Gelatin bacterial cellulose composite material with lotus leaf structure as well as preparation method and application of gelatin bacterial cellulose composite material

Abstract

The invention discloses a gelatin bacterial cellulose composite material with a lotus leaf structure as well as a preparation method and application thereof, and belongs to the technical field of packaging and fresh keeping. The preparation method comprises the following steps: accurately copying a micro-nano structure on the surface of the lotus leaf by utilizing a polydimethylsiloxane template technology, mixing a gelatin solution, a bacterial cellulose solution, glycerol and a functional active substance curcumin to obtain a film forming solution, drying the film forming solution on a template to form a film, and then removing the template. The surface of the material naturally presents a lotus leaf bionic structure, and the material is endowed with excellent hydrophobic performance without additional chemical modification or hydrophobic coating. The method is simple and convenient in process, healthy and harmless, and the prepared functional composite film integrates hydrophobicity, antibacterial property, oxidation resistance, ultraviolet shielding property and good mechanical property, is suitable for the packaging and fresh-keeping fields of food, medicines, agricultural products and the like, can effectively prolong the shelf life, and meets the development requirements of green packaging.

Description

Technical Field

[0001] The invention belongs to the technical field of packaging and fresh-keeping, and particularly relates to a gelatin-bacterial cellulose composite material with a lotus leaf structure, a preparation method thereof, and an application thereof. Background Art

[0002] With the global population growing and the demand for food continuing to climb, food safety has become a global concern. As a key barrier to product spoilage caused by environmental factors such as temperature, light, humidity, and gases, food packaging is becoming increasingly important. Currently, petroleum-based polymers dominate the food packaging market due to their low cost and good processability. However, their non-degradability has led to serious environmental pollution issues and the continuous release of microplastics during use, posing potential health risks. Therefore, developing materials based on natural, sustainable biomass sources and incorporating cutting-edge technologies such as active packaging to impart multifunctionality to these materials is seen as a promising solution aimed at extending the shelf life of food while meeting the increasingly complex demands of consumers.

[0003] Food preservation is highly dependent on moisture control, as it directly impacts microbial growth, enzyme activity, chemical reaction rates, and physical structure, ultimately determining the shelf life, safety, and quality of the product. The preservation of fresh food places particularly stringent demands on the hydrophobic properties of packaging materials. However, most packaging films made from biomass substrates are inherently hydrophilic, significantly limiting their application in packaging such highly moisture-sensitive foods. Currently, the main strategies for improving film hydrophobicity include chemical modification and the application of hydrophobic coatings. However, these methods require the introduction of organic compounds during the preparation process, making it difficult to ensure absolute safety and harmlessness when applied to food contact materials. Patent publication number CN 117986655 B proposes a lotus leaf essential oil composite gelatin biomimetic packaging film. This film is coated with carnauba wax, a water-transporting material, on one side of the film that mimics the lotus leaf structure. This coating increases the preparation process and production costs, and can also damage the lotus leaf biomimetic structure. Furthermore, this lotus leaf essential oil composite gelatin biomimetic packaging film uses toxic substances such as acetone as raw materials and is not fully degradable.

[0004] Therefore, there is an urgent need to develop a biodegradable active packaging material that is healthy and harmless, has excellent hydrophobicity, and has multiple functions such as antibacterial, antioxidant, and UV shielding. Summary of the Invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to provide a gelatin bacterial cellulose composite material with a lotus leaf structure, a preparation method and application thereof. The gelatin bacterial cellulose composite material has a lotus leaf microstructure and can have the functions of hydrophobicity, health and harmlessness, antibacterial, antioxidant, UV shielding, etc. without additional chemical modification or application of a hydrophobic coating. It can be used to extend the shelf life of food, medicine, agricultural products, etc.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The first object of the present invention is to provide a method for preparing a gelatin-cellulose composite material having a lotus leaf structure, comprising the following steps: Fresh lotus leaves were washed and fixed, and the PDMS mixture was transferred to the surface of the lotus leaves. After the PDMS mixture was vacuum cured, the lotus leaves were removed to obtain a PDMS template with lotus leaf surface microstructures. The gelatin solution and the bacterial cellulose solution are stirred and mixed to obtain a gelatin-bacterial cellulose mixed solution, and glycerol and curcumin are added to the gelatin-bacterial cellulose solution. After stirring, vacuum defoaming is performed to obtain a film-forming solution; The film-forming liquid is slowly transferred onto the PDMS template, and after drying to form a film, the PDMS template is removed to obtain a gelatin-cellulose composite packaging material with a lotus leaf structure.

