CN111187434B

CN111187434B - Edible collagen film and preparation method thereof

Info

Publication number: CN111187434B
Application number: CN202010111127.6A
Authority: CN
Inventors: 吴国平; 钟婵; 后鹏飞
Original assignee: Jiangxi Agricultural University
Current assignee: Jiangxi Agricultural University
Priority date: 2020-02-24
Filing date: 2020-02-24
Publication date: 2021-08-13
Anticipated expiration: 2040-02-24
Also published as: CN111187434A

Abstract

The invention belongs to the technical field of packaging, and relates to a collagen edible film and a preparation method thereof. The preparation method comprises the steps of stirring and uniformly mixing the fish scale collagen matrix liquid, the protocatechuic acid improvement liquid and the plasticizing liquid, then carrying out ultrasonic treatment to fully mix and degas all the components to obtain ultrasonic mixed degassing liquid, then uniformly pouring the ultrasonic mixed degassing liquid on the organic silicon resin, drying, cooling to room temperature, and removing the film to obtain the edible collagen film. The edible collagen protein film prepared by the method has the thickness of 0.036-0.046mm, the transparency of 1.45-3.89, the elongation at break of 90.23-118.04%, the ultraviolet ray barrier rate of 99.10-99.71% and the water vapor barrier rate of 0.78-0.87 multiplied by 10^‑10gm^‑1·s^‑1·Pa^‑1The paint has the advantages of high ductility, high barrier property and high safety, and the preparation process is simple and has no pollution to the environment.

Description

Edible collagen film and preparation method thereof

Technical Field

The invention belongs to the technical field of edible food film packaging, and particularly relates to a collagen edible film and a preparation method thereof.

Background

Compared with the traditional synthetic packaging material, the edible film takes natural macromolecules as the substrate raw material and forms a film with certain mechanical strength and barrier property through intermolecular force. The edible film has digestibility and degradability, can reduce the harm to human health and reduce the pollution to the environment, and has attracted more and more attention in the food industry.

The fibrous collagen has the characteristics of good biocompatibility, good film-forming property, high nutritive value and the like, and is widely applied to the field of biological materials. In recent years, epidemic diseases such as global mad cow disease, foot and mouth disease, African swine fever and the like frequently occur, fish scale collagen can effectively replace collagen obtained from skins or bones of pigs, cattle and the like, the risk of disease cross infection is reduced, and the resource utilization of fish processing byproducts is improved. The fish scale collagen has the advantages of good safety, high cost performance, excellent quality and the like.

However, the film made of pure collagen has poor mechanical property and barrier property, and has no biological activities such as oxidation resistance, antibiosis and the like, thereby greatly limiting the application range of the film. Although chemically modified collagen (such as cross-linking and grafting reaction) can promote the formation of a collagen dense network structure and improve the mechanical properties of a collagen film, the preparation process is complex, chemical reagents are more remained, the environment pollution is serious, and the environment-friendly edible film preparation is difficult to realize.

CN109769920A discloses a preparation method of a fish scale protein-mesona blume-asparagus powder nutritional edible film, which is characterized in that mesona blume and tilapia fish scale collagen are mixed in proportion, and glycerin, sodium carboxymethylcellulose, asparagus powder and cranberry powder which improve mechanical properties and surface properties are added, so that the obtained edible film has antibacterial properties, oxidation resistance and good mechanical properties. However, the invention patent application has the following disadvantages: (1) although the breaking elongation of the edible film can be improved by adding the mesona blume gum, the final breaking elongation is only 40.22-51.73%, and compared with the presently reported edible film, the breaking elongation is lower, and the use limitation exists; (2) the Mesona gum in the edible film has a molecular weight of 80-150kDa, belongs to a macromolecular substance, and changes the mechanical property and the barrier property of the film through strong interaction (such as covalent cross-linking generated by a Maillard reaction) with collagen, but the Maillard reaction is that carboxyl of sugar and amino of protein (amino acid) generate a carbonylamine reaction, so that the nutrition loss of the collagen, especially essential amino acid for human body can be caused.

CN103554532B discloses a ferulic acid-collagen antibacterial film and a preparation method and application thereof, wherein the ferulic acid-collagen antibacterial film with excellent mechanical properties is obtained by adding ferulic acid, glycerol, dialdehyde starch and sodium alginate. When the thickness is 0.21mm, the tensile strength of the ferulic acid-collagen antibacterial film reaches 1.80-2.03MPa, and the elongation at break is 98.12-118.73%. However, the invention patent application has the following disadvantages: (1) the thickness of the collagen film prepared by the method is about 0.21 mm. Although the increased thickness can increase the mechanical and barrier properties of the collagen film, it can also affect the appearance of the food, affect the acceptance of the food by consumers, and have use limitations. (2) Although the mechanical properties of the edible collagen film are improved, ferulic acid can achieve this effect only when used in combination with dialdehyde starch and sodium alginate. In addition, the process of the patent application is complex and the preparation cost is high.

