential oil for later use;

[0013] (3) Take the halloysite nanotubes treated with alkali in step (1) and the mixed essential oil in step (2), add organic solvent to mix, then treat with water bath sonication, vacuum dry and centrifuge, collect halloysite nanotubes loaded with mixed essential oil, wash with organic solvent, centrifuge, dry, pulverize and collect halloysite nanotube powder loaded with essential oil for later use.

[0014] (4) Prepare polylysine solution and polyglutamic acid solution respectively. First, add halloysite nanotube powder loaded with essential oil in step (3) to the polylysine solution, stir, mix, and centrifuge. After washing the collected solid phase, complete the first layer of encapsulation. Then add the polyglutamic acid solution, stir, mix, and centrifuge. After washing the collected solid phase, complete the second layer of encapsulation. Then complete the third layer of encapsulation in the same way as the first layer of encapsulation. Then complete the fourth layer of encapsulation in the same way as the second layer of encapsulation. After drying and pulverizing, collect the powder for later use.

[0015] (5) Take polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) according to the weight parts, mix and melt them, and then extrude and stretch them through a twin-screw extruder to obtain a film, which is the packaging material.

[0016] As an improved technical solution, in step (1), the halloysite nanotubes and alkaline solution are mixed at a mass-volume ratio of 1:8-12, and the alkaline solution is a 0.5 mol / L sodium hydroxide solution or potassium hydroxide solution; the mixture is subjected to ultrasonic treatment in a water bath for 20-40 min and magnetic stirring for 20-28 h.

[0017] As an improved technical solution, the honeysuckle essential oil and the saxifrage essential oil in step (2) are mixed evenly in a volume ratio of 1:1-4.

[0018] As an improved technical solution, the halloysite nanotubes treated with alkali solution in step (3), the mixed essential oils in step (2), and the organic solvent are mixed in a mass-volume ratio of 1:1:3-5.

[0019] As an improved technical solution, the concentrations of the polylysine solution and polyglutamic acid solution prepared in step (4) are 1-3 mg / ml, respectively. The powder in step (3) is mixed with the polylysine solution at a mass-volume ratio of 1:4-6 to complete the first layer of encapsulation. During the second and fourth layers of encapsulation, the solid phase is mixed with the polyglutamic acid solution at a mass-volume ratio of 1:5, respectively. During the third layer of encapsulation, the solid phase is mixed with the polylysine solution at a mass-volume ratio of 1:5.

[0020] As an improved technical solution, in step (5), the inlet temperature of the twin-screw extruder is 150°C, the heating zone temperature is 160-170°C, and the screw speed is 50 r / min.

[0021] After adopting the above technical solution, the beneficial effects of the present invention are:

[0022] This invention loads halloysite nanotubes (HNTs) with Xanthoceras sorbifolium essential oil, which has good antioxidant properties, and honeysuckle essential oil, which has broad-spectrum antibacterial and anti-inflammatory activities. Using layer-by-layer assembly technology, a coating of positively charged food-grade natural antibacterial agent polylysine and negatively charged polyglutamic acid is applied to the negatively charged HNT surface after alkali treatment. Simultaneously, leveraging the solubility of polylysine and polyglutamic acid in water vapor released during food spoilage, a water-sensitive loading system with adjustable release rates of active substances is prepared. Furthermore, polylysine's broad-spectrum antibacterial properties can synergistically enhance antibacterial effects with functional essential oils, while polyglutamic acid's strong water absorption can serve as a desiccant in the active packaging, preventing fogging. Through the blending of PHBV, PLA, and a bio-based active carrier, the material is endowed with biodegradability and modified atmosphere packaging, enabling intelligent controlled release of multi-effect natural active substances with antioxidant and antibacterial capabilities, achieving long-term preservation. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0024] Example 1

[0025] A bio-based active food packaging material comprises the following components by weight: 70 parts polylactic acid, 30 parts polyhydroxybutyrate-valerate copolyester, 0.5 parts chain extender ADR 43700, 3 parts tributyl acetylacetate, and 4 parts halloysite nanotube powder loaded with essential oils.

[0026] Its preparation method includes the following steps:

[0027] (1) Take halloysite nanotubes and add alkaline solution (0.5 mol / L sodium hydroxide) at a mass-volume ratio of 1:8 and mix. Sonicate in water bath for 30 min, stir magnetically for 24 h, wash with deionized water until neutral, centrifuge at 8000 r / min for 10 min, separate and collect halloysite nanotubes, and dry at 60℃ to constant weight for later use.

