Preparation method and application of biomass-based intelligent active packaging film

Abstract

The invention belongs to the technical field of intelligent food packaging films, and particularly relates to a preparation method and application of a biomass-based active packaging film. According to the film, a double-network skeleton is constructed by using wood nano cellulose / sodium alginate, so that the film is endowed with excellent flexibility, ultraviolet shielding property and antibacterial activity; furthermore, zein nanoparticles loaded with curcumin are uniformly embedded into the matrix, so that ammonia-sensitive color development and curcumin slow release synergism are realized. Due to the introduction of the curcumin-zein nanoparticles, the mechanical strength, the water-oxygen barrier property, the oxidation resistance and the antibacterial property of the film are further remarkably improved, and reversible color change occurs in the presence of NH3, so that the meat product decay visual detection is realized. Fresh shrimps are packaged with the film and stored at 4 DEG C, the activity of polyphenol oxidase can be remarkably inhibited, blackening and microbial proliferation are delayed, and a green, visible and controllable multifunctional packaging strategy is provided for a meat supply chain.

Description

[Technical Field]

[0001] This invention relates to a method for preparing and applying a biomass-based intelligent active packaging film, belonging to the field of intelligent food packaging technology. [Background Technology]

[0002] Traditional petroleum-based plastic packaging films, due to their lightweight, transparency, and excellent mechanical and barrier properties, have become indispensable materials in the food, pharmaceutical, and agricultural sectors. However, the resource waste, white pollution, and difficulty in degradation they cause not only pose a long-term threat to the environment but also hinder the sustainable development of food packaging materials. Currently, approximately 70% of fresh meat products still rely on petroleum-based plastic packaging (such as polyethylene and polypropylene), which only provides physical isolation. This packaging cannot monitor freshness in real time, nor does it have active antibacterial capabilities, leading to rapid spoilage of meat products during distribution and storage due to microbial growth, shortening shelf life and producing harmful metabolites.

[0003] Therefore, intelligent-active integrated packaging based on renewable, biodegradable, and widely available biomass has become a research focus. By embedding optical indicators, color / fluorescence signals are generated for characteristic metabolites such as biogenic amines and sulfides released from meat spoilage, enabling non-destructive and visual tracking of freshness; simultaneously loading natural antibacterial / antioxidant agents actively inhibits microbial proliferation and lipid oxidation, significantly extending shelf life, and providing a green and efficient solution to replace petroleum-based plastics. [Summary of the Invention]

[0004] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a method for preparing and applying a biomass-based intelligent active packaging film. This intelligent active packaging film uses lignocellulose nanofibers and sodium alginate as the matrix, with zein nanoparticles loaded with curcumin uniformly dispersed within them. On one hand, the controlled, sustained release of curcumin achieves long-lasting antioxidant and antibacterial effects, significantly delaying food spoilage and extending shelf life. On the other hand, relying on the stability and pH-responsive characteristics of curcumin in the nanocarrier, the film undergoes a visible color change in response to changes in food freshness, enabling visual monitoring of freshness. The entire system is completely biodegradable, possessing both intelligent indication and active preservation functions.

[0005] The technical solution of this invention: a method for preparing a biomass-based intelligent active packaging film, characterized by comprising the following steps:

[0006] (1) Preparation of wood-based nanocellulose filaments: Cellulose fibers are pulped to obtain cellulose fibers with a freeness of 40-80°SR; the cellulose fibers are pretreated with a eutectic solvent composed of arginine hydrochloride and organic acid at a reaction temperature of 70-120℃ and a reaction time of 1-3h, wherein the mass ratio of the eutectic solvent to the cellulose fibers is 20:1; after the reaction, the product is washed to neutral and prepared into an aqueous suspension, which is then subjected to high-pressure homogenization at a pressure of 500-800 bar for 10-30 min to obtain a wood-based nanocellulose filament suspension containing 10-20 wt% lignin;

[0007] (2) Preparation of wood nanocellulose filaments / sodium alginate composite film: The wood nanocellulose filaments obtained in step (1) are mixed with sodium alginate at a mass ratio of (9:1) to (5:5), and glycerol, a plasticizer, is added. The mass of glycerol accounts for 1% to 5% of the total mass of wood cellulose and sodium alginate. The mixture is continuously mixed evenly to obtain a film-forming solution.