Protocatechuic acid (3, 4-dihydroxybenzoic acid) is widely present in many plants and traditional Chinese medicinal materials. It is a natural phenolic compound with good antioxidant, antibacterial and antitumor effects. After being eaten by human body, the health-care food can regulate and improve the immunity of the organism and the intestinal barrier function and is beneficial to the health of the organism. However, no reports on the preparation of edible films by matching protocatechuic acid with collagen exist.

CN106220876A discloses a preparation method of a chitosan-protocatechuic acid graft copolymer membrane. The patent application of the invention takes chitosan and protocatechuic acid as reaction substrates, and takes 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride (EDC)/N-hydroxysuccinimide (NHS) as a cross-linking agent to modify chitosan. The modified chitosan-protocatechuic acid graft copolymer membrane has obviously improved mechanical property and physical and chemical properties and higher antioxidant activity. However, the invention patent application has the following disadvantages: (1) the modification of chitosan membrane by protocatechuic acid is the premise of realizing the improvement of the performance of chitosan-protocatechuic acid graft copolymer membrane. The grafting reaction of protocatechuic acid and chitosan is completed in the presence of EDC and NHS crosslinking agent. Although EDC and NHS are non-toxic as cross-linking agents, the cleaning or dialysis of EDC and NHS after reaction adds complexity to the process of making edible films. (2) In the preparation process of the chitosan-protocatechuic acid graft copolymer membrane, the chitosan and the graft copolymer need to be dissolved in 2% acetic acid, and the graft copolymer membrane needs to be soaked in 0.1-1mol/L sodium hydroxide. The use of these acids and bases not only increases their risk of remaining in the edible film, but also the discharge of sewage causes environmental pollution.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides the collagen edible film which is simple in process, natural and environment-friendly, and has high ductility and high barrier property, and the preparation method thereof.

Specifically, the invention provides a preparation method of a collagen edible film, which comprises the following steps:

(1) preparing a film forming solution: uniformly stirring and mixing the scale collagen matrix liquid, the protocatechuic acid improvement liquid and the plasticizing liquid according to the proportion of 2-4 parts by weight of scale collagen, 0.2-0.8 part by weight of protocatechuic acid and 0.4-1 part by weight of plasticizer to obtain a modified scale collagen matrix film forming liquid; the scale collagen matrix solution is a crude scale collagen aqueous solution with the concentration of 5-10 wt%, the protocatechuic acid improvement solution is a protocatechuic acid aqueous solution with the concentration of 1-4 wt%, and the plasticizing solution is a plasticizer aqueous solution with the concentration of 1-2.5 wt%;

(2) ultrasonic mixing and degassing: carrying out ultrasonic treatment on the modified fish scale collagen matrix film-forming solution to fully mix and degas all components to obtain ultrasonic mixed degassing liquid;

(3) preparing the collagen edible film: and uniformly pouring the ultrasonic mixed degassing liquid on organic silicon resin, drying, cooling to room temperature, and removing the film to obtain the edible collagen film.

Further, the concentration of the fish scale collagen matrix liquid is 5-10 wt%, and the fish scale collagen matrix liquid is obtained by dissolving crude fish scale collagen powder in water at 60-70 ℃ with stirring.

Further, the protocatechuic acid-modified solution has a concentration of 1 to 4 wt%, which is obtained by dissolving protocatechuic acid powder in water with stirring.

Further, the plasticizing liquid has a concentration of 1 to 2.5wt%, which is obtained by dissolving a plasticizer in water with stirring.

Further, the modified fish scale collagen matrix film-forming solution is obtained by uniformly mixing the fish scale collagen matrix solution, the protocatechuic acid modified solution and the plasticizing solution in a ratio of 2:1:2(v: v: v).

Further, the crude extraction fish scale collagen powder is prepared by leaching fish scales at 70-90 ℃ for 1-3h and drying.

Further, the fish scale is selected from at least one of grass carp scale, silver carp scale and carp scale.

Further, the effective concentration of the protocatechuic acid powder is 95-99%.

Further, the plasticizer is selected from at least one of glycerol, sorbitol and ethylene glycol.

Further, the ultrasonic treatment conditions comprise that the ultrasonic frequency is 20-30KHz and the ultrasonic time is 15-20 min.

