Preparation method and application of chitosan / polyvinyl alcohol electrostatic spinning membrane loaded with beta-cyclodextrin and essential oil

Abstract

The invention provides a preparation method and application of a chitosan / polyvinyl alcohol electrostatic spinning membrane loaded with beta-cyclodextrin and essential oil, and the preparation method comprises the following steps: putting chitosan in 1% (w / v) acetic acid, stirring at 85 DEG C until the chitosan is completely dissolved, and preparing a 1% (w / v) chitosan solution; stirring polyvinyl alcohol at 85 DEG C to prepare a 10% (w / v) polyvinyl alcohol solution; mixing the chitosan solution and the polyvinyl alcohol solution to prepare a shell spinning solution; mixing essential oil and beta-cyclodextrin, adding the mixture into a mixed solution of chitosan and polyvinyl alcohol, stirring and mixing, and standing for defoaming to obtain a core layer spinning solution; respectively injecting the shell layer spinning solution and the core layer spinning solution into an outer layer channel and an inner layer channel of a coaxial needle head by adopting a coaxial electrostatic spinning device, and then spinning; the chitosan / polyvinyl alcohol coaxial electrostatic spinning film loaded with beta-cyclodextrin and essential oil is obtained on a receiving device, and a non-direct-contact slow-release fiber film is developed, so that the shelf life of bread is prolonged, and the quality of the bread is kept.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of biological materials, and particularly relates to a preparation method and application of a chitosan / polyvinyl alcohol coaxial electrospun film loaded with beta-cyclodextrin and essential oil. BACKGROUND

[0002] Coaxial electrospinning technology synchronously delivers two fluids with the help of a coaxial needle, thereby preparing core-shell structure fibers, which are widely used in the fields of drug delivery systems and multi-component material preparation. In such core-shell nanofibers, the spinnable biopolymer constitutes the fiber shell, and the active substance is wrapped in the core part. The shell can become a physical barrier to regulate the long-term release of active substances by virtue of its slow diffusion and degradation characteristics, which plays a key role in maintaining the effectiveness and stability of drugs or active compounds.

[0003] Compared with single-axis electrospinning, the core-shell structure of coaxial fibers can effectively prevent the burst release problem caused by mixed wall material nanofibers. The shell layer can act as a barrier to control the release rate of active ingredients in the core layer, achieving more precise and controllable release, which is crucial for maintaining the effectiveness and stability of drugs or active compounds. How to select appropriate polymers and process parameters is the key to producing core-shell nanofibers by coaxial electrospinning. SUMMARY

[0004] The purpose of the present application is to provide a preparation method and application of a chitosan / polyvinyl alcohol electrospun film loaded with beta-cyclodextrin and essential oil, in order to solve the burst release problem caused by mixed wall material nanofibers and the problem of how to maintain the effectiveness and stability of drugs or active compounds in the existing technology using single-axis electrospinning.

[0005] The purpose of the present application is achieved as follows: A chitosan / polyvinyl alcohol electrospun film loaded with beta-cyclodextrin and essential oil, the raw materials of which include deionized water, chitosan, acetic acid, polyvinyl alcohol, beta-cyclodextrin and essential oil.

[0006] Further, a preparation method of a chitosan / polyvinyl alcohol electrospun film loaded with beta-cyclodextrin and essential oil, the method comprising the following steps: Step S1: chitosan is placed in acetic acid and stirred until completely dissolved to prepare a chitosan solution; polyvinyl alcohol is added to deionized water and stirred to prepare a polyvinyl alcohol solution; the chitosan solution and the polyvinyl alcohol solution are mixed and stirred to prepare a shell spinning solution; Step S2: essential oil and beta-cyclodextrin are mixed to obtain a beta-cyclodextrin and essential oil mixed solution, which is added to the chitosan and polyvinyl alcohol mixed solution, stirred and mixed, and then left to stand and defoam to obtain a core spinning solution; Step S3: using a coaxial electrospinning device, the shell spinning solution obtained in step S1 and the core spinning solution obtained in step S2 are injected into the outer channel and inner channel of the coaxial needle respectively, and then spinning is carried out; the β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning film is collected on the receiving device. The raw materials in claim 1 include water, but there is no water in claim 2. Check it out Further, the concentration of acetic acid in step S1 is 0.5%-1.5% (w / v); The concentration of the chitosan solution is 0.5%-1.5% (w / v); The concentration of the polyvinyl alcohol solution is 9%-12% (w / v); The chitosan solution and the polyvinyl alcohol solution are mixed in a ratio of 1-5:5-9 by volume; The temperature of the stirring is 75-90°C; the stirring time is 2-7 hours; and the stirring rate is 500-700 revolutions / minute.