[0008] (3) Preparation of intelligent active packaging film: Add curcumin-loaded zein nanoparticle dispersion as an indicator to the film-forming solution obtained in step (2). The mass of the nanoparticles accounts for 1-20% of the total mass of the film-forming solution. Stir until uniformly dispersed to obtain a stable composite film-forming solution. Pour the composite film-forming solution into a mold for casting and dry at 40°C for 8-12 hours to obtain the biomass-based intelligent active packaging film.

[0009] Preferably, in step (1), the cellulose fiber is bamboo chemimechanical pulp or wood chemimechanical pulp; the organic acid is lactic acid, formic acid, citric acid, etc.

[0010] Preferably, the concentration of the lignocellulosic nanofiber suspension in step (1) is 1 wt% to 5 wt%.

[0011] A biomass-based intelligent active packaging film prepared by the above steps is characterized in that: the film comprises a matrix formed by lignocellulose nanofibers and sodium alginate, and curcumin-zein nanoparticles dispersed in the matrix; wherein the lignin retained in situ in the lignocellulose nanofibers endows the film with antioxidant, antibacterial and ultraviolet blocking properties; the lignocellulose, sodium alginate, curcumin and zein are all natural organic polymers, endowing the film with natural biodegradability; the curcumin-zein nanoparticles change color from bright yellow to reddish brown when in contact with volatile ammonia gas, and can controllably release curcumin, realizing a visual response to ammonia release during the spoilage of fresh meat and a dual function of synergistic antibacterial preservation.

[0012] Furthermore, the application of the aforementioned biomass-based intelligent active packaging film in the preservation of fresh meat products is described. The method of use is as follows: the fresh meat products are sealed and packaged using the aforementioned intelligent active packaging film, and then stored, transported, and sold at 4°C.

[0013] The biomass-based smart active packaging film of the present invention has the following advantages and beneficial effects:

[0014] (1) The biomass-based smart active packaging film prepared by the method of the present invention has mechanical strength, water and oxygen barrier properties, antioxidant, antibacterial and degradable properties, and undergoes reversible color change in the presence of NH3, so as to realize the visual detection of meat product spoilage.

[0015] (2) The biomass-based intelligent active packaging film prepared by the method described in this invention has a reasonable structural design and high safety. All materials used are within the permitted range of my country's national food safety standard "Standard for the Use of Food Additives" (GB2760-2014).

[0016] (3) The biomass-based smart active packaging film prepared by the method described in this invention can extend the shelf life of fresh shrimp by 2 days when stored at 4°C compared to PE film. Attached Figure Description

[0017] Figure 1 Transmission electron microscopy image of woody cellulose nanofibers;

[0018] Figure 2 Images of the intelligent active packaging film and its scanning electron microscope (SEM) image;

[0019] Figure 3 Image showing the antibacterial properties of intelligent active packaging film against Escherichia coli and Staphylococcus aureus;

[0020] Figure 4 Antioxidant diagrams of smart active packaging films with different amounts of nanoparticles added;

[0021] Figure 5 Soil degradation diagram of intelligent active packaging film;

[0022] Figure 6 The color change diagram for the smart packaging film after four recycling cycles.

[0023] Figure 7 A schematic diagram illustrating the mechanism of applying intelligent active packaging film to meat product packaging.

[0024] Figure 8 Comparison of appearance and film color of fresh shrimp packaged in PE and smart active packaging film after 5 days of storage at 4℃;

[0025] Figure 9The graph shows the change in total volatile basic nitrogen of fresh shrimp packaged in PE and smart active packaging films after 5 days of storage at 4℃.

