CN114687075A

CN114687075A - Preservative film and preparation method and application thereof

Info

Publication number: CN114687075A
Application number: CN202210552448.9A
Authority: CN
Inventors: 梅清逸; 郑晨娜; 刁勇
Original assignee: Huaqiao University
Current assignee: Huaqiao University
Priority date: 2022-01-27
Filing date: 2022-05-19
Publication date: 2022-07-01
Anticipated expiration: 2042-05-19
Also published as: CN114411335A; CN114687075B

Abstract

The invention relates to the technical field of food preservation, and provides a preservative film and a preparation method and application thereof. The invention provides a preparation method of a preservative film, which comprises the following steps: mixing polyvinyl butyral, cinnamon essential oil and absolute ethyl alcohol to obtain a spinning solution; and (3) carrying out electrostatic spinning on the spinning solution to obtain the preservative film. The method provided by the invention adopts the polyvinyl butyral as the spinning main body, has better compatibility with the cinnamon essential oil, reduces the volatilization speed of the cinnamon essential oil, enables the cinnamon essential oil to be slowly released for a long time in the preservation process, and improves the sensory acceptability and the preservation time of the preserved objects. The invention adopts the electrostatic spinning mode, has simple operation, does not need to adopt complex sterilization and preservation procedures in the preservation process, and has relatively low cost. Meanwhile, the preservative film is prepared from nontoxic raw materials and an organic solvent, and the obtained preservative film is higher in safety.

Description

Preservative film and preparation method and application thereof

Technical Field

The invention relates to the technical field of food preservation, in particular to a preservative film and a preparation method and application thereof.

Background

The yield of aquatic products in China accounts for more than 30% of the total yield of aquatic products all over the world, and the total quantity of import and export of aquatic products is in a growing trend in recent years, wherein prawns, tilapia and large yellow croakers are used as main export varieties. With the increase of the total quantity of imports and exports of aquatic products, the problem of storage of the aquatic products is accompanied, and chemical preservatives mainly comprising potassium sorbate and sodium benzoate are frequently used in the market at present, and although the chemical preservatives have good preservation effect, the chemical preservatives can cause damage to human health after being excessively ingested for a long time. In recent years, with the emphasis on food safety, natural preservatives have been paid attention to because of their higher safety.

Patent No. 201410187384.2 discloses a preservation method of large yellow croaker, which comprises sterilizing large yellow croaker with ozone water, then using tea polyphenols, nisin and chitosan as composite antistaling agent, and then packaging the large yellow croaker in modified atmosphere, so that the large yellow croaker has no abnormal odor, high safety and good sensory acceptance, but the method has high production cost and cannot be applied in large scale.

Cinnamon Essential Oil (CEO for short) is a fat-soluble natural mixture which is extracted from aromatic plants and has volatility and strong fragrance, has a good bacteriostatic effect on common food-borne pathogenic bacteria such as escherichia coli, shewanella putrefaciens and staphylococcus aureus, is low in cost, and can be used for food fresh keeping. However, CEO has strong volatility and pungent smell, and the initial volatile concentration is higher when the aquatic product is preserved for fresh use, so that the organoleptic acceptability of the aquatic product such as flavor, color and the like is reduced.

Disclosure of Invention

In view of the above, the invention provides a preservative film and a preparation method and application thereof. The preservative film provided by the invention can effectively solve the problem of easy volatilization of CEO, improves the sensory acceptability and the preservation time of aquatic products, and has the advantages of simple preparation method and low cost.

In order to achieve the above object, the present invention provides the following technical solutions:

a preparation method of a preservative film comprises the following steps:

mixing polyvinyl butyral, cinnamon essential oil and absolute ethyl alcohol to obtain a spinning solution;

and (3) carrying out electrostatic spinning on the spinning solution to obtain the preservative film.

Preferably, the mixing is: firstly, dissolving polyvinyl butyral in absolute ethyl alcohol to obtain a polymer solution, and then dissolving cinnamon essential oil in the polymer solution to obtain a spinning solution.

Preferably, the mass volume ratio of the polyvinyl butyral to the absolute ethyl alcohol in the polymer solution is 5-10 g:100 mL.

Preferably, the volume of the cinnamon essential oil accounts for 0.5-7.0% of the volume of the polymer solution.