[0007] Further, the essential oil in step S2 has antibacterial properties.

[0008] Further, in step S2, the essential oil and β-cyclodextrin are mixed in a molar ratio of 1-2:1-2; The amount of β-cyclodextrin@essential oil mixed solution added to the chitosan / polyvinyl alcohol mixed solution is 4%-24% (w / v); The standing time of the chitosan / polyvinyl alcohol mixed solution is 6-24 hours.

[0009] Further, in step S3, the electrospinning process conditions are: positive voltage 15.00-25.00 kilovolts, negative voltage -1.00--2.00 kilovolts; The flow rate of the shell and core spinning solutions is 0.04-0.08 millimeters / minute; The receiving distance is 12.00-16.00 centimeters; and the receiving speed is 20-35 revolutions / minute.

[0010] The application of a β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol electrospinning film, the application of the β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning film in the preservation of baked goods, specifically includes: Step 1: weigh 220 grams of water, 4 grams of dry yeast, 300 grams of ordinary flour and 3 grams of salt; mix them to make a dough; let it ferment for 2 hours; then divide it into several doughs of the same size; bake at a temperature of 220°C for about 15 minutes; Step 2: Place the dough product into a sterile culture dish, place the beta-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film therein, and place the dough product with the non-beta-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film as a blank, cover the culture dish, and seal it with plastic wrap; Step 3: After the dough product is stored under the non-beta-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film and the beta-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film for 9 days, respectively, observe the deterioration of the surface of the bread; Further, the mass of the dough product in step 2 is 10±0.5 grams; and the mass of the film is 50 milligrams.

[0011] Further, the fibrous film is preserved by non-direct contact.

[0012] Further, the dough product in step 3 is any one of the baked goods.

[0013] Compared with the prior art, the present application has the following beneficial effects: The present application uses the coaxial electrospinning technology to prepare the beta-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol solution into a sustained-release film. The core-shell structure and the molecular embedding technology are synergistic, the coaxial electrospinning core-shell structure design is adopted: the outer sheath (chitosan polyvinyl alcohol) as a physical barrier, the core layer loaded with beta-cyclodextrin embedded essential oil, forming a “double controlled release system”, the multi-dimensional synergistic enhancement of the antibacterial function, forming a “1+1>2” synergistic antibacterial effect, while ensuring the stability of the antibacterial performance of the essential oil during storage and use. The preparation method of the present application avoids the burst problem caused by the mixed wall material nanofiber caused by the single-axis electrospinning; the nanofiber film formed by electrospinning has high specific surface area and porous structure, which can increase the contact area with microorganisms, while ensuring the air permeability of the material, and improving the practicability in the application scene of the actual baked product. BRIEF DESCRIPTION OF DRAWINGS

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiment description. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creating laborious work.

[0015] Figure 1 It is a principle diagram of the coaxial electrospinning sustained-release film in the present application; Figure 2 It is the encapsulation efficiency of the coaxial electrospinning sustained-release film; Figure 3 is the rheological property of the spinning solution; Figure 4Field emission scanning electron microscope and intuitive diagram of coaxial electrostatic spinning slow-release film; Figure 5 DPPH free radical scavenging rate of coaxial electrostatic spinning slow-release film with different concentrations; Figure 6 is the cumulative release amount and release rate of coaxial electrostatic spinning slow-release film with different concentrations at room temperature and 4℃; Figure 7 FT-IR diagram of coaxial electrostatic spinning slow-release film with different concentrations.