[0026] Abbreviations: LCNF / SA, wood nanocellulose filaments / sodium alginate film; Z-curNPs, zein nanoparticles loaded with curcumin; LCNF / SA / Z-cur, wood nanocellulose filaments / sodium alginate / turmeric zein nanoparticles composite film. Detailed Implementation

[0027] The present invention will be further described below with reference to specific embodiments. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Those skilled in the art can make appropriate modifications or additions to the present invention, but all such modifications or additions shall fall within the scope of the claims set forth in the present invention.

[0028] Example 1

[0029] The preparation and application of a biomass-based smart active packaging film includes the following steps:

[0030] 1. Preparation of wood-based nanocellulose fibers: 5g of chemimechanical pulp was beating with PFI to obtain chemimechanical pulp fibers with a freeness of 60°SR; then it was mixed with arginine hydrochloride / lactic acid eutectic solvent at a ratio of 1:20 and pretreated at 90℃ for 2h; after the reaction, it was washed with deionized water until neutral and a 2wt% suspension was prepared. The suspension was homogenized under high pressure at 700 bar for 30min to obtain wood-based nanocellulose fibers containing lignin.

[0031] Figure 1 The image shows a transmission electron microscope (TEM) image of the lignin-containing cellulose nanofibers. The image reveals highly fibrillated filaments with a large aspect ratio and uniformly distributed lignin nanoparticles on the surface, confirming that lignin is retained in situ within the nanofibers, providing a structural basis for subsequent antioxidant, antibacterial, and UV-blocking functions.

[0032] 2. Preparation of wood nanocellulose filament / sodium alginate composite membrane: Sodium alginate was prepared to a concentration of 1 wt% and mixed with the wood nanocellulose filaments obtained in step 1 at a mass ratio of 4:6. 2 wt% glycerol was added as a plasticizer, and the mixture was magnetically stirred for 30 min to make the solution uniformly mixed, thus obtaining the wood nanocellulose filament / sodium alginate film-forming solution.

[0033] 3. Preparation of intelligent active packaging film: The lignocellulose nanofiber / sodium alginate film-forming solution obtained in step 2 was added to 5 wt% of zein nanoparticles loaded with curcumin as an indicator, and the mixture was magnetically stirred for 30 min to obtain a uniform composite solution; then 40 mL of the composite solution was poured into a circular mold with a diameter of 9 cm to form a film, and then dried in an oven at 40 ℃ for 10 h to obtain a biomass-based intelligent active packaging film.

[0034] Figure 2 The image shown is a photograph of the intelligent active packaging film and a scanning electron microscope (SEM) image. It can be seen that the film has good transmittance and smoothness, indicating good compatibility between the materials, proving the successful preparation of the intelligent active packaging film.

[0035] Example 2

[0036] The preparation of a biomass-based smart active packaging film includes the following steps:

[0037] 1. Preparation of wood-based nanocellulose fibers: 5g of chemimechanical pulp was beating with PFI to obtain chemimechanical pulp fibers with a freeness of 60°SR; then it was mixed with arginine hydrochloride / lactic acid eutectic solvent at a ratio of 1:20 and pretreated at 90℃ for 2h; after the reaction, it was washed with deionized water until neutral and a 2wt% suspension was prepared. The suspension was homogenized under high pressure at 700 bar for 30min to obtain wood-based nanocellulose fibers containing lignin.

[0038] 2. Preparation of wood nanocellulose filament / sodium alginate composite membrane: Sodium alginate was prepared to a concentration of 1 wt% and mixed with the wood nanocellulose filaments obtained in step 1 at a mass ratio of 4:6. 2 wt% glycerol was added as a plasticizer, and the mixture was magnetically stirred for 30 min to make the solution uniformly mixed, thus obtaining the wood nanocellulose filament / sodium alginate film-forming solution.