[0007] Preferably, the PDMS mixture is prepared by mixing polymethyl silicone oil and a curing agent and then defoaming in vacuum.

[0008] Further preferably, the usage ratio of the polymethyl silicone oil to the curing agent is (10-12): (1-3).

[0009] Preferably, the PDMS mixture is removed from the lotus leaf after vacuum curing, the vacuum curing temperature is 40-60 ° C, and the curing time is 10-13 hours.

[0010] Preferably, when the gelatin solution and the bacterial cellulose solution are stirred and mixed, the concentration of the gelatin solution is 2.5-3.5 wt%, the concentration of the bacterial cellulose is 0.5%-0.8 wt%, and the volume ratio of the gelatin solution to the bacterial cellulose solution is 1:4.

[0011] Further preferably, in the stirring and mixing of the gelatin solution and the bacterial cellulose solution, the stirring rate is 400-500 r / min and the stirring time is 0.5-1 h.

[0012] Preferably, glycerol and curcumin are added to the gelatin / bacterial cellulose solution, stirred and then vacuum defoamed to obtain a film-forming liquid, wherein the content of glycerol in the film-forming liquid is 0.5-1.5 wt%, and the content of curcumin is 0.05-0.2 wt%.

[0013] Preferably, the film-forming liquid is slowly transferred to the PDMS template, and removed from the PDMS template after drying to form a film. The drying temperature for the film is 50-60° C., and the drying time is 4-8 hours.

[0014] The second object of the present invention is to provide a gelatin-cellulose composite packaging material with a lotus leaf structure prepared by the above preparation method.

[0015] The third object of the present invention is to propose the application of the above-mentioned gelatin-cellulose composite packaging material with lotus leaf structure in the field of food, medicine or agricultural product packaging.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention proposes a method for preparing a gelatin-cellulose composite material with a lotus leaf structure. Inspired by the surface structure of lotus leaves found in nature, this method utilizes polydimethylsiloxane (PDMS) template technology to precisely replicate the inherent superhydrophobic micro-nanostructure of lotus leaves onto the surface of gelatin-based packaging materials, significantly enhancing their hydrophobic properties and effectively overcoming the application limitations of gelatin-based materials in food packaging due to their hydrophilic nature. This template replication method achieves excellent hydrophobicity without the need for chemical modification or hydrophobic additives, while also reducing production costs. The introduction of the functional active ingredient curcumin significantly enhances the mechanical properties of the film while also imparting strong antioxidant and antimicrobial properties. The combination of gelatin and the bacterial cellulose matrix, synergistic with the curcumin active ingredient, achieves functional complementarity and multifunctional integration. Furthermore, the prepared composite film is entirely biomass-based and fully biodegradable. The widely available raw material further reduces production costs, aligning with the sustainable development trend of green packaging. Overall, this method is simple, harmless, and the resulting film exhibits multiple excellent functions, making it suitable for fresh food preservation.