[0016] Figure 8 XRD diagram of coaxial electrostatic spinning slow-release film with different concentrations.

[0017] Figure 9 Antibacterial effect diagram and laser confocal diagram of coaxial electrostatic spinning slow-release film with different concentrations.

[0018] Figure 10 Preservation effect diagram of coaxial electrostatic spinning slow-release film with different concentrations on bread. DETAILED DESCRIPTION

[0019] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor should belong to the scope of protection of the present application. If not specifically indicated, the technical means used in the embodiments is the conventional means familiar to those skilled in the art.

[0020] As shown in Figure 1 The present application provides a preparation method of a β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol electrostatic spinning film, which comprises the following steps: Step S1: chitosan is placed in acetic acid and stirred until completely dissolved to prepare a chitosan solution; polyvinyl alcohol is stirred to prepare a polyvinyl alcohol solution; and the chitosan solution and the polyvinyl alcohol solution are mixed to prepare a shell spinning solution; Step S2: essential oil and β-cyclodextrin are mixed to obtain a β-cyclodextrin@essential oil mixed solution, and the mixed solution is added to the chitosan and polyvinyl alcohol mixed solution, stirred and mixed, and then left to defoam to obtain a core spinning solution; Step S3: the shell spinning solution obtained in step S1 and the core spinning solution obtained in step S2 are respectively injected into the outer channel and the inner channel of a coaxial needle by using a coaxial electrostatic spinning device, and then spinning is performed; and the β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrostatic spinning film is collected on a receiving device.

[0021] Specifically, the preparation method of the present application is to dissolve chitosan in an acidic solution and mix with a polyvinyl alcohol solution to prepare a shell spinning solution, add essential oil and β-cyclodextrin to the chitosan / polyvinyl alcohol mixed solution to prepare a core layer, and prepare a chitosan / polyvinyl alcohol coaxial electrospinning membrane loaded with β-cyclodextrin@essential oil; β-cyclodextrin can successfully encapsulate essential oil, and the encapsulation rate of essential oil in β-cyclodextrin@essential oil fiber membranes of different concentrations reaches more than 85%, with good encapsulation effect Figure 2 、 Figures 7-8 ), and the best encapsulation effect is 20%, which can reach more than 90%. And the membrane loaded with 20% β-cyclodextrin@essential oil has strong antioxidant capacity Figure 5 ), obvious antibacterial effect Figures 9-10 ), and good sustained-release effect (Figure 6); the coaxial electrospinning sustained-release membrane prepared by the present application has great advantages compared with other preservative films for releasing essential oil, and is a non-direct contact sustained-release fiber film, which can prolong the shelf life of baked foods and maintain their quality.

[0022] Moreover, chitosan is a natural amino polysaccharide with good biocompatibility, degradability, and antibacterial properties. Polyvinyl alcohol is a synthetic polymer with no toxicity and good biocompatibility. The mechanical properties of these two materials are complementary, the spinning process is adaptable, the function is adjustable, and the degradation is controllable. The fibers spun from the two materials are suitable for different scenarios such as medical dressings to promote wound healing, food packaging to resist bacteria and preserve freshness, etc. Moreover, β-cyclodextrin has a unique structure of "hollow conical cavity", which can form a stable "host-guest inclusion compound" with essential oil, significantly improving the application defects of essential oil, enhancing the stability, and controlling the release rate. Combining coaxial electrospinning technology with β-cyclodextrin encapsulated essential oil forms a "double controlled release system", ensuring the sustained release of essential oil, and can improve the practicality in the application scenario of actual baked products.

[0023] Optionally, the concentration of acetic acid in step S1 is 0.5-1.5% (w / v); the concentration of the prepared chitosan solution is 0.5-1.5% (w / v); and the concentration of the prepared polyvinyl alcohol solution is 9-12% (w / v); the stirring temperature is 75-90°C.

[0024] Optionally, the chitosan solution and polyvinyl alcohol solution in step S1 are mixed in a volume ratio of 1-5:5-9; the mixed solution is stirred at 500-700 rpm; and the stirring time is 2-7 hours.