[0028] (2) Take honeysuckle essential oil and saxifrage essential oil, mix them in a volume ratio of 1:1, and set aside the mixed essential oil.

[0029] (3) Take the halloysite nanotubes treated with alkali in step (1), the mixed essential oil and organic solvent (anhydrous ethanol) in step (2) in a mass-volume ratio of 1:1:3, and treat them with ultrasonic water bath for 30 min. Then, use a vacuum dryer (use a vacuum pump to evacuate at 30°C for 30 minutes and then restore to normal pressure, repeat this cycle three times) to vacuum dry and centrifuge (centrifuge at 8000 r / min for 10 minutes). Collect the halloysite nanotubes loaded with mixed essential oil, wash them with organic solvent (ethanol), centrifuge them, dry and pulverize the collected powder for later use.

[0030] (4) Prepare 1 mg / ml polylysine solution and 1 mg / ml polyglutamic acid solution respectively. First, add the powder from step (3) to the polylysine solution at a mass-volume ratio of 1:4, stir, mix, and centrifuge. After washing, the collected solid phase completes the first layer of encapsulation. Take the solid phase and add it to the polyglutamic acid solution at a mass-volume ratio of 1:4, stir, mix, and centrifuge. After washing, the collected solid phase completes the second layer of encapsulation. Then, complete the third layer of encapsulation in the same manner as the first layer of encapsulation, and complete the fourth layer of encapsulation in the same manner as the second layer of encapsulation. Dry and pulverize the collected powder at 40°C for later use.

[0031] (5) Polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) are mixed and melted according to the weight proportions. After being extruded and stretched by a twin-screw extruder, a film of 0.04 mm is obtained, which is the packaging material. The inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 165℃, and the screw speed is 50r / min.

[0032] Example 2

[0033] A bio-based active food packaging material comprises the following components by weight: 80 parts polylactic acid, 20 parts polyhydroxybutyrate-valerate copolyester, 0.5 parts chain extender ADR 43700, 3 parts tributyl acetylacetate, and 4 parts halloysite nanotube powder loaded with essential oils.

[0034] Its preparation method includes the following steps:

[0035] (1) Take halloysite nanotubes and add alkaline solution (0.5 mol / L sodium hydroxide) at a mass-volume ratio of 1:10. Mix them, sonicate in water bath for 30 min, stir magnetically for 24 h, wash with deionized water until neutral, centrifuge at 8000 r / min for 10 min, separate and collect halloysite nanotubes, and dry at 60℃ to constant weight for later use.

[0036] (2) Take honeysuckle essential oil and saxifrage essential oil, mix them in a volume ratio of 1:2, and then use the resulting mixed essential oil for later use.

[0037] (3) Take the halloysite nanotubes treated with alkali in step (1), the mixed essential oil and organic solvent (anhydrous ethanol) in step (2) in a mass-volume ratio of 1:1:4, and treat them with ultrasonic water bath for 30 min. Then, use a vacuum dryer (use a vacuum pump to evacuate at 30°C for 30 minutes and then restore to normal pressure, repeat this cycle three times) to vacuum dry and centrifuge (centrifuge at 8000 r / min for 10 minutes). Collect the halloysite nanotubes loaded with mixed essential oil, wash them with organic solvent (ethanol), centrifuge them, dry and pulverize the collected powder for later use.

[0038] (4) Prepare 2 mg / ml polylysine solution and 2 mg / ml polyglutamic acid solution respectively. First, add the powder from step (3) to the polylysine solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the first layer of encapsulation. Take the solid phase and add it to the polyglutamic acid solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the second layer of encapsulation. Then, complete the third layer of encapsulation in the same manner as the first layer of encapsulation. After completing the fourth layer of encapsulation in the same manner as the second layer of encapsulation, dry and pulverize the collected powder at 40°C for later use.

[0039] (5) Polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) are mixed and melted according to the weight proportions. After being extruded and stretched by a twin-screw extruder, a film of 0.05 mm is obtained, which is the packaging material. The inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 165℃, and the screw speed is 50r / min.

[0040] Example 3

[0041] A bio-based active food packaging material comprises the following components by weight: 75 parts polylactic acid, 25 parts polyhydroxybutyrate-valerate copolyester, 0.5 parts chain extender ADR 43700, 3 parts tributyl acetylacetate, and 2 parts halloysite nanotube powder loaded with essential oils.

