Apigenin-chitosan composite coating liquid as well as preparation method and application thereof
By precisely formulating the apigenin-chitosan composite coating solution, the problem of instability in chitosan composite coatings has been solved, achieving an all-natural, multi-layered synergistic preservation effect. It is suitable for the preservation of fruits and vegetables such as strawberries, meeting the industry's needs for green, safe, and economical products.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- NORTHEAST AGRICULTURAL UNIVERSITY
- Filing Date
- 2026-02-10
- Publication Date
- 2026-05-05
AI Technical Summary
Existing chitosan composite preservative coatings suffer from unstable and short-lasting preservation effects due to improper selection of active ingredients and suboptimal formulation. Furthermore, traditional plant essential oils are volatile and their off-flavors affect the flavor of fruits. Research lacks in-depth exploration of the optimal synergistic conditions.
A apigenin-chitosan composite coating solution is provided. By determining that the optimal ratio of apigenin in the chitosan matrix is 0.1%-0.3% (w/v), especially 0.2% (w/v) is the optimal concentration, an all-natural, synergistic preservative film is formed. The film consists of chitosan or its derivatives, apigenin or its extracts, and an acidic aqueous solution. The preparation method is simple.
It achieves multiple functions of efficient and long-lasting preservation, including improved moisture resistance, enhanced antibacterial properties, strengthened antioxidant properties, and improved texture retention, without any odor interference, which meets the needs of green industries.
Smart Images
Figure CN121970808A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of postharvest preservation technology of fruits and vegetables, specifically relating to a apigenin-chitosan composite coating liquid and its preparation method and application. Background Technology
[0002] Strawberries have thin skins and delicate tissues, and their high respiration and metabolism after harvest make them extremely susceptible to rapid decay due to mechanical damage and microbial infection. Their shelf life at room temperature is typically only 3-5 days, resulting in huge post-harvest losses. To extend shelf life, traditional chemical preservation methods pose a risk of harmful residues, while physical preservation methods involve expensive equipment and complex operations, neither of which can meet the industry's demands for green, safe, and economical practices.
[0003] In recent years, edible coating technology based on chitosan has become a research hotspot due to its excellent film-forming properties, biocompatibility, and natural antibacterial properties. The degree of deacetylation of chitosan is a key parameter; generally, the higher the degree of deacetylation, the more free amino groups on its molecular chain, resulting in stronger antibacterial activity and film-forming performance. However, pure chitosan films have inherent defects such as weak mechanical strength, poor water vapor barrier properties, and a limited antibacterial spectrum, making their preservation effect insufficient when used alone. Therefore, existing technologies generally employ a strategy of adding natural active ingredients to chitosan for modification. For example, peppermint essential oil (0.5%-1.5%, v / v) is dispersed in a chitosan acetic acid solution using an emulsifier (such as Tween-80) to form a composite coating for the preservation of purple sweet potatoes (see Non-Patent Literature 1: Liu Xu et al., "Preservation Effect of Essential Oil-Chitosan Composite Coating on Purple Sweet Potatoes"). Similarly, techniques for combining other plant essential oils (such as carvacrol and tea tree oil) or complex plant extracts with chitosan or its derivatives (such as quaternized chitosan) have also been reported (see Non-Patent Literature 2: Chen Li et al., "Green and facile fabrication of multifunctional cellulose nanocrystal and carvacrol together reinforced chitosan bio-nanocomposite coatings for fruit preservation", Non-Patent Literature 3: Ying Liu et al., "High-adhesion antimicrobial composite coating incorporating quaternary chitosan and tea tree oil for enhanced preservation of fruits and vegetables").
[0004] However, existing technologies have obvious limitations:
[0005] 1. Limited selection of active ingredients: The use of plant essential oils or mixed extracts with complex, volatile and unstable properties results in large fluctuations and poor durability in preservation effects, and may introduce off-flavors that affect the flavor of the fruit.