[0025] Optionally, in step S2, the essential oil and β-cyclodextrin are mixed in a molar ratio of 1-2:1-2; β-cyclodextrin@essential oil is added to the chitosan / polyvinyl alcohol mixed solution, and the concentration of β-cyclodextrin@essential oil is 0%, 4%, 8%, 12%, 16%, 20% and 24% (w / v) respectively; the standing time is 6-24 hours.

[0026] The essential oil in step S2 is any one with antibacterial property, such as eugenol essential oil, carvacrol essential oil, mint essential oil, lemon essential oil, tea tree essential oil, orange peel essential oil, etc.

[0027] Optionally, in step S3, the electrospinning process conditions are: positive voltage is 15.00-25.00 kilovolts, negative voltage is -1.00--2.00 kilovolts; the flow rate of the shell layer and core layer spinning solution is 0.04-0.08 millimeters / minute, the receiving distance is 12.00-16.00 centimeters, and the receiving speed is 20-35 revolutions / minute. This process condition ensures the balance between the spinning solution supply amount and the stretching amount, avoiding fiber adhesion caused by too high flow rate or broken filament caused by too low flow rate.

[0028] Control group Preparation of coaxial electrospun membrane.

[0029] (1) Chitosan is placed in 1% (w / v) acetic acid and stirred at 85°C until completely dissolved to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol is stirred at 85°C to prepare a 10% (w / v) polyvinyl alcohol solution. The chitosan solution and polyvinyl alcohol solution are mixed at 3:7 and stirred at 600 revolutions / minute for 4-5 hours to prepare a shell layer spinning solution.

[0030] (2) No core layer.

[0031] (3) The shell layer spinning solution obtained in step (1) is injected into the coaxial needle channel, and then electrospinning is performed; the chitosan / polyvinyl alcohol coaxial electrospun membrane is collected on the receiving device; the electrospinning process conditions are: positive voltage is 20.00 kilovolts, negative voltage is -1.50 kilovolts, flow rate of shell layer and core layer solution is 0.06 millimeters / minute, receiving distance is 14.00 centimeters, and receiving speed is 25 revolutions / minute.

[0032] Example 1 Preparation of coaxial electrospun membrane.

[0033] (1) The chitosan was placed in 0.5% (w / v) acetic acid and stirred at 75°C until completely dissolved to prepare a 0.5% (w / v) chitosan solution. The polyvinyl alcohol was added to deionized water and stirred at 75°C to prepare a 9% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at a ratio of 2:8 and stirred at 500 rpm for 2-3 hours to prepare a shell spinning solution.

[0034] (2) For the core layer, essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:2 at 4% (w / v) respectively, and then the mixed solution was left to stand for 6 hours to remove bubbles and was ready for use.

[0035] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of a coaxial needle respectively, and then spinning was performed. The β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning membrane was collected on a receiving device. The electrospinning process conditions were as follows: positive voltage 15.00 kV, negative voltage -1.00 kV, flow rate of the shell and core layer solutions 0.04 mm / min, receiving distance 12.00 cm, and receiving speed 20 rpm.

[0036] Example 2 Preparation of a coaxial electrospinning membrane.

[0037] (1) The chitosan was placed in 1.5% (w / v) acetic acid and stirred at 80°C until completely dissolved to prepare a 1.5% (w / v) chitosan solution. The polyvinyl alcohol was added to deionized water and stirred at 80°C to prepare an 11% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at a ratio of 1:9 and stirred at 700 rpm for 4-5 hours to prepare a shell spinning solution.

[0038] (2) For the core layer, essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 2:1 at 8% (w / v) respectively, and then the mixed solution was left to stand for 24 hours to remove bubbles and was ready for use.

[0039] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of a coaxial needle respectively, and then spinning was performed. The β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning membrane was collected on a receiving device. The electrospinning process conditions were as follows: positive voltage 25.00 kV, negative voltage -2.00 kV, flow rate of the shell and core layer solutions 0.08 mm / min, receiving distance 16.00 cm, and receiving speed 30 rpm.