Further, the ultrasonic mixed degassing liquid is 18-25L/m²Poured evenly over the silicone resin.

Further, the drying conditions comprise that the temperature is 25-40 ℃, the humidity is 50-60%, and the time is 20-24 h.

According to a specific embodiment of the present invention, the method for preparing the collagen edible film comprises the following steps:

(1) preparing a film forming solution:

s1, preparing a fish scale collagen matrix liquid: dissolving the crude scale collagen powder in water of 60-70 deg.C under stirring to obtain 5-10 wt% scale collagen matrix solution;

s2, protocatechuic acid improvement solution: dissolving protocatechuic acid powder in water under stirring to obtain 1-4 wt% protocatechuic acid modified solution;

s3, preparation of plasticizing liquid: dissolving the plasticizer in water under stirring to obtain 1-2.5wt% plasticizing liquid;

s4, preparing a modified fish scale collagen matrix film forming solution: uniformly stirring and mixing the scale collagen matrix liquid, the protocatechuic acid improvement liquid and the plasticizing liquid in a ratio of 2:1:2(v: v: v) to obtain a modified scale collagen matrix film forming liquid;

(2) ultrasonic mixing and degassing: carrying out ultrasonic treatment on the modified fish scale collagen matrix film forming solution for 15-20min at the ultrasonic frequency of 20-30KHz so as to fully mix and degas all components to obtain an ultrasonic mixed degassing solution;

(3) preparing the collagen edible film: the ultrasonic mixed degassing liquid is mixed according to the volume of 18-25L/m²Uniformly pouring the collagen edible film on the organic silicon resin, then placing the organic silicon resin at the temperature of 25-40 ℃ and the humidity of 50-60% for drying for 20-24h, cooling to room temperature after drying is finished, and removing the film to obtain the collagen edible film.

In addition, the invention also provides the collagen edible film prepared by the method.

The collagen edible film provided by the invention takes fish scale collagen as a substrate, and protocatechuic acid is creatively added in the formula, so that the ductility and the barrier property of the prepared collagen edible film are remarkably improved compared with those of the edible film prepared by the prior art. Meanwhile, the preparation process of the collagen edible film is simple, safe and pollution-free. The compounded protocatechuic acid can promote the interaction (such as hydrogen bond interaction, electrostatic interaction and hydrophobic interaction) between collagen molecules and between the collagen molecules and plasticizer molecules to be obviously changed. Protocatechuic acid is a kind of micromolecular phenolic compound with polyhydroxy, can generate cross-linking reaction with collagen and plasticizer (such as glycerol, sorbitol, ethylene glycol and the like), and is stably embedded in a collagen molecular network structure. On one hand, the collagen network is filled with protocatechuic acid, so that the mesh spacing is increased, and the ductility of the edible collagen film is obviously improved. The improvement of the ductility is more beneficial to the film coating or spraying of the edible film, and the edible film is applied to the surface of food to improve the protective effect of the edible film on the food; on the other hand, the existence of protocatechuic acid in the meshes can also reduce the free space of the collagen network, limit the diffusion rate of water molecules and obviously improve the barrier property of the collagen edible film to water vapor. And moreover, the benzene ring structure in the protocatechuic acid can effectively absorb ultraviolet rays, the transmittance of the ultraviolet rays is reduced, and the barrier property of the collagen edible film to the ultraviolet rays is obviously improved. The enhancement of the barrier property is more beneficial to preventing the food from being interfered by external environmental factors and reducing the deterioration and damage of the food. In addition, protocatechuic acid is an active substance with multiple physiological functions of oxidation resistance, antibiosis, tumor resistance, immunity improvement and the like, and can also endow the collagen edible film with functional characteristics of oxidation resistance, antibiosis and the like. Meanwhile, after being eaten, the protocatechuic acid can adjust and improve the immunity and the intestinal barrier function of the organism, is beneficial to the health of the organism, and better realizes the active packaging function of the edible film and the function of being beneficial to the health of the organism.