[0006] 2. Coding optimization is crude: The amount of active ingredients added is mostly based on experience and set within a wide range. The research focuses on verifying "whether there is an effect" and lacks systematic and detailed exploration of the optimal synergistic ratio. Furthermore, it fails to reveal the possible nonlinear relationship between concentration and effect.
[0007] 3. Most studies remain at the level of verifying the overall effect of composite membranes, and lack in-depth exploration of the optimal synergistic conditions between specific active ingredients and chitosan matrix.
[0008] Therefore, there is an urgent need in this field to develop a new food preservation coating technology based on optimized formulation, stable effect, and all-natural ingredients. Summary of the Invention
[0009] This invention aims to overcome the shortcomings of existing technologies and solve the problems of unstable and short-lasting preservation effects caused by improper selection of active ingredients and suboptimal ratios in existing chitosan composite preservative coatings. Specifically, it provides an optimal ratio range for apigenin-chitosan composite coating liquid, thereby achieving a highly efficient, long-lasting, and synergistic all-natural coating for preservation.
[0010] To achieve the above objectives, the present invention provides the following technical solution:
[0011] In a first aspect, the present invention provides an apigenin-chitosan composite coating liquid comprising the following components: chitosan or a derivative thereof, apigenin or an apigenin-containing extract, and an acidic aqueous solution; wherein the apigenin or the apigenin-containing extract has a mass-volume concentration of 0.1-0.3% (w / v) in the composite coating liquid, and the chitosan has a mass-volume concentration of 1.0%-1.5% (w / v) in the composite coating liquid.
[0012] The degree of deacetylation of the chitosan or its derivative is not less than 70%.
[0013] The acidic aqueous solution is any one of lactic acid aqueous solution, citric acid aqueous solution, ascorbic acid aqueous solution, or acetic acid aqueous solution.
[0014] The volume concentration of the acidic aqueous solution is 1%.
[0015] The chitosan derivative is any one of carboxymethyl chitosan, chitosan hydrochloride, or chitosan quaternary ammonium salt.
[0016] Secondly, the present invention provides a method for preparing the composite coating liquid, comprising the following steps:
[0017] S1. Dissolve chitosan or its derivatives in an acidic aqueous solution to obtain a film-forming base solution;
[0018] S2. Dissolve apigenin or apigenin-containing extracts in anhydrous ethanol to obtain an active substance stock solution;
[0019] S3. Mix the active ingredient stock solution obtained in step S2 with the film-forming base solution obtained in step S1, adjust the volume and stir to obtain the composite coating solution.
[0020] Thirdly, the present invention also provides the application of the composite coating liquid in the coating and preservation treatment of strawberries.
[0021] Preferably, the coating treatment includes: immersing strawberries in the composite coating solution for 3-8 minutes, removing them and drying them to form a composite preservation film on the surface of the strawberries.
[0022] Fourthly, the present invention provides a cling film formed by coating and drying the composite coating liquid.
[0023] The beneficial effects achieved by this invention are as follows:
[0024] 1. Discovery of a non-obvious, precisely optimal formulation range and its non-linear synergistic effect: Through systematic formulation experiments, this invention determined and verified that the effective concentration range of apigenin in a chitosan matrix to exert a synergistic preservation effect is 0.1% to 0.3% (w / v), with 0.2% (w / v) being the optimal concentration within this range. Experimental data fully demonstrate that, under this formulation, the composite coating achieves optimal preservation of strawberries across the board; however, when the apigenin concentration deviates from this optimal point, increasing to 0.4% or 0.6%, its preservation effect shows a consistent and significant decrease across multiple indicators. This completely overturns the conventional technical bias in the field that "higher concentrations of active ingredients result in better preservation effects or a plateau in preservation."
[0025] 2. Synergistic effect of multiple preservation functions: This composite coating can simultaneously and significantly: a) improve moisture barrier properties and greatly reduce weight loss rate; b) enhance antibacterial properties and effectively inhibit the rise of decay index; c) strengthen antioxidant properties and maximize the retention of vitamin C and organic acids; d) improve texture retention and delay fruit softening.
