Chitosan-guar gum composite material packaging film and preparation method thereof
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-26
- Publication Date
- 2026-03-27
Smart Images
Figure CN121736337A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of polymer functional membrane material technology, and relates to fruit and vegetable preservation packaging technology, specifically a chitosan-guar gum composite packaging film and its preparation method. Background Technology
[0002] Currently, fruits and vegetables with high respiration rates are highly susceptible to quality deterioration under normal temperature conditions. The main problems include microbial spoilage, loss of tissue moisture, and mechanical damage to the skin. Especially in areas where the cold chain logistics system is not yet well-developed, fruits and vegetables with high respiration rates are difficult to obtain stable low-temperature protection during storage and transportation, and are prone to softening, rotting, and discoloration.
[0003] Existing fruit and vegetable packaging films mostly use polyethylene and polyester petrochemical polymer materials, which have poor biodegradability and are difficult to balance mechanical properties with the damage resistance requirements of fruit and vegetable storage and transportation. In addition, these films often lack flexible control characteristics, making them prone to packaging failure and tearing in actual use, and are not suitable for the complex stress conditions of fruits and vegetables with high respiration rates in non-cold chain environments.
[0004] Research on improving fruit and vegetable packaging films often attempts to enhance their water-blocking, antibacterial, or modified atmosphere properties by adding functional fillers or performing composite modifications. Chitosan (CS) and guar gum (GG), as natural polymer materials, have attracted widespread attention due to their abundant sources, good film-forming properties, and certain antibacterial capabilities, making them suitable for constructing biodegradable fruit and vegetable packaging film systems. However, single CS / GG films exhibit poor mechanical properties, with limited tensile and tear resistance, and poor stability under humid and hot conditions. Some studies have introduced inorganic nanofillers such as nano-silica, montmorillonite, or nano-cellulose for reinforcement modification. Although this improves the film rigidity to some extent, problems such as insufficient toughness, poor dispersibility, and low compatibility still exist, making it difficult to achieve a balance between mechanical reinforcement and flexibility.
[0005] Therefore, there is an urgent need to construct a composite biodegradable membrane material with a multi-component synergistic enhancement mechanism to comprehensively improve its mechanical properties and adaptability, and meet the comprehensive requirements of fruit and vegetable packaging for strength, flexibility and freshness preservation. Summary of the Invention
[0006] The purpose of this invention is to provide a chitosan-guar gum composite packaging film and its preparation method, which synergistically introduces PBAT microspheres and modified nano-zeolite into the composite packaging film material to solve the limitations of single chitosan (CS)-guar gum (GG) materials in terms of preservation performance and the inability to simultaneously achieve mechanical reinforcement and flexibility.
[0007] This invention is achieved using the following technical solution: In a first aspect, a method for preparing a chitosan-guar gum composite packaging film includes the following steps: S1: Preparation of PBAT microsphere packing At room temperature, PBAT solution was added dropwise to polyvinyl alcohol solution, and the mixture was evaporated, washed, and dried to obtain PBAT microspheres. S2: Preparation of TA-modified nano-zeolite fillers TA-modified nano-zeolite was prepared by reacting nano-zeolite in tannic acid (TA), washing and drying it. S3: Preparation of dispersion matrix solution Chitosan was dissolved in a mixed solution of deionized water and glacial acetic acid to obtain a chitosan solution; guar gum was dissolved in deionized water to obtain a guar gum solution; the chitosan solution and the guar gum solution were mixed and a plasticizer was added to disperse the mixture to obtain a dispersion matrix solution. S4: Preparation of composite membrane PBAT microspheres prepared in S1 and TA-modified nano-zeolite prepared in S2 were added to the dispersion matrix solution prepared in S3; after dispersion, a uniform composite dispersion system was formed; the composite dispersion system solution was poured into a petri dish and dried, and after the solvent was completely evaporated, it was peeled off to obtain a composite film.
