Composite tea polyphenol-chitosan preservative and preparation method thereof
By combining modified gellan gum with chitosan, a microcapsule-based composite tea polyphenol-chitosan preservative was prepared, which solved the problems of non-degradability, low safety, and insufficient mechanical strength of existing plastic wrap, and achieved a highly efficient preservation effect.
Patent Information
- Application Number
- CN202511336756.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-12-19
AI Technical Summary
Existing plastic cling film is non-degradable, has low safety and poor air permeability. Chitosan and gellan gum, when used as single preservatives, have insufficient mechanical strength and poor water resistance. Commonly used cross-linking agents have safety issues.
A composite tea polyphenol-chitosan preservative in microcapsule form was prepared by combining modified gellan gum with chitosan. The modified gellan gum was cross-linked by gamma-ray or X-ray radiation, and the composite membrane was prepared as the wall material by combining the ionic cross-linking of chitosan and modified gellan gum with tea polyphenols as the core material.
The mechanical and water-resistant properties of the cling film were improved, significantly enhancing the preservation effect and avoiding the safety issues of commonly used cross-linking agents. The addition of tea polyphenols played a synergistic role.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of composite preservation technology, specifically to a composite tea polyphenol-chitosan preservative and its preparation method. Background Technology
[0002] As people's living standards continue to improve, their demand for food freshness is increasing. To maintain food freshness for a certain period of time, petrochemical plastic-based food preservation films such as PE, PVC, and PVDC have emerged. These films are widely used in the food preservation field because they are inexpensive and easy to use. However, these materials are all non-degradable plastics with low safety index, poor air permeability, and are prone to causing white pollution. Furthermore, under certain media and environmental conditions, they pose a risk of causing cancer.
[0003] Tea polyphenols are polyphenol extracts from tea leaves, possessing antioxidant, anti-aging, and preservative properties. Combining tea polyphenols with other preservatives not only enhances their antibacterial spectrum and preservative effects but also reduces costs and usage while improving preservation. Chitosan, a widely available natural cationic polysaccharide, is one of the most studied food packaging materials due to its biodegradability, non-toxicity, excellent film-forming properties, biocompatibility, and antibacterial activity. However, chitosan has poor antioxidant properties and high water vapor permeability. Gellan gum, a high-molecular-weight linear anionic polysaccharide obtained from the fermentation of *Sphingomonas sphingosine monocytogenes*, is non-toxic, biodegradable, and has good film-forming properties, excellent gelling properties, thermal stability, and acid resistance, making it widely used in the food packaging industry. However, using chitosan or gellan gum alone as a preservative results in insufficient mechanical strength and poor water resistance, limiting their application in food preservation. Commonly used crosslinking agents for polysaccharide membranes include formaldehyde, glyoxal, glutaraldehyde, and epichlorohydrin. Adding crosslinking agents to the film-forming solution or using them in the post-treatment process can improve the mechanical and barrier properties of the membrane. However, the addition of these crosslinking agents may raise safety concerns. Therefore, it is particularly important to seek a novel crosslinking method to modify gellan gum and combine it with chitosan to create a composite preservation film that simultaneously encapsulates tea polyphenols in microcapsules. Summary of the Invention
[0004] Technical Problem to be Solved: To address the aforementioned technical problems, the purpose of this invention is to provide a composite tea polyphenol-chitosan preservative and its preparation method. The preservative is formulated into microcapsules, and a composite preservative film is prepared using chitosan and modified gellan gum as wall materials. This improves the mechanical properties and water-blocking properties of the preservative film. Simultaneously, the use of tea polyphenols as the core material provides a synergistic effect, significantly enhancing the preservative's preservation effect.
[0005] Technical solution: A composite tea polyphenol-chitosan preservative, wherein the preservative is in the form of microcapsules, comprising a core material and a wall material, wherein the core material comprises the following components by weight: 20-60 parts of tea polyphenols; and the wall material comprises the following components by weight: 20-90 parts of chitosan and 20-90 parts of modified gellan gum.
[0006] Furthermore, the core material comprises the following components in parts by weight: 30-55 parts of tea polyphenols.
[0007] Furthermore, the wall material comprises the following components in parts by weight: 30-70 parts chitosan and 40-70 parts modified gellan gum.