[0042] Its preparation method includes the following steps:

[0043] (1) Take halloysite nanotubes and add alkaline solution (0.5 mol / L sodium hydroxide) at a mass-volume ratio of 1:12. Mix them, sonicate in water bath for 30 min, stir magnetically for 24 h, wash with deionized water until neutral, centrifuge at 8000 r / min for 10 min, separate and collect halloysite nanotubes, and dry at 60℃ to constant weight for later use.

[0044] (2) Take honeysuckle essential oil and saxifrage essential oil, mix them in a volume ratio of 1:3, and then use the resulting mixed essential oil for later use.

[0045] (3) Take the halloysite nanotubes treated with alkali in step (1), the mixed essential oil and organic solvent (anhydrous ethanol) in step (2) in a mass-volume ratio of 1:1:5, and treat them with ultrasonic water bath for 30 min. Then, use a vacuum dryer (use a vacuum pump to evacuate at 30°C for 30 minutes and then restore to normal pressure, repeat this cycle three times) to vacuum dry and centrifuge (centrifuge at 8000 r / min for 10 minutes) to collect the halloysite nanotubes loaded with mixed essential oil. Wash them with organic solvent (ethanol), centrifuge, dry and pulverize the collected powder for later use.

[0046] (4) Prepare 3 mg / ml polylysine solution and 3 mg / ml polyglutamic acid solution respectively. First, add the powder from step (3) to the polylysine solution at a mass-volume ratio of 1:6, stir, mix, and centrifuge. After washing, the collected solid phase completes the first layer of encapsulation. Then, add the solid phase to the polyglutamic acid solution at a mass-volume ratio of 1:6, stir, mix, and centrifuge. After washing, the collected solid phase completes the second layer of encapsulation. Then, complete the third layer of encapsulation in the same manner as the first layer of encapsulation, and then complete the fourth layer of encapsulation in the same manner as the second layer of encapsulation. After drying and pulverizing at 40°C, the collected powder is ready for use.

[0047] (5) Polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) are mixed and melted according to the weight proportions. After being extruded and stretched by a twin-screw extruder, a film of 0.06 mm is obtained, which is the packaging material. The inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 165℃, and the screw speed is 50r / min.

[0048] Example 4

[0049] A bio-based active food packaging material comprises the following components by weight: 75 parts polylactic acid, 25 parts polyhydroxybutyrate-valerate copolyester, 0.5 parts chain extender ADR 43700, 3 parts tributyl acetylacetate, and 4 parts halloysite nanotube powder loaded with essential oils.

[0050] Its preparation method includes the following steps:

[0051] (1) Take halloysite nanotubes and add alkaline solution (0.5 mol / L sodium hydroxide) at a mass-volume ratio of 1:10. Mix them, sonicate in water bath for 20 min, stir magnetically for 20 h, wash with deionized water until neutral, centrifuge at 8000 r / min for 10 min, separate and collect halloysite nanotubes, and dry at 60℃ to constant weight for later use.

[0052] (2) Take honeysuckle essential oil and saxifrage essential oil, mix them in a volume ratio of 1:3.5, and set aside the mixed essential oil.

[0053] (3) Take the halloysite nanotubes treated with alkali in step (1), the mixed essential oil and organic solvent (anhydrous ethanol) in step (2) in a mass-volume ratio of 1:1:4, and treat them with ultrasonic water bath for 30 min. Then, use a vacuum dryer (use a vacuum pump to evacuate at 30°C for 30 minutes and then restore to normal pressure, repeat this cycle three times) to vacuum dry and centrifuge (centrifuge at 8000 r / min for 10 minutes). Collect the halloysite nanotubes loaded with mixed essential oil, wash them with organic solvent (ethanol), centrifuge them, dry and pulverize the collected powder for later use.

[0054] (4) Prepare 2 mg / ml polylysine solution and 2 mg / ml polyglutamic acid solution respectively. First, add the powder from step (3) to the polylysine solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the first layer of encapsulation. Take the solid phase and add it to the polyglutamic acid solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the second layer of encapsulation. Then, complete the third layer of encapsulation in the same manner as the first layer of encapsulation. After completing the fourth layer of encapsulation in the same manner as the second layer of encapsulation, dry and pulverize the collected powder at 40°C for later use.

[0055] (5) Polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) are mixed and melted according to the weight proportions. After being extruded and stretched by a twin-screw extruder, a film of 0.05 mm is obtained, which is the packaging material. The inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 160℃, and the screw speed is 50r / min.

