Preparation method and application of chitosan film loaded with chlorogenic acid-zein nanoparticles
By preparing chitosan films loaded with chlorogenic acid-zein nanoparticles, the problems of insufficient mechanical properties of chitosan films and easy oxidation of chlorogenic acid were solved, achieving high stability and wide applicability in food packaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANXI UNIV
- Filing Date
- 2026-03-03
- Publication Date
- 2026-05-05
AI Technical Summary
Existing chitosan films have insufficient mechanical properties and limited barrier properties, and chlorogenic acid is easily oxidized and degraded, making it difficult to achieve long-term and stable antioxidant and antibacterial effects in food packaging.
Chlorogenic acid nanoparticles were prepared using zein as the wall material and then combined with chitosan to form a chitosan film loaded with chlorogenic acid-zein nanoparticles. The structure and properties of the film were improved through hydrogen bonding and electrostatic interactions.
It significantly improves the mechanical properties, barrier properties, and antioxidant properties of chitosan films, achieving long-term sustained release of chlorogenic acid and delaying oxidative deterioration during food storage.
Smart Images
Figure CN121975162A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food packaging technology and relates to a method for preparing chitosan films loaded with chlorogenic acid-zein nanoparticles and their applications. Background Technology
[0002] With consumers increasingly aware of food safety, quality, and environmental protection, the development of novel, biodegradable food packaging materials with spoilage-delaying functions has become a research hotspot in the fields of food science and materials engineering. Traditional petroleum-based plastic packaging is difficult to degrade, causing serious "white pollution," and its single function cannot inhibit microbial spoilage and oxidative deterioration of food during storage. Therefore, packaging films that combine biodegradability and spoilage-delaying functions are an ideal solution to replace traditional plastics and extend the shelf life of food.
[0003] Chitosan (CS), as a natural amino polysaccharide, possesses excellent film-forming properties, biocompatibility, biodegradability, and certain antibacterial properties, making it an ideal substrate for food packaging. However, pure chitosan films suffer from insufficient mechanical properties, limited barrier properties, and single functionality, restricting their application. To impart antioxidant and antibacterial activity to packaging films, natural polyphenolic compounds such as chlorogenic acid (CGA) are often added to the film matrix. Chlorogenic acid is a natural polyphenolic active ingredient with excellent antioxidant and antibacterial activities; however, its chemical properties are extremely unstable, easily affected by light and heat, and prone to oxidative degradation. Furthermore, it has poor water solubility and low bioavailability, making it difficult to achieve long-term stable activity when directly added to films.
[0004] Zein is a natural plant protein with good biocompatibility, biodegradability and hydrophobicity. It is an ideal wall material for encapsulating hydrophobic / amphiphilic active ingredients. It can be prepared into nanoparticles by antisolvent precipitation to physically protect the active ingredients and improve their stability. However, there are currently no reports on the preparation of functional films by combining chlorogenic acid-zein nanoparticles with chitosan.
[0005] Therefore, it is necessary to develop nanoparticles that encapsulate chlorogenic acid using natural zein as the wall material, and combine them with chitosan to prepare functional films with high stability, high activity, and excellent mechanical properties, thereby helping to delay the oxidative deterioration of millet during storage. Summary of the Invention
[0006] To address the shortcomings of existing technologies, the primary objective of this invention is to provide a method for preparing a chitosan film loaded with chlorogenic acid-zein nanoparticles. This method uses zein as a natural wall material to encapsulate and stabilize chlorogenic acid, while simultaneously improving the barrier properties, mechanical properties, thermal properties, and antioxidant properties of the chitosan film. A second objective of this invention is to provide an application of this composite film during the storage of millet, delaying oxidative deterioration during storage.
[0007] To achieve the above objectives, the specific technical solution of the present invention is as follows: In a first aspect, the present invention provides a method for preparing a chitosan film loaded with chlorogenic acid-zein nanoparticles: (1) Preparation of chlorogenic acid-zein nanoparticles: Zein and chlorogenic acid were dissolved in 80% ethanol aqueous solution for 30 min to prepare zein and chlorogenic acid solutions; the prepared zein and chlorogenic acid solutions were mixed at a mass ratio of (1-10):1 and stirred in the dark for 1 h; then a certain volume of deionized water was added to the mixture, and the mixture was stirred for 1 h to remove ethanol by rotary evaporation to prepare chlorogenic acid-loaded zein nanoparticles. (2) Preparation of chitosan film-forming solution: Dissolve chitosan in 1% acetic acid solution by volume, add 50% glycerol by weight of chitosan, heat and stir at 65°C for 30 min until completely dissolved, cool to room temperature to obtain chitosan film-forming solution.