[0026] 3. Clear, stable, and safe active ingredients: It uses apigenin extract, which has a clear chemical structure and stable properties, to replace traditional volatile and complex plant essential oils. This avoids odor interference and efficacy degradation, resulting in a longer-lasting and more reliable preservation effect. The entire system is composed of all-natural edible / biodegradable ingredients, with no chemically synthesized preservatives or heavy metal residues, aligning with the trend towards clean labeling.
[0027] 4. Simple process, low cost, and easy to promote: The preparation process is a simple physical blending process, which does not require complex emulsification equipment or chemical modification steps. The production cost is low and it is suitable for large-scale production and industrial application. Attached Figure Description
[0028] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof.
[0029] In the attached diagram:
[0030] Figure 1 This is a comparison chart of the weight loss rate of strawberries treated with composite coatings of different apigenin concentrations in this invention.
[0031] Figure 2 This is a comparison chart of vitamin C content in strawberries treated with composite coatings of different apigenin concentrations in this invention.
[0032] Figure 3 This is a comparison chart of the total acid content of strawberries treated with composite coatings of different apigenin concentrations in embodiments of the present invention.
[0033] Figure 4 This is a comparison chart of the total sugar content of strawberries treated with composite coatings of different apigenin concentrations in embodiments of the present invention.
[0034] Figure 5 This is a comparison chart of the hardness content of strawberries treated with composite coatings of different apigenin concentrations in embodiments of the present invention. Detailed Implementation
[0035] The present invention will be further described below with reference to embodiments. The following description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any other way. Any person skilled in the art may make equivalent modifications to the disclosed technical content to create equivalent embodiments. Any simple modifications or equivalent changes made to the following embodiments based on the technical essence of the present invention without departing from the scope of the invention are all within the protection scope of the present invention.
[0036] Example 1: Preparation of Composite Coating Liquid
[0037] (1) Preparation of chitosan-based solution: Weigh 1.25 g of chitosan powder (degree of deacetylation ≥95%, molecular weight 500,000), slowly add it to 100 mL of 1% (v / v) acetic acid aqueous solution, and stir magnetically for 4 hours in a 50℃ water bath until completely dissolved to obtain 1.25% (w / v) chitosan-based solution.
[0038] (2) Preparation of apigenin stock solution: Accurately weigh apigenin standard (purity ≥98%), dissolve it in anhydrous ethanol, and dissolve it with ultrasonic assistance to prepare a apigenin stock solution of 10 mg / mL.
[0039] (3) Preparation of composite coating solution: Take the above chitosan-based solution, add the calculated volume of apigenin stock solution, and make up to a total volume of 100 mL with 1% acetic acid solution. Stir magnetically for 1 hour to mix evenly, and prepare four coating solutions with final apigenin concentrations of 0% (control group CK), 0.2% (treatment group A), 0.4% (treatment group B), and 0.6% (treatment group C).
[0040] Note: The concentration of apigenin is calculated as: apigenin mass (g) / total volume of coating solution (mL) × 100%.
[0041] This invention requires a degree of deacetylation of chitosan of not less than 70%. When using chitosan with a high degree of deacetylation (e.g., ≥95%), its performance is superior, and the synergistic effect with apigenin is more significant. Those skilled in the art will understand that for chitosan with a degree of deacetylation of 70% or higher, the preservation purpose can be achieved through conventional adjustments within the system of this invention.
[0042] The acidic aqueous solution is not limited to acetic acid aqueous solution, but can also be other edible acid aqueous solutions commonly used in the field, such as lactic acid, citric acid, and ascorbic acid aqueous solutions, which function to dissolve chitosan and adjust the pH of the system.