[0040] Example 3 Preparation of a coaxial electrospinning membrane.

[0041] (1) Chitosan was placed in 1% (w / v) acetic acid and stirred at 90°C until completely dissolved to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol was added to deionized water and stirred at 90°C to prepare a 12% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at 4:6 and stirred at 600 rpm for 6-7 hours to prepare a shell spinning solution.

[0042] (2) For the core layer, essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:2 at 12% (w / v), respectively, and then the mixed solution was left to stand for 12 hours to remove bubbles, ready for use.

[0043] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of the coaxial needle, respectively, and then spinning was performed; the β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning membrane was collected on the receiving device; the electrospinning process conditions were as follows: positive voltage 20.00 kV, negative voltage -1.50 kV, flow rate of the shell and core layer solutions 0.06 mm / min, receiving distance 14.00 cm, and receiving speed 35 rpm.

[0044] Example 4 Preparation of a coaxial electrospinning membrane.

[0045] (1) Chitosan was placed in 1% (w / v) acetic acid and stirred at 85°C until completely dissolved to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol was added to deionized water and stirred at 85°C to prepare a 10% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at 5:5 and stirred at 600 rpm for 4-5 hours to prepare a shell spinning solution.

[0046] (2) For the core layer, essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:1 at 16% (w / v), respectively, and then the mixed solution was left to stand for 12 hours to remove bubbles, ready for use.

[0047] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of the coaxial needle, respectively, and then spinning was performed; the β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning membrane was collected on the receiving device; the electrospinning process conditions were as follows: positive voltage 20.00 kV, negative voltage -1.50 kV, flow rate of the shell and core layer solutions 0.06 mm / min, receiving distance 14.00 cm, and receiving speed 25 rpm.

[0048] Example 5 Preparation of coaxial electrospun membrane.

[0049] (1) Chitosan was dissolved in 1% (w / v) acetic acid at 85°C to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol was dissolved in deionized water at 85°C to prepare a 10% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at a ratio of 3:7 and stirred at 600 rpm for 4-5 hours to prepare a shell spinning solution.

[0050] (2) For the core layer, 20% (w / v) essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:1, and then the mixed solution was left to stand for 12 hours to remove bubbles, ready for use.

[0051] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of a coaxial needle, respectively, and then electrospinning was performed. The β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun membrane was collected on a receiving device. The electrospinning process conditions were as follows: positive voltage 20.00 kV, negative voltage -1.50 kV, shell and core solution flow rate 0.06 mm / min, receiving distance 14.00 cm, and receiving speed 25 rpm.

[0052] Example 6 Preparation of coaxial electrospun membrane.

[0053] (1) Chitosan was dissolved in 1% (w / v) acetic acid at 85°C to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol was dissolved in deionized water at 85°C to prepare a 10% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at a ratio of 3:7 and stirred at 600 rpm for 4-5 hours to prepare a shell spinning solution.

[0054] (2) For the core layer, 24% (w / v) essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:1, and then the mixed solution was left to stand for 12 hours to remove bubbles, ready for use.

[0055] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of a coaxial needle, respectively, and then electrospinning was performed. The β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun membrane was collected on a receiving device. The electrospinning process conditions were as follows: positive voltage 20.00 kV, negative voltage -1.50 kV, shell and core solution flow rate 0.06 mm / min, receiving distance 14.00 cm, and receiving speed 25 rpm.

[0056] Example 7 Preparation of coaxial electrospinning membrane.

[0057] (1) Chitosan was dissolved in 1% (w / v) acetic acid at 85°C to prepare a 1% (w / v) chitosan solution. Polyvinyl alcohol was dissolved in deionized water at 85°C to prepare a 10% (w / v) polyvinyl alcohol solution. The chitosan solution and the polyvinyl alcohol solution were mixed at a ratio of 3:7 and stirred at 600 rpm for 4-5 hours to prepare a shell spinning solution.