Preferably, the parameters of the electrostatic spinning include: the positive voltage is 5-9 kv, the negative voltage is 0.8-1.5 kv, the receiving distance is 8-20 cm, the spinning speed is 2-5 mL/h, the spinning time is 0.5-2 h, and the inner diameter of the needle is 0.3-0.6 mm.

Preferably, after the spinning solution is obtained, the spinning solution is subjected to ultrasonic treatment, the power of the ultrasonic treatment is 500-700W, the temperature of the ultrasonic treatment is 20-35 ℃, and the time of the ultrasonic treatment is 0.5-1 h.

Preferably, the method further comprises the following steps of: and (3) standing and defoaming the spinning solution.

The invention provides the preservative film obtained by the preparation method in the technical scheme, the thickness of the preservative film is 0.050-0.120 mm, and the preservative film comprises a polyvinyl butyral fiber film matrix and cinnamon essential oil dispersed in polyvinyl butyral fibers.

The invention also provides the application of the preservative film in the technical scheme in the insurance of the large yellow croakers.

The invention provides a preparation method of a preservative film, which comprises the following steps: mixing polyvinyl butyral, cinnamon essential oil and absolute ethyl alcohol to obtain a spinning solution; and (3) carrying out electrostatic spinning on the spinning solution to obtain the preservative film. The method provided by the invention adopts the polyvinyl butyral as the spinning main body, has better compatibility with the cinnamon essential oil, reduces the volatilization speed of the cinnamon essential oil, reduces the initial volatilization concentration of the cinnamon essential oil, has little influence on the flavor and color of aquatic products, improves the sensory acceptability of the preserved aquatic products, and simultaneously ensures that the cinnamon essential oil is slowly released for a long time in the preservation process, thereby prolonging the preservation time of the aquatic products. The invention adopts the electrostatic spinning mode, has simple operation, does not need to adopt complex sterilization and preservation procedures in the preservation process, and has relatively low cost. Meanwhile, the preservative film is prepared from nontoxic raw materials and an organic solvent, and the obtained preservative film is higher in safety.

Furthermore, by controlling the amount of the cinnamon essential oil, the antibacterial performance of the preservative film is improved, and the mechanical property of the preservative film is also improved, so that the preservative film has better elasticity and is not easy to break when in use.

The invention also provides the preservative film prepared by the scheme and application thereof in preservation of large yellow croakers. The application example of the invention shows that the preservative film provided by the invention can effectively inhibit the putrefaction of the large yellow croaker and prolong the shelf life of the large yellow croaker, and has an excellent preservation effect.

Drawings

FIG. 1 is a scanning electron micrograph of a spun film obtained in comparative example 1;

FIG. 2 is a scanning electron microscope image of the preservative film obtained in example 1;

FIG. 3 is an external view of the spun film obtained in comparative example 1 and the wrap film obtained in example 1;

FIG. 4 is a graph showing the appearance of the control sample, PVB sample and PVB + cinnamon essential oil sample at days 0-8;

FIG. 5 is a graph showing changes in pH values of a control sample, a PVB sample and a PVB + cinnamon essential oil sample at days 0-8;

FIG. 6 is a graph of the change in volatile basic nitrogen content from day 0 to day 8 for control, PVB, and PVB + cinnamon essential oil samples;

FIG. 7 is a graph showing the change in the total number of colonies on days 0 to 8 for the control sample, the PVB sample, and the PVB + cinnamon essential oil sample;

FIG. 8 is a graph comparing the effect of the preservative film obtained in example 1 on the sustained release of the CEO in an absolute ethanol solution.

Detailed Description

A preparation method of a preservative film comprises the following steps:

Unless otherwise specified, the starting materials for the preparation used in the present invention are commercially available.