[0043] Example 1 uses ordinary chitosan as the film-forming matrix. It can be understood that, without deviating from the core concept of the present invention (i.e., utilizing the film-forming properties of the polysaccharide matrix to produce a synergistic preservation effect with apigenin), the chitosan can be replaced by its more water-soluble or functionalized derivatives, such as carboxymethyl chitosan, chitosan hydrochloride, or chitosan quaternary ammonium salt.
[0044] These derivatives are chemically modified chitosan products. They retain the basic film-forming properties, biocompatibility, and biodegradability of chitosan, while potentially exhibiting better water solubility (e.g., carboxymethyl chitosan, chitosan hydrochloride) or enhanced antibacterial properties (e.g., chitosan quaternary ammonium salts). When using these derivatives as substitutes, those skilled in the art will understand that, due to their similar molecular chain structure and properties to chitosan, they can be expected to interact similarly with apigenin. In practice, the concentration range of chitosan in Example 1 (1.0%-1.5% w / v) can be referenced, and the dosage can be adjusted through limited conventional experiments to obtain a composite coating solution with comparable film-forming properties and preservation effects. This substitution is based on well-known knowledge of the properties of chitosan and its derivatives and requires no inventive effort.
[0045] Example 1 describes a preferred scheme using apigenin as the active ingredient. It is understood that, without departing from the core concept of the present invention, apigenin can also be an ethanol extract of celery, such as celery obtained by reflux extraction with 70-80% ethanol (i.e., the synergistic preservation effect of the active ingredient apigenin and the chitosan matrix at a specific concentration). The apigenin extract can be equivalently replaced by natural plant extracts rich in apigenin (such as celery leaf extract, celery seed extract, etc.).
[0046] The technical basis for this substitution lies in the fact that the key active substance of this invention is the apigenin molecule itself. As long as the mass content of total apigenin (i.e., apigenin and its glycosides, etc., which can exert the same effect) in the substitute is not less than 50%, the main active ingredient can be ensured to be consistent with the pure product. When using extracts for substitution, those skilled in the art can perform dosage conversion through conventional calculations based on the labeled total apigenin content to ensure that the equivalent apigenin concentration with preservation function in the final composite coating liquid is consistent with the concentration of the pure product in Example 1, i.e., 0.2% (w / v). This substitution is a conventional choice that those skilled in the art can achieve without creative effort based on the teachings of this invention.
[0047] Example 1 provides a preferred embodiment of the present invention. It is understood that the mass-volume concentration of chitosan in the composite coating solution can be adjusted within the range of 1.0%-1.5%. When the concentration is below 1.0%, insufficient film-forming matrix may result in an excessively thin film layer and poor mechanical strength; when the concentration is above 1.5%, excessive solution viscosity may affect the uniformity and operability of the coating. Within the concentration range of 1.0%-1.5% described in this invention, a preservative film with good barrier properties and adhesion can be formed, producing a synergistic preservation effect with apigenin. Those skilled in the art can select and adjust the chitosan concentration within this range according to actual needs, such as for different varieties or ripeness levels of strawberries, without requiring creative effort.
[0048] Example 2: Experiment and Effect Evaluation of Strawberry Coating Preservation
[0049] 1. Materials and Treatment: Fresh "Hongyan" strawberries of uniform size and maturity (approximately 70% ripe), free from inorganic maple damage and disease, were selected and randomly divided into 4 groups. Each group was immersed in one of the four coating solutions prepared in Example 1 for 5 minutes, then removed and air-dried naturally in a sterile, ventilated place at room temperature for 30 minutes to allow a uniform, transparent, and dense composite preservative film to form on its surface. Each group was further divided into 5 subgroups (6 fruits per subgroup), and each subgroup was stored in a perforated polyethylene preservation bag.
[0050] The soaking time for strawberries can be 3 to 8 minutes, and can be adjusted according to the size and ripeness of the strawberries, to ensure that the coating liquid evenly covers the surface of the fruit, thus achieving the preservation purpose of this invention.