[0008] More preferably, in step S1, the PBAT solution uses chloroform as a solvent and has a concentration of 1.2% (w / v); the polyvinyl alcohol solution has a concentration of 0.1% (w / v); and the PBAT solution and the polyvinyl alcohol solution react in a volume ratio of 1:5.
[0009] More preferably, in step S1, the evaporation temperature is 50°C and the time is 8 hours.
[0010] More preferably, in step S1, the particle size of the PBAT microspheres is between 15 and 25 μm.
[0011] In a further preferred embodiment, in step S2, the preparation of nano-zeolite involves mixing zeolite and ethanol at a mass ratio of 2:3 and ball milling the mixture for 48 hours to obtain nano-zeolite with a particle size of less than 100 nm.
[0012] In a further preferred embodiment, step S2 specifically involves: placing tannic acid (TA) and nano-zeolite in a container, adding deionized water and mixing, stirring at room temperature for 2 hours; centrifuging and washing repeatedly with deionized water / anhydrous ethanol until neutral, then filtering; and drying at 50°C for 24 hours to obtain TA-modified nano-zeolite.
[0013] In a further preferred embodiment, in step S4, during dispersion, a high-speed homogenizer is first used for dispersion, followed by ultrasonic dispersion.
[0014] More preferably, in step S4, when dispersing with a high-speed homogenizer, the speed is 10,000 rpm / min for 10 minutes; when dispersing with ultrasound, the speed is 40 kHz for 20 minutes.
[0015] More preferably, in step S4, the proportion of PBAT microspheres added accounts for 0.025–0.1 wt% of the composite membrane mass.
[0016] Secondly, a chitosan-guar gum composite packaging film, wherein the composite film has a thickness between 30 and 60 μm, a tear strength between 2 and 3 N / mm, and a puncture strength between 7 and 18 N / mm.
[0017] Compared with the prior art, the present invention has the following beneficial technical effects: This invention introduces a composite packaging film material of PBAT microspheres and modified nano-zeolite, overcoming the limitations of single chitosan (CS)-guar gum (GG) materials in terms of preservation performance. It significantly extends the shelf life of fruits and vegetables with high respiration rates, maintaining their sensory and nutritional quality. The composite film components are natural and biodegradable, aligning with the trend of green packaging. Its design concept provides a new technical solution for developing efficient and multifunctional fruit and vegetable preservation materials, and has broad application prospects in the field of postharvest preservation of fruits and vegetables. Attached Figure Description
[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0019] Figure 1 The images show SEM test results of the present invention; the upper left corner shows the SEM image of PBAT microspheres; the upper right corner shows the SEM image of TA-modified nano-zeolite; the lower left corner shows the SEM image of composite membrane X1 (Example 1); and the lower right corner shows a partial enlarged view of composite membrane X1 (Example 1) in the lower left image.
[0020] Figure 2 The figure shows the FTIR test spectrum of the present invention; in the figure, red is the infrared spectrum of the TA modified nano-zeolite filler obtained in step S2 of Example 1; black is the infrared spectrum of the original zeolite.
[0021] Figure 3 This is a comparison chart showing the mechanical performance test results of an embodiment of the present invention.
[0022] Figure 4 This is a comparative chart showing the preservation effect of the present invention on strawberries.
[0023] Figure 5This image shows a comparison of the bacterial colonies of Escherichia coli and Staphylococcus aureus between the present invention and polyethylene (PE). Detailed Implementation
[0024] To better understand the above-mentioned objectives, features, and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, unless otherwise specified, the embodiments of the present invention and the features thereof can be combined with each other.
[0025] Many specific details are set forth in the following description in order to provide a full understanding of the invention, but the invention may also be practiced in other ways different from those described herein; obviously, the embodiments in the specification are only some embodiments of the invention, and not all embodiments.
[0026] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.