[0039] 3. Preparation of intelligent active packaging film: The lignocellulose nanofiber / sodium alginate film-forming solution obtained in step 2 was added to 9 wt% of zein nanoparticles loaded with curcumin as an indicator, and the mixture was magnetically stirred for 30 min to obtain a uniform composite solution; then 40 mL of the composite solution was poured into a circular mold with a diameter of 9 cm to form a film, and dried in an oven at 40 ℃ for 10 h to obtain a biomass-based intelligent active packaging film.

[0040] Figure 3 , 4 Figures 5 and 6 show the antibacterial properties of the intelligent active packaging film against Escherichia coli and Staphylococcus aureus, the antioxidant properties of the intelligent active packaging film with different amounts of nanoparticles, and the soil degradation of the intelligent active packaging film, respectively. These figures demonstrate that the intelligent active packaging film possesses excellent antibacterial, antioxidant, and biodegradable properties.

[0041] Example 3

[0042] The preparation of a biomass-based smart active packaging film includes the following steps:

[0043] 1. Preparation of wood-based nanocellulose fibers: 5g of chemimechanical pulp was beating with PFI to obtain chemimechanical pulp fibers with a freeness of 60°SR; then it was mixed with arginine hydrochloride / lactic acid eutectic solvent at a ratio of 1:20 and pretreated at 90℃ for 2h; after the reaction, it was washed with deionized water until neutral and a 2wt% suspension was prepared. The suspension was homogenized under high pressure at 700 bar for 30min to obtain wood-based nanocellulose fibers containing lignin.

[0044] 2. Preparation of wood nanocellulose filament / sodium alginate composite membrane: Sodium alginate was prepared to a concentration of 1 wt% and mixed with the wood nanocellulose filaments obtained in step 1 at a mass ratio of 4:6. 2 wt% glycerol was added as a plasticizer, and the mixture was magnetically stirred for 30 min to make the solution uniformly mixed, thus obtaining the wood nanocellulose filament / sodium alginate film-forming solution.

[0045] 3. Preparation of intelligent active packaging film: The lignocellulose nanofiber / sodium alginate film-forming solution obtained in step 2 was added to 11wt% of zein nanoparticles loaded with curcumin as an indicator, and the mixture was magnetically stirred for 30 min to obtain a uniform composite solution; then 40 mL of the composite solution was poured into a circular mold with a diameter of 9 cm to form a film, and dried in an oven at 40℃ for 10 h to obtain a biomass-based intelligent active packaging film.

[0046] 4. Place the smart active packaging film prepared in steps 1 to 4 above 20 mL of 5% ammonia solution and record the color change of the film every 20 seconds.

[0047] Figure 6 This is a color change diagram of the smart packaging film after four recycling cycles. Over time, the volatilization of ammonia gradually increases, and the film's color changes from an initial bright yellow to a deep yellow, then gradually to orange, and finally to red. Even after four cycles, it still retains some indication capability.

[0048] Application Example 1

[0049] Fresh shrimp were used as the test subject. The fresh shrimp packaged with the intelligent active packaging film prepared in Example 2 was used as the experimental group, and the fresh shrimp packaged with commercially available PE preservation film was used as the control group. The packaged fresh shrimp were stored in a refrigerator at 4°C for 5 days. The changes in the appearance of the fresh shrimp, the color of the film, and the total volatile basic nitrogen content were recorded throughout the experiment to evaluate the preservation effect.