[0051] 2. Storage conditions: After treatment, the strawberries are stored in a simulated shelf environment with a temperature of 25±2℃ and a relative humidity of 65±5% for 5 days.
[0052] 3. Index determination: On days 0, 1, 2, 3, 4 and 5 of storage, samples were taken from each subgroup of each group to determine the weight loss rate, decay index, vitamin C content, total acid content and hardness of strawberries.
[0053] Weight loss rate: calculated by weighing method.
[0054] The decay index is calculated based on the percentage of decayed area, categorized into levels 0-3.
[0055] Vitamin C content: determined by 2,6-dichlorophenolindophenol titration.
[0056] Total acid content: calculated as malic acid by acid-base titration.
[0057] Total sugar content: determined by anthrone colorimetric method.
[0058] Hardness: determined by puncture test using a texture analyzer with a P / 2 probe.
[0059] 4. Experimental Results
[0060] 4.1 Effect of composite coating treatment with different concentrations of apigenin on the weight loss rate of strawberries
[0061] Weight loss rate mainly reflects the water evaporation of strawberries during storage, such as... Figure 1 As shown, the weight loss rate of all groups increased with prolonged storage time. Throughout the storage period, treatment group A consistently exhibited the lowest weight loss rate with the most gradual increase. By day 5 of storage, its weight loss rate was only 0.82%, significantly lower than the 1.43% of the control group (CK), 1.21% of treatment group B, and 1.23% of treatment group C. This indicates that adding 0.2% apigenin effectively optimizes the network structure of the chitosan membrane, enhancing its water vapor barrier properties and thus minimizing water loss from strawberries. When the apigenin concentration increased to 0.4% and 0.6%, the uniformity and density of the membrane may have been affected by the aggregation of some apigenin molecules or excessive interaction with the chitosan molecular chains, leading to a decrease in water-blocking effect.
[0062] 4.2 Effect of different apigenin concentrations in composite coating treatment on strawberry rot index
[0063] The decay index directly reflects the antibacterial and preservative effect of the coating. As shown in Table 1, the decay index of all treatment groups increased over time during storage, but the coating treatment groups were significantly better than the control group (CK) without apigenin. Treatment group A had the lowest decay index of 5.56% on day 1 and maintained its leading advantage throughout. By day 5, its decay index was 38.89%, far lower than the control group (CK) at 83.33%, and also better than treatment group B (61.11%) and treatment group C (55.56%). This indicates that the addition of apigenin significantly enhanced the antibacterial ability of the coating, and the addition of 0.2% achieved the best synergistic effect between chitosan and apigenin in antibacterial aspects. Excessive concentration may alter the surface properties of the membrane or the release kinetics of apigenin, which could be detrimental to the sustained and stable antibacterial effect.
[0064] Table 1. Rot index data of strawberries treated with composite coatings of different apigenin concentrations
[0065] 4.3 Effect of different apigenin concentrations in composite coating treatment on vitamin C content of strawberries
[0066] Vitamin C is an important active nutrient in strawberries, but it is easily oxidized. For example... Figure 2 As shown, the vitamin C content of all groups decreased during storage. Treatment group A exhibited the strongest vitamin C retention capacity, with the slowest rate of decline. On the 5th day of storage, the vitamin C content of strawberries in this group was still as high as 34.13 mg / 100g, while the control group CK had plummeted to 5.33 mg / 100g. Treatment groups B and C had 13.87 and 16.00 mg / 100g, respectively. This indicates that the 0.2% apigenin-chitosan composite coating has excellent antioxidant properties, effectively scavenging reactive oxygen species in the environment, delaying oxidative deterioration of strawberries themselves and caused by microbial infection, thereby protecting easily oxidized nutrients such as vitamin C.