[0017] The packaging material prepared by the present invention has good biodegradability, hydrophobicity, mechanical properties and barrier properties. In addition, it has multiple functions such as antibacterial, antioxidant, and UV shielding. It conforms to the trend of sustainable development of green packaging, has good preservation performance, and can be widely used in the packaging of food, medicine, agricultural products, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of this application. The exemplary embodiments and descriptions of this application are intended to explain this application and do not constitute an improper limitation on this application. In the accompanying drawings: Figure 1 The infrared spectra of the gelatin bacterial cellulose composite multifunctional packaging materials in Examples 1, 2, 3, 4, and 5 of the present invention are as follows; Figure 2The infrared spectrum XRD patterns of the gelatin bacterial cellulose composite multifunctional packaging materials in Examples 1, 2, 3, 4, and 5 of the present invention are as follows; Figure 3 Thermogravimetric diagrams of the gelatin bacterial cellulose composite multifunctional packaging materials in Examples 1, 2, 3, 4, and 5 of the present invention; Figure 4 This is an SEM image of the gelatin bacterial cellulose composite multifunctional packaging material, natural lotus leaf, and PDMS template in Example 1 of the present invention; Figure 5 The UV spectra of the gelatin bacterial cellulose composite multifunctional packaging materials in Examples 1, 2, 3, 4, and 5 of the present invention are shown; Figure 6 The water contact angle of the gelatin bacterial cellulose composite multifunctional packaging material of the present invention; Figure 7 This is a graph showing the antibacterial performance of the gelatin bacterial cellulose composite multifunctional packaging material of the present invention; Figure 8 This is a graph showing the antioxidant properties of the gelatin bacterial cellulose composite multifunctional packaging material of the present invention; Figure 9 This is an appearance diagram of pork packaged in a test using the gelatin-bacterial-cellulose composite multifunctional packaging material of the present invention. DETAILED DESCRIPTION

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0020] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Each smaller range between any intermediate value within a stated value or stated range and any other stated value or intermediate value within the stated range is also encompassed by the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0021] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0022] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be illustrative only.

[0023] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0024] The preparation method of the gelatin-cellulose composite material with a lotus leaf structure proposed in the present invention comprises the following steps: Preparation of PDMS template: A fresh lotus leaf is washed and fixed on a glass culture dish. A PDMS mixture is prepared and poured onto the lotus leaf to completely cover its surface. After the culture dish is vacuum cured, the PDMS template is removed from the lotus leaf to obtain a PDMS template with the lotus leaf surface microstructure. In some embodiments of the present invention, the preparation step of the PDMS mixture includes: mixing polydimethylsiloxane (liquid A) and curing agent (liquid B) in a mass ratio of (10-12): (1-3), and then vacuum defoaming to obtain the mixture.

[0025] In some embodiments of the present invention, the vacuum curing temperature range is 40-60°C, and the curing time is 10-13 hours. Preferably, the heat curing is performed at 50°C for 12 hours, and then the lotus leaf is removed to obtain a PDMS template with a lotus leaf surface microstructure.

[0026] Preparation of membrane-forming solution: taking gelatin solution and bacterial cellulose solution, stirring and mixing to obtain gelatin-bacterial cellulose mixed solution, then adding glycerol and glycerin to the gelatin-bacterial cellulose solution, stirring and vacuum defoaming to obtain membrane-forming solution; In some embodiments of the present invention, the concentration of the gelatin solution is 2.5-3.5 wt %, the concentration of the bacterial cellulose solution is 0.5%-0.8 wt %, and the volume ratio of the gelatin solution to the bacterial cellulose solution is 1:4.

[0027] In some embodiments of the present invention, the gelatin solution and the bacterial cellulose solution are mixed and stirred at a rate of 400-500 r / min for 0.5-1 h.

[0028] In some embodiments of the present invention, the content of glycerol in the membrane-forming solution is 0.5-1.5 wt %, and the content of curcumin is 0.05-0.2 wt %.

[0029] Preparation of gelatin-cellulose composite material with lotus leaf structure: slowly transfer the film-forming liquid prepared above to the PDMS template prepared above, remove the PDMS template after drying to form a film, and obtain gelatin-cellulose composite packaging material with lotus leaf structure, abbreviated as L-GBC film.

[0030] In some embodiments of the present invention, the film-forming drying temperature is 50-60° C., and the drying time is 4-8 hours.

[0031] Gelatin (biotechnology grade, 97%) was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; bacterial cellulose was purchased from Guilin Qihong Technology Co., Ltd.; curcumin was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.; glycerol was purchased from Tianjin Damao Chemical Reagent Factory; and polydimethylsiloxane (PDMS, Sylgard 184) was purchased from Dow Corning.