The invention mixes polyvinyl butyral, cinnamon essential oil and absolute ethyl alcohol to obtain spinning solution. In the present invention, the method of mixing is preferably: firstly, dissolving polyvinyl butyral in absolute ethyl alcohol to obtain a polymer solution, and then dissolving cinnamon essential oil in the polymer solution to obtain a spinning solution. The PVB is used as the main material of the preservative film, the preservative film is higher in safety, and the absolute ethyl alcohol is used as the solvent, so that on one hand, the absolute ethyl alcohol is low in toxicity and beneficial to further improving the safety of the preservative film, and on the other hand, the solubility of the CEO in the spinning solution is beneficial to being improved, and the CEO is easier to disperse into PVB molecules. In the present invention, the mass-to-volume ratio of the polyvinyl butyral to the absolute ethyl alcohol is preferably 5 to 10g:100mL, more preferably 6 to 9g:100mL, even more preferably 6 to 8g:100mL, and most preferably 7g:100mL, and in the present invention, the mass-to-volume ratio of the polyvinyl butyral to the absolute ethyl alcohol is preferably controlled within the above range, which is advantageous for sufficiently dissolving PVB in a solvent and forming a spinning solution with an appropriate viscosity. After the polymer solution is obtained, the present invention preferably sonicates the polymer solution until there are no bubbles in the spinning dope. In the invention, the temperature of ultrasonic treatment is preferably 20-35 ℃, the time power of ultrasonic treatment is 500-700W, and the time of ultrasonic treatment is preferably 0.5-1 h.

In the present invention, the volume of the cinnamon essential oil is preferably 0.5 to 7.0% of the volume of the polymer solution, more preferably 0.5 to 5.0%, even more preferably 1.0 to 3.0%, and most preferably 2.0%. In the invention, the cinnamon essential oil can be used as a bacteriostatic agent to improve the fresh-keeping effect of the fresh-keeping film. Meanwhile, the volume of the cinnamon essential oil is controlled within the range, the slow release effect of the cinnamon essential oil can be improved, the mechanical property of the preservative film can be improved, and the preservative film has better elasticity and is not easy to break when in use. The cinnamon essential oil is dissolved in the polymer solution by stirring preferably. In the specific embodiment of the invention, the stirring is preferably magnetic stirring, and the invention has no special requirements on the specific stirring equipment and conditions, so that the stirred preservative film solution is clear and transparent visually, has no obvious insoluble substances and has no obvious layering. In the invention, after the spinning solution is obtained, the spinning solution is subjected to standing defoaming treatment.

After the spinning solution is obtained, the invention carries out electrostatic spinning on the spinning solution to obtain the preservative film. In the present invention, the parameters of the electrospinning include: the positive voltage is preferably 5-9 kv, more preferably 6-8 kv, further preferably 7-8 kv, and most preferably 7.5 kv; the negative voltage is preferably 0.8-1.5 kv, more preferably 0.8-1.2 kv, further preferably 0.9-1.1 kv, and most preferably 1.0 kv; the receiving distance is preferably 8-20 cm, more preferably 10-18 cm, further preferably 12-16 cm, and most preferably 15 cm; the spinning speed is preferably 2-5 mL/h, more preferably 2.5-4.5 mL/h, further preferably 3-4 mL/h, and most preferably 3.4 mL/h; the spinning time is preferably 0.5-2 h, more preferably 1-1.5 h, and most preferably 1.5 h; the inner diameter of the needle is preferably 0.3 to 0.6mm, more preferably 0.4 to 0.6mm, and further preferably 0.5 to 0.6 mm. In the specific embodiment of the invention, the types of the needles used are preferably 20G and 23G, wherein the 20G needle has an inner diameter of 0.6mm, an outer diameter of 0.9mm, an exposed length of 50mm and a total length of 62 mm; the 23G needle has an inner diameter of 0.3mm, an outer diameter of 0.6mm, an exposed length of 50mm, and a total needle length of 62 mm. In the electrostatic spinning process, charged polymer liquid drops are accelerated at the Taylor cone vertex of the capillary under the action of an electric field force to form a jet trickle, a solvent is evaporated in the jet process of the trickle, and finally the trickle falls on a receiving device to form a fibrous sheet-shaped object similar to a non-woven fabric, namely the preservative film disclosed by the invention. The invention preferably adopts the spinning parameters, is beneficial to obtaining the cellosilk with uniform size and shape, and improves the formability and the mechanical property of the preservative film.

After electrostatic spinning is finished, the obtained preservative film is preferably dried, the drying mode is preferably vacuum drying, and the temperature of the vacuum drying is preferably 20-40 ℃, more preferably 25-35 ℃, and further preferably 28-30 ℃. In a specific embodiment of the present invention, the temperature of the vacuum drying is 30 ℃.

The invention also provides the preservative film prepared by the technical scheme, wherein the thickness of the preservative film is 0.050-0.120 mm, preferably 0.050-0.100 mm, and more preferably 0.060-0.080 mm. In the present invention, the wrap film preferably comprises a polyvinyl butyral fiber film matrix and cinnamon essential oil dispersed in the polyvinyl butyral fiber.