[0067] 4.4 Effects of composite coating treatments with different concentrations of apigenin on total acid, total sugar, and firmness of strawberries
[0068] Total acidity (calculated as malic acid) is an important substance affecting the flavor of strawberries, such as... Figure 3 As shown, the total acid content decreased with storage time. Treatment group A maintained the best acidity, reaching 4.36% on day 5, significantly higher than the acidity of control group CK (1.79%), treatment group B (3.47%), and treatment group C (3.13%). This indicates that a suitable composite coating can effectively reduce the respiration intensity of strawberries and slow down the consumption rate of organic acids as respiratory substrates.
[0069] Changes in total sugar content as follows Figure 4As shown, all treatment groups exhibited a decreasing trend. In the early stage of storage (the first 2 days), the total sugar content of each coating treatment group was higher than that of the control group, with treatment group A showing a relatively prominent protective effect. However, as the storage time increased, the differences between the groups gradually narrowed, and by the 5th day, they tended to be consistent (approximately 0.41-0.43 mg / g), indicating that coating treatment has a certain effect on delaying sugar metabolism, but the long-term effect is mainly dominated by the senescence of the fruit itself.
[0070] Firmness is a key indicator for measuring the texture and storage resistance of strawberries, such as Figure 5 As shown, the firmness of strawberries gradually decreased (softened) during storage. Treatment group A showed the slowest decrease in firmness, maintaining a relatively high firmness of 26.50 g even on day 5, while the control group (CK) had softened to 14.80 g, and treatment groups B and C were 24.10 g and 19.90 g, respectively. This indicates that the 0.2% apigenin-chitosan composite coating can effectively inhibit the activity of cell wall degrading enzymes such as pectinase, or delay fruit softening by maintaining cell membrane integrity.
[0071] Table 2. Key Preservation Indicators for Each Group on Day 5 of Storage
[0072] The above experimental results show that the synergistic effect of apigenin reaches its peak at a concentration of 0.2% (w / v). Based on this finding, and combined with the general knowledge of the dose-effect of active ingredients in the art (i.e., the active ingredient usually has a minimum effective concentration and an upper limit of the effect plateau period), the effective concentration range of apigenin in the composite coating solution of the present invention can be determined to be 0.1% to 0.3% (w / v).
[0073] The lower limit of the range is 0.1% (w / v). This concentration, as the minimum effective dose that can significantly exceed the preservation effect of pure chitosan film, is an effective starting point that can be determined and accepted by those skilled in the art through limited routine experiments.
[0074] The upper limit is 0.3% (w / v). Experimental data shows that the effect significantly decreases when the concentration increases to 0.4%, indicating that the optimal window for synergistic effect is within 0.3%. Setting 0.3% as the upper limit ensures that the active ingredients can fully exert their effects while avoiding the decline in efficacy due to poor membrane structure or compatibility caused by excessively high concentrations (such as ≥0.4%).
[0075] Therefore, any concentration point within the range of 0.1%-0.3% can be selected, and the synergistic preservation purpose of this invention can be achieved through conventional adjustments (such as fine-tuning the chitosan concentration or process parameters). The 0.2% concentration verified in the examples represents the optimal implementation point within this range.
[0076] Conclusion: Based on the above data, it is evident that apigenin and chitosan do not simply exhibit a functional additive effect in the composite coating, but rather produce a significant synergistic preservation effect. Specifically, within a concentration range of 0.1% to 0.3% (w / v), the composite coating achieves a significant synergistic preservation effect. At an apigenin concentration of 0.2% (w / v), all preservation indicators reach their peak values within this range, representing the optimal implementation method. However, when the concentration significantly exceeds this effective range (e.g., increasing to 0.4% or 0.6%), the preservation effect shows a comprehensive and consistent decline.
[0077] This phenomenon indicates that the concentration within the range of 0.1-0.3% (w / v), especially 0.2% (w / v), is the key concentration for triggering the optimal synergistic effect between apigenin and chitosan. At this specific concentration, the two promote each other.