[0056] Example 5

[0057] A bio-based active food packaging material comprises the following components by weight: 75 parts polylactic acid, 25 parts polyhydroxybutyrate-valerate copolyester, 5 parts chain extender ADR 43700, 3 parts tributyl acetylacetate, and 6 parts halloysite nanotube powder loaded with essential oils.

[0058] Its preparation method includes the following steps:

[0059] (1) Take halloysite nanotubes and add alkaline solution (0.5 mol / L sodium hydroxide) at a mass-volume ratio of 1:10. Mix them, sonicate in water bath for 40 min, stir magnetically for 28 h, wash with deionized water until neutral, centrifuge at 8000 r / min for 10 min, separate and collect halloysite nanotubes, and dry at 60℃ to constant weight for later use.

[0060] (2) Take honeysuckle essential oil and saxifrage essential oil, mix them in a volume ratio of 1:4, and set aside the mixed essential oil.

[0061] (3) Take the halloysite nanotubes treated with alkali in step (1), the mixed essential oil and organic solvent (anhydrous ethanol) in step (2) in a mass-volume ratio of 1:1:4, and treat them with ultrasonic water bath for 30 min. Then, use a vacuum dryer (use a vacuum pump to evacuate at 30°C for 30 minutes and then restore to normal pressure, repeat this cycle three times) to vacuum dry and centrifuge (centrifuge at 8000 r / min for 10 minutes). Collect the halloysite nanotubes loaded with mixed essential oil, wash them with organic solvent (ethanol) and centrifuge them. Dry and pulverize the collected powder at 40°C for later use.

[0062] (4) Prepare 2 mg / ml polylysine solution and 2 mg / ml polyglutamic acid solution respectively. First, add the powder from step (3) to the polylysine solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the first layer of encapsulation. Take the solid phase and add it to the polyglutamic acid solution at a mass-volume ratio of 1:5, stir, mix, and centrifuge. After washing, the collected solid phase completes the second layer of encapsulation. Then, complete the third layer of encapsulation in the same manner as the first layer of encapsulation, and then complete the fourth layer of encapsulation in the same manner as the second layer of encapsulation. After drying and pulverizing, the collected powder is ready for use.

[0063] (5) Polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) are mixed and melted according to the weight proportions. After being extruded and stretched by a twin-screw extruder, a film of 0.05 mm is obtained, which is the packaging material. The inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 170℃, and the screw speed is 50r / min.

[0064] To better demonstrate the superior performance of the bio-based active food packaging material of the present invention, two comparative examples are provided. The bio-based active packaging films from Examples 1-5 and Comparative Examples 1-2 were tested for mechanical properties (measurement standard according to GB / T 1040.1-2018), antibacterial properties (measurement standard according to QB / T2591-2003A, test strain: Staphylococcus aureus), antioxidant properties (measurement method: DPPH free radical scavenging method), and biodegradability properties (measurement standard according to GB / T19277.1-2011). The results are shown in Table 1.

[0065] Comparative Example 1

[0066] Mix 100 parts PLA, 2 parts mixed essential oils, 0.5 parts chain extender ADR 43700, and 3 parts tributyl acetylacetate by weight until homogeneous. Add the homogeneous mixture to a twin-screw extruder with an inlet temperature of 150°C and the remaining heating zone temperatures of 150–170°C. Set the screw speed to 50 r / min. After mixing and melting, extrude and stretch the mixture into a film using the twin-screw extruder. Control the winding speed to ensure a film thickness of 0.05 mm.

[0067] Comparative Example 2

[0068] 100 parts by weight of low-density polyethylene (LDPE) and 4 parts by weight of HNTs are mixed evenly. The evenly mixed raw materials are added to a twin-screw extruder with an inlet temperature of 150°C and the remaining heating zone temperature of 160-170°C. The screw speed is 50 r / min. After mixing and melting, the mixture is extruded and stretched into a film by the twin-screw extruder. The winding speed is controlled to make the film thickness about 0.05 mm.

[0069] Table 1

[0070]

[0071] As shown in Table 1, comparing the mechanical properties of Examples 1-3 and Comparative Examples 1-2, adding 25 parts of PHBV can improve the mechanical properties of the packaging material, making it suitable for preparing food packaging film materials and preventing damage during processing and use. Comparing the antibacterial and antioxidant properties of the materials in Examples 2, 4, 5 and Comparative Example 1, adding halloysite nanotubes containing encapsulated essential oils, polylysine, and polyglutamic acid can significantly improve the material's preservation performance. Considering the comprehensive comparison of Examples 1-5 and Comparative Examples 1-2, and taking into account factors such as production cost and performance improvement ratio, the preferred raw material ratio for the bio-based active food packaging material is: 75 parts PLA, 25 parts PHBV, 4 parts halloysite nanotube powder loaded with essential oils, 0.5 parts chain extender, and 3 parts tributyl acetylacetate.