[0050] Figure 7 This diagram illustrates the mechanism of applying intelligent active packaging film to meat product packaging. It shows that zein nanoparticles loaded with curcumin change color in response to changes in ammonia concentration within the meat packaging microenvironment, while simultaneously releasing curcumin in a controlled manner. This achieves long-lasting antioxidant and synergistic antibacterial effects, combining the dual functions of visual freshness indication and active preservation. Figure 8 The images show a comparison of the appearance and film color of fresh shrimp packaged in PE and smart active packaging films after 5 days of storage at 4℃. It can be seen that as storage time increases, the freshness of the shrimp decreases, and the film color changes synchronously. On the 3rd day, the shrimp in the PE group showed obvious signs of spoilage, while the shrimp in the experimental group maintained good freshness. Simultaneously, the film gradually changed from bright yellow to orange, enabling visual monitoring of the spoilage process. Figure 9 The graph shows the changes in total volatile basic nitrogen (TVR) content of fresh shrimp packaged in PE and smart active packaging films after 5 days of storage at 4℃. The TVR content was determined according to GB 5009.228-2016, "Determination of Volatile Basic Nitrogen in Food." According to the current Chinese standard (GB2733-2015), an TVR content of <20 mg / 100g is the acceptable limit for fresh shrimp. At 4℃, compared with the PE control group, the accumulation rate of TVR in the experimental group decreased by 55.2%.

Claims

1. A method for preparing and applying a biomass-based intelligent active packaging film, characterized in that, Includes the following steps: (1) Preparation of wood-based nanocellulose filaments: Cellulose fibers are pulped to obtain cellulose fibers with a freeness of 40-80°SR; the cellulose fibers are pretreated with a eutectic solvent composed of arginine hydrochloride and organic acid at a reaction temperature of 70-120℃ and a reaction time of 1-3h, wherein the mass ratio of the eutectic solvent to the cellulose fibers is 20:1; after the reaction, the product is washed to neutral and prepared into an aqueous suspension, which is then subjected to high-pressure homogenization at a pressure of 500-800 bar for 10-30 min to obtain a wood-based nanocellulose filament suspension containing 10-20 wt% lignin; (2) Preparation of wood nanocellulose filaments / sodium alginate composite film: The wood nanocellulose filaments obtained in step (1) are mixed with sodium alginate at a mass ratio of (9:1) to (5:5), and glycerol, a plasticizer, is added. The mass of glycerol accounts for 1% to 5% of the total mass of wood cellulose and sodium alginate. The mixture is continuously mixed evenly to obtain a film-forming solution. (3) Preparation of intelligent active packaging film: Add curcumin-loaded zein nanoparticle dispersion as an indicator to the film-forming solution obtained in step (2). The mass of the nanoparticles accounts for 1-20% of the total mass of the film-forming solution. Stir until uniformly dispersed to obtain a stable composite film-forming solution. Pour the composite film-forming solution into a mold for casting and dry at 40°C for 8-12 hours to obtain the preparation method of the biomass-based intelligent active packaging film.

2. The preparation method according to claim 1, characterized in that, In step (1), the cellulose fiber is bamboo chemimechanical pulp or wood chemimechanical pulp; the organic acid is lactic acid, formic acid, citric acid, etc.

3. The preparation method according to claim 1, characterized in that, The concentration of the lignocellulose nanofiber suspension in step (1) is 1 wt% to 5 wt%.

4. A biomass-based smart active packaging film prepared by the preparation method according to any one of claims 1 to 3, characterized in that: The film comprises a matrix formed by lignocellulose nanofibers and sodium alginate, and curcumin-zein nanoparticles dispersed in the matrix; wherein the lignin retained in situ in the lignocellulose nanofibers endows the film with antioxidant, antibacterial and ultraviolet blocking properties; the lignocellulose, sodium alginate, curcumin and zein are all natural organic polymers, giving the film natural biodegradability; the curcumin-zein nanoparticles change color from bright yellow to reddish brown when in contact with volatile ammonia gas, and can controllably release curcumin, realizing a visual response to ammonia release during the spoilage of fresh meat and a dual function of synergistic antibacterial preservation.

5. The application of a biomass-based smart active packaging film as described in claim 4 in the preservation of fresh meat products.

6. The application according to claim 5, characterized in that, The applications include: sealing fresh meat products with the intelligent active packaging film and storing, transporting or selling them at 4°C.

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