The invention also provides the application of the preservative film prepared by the technical scheme in the preservation of large yellow croakers. The application of the preservative film of the present invention is not particularly required, and is subject to the manner well known to those skilled in the art.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention.

Example 1

Dissolving PVB in absolute ethyl alcohol according to the mass-volume ratio of 7g to 100mL at room temperature, and carrying out ultrasonic treatment until no bubbles exist in the solution, wherein the ultrasonic temperature is 30 ℃, and the ultrasonic power is 600W; obtaining a polymer solution; after the polymer solution is obtained, the cinnamon essential oil is dripped into the polymer solution, the volume of the cinnamon essential oil accounts for 2% of the volume of the polymer solution, oil drops of the cinnamon essential oil are dispersed into the polymer solution in a magnetic stirring mode, and the stirred spinning solution is clear and transparent visually, and has no obvious insoluble substances or obvious layering. The spinning solution was allowed to stand until there were no air bubbles therein.

The spinning solution was charged into a syringe having a capacity of 5mL, and the type of the needle used was 20G, and electrostatic spinning was performed using an electrostatic spinning machine. The parameters of electrospinning were as follows: the positive voltage is 7.5kv, the negative voltage is 1kv, and the spinning distance is 15 cm; the spinning speed is 3.4 mL/h; spinning for 1.5h to obtain a spinning film, and drying the prepared spinning film in a vacuum drying oven at 30 ℃ to obtain the preservative film, wherein the thickness of the preservative film is 0.062 mm.

Example 2

The volume of cinnamon essential oil was adjusted to 3% of the volume of the spinning solution, and the other conditions were the same as in example 1, and a wrap film was prepared, the wrap film having a thickness of 0.059 mm.

Example 3

The needle type used in the electrostatic spinning was changed to 23G, and the other conditions were the same as in example 1, and a wrap film was prepared, the wrap film having a thickness of 0.066 mm.

Comparative example 1

A spun film having a thickness of 0.102mm was produced under the same conditions as in example 1, except that no cinnamon essential oil was added.

The spinning film obtained in the comparative example 1 and the preservative film obtained in the example 1 are characterized by a scanning electron microscope, and the characterization results are respectively shown in fig. 1 and fig. 2. Wherein FIG. 1 is a scanning electron microscope image of the spun film obtained in comparative example 1, and FIG. 2 is a scanning electron microscope image of the cling film obtained in example 1, with scales of both images being 10.0 μm. As can be seen from fig. 1, the spinning film obtained in comparative example 1 has a phenomenon of multiple fiber doubling, and certain "ravines" exist on the surface of the fiber, and as can be seen from fig. 2, under the same spinning parameters, due to the addition of CEO, CEO is an oily substance, and has a certain swelling effect on PVB, so that the ravines "on the fiber disappear, the doubling phenomenon is not obvious, and the surface is more smooth. Meanwhile, the lapped connection phenomenon is generated between the mutually crossed fiber yarns at a close distance, so that nodes are formed, an interconnected three-dimensional net structure is formed in the preservative film, and the tear resistance of the preservative film is improved.

The tensile strength and elongation at break of the wrap film obtained in example 1 and the spun film obtained in comparative example 1 were measured according to GB/T1040.2-2006, respectively, and the measurement results are shown in Table 1, and the appearance states of both are shown in FIG. 4.

Table 1 test results of tensile strength and elongation at break of example 1 and comparative example 1

As can be seen from Table 1, in example 1, due to the addition of the appropriate amount of CEO, the tensile strength and elongation at break are improved, especially the elongation at break is increased more remarkably, compared with comparative example 1 without the addition of CEO. The test result shows that the addition of the CEO is beneficial to the formation of an interconnected three-dimensional network structure in the preservative film, so that the toughness of the preservative film is improved and the preservative film is not easy to tear.

Fig. 3 is an appearance diagram of the spun film obtained in comparative example 1 and the wrap film obtained in example 1, the left side diagram is an appearance diagram of the spun film obtained in comparative example 1, and the right side diagram is an appearance diagram of the wrap film obtained in example 1. Because the surface of the microscopic fiber yarns is smoother under the swelling action of the CEO, the appearance of the preservative film obtained in the embodiment 1 is smoother and has fewer folds, and the preservative film is more favorable for the adhesion between the preservative film and a preserved object and improves the preservation effect when used for preservation.