[0032] The methods of the present invention are further described below with reference to the accompanying drawings and examples. The following examples utilize conventional instruments and equipment in the art. Unless otherwise specified, the various raw materials and reagents used are conventional commercially available products, with specifications conventional in the art, or can be prepared or formulated by known methods or reagent instructions. Experimental procedures in the following examples, where specific conditions are not specified, generally follow conventional conditions or those recommended by the manufacturer.

[0033] The present invention is described in further detail below with reference to the accompanying drawings: Example 1 (1) Wash the fresh lotus leaf and fix it on a glass culture dish. Mix polydimethylsiloxane solution A and solution B in a mass ratio of 10:1 and defoam under vacuum for 30 minutes to obtain a PDMS mixture. Pour the PDMS mixture on the lotus leaf to completely cover its surface. Heat cure the lotus leaf covered with the PDMS mixture at 50°C for 12 hours, then remove the lotus leaf to obtain a PDMS template with lotus leaf surface microstructure. (2) Weigh a certain amount of gelatin and dissolve it in deionized water. Stir continuously at 80°C at a rate of 500 r / min for 1 hour to obtain a 3 wt% gelatin solution. Weigh a certain amount of bacterial cellulose and dissolve it in deionized water. Stir continuously at room temperature at a rate of 500 r / min for 1 hour to obtain a 0.5 wt% bacterial cellulose solution. Mix the gelatin solution and the bacterial cellulose solution in a volume ratio of 1:2, add 1 wt% glycerol and 0.1 wt% curcumin, and defoam under vacuum to obtain a membrane-forming solution.

[0034] (3) The film-forming liquid was cast on the PDMS template prepared in step (1), and dried in an oven at 60 °C for 6 hours. After complete drying, the PDMS template was removed to obtain a product film, which was a gelatin-cellulose composite material with a lotus leaf structure, denoted as L-GBC-2.

[0035] Example 2 The difference between this embodiment and embodiment 1 is that 0.05 wt% curcumin is added in step (2). The other parts are the same as those in embodiment 1. The obtained product preservative film is recorded as L-GBC-1.

[0036] Example 3 The difference between this embodiment and embodiment 1 is that 0.15 wt% curcumin is added in step (2). The other steps are the same as those in embodiment 1. The obtained product preservative film is recorded as L-GBC-3.

[0037] Example 4 The difference between this embodiment and embodiment 1 is that 0.2 wt% curcumin is added in step (2). The other aspects are the same as those in embodiment 1. The obtained product preservative film is recorded as L-GBC-4.

[0038] Example 5 The difference between this embodiment and embodiment 1 is that curcumin is not added in step (2). Other steps are the same as those in embodiment 1. The obtained preservative film is designated as L-GB.

[0039] Example 6 (1) Wash the fresh lotus leaf and fix it on a glass culture dish. Mix polydimethylsiloxane solution A and solution B in a mass ratio of 10:1 and defoam under vacuum for 30 minutes to obtain a PDMS mixture. Pour the PDMS mixture on the lotus leaf to completely cover its surface. Heat cure the lotus leaf covered with the PDMS mixture at 50°C for 12 hours and then remove the lotus leaf to obtain a PDMS template with lotus leaf surface microstructure. (2) Weigh a certain amount of gelatin and dissolve it in deionized water. Stir continuously at 80°C at a rate of 500 r / min for 1 hour to obtain a 2.5 wt% gelatin solution. Weigh a certain amount of bacterial cellulose and dissolve it in deionized water. Stir continuously at room temperature at a rate of 500 r / min for 1 hour to obtain a 0.4 wt% bacterial cellulose solution. Mix the gelatin solution and the bacterial cellulose solution in a volume ratio of 1:2, add 1 wt% glycerol and 0.1 wt% curcumin, and defoam under vacuum to obtain a membrane-forming solution.

[0040] (3) The film-forming liquid was cast on the PDMS template and dried in an oven at 60 °C for 6 h. After complete drying, the PDMS template was removed to obtain a product film, which was a gelatin-cellulose composite material with a lotus leaf structure, recorded as L-GBC-2-1.