[0008] (3) Preparation of composite film: According to the volume ratio of chlorogenic acid-zein nanoparticles to chitosan film-forming liquid (0.02-0.11):1, the chlorogenic acid-zein nanoparticles obtained in step (1) are dispersed in the chitosan film-forming liquid in step (2) and stirred in the dark for 30 min. After ultrasonic degassing for 30 min, the mixture is poured into a mold and dried in an oven at 45℃ for 12 hours using the casting method to obtain a chitosan film loaded with chlorogenic acid-zein nanoparticles.
[0009] Preferably, in step (1), the volume ratio of deionized water to the mixed solution is 5:1, and the pH of the deionized water is pre-adjusted to 4.
[0010] Preferably, the optimal ratio of chlorogenic acid-zein nanoparticles in step (1) is 5:1, and the optimal ratio of nanoparticles is selected for the preparation of the composite film in step (3).
[0011] Preferably, the optimal content of the chitosan film loaded with chlorogenic acid-zein nanoparticles in step (3) is 8%, and the optimal ratio is selected for the application of the composite film.
[0012] Secondly, the present invention provides a method for preparing a chitosan film loaded with chlorogenic acid-zein nanoparticles.
[0013] Thirdly, the present invention provides the application of the chitosan film loaded with chlorogenic acid-zein nanoparticles in the packaging of millet during storage.
[0014] In summary, the advantages of this invention over the prior art are: This invention uses natural zein as the wall material and prepares chlorogenic acid nanoparticles by antisolvent precipitation. The nanoparticles can form an effective physical protection for chlorogenic acid, solving the problems of easy oxidation and degradation and poor water solubility. Furthermore, the combination of zein and chlorogenic acid improves the bioavailability of the active ingredients, realizes the long-term sustained release of chlorogenic acid in the film, and enhances the antioxidant and antibacterial activities of the film.
[0015] The chlorogenic acid-zein nanoparticles form hydrogen bonds and electrostatic interactions with the chitosan matrix. As a nanofiller phase, the nanoparticles significantly optimize the structure of the chitosan film, thereby improving the barrier properties, mechanical properties, thermal properties and antioxidant properties of the composite film and solving the defects of pure chitosan film.
[0016] The prepared composite film has excellent antioxidant and antibacterial properties, and its mechanical properties and barrier properties are significantly improved. It can be widely used in food packaging and other fields, with broad application scenarios and good industrialization prospects. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0018] Figure 1 Figures show chlorogenic acid-zein nanoparticle solutions obtained in different proportions. Figure 2(a) shows the particle size, PDI, and zeta potential of chlorogenic acid-zein nanoparticles obtained at different ratios; (b) shows the encapsulation efficiency and loading rate of chlorogenic acid-zein nanoparticles obtained at different ratios. Figure 3 The structural characterization diagrams (FTIR and XRD) of the obtained chlorogenic acid-zein nanoparticles (optimal ratio 5:1). Figure 4 Image of a chitosan film loaded with chlorogenic acid-zein nanoparticles; Figure 5 SEM image of chitosan film loaded with chlorogenic acid-zein nanoparticles; Figure 6 Thickness diagram of chitosan film loaded with chlorogenic acid-zein nanoparticles; Figure 7(a) shows the mechanical properties of the chitosan film loaded with chlorogenic acid-zein nanoparticles; (b) shows the antioxidant properties of the chitosan film loaded with chlorogenic acid-zein nanoparticles. Figure 8This is an illustration of the effect of using film to package millet during storage; Figure 9 This is a graph showing the fatty acid values of millet during storage due to oxidation. Detailed Implementation
[0019] This invention provides a method for preparing and applying chitosan films loaded with chlorogenic acid-zein nanoparticles. The technical solution of this invention is clearly and completely described below with reference to specific embodiments, including the following steps: Example 1: Preparation and Characterization of Chlorogenic Acid-Zezyme Nanoparticles 1. Preparation of chlorogenic acid-zein nanoparticles 0.3 g of zein and 0.03 g, 0.06 g, 0.15 g, and 0.3 g of chlorogenic acid (CGA) were weighed and dissolved in 30 ml of 80% ethanol aqueous solution and 1 ml of 80% ethanol aqueous solution for 30 min to prepare zein and chlorogenic acid solutions. The prepared zein and chlorogenic acid solutions were mixed at a mass ratio of 10:1, 5:1, 2:1, and 1:1, and stirred in the dark for 1 h to dissolve. Then, 150 ml of deionized water (pre-adjusted to pH=4 with 1 mol / L) was added to the mixture, and the mixture was stirred continuously for 1 h. The ethanol was then removed by rotary evaporation to prepare a chlorogenic acid-loaded zein nanoparticle suspension, named ZCNPs.