Application example 1

Removing head and viscera of fresh Pseudosciaena crocea, cleaning the rest part with clear water, cutting into fish meat pieces with the same weight, and ensuring the freshness of the fish meat pieces to be consistent. A piece of fish meat was completely wrapped with the wrap film of example 1 and the spun film of comparative example 1, and air between the film layer and the fish meat was discharged, and the samples were named PVB + cinnamon essential oil and PVB, and a piece of fish which was not wrapped with any film was named a control sample. The three samples are marked as a group, the group of samples are placed in a refrigeration environment at 0-4 ℃, the appearance of the samples is observed every 48 hours, and the total number of colonies, the content of volatile basic nitrogen (TVB-N) and the pH value of each sample are detected and recorded, so that the change of the quality of the large yellow croaker is analyzed. Each set of experiments was set up with 2 parallel groups simultaneously. The experimental time was 8 days.

Fig. 4 is a graph of the appearance of each sample on

days

0, 2, 4, 6, and 8 of a set of samples, with control sample, PVB sample, and PVB + cinnamon essential oil sample on the left-hand side to the right-hand side. As can be seen from FIG. 3, the freshness of the fish fillets preserved by using the preservative film of example 1 is superior to that of the spun film of comparative example 1, and at the 8 th day, the fish fillets still maintain better viscoelasticity, and the meat quality and color are almost the same as those of the fish fillets on the 0 th day without deterioration. The fish fillets preserved with the spinning film of comparative example 1 exhibited slight viscoelastic deterioration on day 6. The control sample fish fillet has the largest freshness change degree, and the deterioration phenomenon occurs already on day 4, and the remarkable deterioration phenomena such as viscoelasticity deterioration, blackening and the like occur already on day 8. The preservative film prepared in the embodiment 1 has a good preservation effect, and is beneficial to improving the sensory acceptability of the large yellow croaker in preservation.

FIG. 5 is a graph showing the pH change of three samples during freshness preservation. As can be seen from fig. 4, the initial pH of the three coupons was 7.2. As the freshness time increased, the pH of the control sample increased from 7.2 to about 7.5 from day 2, after which the pH remained between 7.45 and 7.55, and the control sample was at a higher pH from day 2 to day 8. The pH of the sample using the spun film of comparative example 1 rose to the maximum on day 2, after which the pH remained no lower than 7.35 although a drop occurred. The pH value of the preservative film adopting the preservative film of the embodiment 1 is stable from day 0 to day 6 and is basically maintained at 7.2 until the pH value rises to 7.35 on day 8, the pH value of the whole preservative film is similar to the initial pH value in most of the preservation period, and even if the pH value of the whole preservative film rises, the change value is small, which shows that the preservative film obtained in the embodiment 1 has good preservation effect.

FIG. 6 is a graph showing the change in TVB-N content during freshness keeping of three samples, wherein the abscissa shows the TVB-N content per 100g of fish meat for the three samples. The TVB-N refers to basic nitrogen-containing substances such as ammonia and amines generated by decomposition of proteins under the action of enzymes and bacteria in the putrefaction process of animal food, and the higher the content of the basic nitrogen-containing substances, the more the amino acids in the food are destroyed, the more the nutritional value of the food is lost. As can be seen from fig. 6, the TVB-N contents of the three samples are not much different at day 0, and after day 2, the TVB-N contents of the three samples all start to increase at the rate of the control > PVB + cinnamon essential oil. On day 8, the TVB-N content of the control sample was the highest, reaching 193.2mg/100g, followed by the PVB sample, with a TVB-N content of 120.05mg/100g and the PVB + cinnamon essential oil sample at the lowest, reaching 71.4mg/100 g. As can be seen from figure 6, the preservative film prepared by the invention can effectively inhibit the growth of bacteria and prevent the loss of nutrient substances in the fish meat of the large yellow croaker due to the addition of CEO.

FIG. 7 is a graph showing the change in the total number of colonies during freshness keeping of three samples. As can be seen from fig. 7, the total number of colonies of the three samples on day 0 is not much different, and after day 2, the total number of colonies of the three samples increases, but on day 8, the total number of colonies of the PVB + cinnamon essential oil sample decreases, and the total number of colonies of the control sample and the PVB sample still increases, indicating that the preservative film prepared by the invention can achieve a good bacteriostatic effect, and prevent the large yellow croaker from rotting in a short time, thereby improving the preservation period of the large yellow croaker.