[0041] Example 7 (1) Wash the fresh lotus leaf and fix it on a glass culture dish. Mix polydimethylsiloxane solution A and solution B in a mass ratio of 10:1 and defoam under vacuum for 30 minutes to obtain a PDMS mixture. Pour the PDMS mixture on the lotus leaf to completely cover its surface. Heat cure the lotus leaf covered with the PDMS mixture at 50°C for 12 hours and then remove the lotus leaf to obtain a PDMS template with lotus leaf surface microstructure. (2) Weigh a certain amount of gelatin and dissolve it in deionized water. Stir continuously at 80°C at a rate of 500 r / min for 1 hour to obtain a 3.5 wt% gelatin solution. Weigh a certain amount of bacterial cellulose and dissolve it in deionized water. Stir continuously at room temperature at a rate of 500 r / min for 1 hour to obtain a 0.6 wt% bacterial cellulose solution. Mix the gelatin solution and the bacterial cellulose solution in a volume ratio of 1:2, add 1 wt% glycerol and 0.1 wt% curcumin, and defoam under vacuum to obtain a membrane-forming solution.

[0042] (3) The film-forming liquid was cast on the PDMS template and dried in an oven at 60 °C for 6 hours. After complete drying, the PDMS template was removed to obtain a product film, which was a gelatin-cellulose composite material with a lotus leaf structure, recorded as L-GBC-2-2.

[0043] Comparative Example 1 The difference between this comparative example and Example 1 is that curcumin is not added in step (2), and no PDMS template is used for film casting of the film-forming liquid in step (3). The other aspects are the same as those in Example 1. The obtained product fresh-keeping film is recorded as GB.

[0044] Comparative Example 2 The difference between this comparative example and Example 1 is that 0.05% curcumin is added in step (2), and no PDMS template is used when the film-forming liquid is cast into the film in step (3). Other aspects are the same as in Example 1. The obtained product preservative film is recorded as GBC-1.

[0045] Comparative Example 3 The difference between this comparative example and Example 1 is that 0.1% curcumin is added in step (2), and no PDMS template is used when the film-forming liquid is cast into the film in step (3). Other aspects are the same as in Example 1. The obtained product preservative film is recorded as GBC-2.

[0046] Comparative Example 4 The difference between this comparative example and Example 1 is that 0.15% curcumin is added in step (2), and no PDMS template is used when the film-forming liquid is cast into the film in step (3). Other aspects are the same as in Example 1. The obtained product preservative film is recorded as GBC-3.

[0047] Comparative Example 4 The difference between this comparative example and Example 1 is that 0.2% curcumin is added in step (2), and no PDMS template is used when the film-forming liquid is cast into the film in step (3). Other aspects are the same as in Example 1. The obtained product preservative film is recorded as GBC-4.

[0048] The products prepared in the above examples and comparative examples were analyzed and the results were as follows: Infrared spectroscopy analysis: Figure 1 As shown, 3287 cm -1 The absorption peak at 1032 cm can be attributed to the OH stretching vibration of amide A (NH stretching) and the hydrogen bond network in the bacterial cellulose structure. -1 The peak at 2933 cm is attributed to the COC stretching vibration of the pyranose ring backbone in the bacterial cellulose structure. The stretching vibration of the alkyl group in the cellulose molecule is at 2933 cm -1 and 2879 cm -1 1647 cm -1 The peak at 1533 cm represents the C=O stretching vibration of amide I band, while the peak at 1533 cm -1 The peak at 1236 cm shows the coupling of NH bending vibration and CN stretching vibration of amide II band; in addition, -1 The peaks at 3287 cm represent the stretching vibrations of CN and NH. -1 The OH / NH peak and 1647 cm -1 Changes in the intensity, shape, or position of the C=O peak (e.g., the C=O peak) indicate the presence of complex intermolecular interactions within the sample, particularly extensive hydrogen bonding. This dense network of intermolecular interactions significantly enhances the film's mechanical strength and effectively extends its service life. XRD analysis: Figure 2 As shown, all samples were θ A broad peak appeared near 22°, due to the overlap of the BC crystalline diffraction peak with the amorphous region of gelatin. Weak peaks were observed at 14° and 16° for GB-1, L-GBC-1, L-GBC-2, L-GBC-3, and L-GBC-4, indicating that curcumin was in the initial crystallization stage. These peaks indicate that curcumin formed a small amount of crystals upon addition, and the overall similarity of the peaks suggests good compatibility between gelatin, BC, and curcumin.