[0027] In a first aspect, a method for preparing a chitosan-guar gum composite packaging film includes the following steps: S1: Preparation of PBAT microsphere packing material (emulsion-solvent evaporation method) PBAT was dissolved in chloroform at room temperature to obtain a 1.2% (w / v) PBAT solution. The PBAT solution was added dropwise to a 0.1% (w / v) polyvinyl alcohol solution at a volume ratio of 1:5, and the mixture was stirred at a constant mechanical stirring temperature (600 rpm) at room temperature. Then, the mixture was heated to 50°C for 8 hours under constant mechanical stirring (450 rpm) to evaporate the solvent. Finally, the mixture was washed and filtered three or more times with distilled water and dried at 60°C for 24 hours to obtain PBAT microspheres with a particle size between 15 and 25 μm.
[0028] S2: Preparation of TA-modified nano-zeolite fillers Zeolite and ethanol were mixed in a mass ratio of 2:3 and ball-milled for 48 hours to obtain nano-zeolite with a particle size of less than 100 nm.
[0029] Take 0.25g of tannic acid (TA) and 2.5g of nano-zeolite and place them in a 1000mL beaker. Add 500mL of deionized water and stir magnetically at room temperature for 2h. Then, centrifuge and wash three times with deionized water / anhydrous ethanol alternately until neutral. Filter by suction. Finally, dry at 50°C for 24h to obtain TA-modified nano-zeolite, called Zeolite / TA.
[0030] S3: Preparation of dispersion matrix solution Mix 42 mL of deionized water and 8 mL of glacial acetic acid, then add 0.5 g of chitosan and stir at 50 °C until completely dissolved to obtain a chitosan solution. Dissolve 0.5 g of guar gum in 50 mL of deionized water and stir at 50 °C until completely dissolved to obtain a guar gum solution. Mix the chitosan solution and the guar gum solution, and add 0.2 g of glycerol as a plasticizer. Disperse the mixture using a high-speed homogenizer at 10,000 rpm / min for 10 minutes.
[0031] S4: Preparation of composite membrane The PBAT microspheres prepared in step S1 and the TA-modified nano-zeolite prepared in step S2 were added to the dispersion matrix solution obtained in step S3. The mixture was dispersed using a high-speed homogenizer at 10000 rpm / min for 10 min, followed by ultrasonic dispersion at 40 kHz for 20 min to form a homogenous composite dispersion system. The dispersion solution was poured into a petri dish and dried on a 50°C heating plate. After complete solvent evaporation, the mixture was peeled off to obtain the composite membrane. Furthermore, the PBAT microspheres were added at a ratio of 0.025–0.1 wt% of the composite membrane mass.
[0032] The present invention will be further described in detail below through specific embodiments, but it is not limited thereto. Example 1
[0033] S1: Preparation of PBAT microsphere packing PBAT was dissolved in chloroform at room temperature to obtain a 1.2% (w / v) PBAT solution. The PBAT solution was added dropwise to a 0.1% (w / v) polyvinyl alcohol solution at a volume ratio of 1:5, and the mixture was stirred at a constant mechanical stirring temperature (600 rpm) at room temperature. Then, the mixture was heated to 50°C for 8 hours under constant mechanical stirring (450 rpm) to evaporate the solvent. Finally, the mixture was washed and filtered three or more times with distilled water and dried at 60°C for 24 hours to obtain PBAT microspheres with a particle size between 15 and 25 μm.
[0034] S2: Preparation of TA-modified nano-zeolite fillers Zeolite and ethanol were mixed in a mass ratio of 2:3 and ball-milled for 48 hours to obtain nano-zeolite with a particle size of less than 100 nm.
[0035] Take 0.25g of tannic acid (TA) and 2.5g of nano-zeolite and place them in a 1000mL beaker. Add 500mL of deionized water and stir magnetically at room temperature for 2h. Then, centrifuge and wash three times with deionized water / anhydrous ethanol alternately until neutral. Filter by suction. Finally, dry at 50°C for 24h to obtain TA-modified nano-zeolite, called Zeolite / TA.