[0008] Furthermore, the preparation method of the modified gellan gum is as follows: Step 1: Weigh an appropriate amount of gellan gum powder and mix it with deionized water. Heat the mixture in a water bath at 70-80℃ to dissolve it and prepare a gellan gum solution with a mass fraction of 0.5-2.5%. Step 2: Mix the gellan gum solution with a 2-5% ionic crosslinking agent solution at a volume ratio of (10-50):1 to obtain a mixed solution; Step 3: Add reducing agent to the mixed solution, stir magnetically, and react completely for 30-60 minutes. Remove metal precipitates by precipitation and filtration. Step 4: Radiation crosslinking is performed on the gellan gum solution after removing the metal precipitate to obtain the modified gellan gum solution.
[0009] Furthermore, in step 2, the ionic crosslinking agent solution is a sodium chloride solution, a potassium chloride solution, or a calcium chloride solution.
[0010] Furthermore, in step 3, the reducing agent is hydrazine hydrate, L-ascorbic acid, or glucose; the reducing agent has the same molar number of metal ions as the ion crosslinking agent solution.
[0011] Furthermore, in step 4, the radiation crosslinking is performed by gamma-ray irradiation or X-ray irradiation, with an irradiation dose of 5-20 kGy.
[0012] A composite tea polyphenol-chitosan preservative and its preparation method, comprising the following steps: S1: Weigh chitosan and modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 40-100 times its weight of water to obtain a wall material solution, and degas it using ultrasound for later use; S3: Add core material tea polyphenols to the wall material solution, stir evenly and then homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained.
[0013] Furthermore, the reaction temperature in step S2 is 70-80℃.
[0014] Beneficial effects: This invention modifies gellan gum by crosslinking it. First, an ionic crosslinking agent is added to the gellan gum, avoiding potential safety issues associated with commonly used polysaccharide crosslinking agents such as formaldehyde and glyoxal. This is achieved by altering the Na+ content. + K + and Ca 2+ The concentration of ions can adjust the mechanical properties of gellan gum; however, the gel strength of gellan gum may decrease with the increase of ion concentration. Radiation crosslinking can stabilize the gel strength of gellan gum, achieving a more stable preservation effect. At the same time, the method of preparing hydrogels by radiation crosslinking also has the advantages of pure products, easy reaction control, and low temperature.
[0015] The chitosan-modified gellan gum composite membrane prepared by this invention improves the problems of insufficient mechanical strength and poor water resistance of single chitosan membranes or gellan gum membranes. Strong ionic cross-linking can be generated between the positively charged groups of chitosan and the negatively charged groups of gellan gum, which enhances the mechanical properties of the composite membrane.
[0016] This invention provides a composite tea polyphenol-chitosan preservative and its preparation method. The preservative is in the form of microcapsules, wherein a chitosan-modified gellan gum composite film is used as the wall material, which improves the problems of poor antioxidant properties, high water vapor permeability, and poor mechanical properties of single films. At the same time, tea polyphenols are used as the core material, and the addition of tea polyphenols can play a synergistic role to significantly improve the preservation effect of the preservative. Detailed Implementation
[0017] This invention proposes a composite tea polyphenol-chitosan preservative and its preparation method. To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following will provide a more detailed description of the invention with reference to specific examples. It should be understood that the specific examples described herein are only for explaining the invention and are not intended to limit the invention.
[0018] Example 1 The preparation method of modified gellan gum is as follows: Step 1: Weigh an appropriate amount of gellan gum powder and mix it with deionized water. Heat the mixture in an 80°C water bath to dissolve the gellan gum powder and prepare a 0.5% gellan gum solution. Step 2: Mix the gellan gum solution with a 2% potassium chloride solution at a volume ratio of 10:1 to obtain a mixed solution; Step 3: Add glucose as a reducing agent to the mixed solution, stir magnetically, and allow to react completely for 60 minutes. Remove the metal precipitate by precipitation and filtration. Step 4: The gellan gum solution after removing the metal precipitate is subjected to gamma-ray radiation crosslinking with an irradiation dose of 8 kGy to obtain the modified gellan gum solution. Example 2
[0019] The preparation method of modified gellan gum is as follows: Step 1: Weigh an appropriate amount of gellan gum powder and mix it with deionized water. Heat the mixture in a 75°C water bath to dissolve the gellan gum powder and prepare a 2% gellan gum solution. Step 2: Mix the gellan gum solution with a 5% calcium chloride solution at a volume ratio of 50:1 to obtain a mixed solution; Step 3: Add the reducing agent L-ascorbic acid to the mixed solution, stir magnetically, and react completely for 30 minutes. Remove the metal precipitate by precipitation and filtration. Step 4: Cross-link the gellan gum solution after removing the metal precipitate with X-ray radiation at a dose of 15 kGy to obtain the modified gellan gum solution.