[0049] Thermogravimetric analysis: Figure 3As shown, all samples maintained a steady weight loss below 180°C, primarily due to the evaporation of water and glycerol from the film. When the temperature reached 180°C, the film began to melt, and its weight dropped dramatically. Notably, all samples had nearly identical thermal decomposition temperatures, demonstrating the good thermal stability and compatibility of curcumin with gelatin and bacterial cellulose, potentially extending the lifespan of the packaging film.

[0050] SEM analysis: Figure 4 As shown in Figure 1, the surface of the lotus leaf is covered with a large number of evenly distributed nipple-like microstructures, which significantly increases its surface roughness. A similar hollow structure to that of the lotus leaf was observed on the surface of the PDMS template. Through the PDMS template transfer technology, the micro-nanostructure characteristics of the lotus leaf surface were successfully replicated ( Figure 4 Surface morphology of biomimetic membrane prepared by PDMS template ( Figure 4 These results confirm the successful preparation of functional membranes with lotus leaf-inspired surface properties.

[0051] UV spectroscopy analysis: Figure 5 As shown, the L-GBC films exhibit optical transparency (low absorbance / high transmittance) in the 80-200 nm range, indicating that gelatin-bacterial cellulose molecules minimally absorb or scatter light in this region of the electromagnetic spectrum. However, increasing curcumin content increases the UV shielding effect of the L-GBC films in the 200-400 nm range, due to curcumin's high UV absorption capacity. The transmittance of the L-GBC films prepared in each example gradually increases with increasing wavelength, indicating that the addition of curcumin enhances the UV shielding ability of the L-GBC films. L-GBC films exhibit excellent UV protection, delaying oxidation and rancidity in foods, extending their shelf life, and enhancing their functionality.

[0052] Water contact angle analysis: Figure 6 As shown in Figure 1, (a, f) are the water contact angles of GB, GBC-1, L-GBC-1, L-GBC-2, L-GBC-3, and L-GBC-4 films, respectively. The GB film initially exhibited a contact angle of 85.8° due to its hydrophilic groups. The introduction of curcumin formed hydrogen bonds between its hydroxyl groups and water molecules, reducing the contact angle to 78.9°. The construction of a papillary structure via PDMS template transfer increased the surface roughness of the film, significantly increasing the contact angle to 139° and improving its hydrophobic properties. However, excessive curcumin content was found to reduce the contact angle. These experimental results confirm the successful preparation of hydrophobic films based on the lotus leaf biomimetic principle. Antioxidant properties: Figure 7As shown in Figure 2, L-GBC films have a certain ability to scavenge DPPH free radicals, which is attributed to the presence of free NH2 groups in the gelatin structure; these groups can react with DPPH free radicals and H + Ions react to form stable NH4 + ions. Adding curcumin significantly boosted the antioxidant activity of the composite film, increasing it from an initial 2.78% to 86%. This improvement is primarily attributed to the active methoxy and hydroxyl groups in the curcumin molecule. Therefore, the curcumin-modified film exhibits antioxidant properties, effectively maintaining food quality.

[0053] Antibacterial properties: Figure 8 As shown, the curcumin-containing membrane significantly reduced the colony counts of Gram-positive bacteria (Staphylococcus aureus) and Gram-negative bacteria (Escherichia coli) compared to the control group, and the antibacterial effect showed a gradient enhancement with increasing curcumin concentration. The antibacterial mechanism mainly involves the specific inhibitory effect of curcumin on cytoskeletal proteins, which are essential for bacterial division and play a key role in regulating cell proliferation.