[0036] S3: Preparation of dispersion matrix solution Mix 42 mL of deionized water and 8 mL of glacial acetic acid, then add 0.5 g of chitosan and stir at 50 °C until completely dissolved to obtain a chitosan solution. Dissolve 0.5 g of guar gum in 50 mL of deionized water and stir at 50 °C until completely dissolved to obtain a guar gum solution. Mix the chitosan solution and the guar gum solution, and add 0.2 g of glycerol as a plasticizer. Disperse the mixture using a high-speed homogenizer at 10,000 rpm / min for 10 minutes.
[0037] S4: Preparation of composite membrane 0.05 g of modified zeolite (Zeolite / TA) and 0.025 g of PBAT microspheres were added to the dispersion matrix solution obtained in step S3. The solution was dispersed at 10,000 rpm / min for 10 min using a high-speed homogenizer and then ultrasonically dispersed at 40 kHz for 20 min. After that, the solution was poured into a petri dish and dried on a heating table at 50°C. After the solvent was completely evaporated, the solution was peeled off to obtain the target composite membrane X1. Example 2
[0038] Steps S1 to S3 are the same as in Example 1.
[0039] S4: Preparation of composite membrane 0.05 g of modified zeolite (Zeolite / TA) and 0.005 g of PBAT microspheres were added to the dispersion matrix solution obtained in step S3. The solution was dispersed at 10,000 rpm / min for 10 min using a high-speed homogenizer and then ultrasonically dispersed at 40 kHz for 20 min. After that, the solution was poured into a petri dish and dried on a heating table at 50°C. After the solvent was completely evaporated, the solution was peeled off to obtain the target composite membrane X2. Example 3
[0040] Steps S1 to S3 are the same as in Example 1.
[0041] S4: Preparation of composite membrane 0.05 g of modified zeolite (Zeolite / TA) and 0.100 g of PBAT microspheres were added to the dispersion matrix solution obtained in step S3. The solution was dispersed at 10,000 rpm / min for 10 min using a high-speed homogenizer and then ultrasonically dispersed at 40 kHz for 20 min. After that, the solution was poured into a petri dish and dried on a heating table at 50°C. After the solvent was completely evaporated, the solution was peeled off to obtain the target composite membrane X3.
[0042] Comparative Example 1 Mix 42 mL of deionized water and 8 mL of glacial acetic acid, then add 0.5 g of chitosan and stir at 50 °C until completely dissolved to obtain a chitosan solution. Dissolve 0.5 g of guar gum in 50 mL of deionized water and stir at 50 °C until completely dissolved to obtain a guar gum solution. Mix the chitosan solution and the guar gum solution, and add 0.2 g of glycerol as a plasticizer. Disperse the mixture using a high-speed homogenizer at 10000 rpm / min for 10 minutes. Pour the solution into a petri dish and place it on a 50 °C heating plate until the solution completely evaporates. The final product is the filler-free composite membrane X0.
[0043] Performance tests were conducted on the above composite membranes X0, X1, X2, and X3: 1. The particle size and structure of the PBAT microsphere packing obtained in step S1 and the TA modified nano-zeolite packing obtained in step S2 were characterized by SEM testing.
[0044] like Figure 1 As shown in the figure, the upper left corner is the SEM image of PBAT microspheres; the upper right corner is the SEM image of TA-modified nano-zeolite; the lower left corner is the SEM image of composite membrane X1 (Example 1); and the lower right corner is a partial magnified view of composite membrane X1 (Example 1) in the lower left figure.
[0045] Through the Figure 1 Analysis shows that the PBAT microspheres obtained in step S1 have a concentrated particle size distribution of 15–25 μm and exhibit a typical porous structure; the nano-zeolite particles obtained in step S2 have a particle size of less than 100 nm. The filler in the composite membrane X1 is relatively uniformly distributed, and the interfacial bonding between the filler and the matrix is good.