[0020] Depend on Figure 1 It can be seen that as the proportion increases, the color of ZCNPs gradually darkens, indicating the formation of ZCNPs.
[0021] 2. Characterization of chlorogenic acid-zein nanoparticles (1) The particle size, PDI and zeta potential of chlorogenic acid-zein nanoparticles obtained with different proportions are shown in Figure 2(a). As the proportion of chlorogenic acid increases, the particle size increases, and the overall particle size is less than 200 nm. After adding chlorogenic acid, the PDI is still stable between 0.2 and 0.3, indicating that the nanoparticles are evenly distributed. The zeta potential shows a trend of first increasing and then decreasing, indicating that the stability of the nanoparticles first increases and then decreases.
[0022] (2) The encapsulation efficiency and loading rate of chlorogenic acid-zein nanoparticles obtained at different ratios are shown in Figure 2(b). As shown in the figure, EE% and LC% generally decrease with increasing ratio. The encapsulation efficiency ranges from 59.68% to 77.70%, and the loading rate ranges from 10.67% to 18.24%. At 10:1 and 5:1, the encapsulation efficiency and loading rate are relatively high, which may be because almost all of the added chlorogenic acid is loaded into the zein nanoparticles. At 2:1 and 1:1, the encapsulation efficiency and loading rate decrease, possibly because too much free chlorogenic acid will adhere to the surface of the nanoparticles. Therefore, based on the previous particle size, PDI, and ZETA potential, a ratio of 5:1, which can load more chlorogenic acid, was selected for structural characterization.
[0023] (3) Structural characterization of the obtained chlorogenic acid-zein nanoparticles (optimal ratio 5:1), such as Figure 3 FTIR spectra: The chlorogenic acid-loaded zein nanoparticles show shifts at different characteristic absorption peaks, indicating an interaction between the two. (FTIR spectra are also present in the 1000-2000 cm⁻¹ range.) -1 The absence of characteristic peaks for CGA indicates that it was encapsulated. XRD pattern: As shown in the figure, both zein and the two nanoparticles are in an amorphous state. The presence of numerous and sharp characteristic peaks for chlorogenic acid indicates that it is highly crystalline. The weakening or even disappearance of many CGA characteristic peaks after nanoparticle formation further demonstrates that chlorogenic acid is encapsulated by zein.
[0024] Example 2: Preparation and characterization of chitosan films loaded with chlorogenic acid-zein nanoparticles 1. Preparation of chitosan film-forming solution Dissolve 2g of chitosan in 100ml of 1% acetic acid solution, add 50% glycerol by weight of chitosan, heat and stir at 65℃ for 30min until completely dissolved, cool to room temperature to obtain chitosan film-forming solution.
[0025] 2. Preparation of chitosan films loaded with chlorogenic acid-zein nanoparticles The chlorogenic acid-zein nanoparticles were dispersed in the chitosan film-forming solution at concentrations of 2%, 5%, 8%, and 11% of the chitosan film-forming solution volume, respectively. The mixture was stirred in the dark for 30 minutes, followed by ultrasonic degassing for 30 minutes. The mixture was then poured into a mold and cast using a casting method. The film was dried in a 45°C oven for 12 hours to obtain chitosan films loaded with chlorogenic acid-zein nanoparticles. Pure chitosan films were also prepared simultaneously. These were named CS pure chitosan film and composite films containing 2% ZCNPs-CS, 5% ZCNPs-CS, 8% ZCNPs-CS, and 11% ZCNPs-CS, respectively. The chitosan films loaded with chlorogenic acid-zein nanoparticles are shown below. Figure 4 As shown.
[0026] 3. Characterization of chitosan films loaded with chlorogenic acid-zein nanoparticles (1) SEM images of chitosan films loaded with chlorogenic acid-zein nanoparticles, as shown in Figure 1. Figure 5 As shown, the surface of the pure chitosan film is smooth, and no delamination or cracks were observed. The addition of nanoparticles caused the surface of the film to become rougher, and at 11%, ZCNPs formed obvious aggregates.
[0027] (2) The thickness of the chitosan film loaded with chlorogenic acid-zein nanoparticles is as follows: Figure 6 Compared with CS, the film thickness increases with increasing content, but remains at around 0.6 mm overall, indicating that the nanoparticles are evenly distributed in chitosan.
[0028] (3) The mechanical properties of the chitosan film loaded with chlorogenic acid-zein nanoparticles are shown in Figure 7(a). With the increase of ZCNPs, the TS and EAB of the film were greatly improved. Compared with CS, the tensile strength increased from 3.36 MPa to a maximum of 9.40 MPa, and the elongation at break increased from 22.17% to a maximum of 49.46%. This may be because ZCNPs fill the gaps between chitosan molecules, reduce defects in the film, make the film structure more compact, and thus increase the flexibility of the polymer chain. The antioxidant properties of the chitosan film loaded with chlorogenic acid-zein nanoparticles are shown in Figure 7(b). It can be seen from the figure that the DPPH free radical scavenging and ABTS scavenging abilities of the film increase with the increase of ZCNPs, and the hydrogen bonding between the chitosan matrix and the nanoparticles can reduce the oxidative loss of chlorogenic acid, thus increasing the antioxidant properties.