[0054] Pork preservation: Figure 8 As shown, the L-GBC-2 group exhibited significant advantages over the six-day storage period. Initially (days 0-2), all three groups maintained a bright red color, but by day 2, the CK group showed signs of dark red oxidation, while the PE group developed a microscopic slime layer due to condensation within the membrane. By the critical third day, the CK group experienced accelerated browning, while the L-GBC-2 group, thanks to its superhydrophobic microstructure, allowed water droplets to roll off its surface, maintaining a cherry red color and free of microbial growth. The differences became even more pronounced by day 5, with the CK group completely spoiling, the PE group experiencing extensive spoilage and emitting a rancid odor, and the L-GBC-2 group exhibiting only a slightly darker color due to myoglobin oxidation, with clear muscle texture and no slime. By the end of day 6, the L-GBC-2 group showed only localized browning at the edges, while the center remained elastic and showed no significant deterioration, while the control group had already deteriorated prematurely. These experimental results demonstrate that the multifunctional packaging material prepared by this invention offers unique advantages over PE film, extending the shelf life of pork by two days.

[0055] In summary, the plastic wrap prepared by the present invention exhibits antibacterial activity against both Staphylococcus aureus and Escherichia coli, with a DPPH free radical scavenging capacity of up to 86%. Its unique microstructure imparts hydrophobic properties, and the film is environmentally nontoxic and fully biodegradable. Pork preservation results indicate that it can extend the shelf life of pork by two days, suggesting broad application prospects in the food packaging field.

[0056] The above are merely preferred embodiments of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.

Claims

1. A method for preparing a gelatin-cellulose composite material with a lotus leaf structure, characterized in that: The following steps are involved: Fresh lotus leaves were washed and fixed, and the PDMS mixture was transferred to the surface of the lotus leaves. After the PDMS mixture was vacuum cured, the lotus leaves were removed to obtain a PDMS template with lotus leaf surface microstructures. The gelatin solution and the bacterial cellulose solution are stirred and mixed to obtain a gelatin-bacterial cellulose mixed solution, and glycerol and curcumin are added to the gelatin-bacterial cellulose solution. After stirring, vacuum defoaming is performed to obtain a film-forming solution; The film-forming liquid is slowly transferred onto the PDMS template, and after drying to form a film, the PDMS template is removed to obtain a gelatin-cellulose composite packaging material with a lotus leaf structure.

2. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1, characterized in that: The PDMS mixture is prepared by mixing polymethyl silicone oil and a curing agent and then performing vacuum defoaming.

3. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 2, characterized in that: The dosage ratio of the polymethyl silicone oil to the curing agent is (10-12): (1-3).

4. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1, wherein: The PDMS mixture was removed from the lotus leaf after vacuum curing, wherein the vacuum curing temperature was 40-60 °C and the curing time was 10-13 h.

5. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1, wherein: The gelatin solution and the bacterial cellulose solution are stirred and mixed, wherein the concentration of the gelatin solution is 2.5-3.5 wt%, the concentration of the bacterial cellulose is 0.5%-0.8 wt%, and the volume ratio of the gelatin solution to the bacterial cellulose solution is 1:

4.

6. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1 or 5, characterized in that: The gelatin solution and the bacterial cellulose solution are stirred and mixed at a stirring rate of 400-500 r / min and a stirring time of 0.5-1 h.

7. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1, wherein: Glycerol and curcumin are added to the gelatin-bacterial cellulose solution, stirred, and then vacuum-defoamed to obtain a film-forming liquid, wherein the content of glycerol in the film-forming liquid is 0.5-1.5 wt %, and the content of curcumin is 0.05-0.2 wt %.

8. The method for preparing the gelatin-cellulose composite material with lotus leaf structure according to claim 1, wherein: The film-forming liquid is slowly transferred to the PDMS template, and removed from the PDMS template after drying to form a film. The drying temperature for the film is 50-60° C., and the drying time is 4-8 hours.

9. A gelatin-cellulose composite material with a lotus leaf structure prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the gelatin-cellulose composite material with lotus leaf structure according to claim 9 in the field of food, medicine or agricultural product packaging.

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