[0046] 2. The TA-modified nano-zeolite filler prepared in step S2 was characterized by FTIR testing.
[0047] like Figure 2 The infrared spectroscopy analysis results show that in step S2, tannic acid (TA) successfully and sufficiently coated the surface of the nano-zeolite. FTIR spectra revealed a significant enhancement of the OH stretching vibration peak at approximately 3400 cm⁻¹ after treatment, along with the appearance of a new characteristic absorption peak belonging to the aromatic ring structure of tannic acid. This confirms that tannic acid (TA) was effectively grafted onto the zeolite surface through hydrogen bonding. This surface modification not only inhibits the aggregation of nanoparticles and promotes their uniform dispersion in the chitosan-guar gum matrix, but more importantly, it introduces abundant phenolic hydroxyl and other active groups, which can form a broad hydrogen-bonded cross-linking network with the polymer matrix, thus providing a key mechanism for the mechanical reinforcement of the composite material.
[0048] 3. According to GB / T1040-2006 "Determination of Tensile Properties of Plastics", the mechanical properties of composite film X0 (Comparative Example 1), composite film X1 (Example 1), composite film X2 (Example 2), and composite film X3 (Example 3) were tested. The results are shown in […]. Figure 3 The summary is shown in Table 1 below.
[0049] Table 1 Summary of relevant mechanical property tests of samples
[0050] like Figure 4 The image shows the preservation effect tests of strawberries in air, polyethylene (PE), composite film X0 (Comparative Example 1), composite film X1 (Example 1), composite film X2 (Example 2), and composite film X3 (Example 3).
[0051] In summary, as shown in Table 1, composite membrane X1 (Example 1) achieved a tensile strength of 4.28 MPa, an elongation at break of 134.06%, a tear load of 2.38 N / mm, a puncture load of 7.69 N / mm, and a yield strength of 0.73 MPa. Although some individual properties of composite membrane X1 are slightly inferior to those of composite membrane X2, combined with... Figure 4 It can be seen that composite film X1 (Example 1) has the best preservation ability for strawberries, and the freshness of strawberries is significantly higher than that of others within 7 days. The comprehensive test data results of the composite film prepared in the example are all better than those of composite film X0 (Comparative Example 1), indicating that the chitosan-guar gum composite packaging film prepared by the present invention has significant mechanical reinforcement properties.
[0052] 4. According to GB / T31402-2015 Test Method for Antibacterial Properties of Plastic Surfaces, antibacterial tests were conducted on existing composite films (polyethylene (PE) was selected in this invention), composite film X0 (Comparative Example 1), composite film X1 (Example 1), composite film X2 (Example 2), and composite film X3 (Example 3). The results are shown in Table 2.
[0053] Table 2 Summary of Antibacterial Performance Tests for Samples
[0054] Note: Antibacterial rate (%) = (PE colony count - sample colony count) / PE colony count × 100% like Figure 5 As shown in the figure, the upper left corner shows the colony diagram of polyethylene (PE)-Escherichia coli; the upper right corner shows the colony diagram of polyethylene (PE)-Staphylococcus aureus; the lower left corner shows the colony diagram of composite membrane X1-Escherichia coli; and the lower right corner shows the colony diagram of composite membrane X1-Staphylococcus aureus.
[0055] Antibacterial test results showed that composite membrane X1 (Example 1) performed best in inhibiting Escherichia coli and Staphylococcus aureus, with antibacterial rates of 92.41% and 87.77%, respectively. In contrast, composite membrane X0 (Comparative Example 1) had antibacterial rates of only 57.24% and 67.68%, while composite membrane X3 (Example 3) had poor dispersibility due to excessive PBAT microsphere content, resulting in antibacterial rates of only 40.00% and 55.90%. These results indicate that the synergistic effect of an appropriate amount of PBAT microspheres and TA-modified nano-zeolite is key to improving antibacterial performance.