[0078] Based on the above embodiments 1 and 2, the present invention achieves the following beneficial effects:
[0079] 1. Discovery of a non-obvious, precisely optimal formulation range and its non-linear synergistic effect: Through systematic formulation experiments, this invention determined and verified that the effective concentration range of apigenin in a chitosan matrix to exert a synergistic preservation effect is 0.1% to 0.3% (w / v), with 0.2% (w / v) being the optimal concentration within this range. Experimental data fully demonstrate that, under this formulation, the composite coating achieves optimal preservation of strawberries across the board; however, when the apigenin concentration deviates from this optimal point, increasing to 0.4% or 0.6%, its preservation effect shows a consistent and significant decrease across multiple indicators. This completely overturns the conventional technical bias in the field that "higher concentrations of active ingredients result in better preservation effects or a plateau in preservation."
[0080] 2. Synergistic effects of multiple preservation functions: Within the effective ratio range of 0.1% to 0.3% (w / v), especially at the optimal ratio of 0.2% (w / v), apigenin and chitosan do not simply have additive properties, but rather produce a synergistic effect. This composite coating can simultaneously and significantly: a) improve moisture barrier properties and greatly reduce weight loss; b) enhance antibacterial properties and effectively inhibit the rise of the decay index; c) strengthen antioxidant properties and maximize the retention of vitamin C and organic acids; d) improve texture retention and delay fruit softening. This comprehensive synergistic preservation effect is far superior to single chitosan films and other composite films with suboptimal ratios.
[0081] 3. Clear, stable, and safe active ingredients: It uses apigenin extract, which has a clear chemical structure and stable properties, to replace traditional volatile and complex plant essential oils. This avoids odor interference and efficacy degradation, resulting in a longer-lasting and more reliable preservation effect. The entire system is composed of all-natural edible / biodegradable ingredients, with no chemically synthesized preservatives or heavy metal residues, aligning with the trend towards clean labeling.
[0082] 4. Simple process, low cost, and easy to promote: The preparation process is a simple physical blending process, which does not require complex emulsification equipment or chemical modification steps. The production cost is low and it is suitable for large-scale production and industrial application.
[0083] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A apigenin-chitosan composite coating liquid, characterized in that, The composite coating solution comprises the following components: chitosan or its derivatives, apigenin or apigenin-containing extract, and an acidic aqueous solution; wherein the apigenin or apigenin-containing extract has a mass-volume concentration of 0.1-0.3% (w / v) in the composite coating solution, and the chitosan has a mass-volume concentration of 1.0%-1.5% (w / v) in the composite coating solution.
2. The composite coating liquid according to claim 1, characterized in that, The degree of deacetylation of the chitosan or its derivative is not less than 70%.
3. The composite coating liquid according to claim 1, characterized in that, The acidic aqueous solution is any one of lactic acid aqueous solution, citric acid aqueous solution, ascorbic acid aqueous solution, or acetic acid aqueous solution.
4. The composite coating liquid according to claim 1, characterized in that, The volume concentration of the acidic aqueous solution is 1%.
5. The composite coating liquid according to claim 1, characterized in that, The chitosan derivative is any one of carboxymethyl chitosan, chitosan hydrochloride, or chitosan quaternary ammonium salt.
6. A method for preparing the composite coating liquid according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Dissolve chitosan or its derivatives in an acidic aqueous solution to obtain a film-forming base solution; S2. Dissolve apigenin or apigenin-containing extracts in anhydrous ethanol to obtain an active substance stock solution; S3. Mix the active ingredient stock solution obtained in step S2 with the film-forming base solution obtained in step S1, adjust the volume and stir to obtain the composite coating solution.
7. The application of the composite coating liquid according to any one of claims 1 to 5 for coating and preserving strawberries.
8. The application according to claim 7, characterized in that, The coating preservation treatment includes: immersing strawberries in the composite coating solution for 3-8 minutes, removing them and drying them to form a composite preservation film on the surface of the strawberries.
9. A cling film formed by coating and drying the composite coating liquid according to any one of claims 1 to 5.