[0029] (4) The barrier properties of chitosan films loaded with chlorogenic acid-zein nanoparticles are shown in Table 1. From left to right, they are water content, swelling ratio, water solubility, water vapor permeability and oxygen permeability. From the table, it can be seen that the incorporation of ZCNPs significantly improves the barrier properties of the film compared with CS.
[0030] Table 1 shows the barrier properties of chitosan films loaded with chlorogenic acid-zein nanoparticles.
[0031] Note: Different lowercase letters indicate significant differences in the same column of data (p<0.05).
[0032] Based on the characterization of chitosan films loaded with chlorogenic acid-zein nanoparticles, 8% ZCNPs-CS was selected for millet packaging during the storage period.
[0033] Example 3: Application of chitosan films loaded with chlorogenic acid-zein nanoparticles 1. Analysis of lipid oxidation during the storage of Jinmiao K1 millet. A blank control group was set up during the storage period. Oxidation was accelerated by 8% ZCNPs-CS and CGA-CS at 50℃ and 60% humidity for 8 weeks, and samples were taken every 2 weeks. Figure 8 This image shows the effect of using chitosan film to package millet during storage.
[0034] 2. The fatty acid value of millet during storage is as follows: Figure 9 Overall, the fatty acid content of the blank control millet increased rapidly, while the rate of increase of chlorogenic acid chitosan film packaging slowed significantly, and the increase of nanoparticle chitosan film packaging group was the smallest. The reason is that the antioxidant properties of chlorogenic acid can scavenge oxidative free radicals, while the filling of film pores by zein chlorogenic acid nanoparticles can enhance the barrier effect and achieve the slow release of chlorogenic acid, further improving the antioxidant effect.
[0035] In summary, chitosan films loaded with chlorogenic acid-zein nanoparticles can delay the oxidative deterioration of millet during storage.
[0036] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.
Claims
1. A method for preparing a chitosan film loaded with chlorogenic acid-zein nanoparticles, characterized in that, Includes the following steps: (1) Preparation of chlorogenic acid-zein nanoparticles: Zein and chlorogenic acid were dissolved in an ethanol aqueous solution for 30 min to prepare a zein and chlorogenic acid solution; the prepared zein and chlorogenic acid solution were mixed and stirred in the dark for 1 h; then a certain volume of deionized water was added to the mixture, and the mixture was stirred for 1 h to remove ethanol by rotary evaporation to prepare a chlorogenic acid-loaded zein nanoparticle suspension. (2) Preparation of chitosan film-forming solution: Dissolve chitosan in acetic acid solution, add glycerol and heat and stir for 30 minutes until completely dissolved, cool to room temperature to obtain chitosan film-forming solution. (3) Preparation of composite film: The chlorogenic acid-zein nanoparticles obtained in step (1) are dispersed in the chitosan film-forming solution in step (2) and stirred in the dark for 30 min. After ultrasonic degassing for 30 min, the mixture is poured into a mold and dried in an oven at 45℃ for 12 hours to obtain a chitosan film loaded with chlorogenic acid-zein nanoparticles.
2. The method for preparing chitosan films loaded with chlorogenic acid-zein nanoparticles as described in claim 1, characterized in that, The mass ratio of zein to chlorogenic acid in step (1) is (1-10):1, the volume fraction of the ethanol aqueous solution in step (1) is 80%, and the volume ratio of deionized water to the mixture is 5:
1.
3. The method for preparing chitosan films loaded with chlorogenic acid-zein nanoparticles as described in claim 1, characterized in that, In step (2), the volume fraction of the acetic acid solution is 1%, the amount of glycerol added is 50% of the mass of chitosan, and the heating temperature is 65℃.
4. The method for preparing chitosan films loaded with chlorogenic acid-zein nanoparticles as described in claim 1, characterized in that, In step (3), the volume ratio of nanoparticles to chitosan film-forming solution is (0.02-0.11):
1.
5. A method for preparing a chitosan film loaded with chlorogenic acid-zein nanoparticles, characterized in that, Chitosan films of chlorogenic acid-zein nanoparticles prepared by the method according to any one of claims 1-4.
6. The chitosan film loaded with chlorogenic acid-zein nanoparticles as described in claim 5 can effectively delay the oxidative deterioration of millet during storage.