Application example 2

The preservative film obtained in example 1 and the absolute ethyl alcohol solution of CEO were subjected to a slow-release effect comparison experiment. The initial concentration of CEO in the wrap obtained in example 1 was 0.25 μ l/mL, at which the CEO retention was 100%, the sample was designated as PVB + cinnamon essential oil, the CEO concentration in an absolute ethanol solution of CEO was adjusted to be the same as in example 1, and the sample was designated as a control. The two samples were subjected to a sustained release effect test under the same conditions (25 ℃). The CEO concentration in both samples was measured every 24 h. The concentration of cinnamon essential oil was diluted to 16. mu.l/mL, 8. mu.l/mL, 4. mu.l/mL, 2. mu.l/mL, 1. mu.l/mL, 0.5. mu.l/mL, 0.25. mu.l/mL, 0.125. mu.l/mL, 0.0625. mu.l/mL, and the absorbance values thereof at different concentrations were measured, respectively. And performing linear regression analysis on the concentration and the absorbance of the cinnamon essential oil to obtain a fitting equation. And for the PVB + cinnamon essential oil sample, dissolving the preservative film with the same area every 24 hours to determine the absorbance, and for the control experiment, taking the solution with the same mass every 24 hours to determine the absorbance. And converting the absorbance into the existing concentration of the CEO by fitting an equation, calculating the ratio of the existing concentration of the CEO to the initial concentration to obtain the retention rate of the CEO, and measuring for 7 times.

The comparison result of the effect of slowly releasing the absolute ethanol solution of the wrap film obtained in example 1 and the CEO is shown in fig. 8, and it can be seen from fig. 8 that the retention rate of the CEO in the absolute ethanol solution of the CEO is 40% after 7 days, and the retention rate of the CEO in the wrap film of example 1 is still 60% or more. The experiment results show that the preservative film prepared by the invention can effectively reduce the volatilization speed of CEO, can effectively inhibit bacteria and is beneficial to long-acting preservation.

The mechanical properties of the preservative films prepared in the examples 2 and 3 were measured according to the method described in GB/T1040.2-2006, and the preservation effect and the sustained release effect of the preservative films prepared in the examples 2 and 3 were measured by the methods described in the application examples 1 and 2, and the performance effect of the preservative films prepared in the examples 2 and 3 was similar to that of the preservative film prepared in the example 1.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.

Claims

1. The preparation method of the preservative film is characterized by comprising the following steps of:

2. The method of claim 1, wherein the mixing is: firstly, dissolving polyvinyl butyral in absolute ethyl alcohol to obtain a polymer solution, and then dissolving cinnamon essential oil in the polymer solution to obtain a spinning solution.

3. The preparation method according to claim 2, wherein the mass-to-volume ratio of the polyvinyl butyral to the absolute ethanol in the polymer solution is 5-10 g:100 mL.

4. The method according to claim 3, wherein the volume of the cinnamon essential oil is 0.5-7.0% of the volume of the polymer solution.

5. The method for preparing as claimed in claim 1, wherein the parameters of electrospinning include: the positive voltage is 5-9 kv, the negative voltage is 0.8-1.5 kv, the receiving distance is 8-20 cm, the spinning speed is 2-5 mL/h, the spinning time is 0.5-2 h, and the inner diameter of the needle is 0.3-0.6 mm.

6. The preparation method according to claim 2, characterized in that after the spinning solution is obtained, the method further comprises the step of carrying out ultrasonic treatment on the spinning solution, wherein the power of the ultrasonic treatment is 500-700W, the temperature of the ultrasonic treatment is 20-35 ℃, and the time of the ultrasonic treatment is 0.5-1 h.

7. The method of claim 1, further comprising, prior to electrospinning: and (3) standing and defoaming the spinning solution.

8. The preservative film prepared by the preparation method of any one of claims 1 to 7, wherein the thickness of the preservative film is 0.050 to 0.120mm, and the preservative film comprises a polyvinyl butyral fiber film matrix and cinnamon essential oil dispersed in the polyvinyl butyral fibers.

9. Use of the preservative film according to claim 8 for preserving large yellow croaker.