[0058] (2) For the core layer, 24% (w / v) essential oil and β-cyclodextrin were added to the chitosan / polyvinyl alcohol mixed solution at a molar ratio of 1:1, and then the mixed solution was left to stand for 12 hours to remove bubbles, ready for use.

[0059] (3) The shell spinning solution obtained in step (1) and the core spinning solution obtained in step (2) were injected into the outer channel and the inner channel of a coaxial needle, respectively, and then electrospinning was performed. The β-cyclodextrin@essential oil loaded chitosan / polyvinyl alcohol coaxial electrospinning membrane was collected on a receiving device. The electrospinning process conditions were as follows: positive voltage 20.00 kV, negative voltage -1.50 kV, shell and core solution flow rate 0.06 mm / min, receiving distance 14.00 cm, and receiving speed 25 rpm.

[0060] The essential oil in this example is any one of the antibacterial essential oils, which are not exemplified one by one.

[0061] In the above examples, the chitosan solution and the polyvinyl alcohol solution are mixed in a ratio of 3:7 by volume, the advantages are complementary, the molecular interaction is enhanced, and the performance of the two materials is coordinated. If the proportion of chitosan is too high, the amino group density of chitosan exceeds the binding capacity of the hydroxyl group of polyvinyl alcohol, and the unbound amino group will cause the electrostatic repulsion between chitosan molecules to increase, resulting in "local aggregation"; if the proportion of polyvinyl alcohol is too high: the excess of hydroxyl groups of polyvinyl alcohol weakens the hydrogen bond interaction with chitosan, leading to uneven dispersion of chitosan in the solution, and subsequent uneven film formation. Essential oil and β-cyclodextrin are mixed in a ratio of 1:1 by mole, so that each cavity of β-cyclodextrin is filled with essential oil molecules, and each essential oil molecule has a cavity to accommodate, forming a compact and not easily dissociated inclusion complex, avoiding intermolecular repulsion or cavity waste, and significantly improving the anti-volatility, anti-oxidation and anti-photolysis stability of essential oil. Gradient test was conducted on the β-cyclodextrin@essential oil in step (2), and the concentrations were 4%, 8%, 12%, 16%, 20% and 24% respectively; the encapsulation rate of essential oil in the β-cyclodextrin@essential oil fiber film of different concentrations all reached more than 85%, the best concentration for encapsulation effect was 20%, which could reach more than 90%, and the film was more uniform and dense, and the DPPH free radical scavenging rate could reach more than 80%, while the blank control group was only about 30%. Whether in room temperature environment or in 4℃ environment, as the temperature rises, the release of phenolic substances will be accelerated, the release amount of essential oil in 4%-24% group increases with the increase of concentration in 4℃ environment, and the release rate increases with the increase of concentration, but the overall is much lower than that in room temperature, and the 20% group has the most obvious slow release and antibacterial effect. As shown in Figure 2 , it has good encapsulation effect; the rheological properties of β-cyclodextrin@essential oil spinning solution of different concentrations are shown in FIG. 3, Figure 3A which is the viscosity graph of the spinning solution, the viscosity of the solution is crucial for the preparation of nanomaterials, especially the fiber diameter, when the viscosity increases, the nanofiber diameter of the nanomaterials will also increase, and as the shear rate increases, the viscosity of the spinning solution gradually decreases, the solution in the figure meets the "shear thinning" characteristics, and has spinnability, Figure 3B which is the frequency graph of the spinning solution, as the frequency increases, G' and G'' both increase, G' is always greater than G'', which indicates that the spinning solution is dominated by elastic properties and exhibits viscoelastic solid characteristics, enhancing the structural stability of the material and having good viscoelasticity; the SEM and intuitive graphs of the fiber film are shown in Figure 4 , there are beaded fibers and fiber adhesion defects in 0%, 4%, 12%, 16% and 24% fibers, the shape of 20% fiber is clear and uniform compared with other groups, and the porous structure formed on the surface is also clearer and denser; the higher the concentration of β-cyclodextrin@essential oil in 4%-20% group, the stronger the antioxidant capacity, as shown in Figure 5 ; the antibacterial effect of 20% and 24% groups is obvious, as shown in Figures 9-10 , combined with Figure 9From the inhibition experiment and laser confocal image of E. coli and S. aureus, it can be seen that the number of live bacteria in the bacterial solution and culture medium without fiber film is the largest, and the inhibition effect of the β-cyclodextrin@ essential oil fiber film with different concentrations on E. coli and S. aureus is different. Compared with the films of other groups, the 20% has the highest antibacterial activity on the two microorganisms. These bacteriostatic results also show that the antibacterial activity of essential oil can be maintained after being encapsulated by β-cyclodextrin. It has a slow-release effect, and the slow-release effect is better at 4°C, as shown in Figure 6, Figure 6A With Figure 6B The release amount and release rate of the β-cyclodextrin@ essential oil fiber film with different concentrations at room temperature, Figure 6C With Figure 6D The release amount and release rate of the β-cyclodextrin@ essential oil fiber film with different concentrations at 4°C, whether at room temperature or at 4°C, the release of phenolic substances will be accelerated with the increase of temperature. The release amount of essential oil of the 4%-24% group increases with the increase of concentration, and the release rate increases with the increase of concentration, but the overall is much lower than that at room temperature. Compared with other preservative films for slow release of essential oil, it has great advantages.