[0020] The gel strength of the modified gellan gum was determined using a TA·XT2i physical property tester. The measurement parameters were: initial speed 6.0 mm / s; final speed 4.0 mm / s; subsequent speed 8.0 mm / s; distance 20.0 mm. The maximum force required to break the gel was taken as the gel strength value. Three parallel measurements were performed, and the average value was taken.
[0021] Table 1. Strength of Modified Gel
[0022] As shown in Table 1, the modified gellan gum of Example 2 has a better gel strength than that of Example 1. Therefore, Example 2 was selected as the gellan gum modification condition. Example 3
[0023] A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 20 parts of chitosan and 20 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 100 times its weight of water to obtain a wall material solution. The reaction temperature is 80℃. Degas the solution using ultrasound and set aside for later use. S3: Add 20 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained.
[0024] Example 4 A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 90 parts of chitosan and 90 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 80 times its weight of water to obtain a wall material solution. The reaction temperature is 75℃. Degas the solution using ultrasound and set aside for later use. S3: Add 60 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Example 5
[0025] A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 80 parts of chitosan and 70 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 100 times its weight of water to obtain a wall material solution. The reaction temperature is 80℃, and the solution is degassed by ultrasound for later use. S3: Add 60 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Example 6
[0026] A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 50 parts of chitosan and 50 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material. S2: Mix the wall material with 50 times its mass of water to obtain a wall material solution. The reaction temperature is 70℃, and the solution is degassed by ultrasound for later use. S3: Add 40 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Example 7
[0027] A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 40 parts of chitosan and 40 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 40 times its mass of water to obtain a wall material solution. The reaction temperature is 80℃, and the solution is degassed by ultrasound for later use. S3: Add 35 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Example 8
[0028] A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 80 parts of chitosan and 60 parts of modified gellan gum according to the weight parts of each component in the wall material, and mix the chitosan and modified gellan gum to obtain the wall material; S2: Mix the wall material with 60 times its mass of water to obtain a wall material solution. The reaction temperature is 78℃, and the solution is degassed by ultrasound for later use. S3: Add 30 parts of core material tea polyphenols to the wall material solution, stir evenly and then homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained.
[0029] Comparative Example 1 The difference between this comparative example and Example 6 is that unmodified gellan gum is used, specifically: A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 50 parts of chitosan and 50 parts of unmodified gellan gum according to the weight parts of the components in the wall material to obtain the wall material; S2: Mix the wall material with 50 times its mass of water to obtain a wall material solution. The reaction temperature is 70℃, and the solution is degassed by ultrasound for later use. S3: Add 40 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Comparative Example 2
[0030] The difference between this comparative example and Example 6 is that only ion-crosslinked modified gellan gum is used. Specifically: A compound tea polyphenol preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 50 parts of chitosan and 50 parts of ion-crosslinked modified gellan gum according to the weight parts of the components in the wall material to obtain the wall material. S2: Mix the wall material with 50 times its mass of water to obtain a wall material solution. The reaction temperature is 70℃, and the solution is degassed by ultrasound for later use. S3: Add 40 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained. Comparative Example 3
[0031] The difference between this embodiment and Embodiment 6 is that only radiation-crosslinked modified gellan gum is used, specifically: A composite tea polyphenol-chitosan preservative and its preparation method, the preparation steps are as follows (parts by weight): S1: Weigh 50 parts of chitosan and 50 parts of radiation-crosslinked modified gellan gum according to the weight parts of the components in the wall material to obtain the wall material; S2: Mix the wall material with 50 times its mass of water to obtain a wall material solution. The reaction temperature is 70℃, and the solution is degassed by ultrasound for later use. S3: Add 40 parts of core material tea polyphenols to the wall material solution, stir evenly and homogenize to obtain microcapsule suspension; S4: Cool the prepared microcapsule suspension to room temperature, then place it in a 4℃ environment and let it stand for 12 hours. After freeze-drying, the microcapsule preservative is obtained.