[0056] The above description is merely a specific embodiment of the present invention, enabling those skilled in the art to understand or implement the present invention. Although detailed descriptions have been provided with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments, and they should all be covered within the protection scope of the claims.
Claims
1. A method for preparing a chitosan-guar gum composite packaging film, characterized in that: Includes the following steps: S1: Preparation of PBAT microsphere packing At room temperature, PBAT solution was added dropwise to polyvinyl alcohol solution, and the mixture was evaporated, washed, and dried to obtain PBAT microspheres. S2: Preparation of TA-modified nano-zeolite fillers TA-modified nano-zeolite was prepared by reacting nano-zeolite in tannic acid, washing and drying it. S3: Preparation of dispersion matrix solution Chitosan was dissolved in a mixed solution of deionized water and glacial acetic acid to obtain a chitosan solution; guar gum was dissolved in deionized water to obtain a guar gum solution; the chitosan solution and the guar gum solution were mixed and a plasticizer was added to disperse the mixture to obtain a dispersion matrix solution. S4: Preparation of composite membrane PBAT microspheres prepared in S1 and TA-modified nano-zeolite prepared in S2 were added to the dispersion matrix solution prepared in S3; after dispersion, a uniform composite dispersion system was formed; the composite dispersion system solution was poured into a petri dish and dried, and after the solvent was completely evaporated, it was peeled off to obtain a composite film.
2. The method for preparing the chitosan-guar gum composite packaging film according to claim 1, characterized in that: In step S1, the PBAT solution uses chloroform as a solvent and has a concentration of 1.2% (w / v); the polyvinyl alcohol solution has a concentration of 0.1% (w / v); the PBAT solution and the polyvinyl alcohol solution react in a volume ratio of 1:
5.
3. The method for preparing the chitosan-guar gum composite packaging film according to claim 2, characterized in that: In step S1, the evaporation temperature is 50°C and the time is 8 hours.
4. The method for preparing the chitosan-guar gum composite packaging film according to claim 3, characterized in that: In step S1, the particle size of the PBAT microspheres obtained is between 15 and 25 μm.
5. The method for preparing the chitosan-guar gum composite packaging film according to claim 1, characterized in that: In step S2, the preparation of nano-zeolite is carried out by mixing zeolite and ethanol in a mass ratio of 2:3 and ball milling for 48 hours to obtain nano-zeolite with a particle size of less than 100 nm.
6. The method for preparing the chitosan-guar gum composite packaging film according to claim 5, characterized in that: Step S2 is as follows: Tannic acid and nano zeolite are placed in a container and mixed with deionized water, and stirred at room temperature for 2 hours; after centrifugation, they are washed repeatedly with deionized water / anhydrous ethanol until neutral, and then filtered; dried at 50°C for 24 hours to obtain TA-modified nano zeolite.
7. The method for preparing the chitosan-guar gum composite packaging film according to claim 1, characterized in that: In step S4, during dispersion, a high-speed homogenizer is first used for dispersion, followed by ultrasonic dispersion.
8. The method for preparing the chitosan-guar gum composite packaging film according to claim 7, characterized in that: In step S4, when dispersing with a high-speed homogenizer, the speed is 10,000 rpm / min for 10 minutes; when dispersing with ultrasound, the speed is 40 kHz for 20 minutes.
9. The method for preparing the chitosan-guar gum composite packaging film according to claim 8, characterized in that: In step S4, the proportion of PBAT microspheres added is 0.025–0.1 wt% of the composite membrane mass.
10. The chitosan-guar gum composite packaging film according to any one of claims 1-9, characterized in that: The composite film has a thickness between 30 and 60 μm, a tear strength between 2 and 3 N / mm, and a puncture strength between 7 and 18 N / mm.