[0062] Example 8 The β-cyclodextrin@ essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film is used for the preservation application of baked products.

[0063] (1): Take 220 grams of water, 4 grams of dry yeast, 300 grams of ordinary flour and 3 grams of salt. Mix them to make dough. Let it ferment for 2 hours. Then divide it into several doughs of the same size. Bake at a temperature of 220°C for about 15 minutes; (2): Place the baked product (10±0.5 grams) in a sterile culture dish, place the β-cyclodextrin@ essential oil loaded chitosan / polyvinyl alcohol coaxial electrospun film (50 milligrams) therein, cover the culture dish and seal it with a preservative film; (3): After storing the baked product under the chitosan / polyvinyl alcohol coaxial electrospun film without β-cyclodextrin@ essential oil and the chitosan / polyvinyl alcohol coaxial electrospun film loaded with different concentrations of β-cyclodextrin@ essential oil for 9 days, observe the deterioration of the surface of the bread.

[0064] The baked product in this example is any one of the baked products, such as bread, cake, biscuit, etc. Here, they are not exemplified one by one.

[0065] In the above examples, it can be observed that the breads with the chitosan / polyvinyl alcohol coaxial electrospun film without β-cyclodextrin / essential oil have a more serious degree of spoilage than the breads with the chitosan / polyvinyl alcohol coaxial electrospun film loaded with β-cyclodextrin / essential oil. This indicates that the β-cyclodextrin / essential oil in the chitosan / polyvinyl alcohol coaxial electrospun film loaded with β-cyclodextrin / essential oil has a role in preventing the deterioration and antibacterial effect on the bread. However, the fiber film containing a higher concentration of β-cyclodextrin / essential oil shows a stronger ability to inhibit the deterioration and degradation of the bread, and the film containing 20% β-cyclodextrin / essential oil has the most significant antibacterial effect, inhibiting the deterioration speed of the bread and appropriately prolonging the shelf life of the bread.

[0066] The above merely provides a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A chitosan / polyvinyl alcohol electrospun membrane loaded with β-cyclodextrin@essential oil, characterized in that, The raw materials include deionized water, chitosan, acetic acid, polyvinyl alcohol, β-cyclodextrin, and essential oils.

2. A method for preparing a chitosan / polyvinyl alcohol electrospun membrane loaded with β-cyclodextrin@essential oil, characterized in that, The method includes the following steps: Step S1: Chitosan is placed in acetic acid and stirred until completely dissolved to prepare a chitosan solution; polyvinyl alcohol is added to deionized water and stirred to prepare a polyvinyl alcohol solution; the chitosan solution and polyvinyl alcohol solution are mixed and stirred to prepare a shell spinning solution; Step S2: Mix the essential oil and β-cyclodextrin to obtain a β-cyclodextrin@essential oil mixed solution. Add the mixed solution to the chitosan and polyvinyl alcohol mixed solution, stir and mix, and let stand to defoam to obtain the core spinning solution. Step S3: Using a coaxial electrospinning device, the shell spinning solution obtained in step S1 and the core spinning solution obtained in step S2 are injected into the outer and inner channels of the coaxial needle, respectively, and then spinning is performed; the chitosan / polyvinyl alcohol coaxial electrospun membrane loaded with β-cyclodextrin@essential oil is collected on the receiving device.