[0032] Mechanical property testing: The mechanical properties of the microcapsule preservative were tested using a TA-DGF biaxial tensile tester with a trigger force of 0.01 N and a test speed of 1.00 mm / s. The tensile force at the fracture of the microcapsule preservative was recorded. The test was repeated 3 times, and the tensile strength was calculated.
[0033] Table 2 Mechanical properties of each embodiment
[0034] As can be seen from Table 2, the mechanical properties of the microcapsule preservative with modified gellan gum are stronger than those with unmodified gellan gum or microcapsule preservative with single crosslinking. The modified gellan gum improves the mechanical properties of the composite film.
[0035] Moisture permeability and air permeability were measured using the national standard method.
[0036] Table 3. Water permeability and air permeability of each embodiment
[0037] Table 3 shows that the water vapor transmission coefficient of the composite chitosan-modified gellan gum preservative is lower than that of the composite chitosan-unmodified or single-crosslinked modified gellan gum preservative. This indicates that the addition of modified gellan gum can reduce the water vapor transmission of the composite preservative, thereby increasing the water resistance of the membrane. Furthermore, the composite microencapsulated preservative can inhibit oxygen transmission while increasing carbon dioxide transmission, creating a low-oxygen, high-carbon dioxide environment to achieve a preservation effect.
Claims
1. A composite tea polyphenol-chitosan preservative, characterized in that, The preservative is in the form of microcapsules, and the microcapsules comprise a core material and a wall material, the core material comprises the following components by weight parts: tea polyphenols 20-60 parts; the wall material comprises the following components by weight parts: chitosan 20-90 parts, modified gellan gum 20-90 parts.
2. The composite tea polyphenol-chitosan preservative according to claim 1, characterized in that, The core material comprises the following components by weight parts: tea polyphenols 30-55 parts.
3. The composite tea polyphenol-chitosan preservative according to claim 1, characterized in that, The wall material comprises the following components by weight parts: chitosan 30-70 parts, modified gellan gum 40-70 parts.
4. The composite tea polyphenol-chitosan preservative according to claim 1, characterized in that, The preparation method of the modified gellan gum is as follows: Step 1: a proper amount of gellan gum powder is mixed with deionized water, and the mixture is dissolved in a water bath at 70-80 DEG C to prepare a gellan gum solution with a mass fraction of 0.5-2.5%; Step 2: the gellan gum solution is mixed with an ionic crosslinking agent solution with a concentration of 2-5% according to a volume ratio of (10-50): 1 to obtain a mixed solution; Step 3: a reducing agent is added to the mixed solution, and the mixture is magnetically stirred for 30-60 min until the reaction is completed, and then the metal precipitate is removed by precipitation and filtration; Step 4: the gellan gum solution after removing the metal precipitate is subjected to radiation crosslinking to obtain a modified gellan gum solution.
5. The composite tea polyphenol-chitosan preservative according to claim 4, characterized in that, The ionic crosslinking agent solution in step 2 is a sodium chloride solution, a potassium chloride solution or a calcium chloride solution.
6. The composite tea polyphenol-chitosan preservative according to claim 4, characterized in that, The reducing agent in step 3 is hydrazine hydrate, L-ascorbic acid or glucose; the molar number of the reducing agent is the same as that of the metal ions in the ionic crosslinking agent solution.
7. The composite tea polyphenol-chitosan preservative according to claim 4, characterized in that, The radiation crosslinking in step 4 is gamma ray irradiation or X-ray irradiation, and the irradiation dose is 5-20 kGy.
8. A composite tea polyphenol-chitosan preservative and its preparation method, characterized in that, The method comprises the following steps: S1: chitosan and modified gellan gum are weighed according to the weight parts of each component in the wall material, and then the chitosan and the modified gellan gum are mixed to obtain the wall material; S2: the wall material is mixed with 40-100 times the mass of water to obtain a wall material solution, which is ultrasonically degassed for standby; S3: the core material tea polyphenol is added to the wall material solution, and then the mixture is stirred and homogenized to obtain a microcapsule suspension; S4: the prepared microcapsule suspension is cooled to room temperature, and then it is placed in a 4 DEG C environment for 12 h, and then it is freeze-dried to obtain a microcapsule preservative.
9. The composite tea polyphenol-chitosan preservative according to claim 8, characterized in that, The reaction temperature in step S2 is 70-80 DEG C.