[0072] The film materials prepared in Example 2 and Comparative Example 2 were cut into 30*30cm preservation bags. Fresh cherry tomatoes were placed inside and sealed, and stored at 20°C and 70% humidity for 21 days. The preservation effect was observed. The experimental results showed that the cherry tomatoes in Example 2 lost 11.3% of their weight after 21 days of storage, with no obvious changes in appearance and no signs of spoilage or mold. In contrast, the cherry tomatoes in Comparative Example 2 lost 32.7% of their weight after 21 days of storage, and most of the tomatoes showed wrinkles and black or green mold spots.

[0073] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A bio-based active food packaging material, characterized in that... The food packaging material comprises the following components by weight: 70-80 parts polylactic acid, 20-30 parts polyhydroxybutyrate-valerate copolyester, 0.5 parts chain extender ADR 43700, 3 parts tributyl acetylacetonate, and 2-6 parts halloysite nanotube powder loaded with essential oils; the essential oils loaded in the halloysite nanotube powder include honeysuckle essential oil and *Sapindus mukorossi* essential oil. The preparation method of the bio-based active food packaging material includes the following steps: (1) Take halloysite nanotubes, add alkaline solution, then treat with ultrasonic water bath, stir magnetically, wash until neutral, centrifuge, separate and collect halloysite nanotubes, and dry them for later use. (2) Take honeysuckle essential oil and sago palm essential oil, stir and mix them to obtain a mixed essential oil for later use; (3) Take the halloysite nanotubes treated with alkali in step (1) and the mixed essential oil in step (2), add organic solvent to mix, then treat with water bath sonication, vacuum dry and centrifuge, collect halloysite nanotubes loaded with mixed essential oil, wash with organic solvent, centrifuge, dry, pulverize and collect halloysite nanotube powder loaded with essential oil for later use. (4) Prepare polylysine solution and polyglutamic acid solution respectively. First, add halloysite nanotube powder loaded with essential oil in step (3) to the polylysine solution, stir, mix, and centrifuge. After washing the collected solid phase, complete the first layer of encapsulation. Then add the polyglutamic acid solution, stir, mix, and centrifuge. After washing the collected solid phase, complete the second layer of encapsulation. Then complete the third layer of encapsulation in the same way as the first layer of encapsulation. Then complete the fourth layer of encapsulation in the same way as the second layer of encapsulation. After drying and pulverizing, collect the powder for later use. (5) Take polylactic acid, polyhydroxybutyrate copolyester, chain extender, tributyl acetyl citrate and the powder prepared in step (4) according to the weight parts, mix and melt them, and then extrude and stretch them through a twin-screw extruder to obtain a film, which is the packaging material.

2. The bio-based active food packaging material according to claim 1, characterized in that: In step (1), halloysite nanotubes are mixed with alkaline solution at a mass-to-volume ratio of 1:8-12, wherein the alkaline solution is a 0.5 mol / L sodium hydroxide solution or potassium hydroxide solution; the mixture is subjected to ultrasonic treatment in a water bath for 20-40 min and magnetic stirring for 20-28 h.

3. The bio-based active food packaging material according to claim 1, characterized in that: In step (2), honeysuckle essential oil and saxifrage essential oil are mixed evenly in a volume ratio of 1:1-4.

4. The bio-based active food packaging material according to claim 1, characterized in that: The halloysite nanotubes treated with alkali in step (3), the mixed essential oils in step (2), and the organic solvents are mixed in a mass-volume ratio of 1:1:3-5.

5. The bio-based active food packaging material according to claim 1, characterized in that: The concentrations of the polylysine solution and polyglutamic acid solution prepared in step (4) are 1-3 mg / ml, respectively. The powder in step (3) is mixed with the polylysine solution at a mass-volume ratio of 1:4-6 to complete the first layer of encapsulation. During the second and fourth layers of encapsulation, the solid phase is mixed with the polyglutamic acid solution at a mass-volume ratio of 1:5, respectively. During the third layer of encapsulation, the solid phase is mixed with the polylysine solution at a mass-volume ratio of 1:

5.

6. The bio-based active food packaging material according to claim 1, characterized in that: In step (5), the inlet temperature of the twin-screw extruder is 150℃, the heating zone temperature is 160~170℃, and the screw speed is 50r / min.

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