3. The method for preparing a chitosan / polyvinyl alcohol electrospun membrane loaded with β-cyclodextrin@essential oil according to claim 2, characterized in that, The concentration of acetic acid in step S1 is 0.5%-1.5% (w / v); The concentration of the chitosan solution is 0.5%-1.5% (w / v). The concentration of the polyvinyl alcohol solutions is 9%-12% (w / v). The chitosan solution and polyvinyl alcohol solution are mixed in a volume ratio of 1-5:5-9; The stirring temperature is 75-90℃; the stirring time is 2-7 hours; and the stirring speed is 500-700 rpm.

4. The method for preparing a chitosan / polyvinyl alcohol electrospun membrane loaded with β-cyclodextrin@essential oil according to claim 2, characterized in that, The essential oil described in step S2 has antibacterial properties.

5. The method for preparing a chitosan / polyvinyl alcohol electrospun membrane loaded with β-cyclodextrin@essential oil according to claim 2, characterized in that, In step S2, the essential oil and β-cyclodextrin are mixed in a molar ratio of 1-2:1-2; The amounts of β-cyclodextrin@essential oil mixture added to the chitosan / polyvinyl alcohol mixture were 4%-24% (w / v). The chitosan / polyvinyl alcohol mixed solution was allowed to stand for 6-24 hours.

6. The method for preparing a chitosan / polyvinyl alcohol electrospun film loaded with β-cyclodextrin@essential oil according to claim 2, characterized in that, The electrospinning process conditions described in step S3 are: positive voltage of 15.00-25.00 kV and negative voltage of -1.00-2.00 kV; The flow rate of the spinning solution for the shell and core layers is 0.04-0.08 mm / min; The receiving distance is 12.00-16.00 cm; the receiving speed is 20-35 rpm.

7. An application of the chitosan / polyvinyl alcohol electrospun film loaded with β-cyclodextrin@essential oil as described in claim 1, characterized in that, The application of the chitosan / polyvinyl alcohol coaxial electrospun film loaded with β-cyclodextrin@essential oil in the preservation of baked goods specifically includes: Step 1: Weigh out 220g water, 4g dry yeast, 300g all-purpose flour and 3g salt; mix them to form a dough; let it ferment for 2 hours; then divide it into several equal-sized dough balls; bake at 220℃ for about 15 minutes. Step 2: Place the dough product in a sterile petri dish, place the chitosan / polyvinyl alcohol coaxial electrospun membrane loaded with β-cyclodextrin@essential oil in the dish, and use the dough product without the chitosan / polyvinyl alcohol coaxial electrospun membrane loaded with β-cyclodextrin@essential oil as a blank, cover the petri dish and seal it with plastic wrap. Step 3: After storing the bread products for 9 days in chitosan / polyvinyl alcohol coaxial electrospun membranes without β-cyclodextrin@essential oil and in chitosan / polyvinyl alcohol coaxial electrospun membranes loaded with β-cyclodextrin@essential oil, observe the spoilage on the bread surface.

8. The application of the chitosan / polyvinyl alcohol electrospun film loaded with β-cyclodextrin@essential oil according to claim 7, characterized in that, The mass of the dough product in step 2 is 10 ± 0.5 grams; the mass of the membrane is 50 milligrams.

9. The application of the chitosan / polyvinyl alcohol electrospun film loaded with β-cyclodextrin@essential oil according to claim 7, characterized in that, Chitosan / polyvinyl alcohol coaxial electrospun membranes loaded with β-cyclodextrin@essential oils preserve food through indirect contact.

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