Compared with the prior art, the edible collagen film provided by the invention has the characteristics of high safety, high ductility, high barrier property and the like, can meet the requirements of consumers on healthy nutritional food, can also meet the requirements of high-efficiency utilization of industrial resources and sustainable development of environment, has a wider application prospect, and has the following beneficial effects:

(1) the edible collagen film can be modified into the edible collagen film with high transparency (1.45-3.89), high ductility (elongation at break 90.23-118.04%) and high barrier property (ultraviolet barrier rate 99.10-99.71%, water vapor transmission rate 0.78-0.8710%) by only using a small amount of protocatechuic acid^-10·gm^-1·s^-1·Pa^-1) The novel collagen edible film. In the whole preparation process, the performance of the collagen film is improved only by being supplemented with plasticizing liquid. Thus, the invention can achieve the same or even better improvement of the ductility and the barrier property under the condition of avoiding using other modifying agents (such as macromolecular substance starch, glue and the like). Meanwhile, macromolecular additives are avoided, the low thickness (0.036-0.046mm) of the edible collagen film can be kept, the use of solution is reduced, the process can be simplified, and the cost is reduced.

(2) The protocatechuic acid is used for filling a collagen molecular network structure and the interaction between the protocatechuic acid and collagen molecules so as to improve the mechanical property and the barrier property of the collagen edible film. Protocatechuic acid does not react irreversibly with collagen, and does not cause loss of amino acids in collagen molecules, especially essential amino acids for human body. Therefore, the invention not only can obviously improve the mechanical property and the barrier property of the collagen edible film, but also can furthest reserve the nutritional characteristics of the matrix collagen.

(3) The collagen and protocatechuic acid used in the invention are compounds derived from natural food, the used plasticizer such as glycerol and the like is a food additive which can be used and is specified in the national standard for food safety (GB 2760-2014), and in the preparation process of the edible collagen film, no acid, no alkali and no organic reagent are used. Therefore, the invention can avoid the residue of toxic and harmful substances on the prepared collagen edible film and reduce the harm to the human health; meanwhile, in the preparation process of the edible collagen film, no acid or alkali or organic reagent is used, so that the discharge of harmful waste water can be avoided, and the pollution to the environment is reduced.

(4) The collagen used in the invention is derived from a byproduct of aquatic product processing, namely fresh water fish scales. Compared with collagen from other sources or matrix raw materials from other sources, the utilization of the collagen in the fish scales can change waste into valuable, and the effective resource utilization of the protein is improved; meanwhile, the environmental pollution of aquatic product processing byproducts can be reduced, and the sustainable development of green is realized.

Detailed Description

The present invention will be described in more detail with reference to examples. It should be understood that the embodiments of the present invention are exemplary, are intended to be illustrative of the present invention, and are not to be construed as limiting the present invention. The examples do not show the specific techniques or conditions, and the techniques or conditions are described in the technical field. The reagents used, except for the collagen, are conventional products which are commercially available.

In the following examples and comparative examples:

the crude scale collagen powder is prepared by the following method: and (3) putting 30g of fully dried grass carp scales in 500mL of water, leaching for 2h at 80 ℃, filtering, and performing spray drying on the filtrate to obtain crude scale collagen powder.

The effective concentration of protocatechuic acid powder was 97%.

Example 1

(1) Preparing a film forming solution:

s1, preparing a fish scale collagen matrix liquid: stirring and dissolving the crude scale collagen powder in water at 60 ℃ to obtain 7.5 wt% of scale collagen matrix liquid;

s2, preparation of protocatechuic acid improvement solution: dissolving protocatechuic acid powder in water under stirring to obtain 2 wt% protocatechuic acid modified solution;

s3, preparation of plasticizing liquid: dissolving a plasticizer glycerol in water by stirring to obtain 1 wt% plasticizing liquid;

s4, preparing a modified fish scale collagen matrix film forming solution: and (3) uniformly stirring and mixing the fish scale collagen matrix liquid in the step S1, the protocatechuic acid improvement liquid in the step S2 and the plasticizing liquid in the step S3 according to the ratio of 2:1:2(v: v: v), so as to obtain the modified fish scale collagen matrix film forming liquid.

(2) Ultrasonic mixing and degassing: and (2) carrying out ultrasonic treatment on the modified fish scale collagen matrix film forming solution obtained in the step (1), wherein the ultrasonic frequency is 25KHz, the ultrasonic time is 15min, and fully mixing and degassing to obtain an ultrasonic mixed degassing solution.

(3) Preparing the collagen edible film: the ultrasonic mixed degassing liquid obtained in the step (2) is mixed according to the volume of 20L/m²Uniformly pouring the collagen edible film on the organic silicon resin, then placing the organic silicon resin at the temperature of 25 ℃ and the humidity of 50% for drying for 20h, cooling to room temperature after drying is finished, and uncovering the film to obtain the collagen edible film.

Example 2

(1) Preparing a film forming solution:

s1, preparing a fish scale collagen matrix liquid: stirring and dissolving the crude scale collagen powder in 65 ℃ water to obtain 6.25 wt% of scale collagen matrix liquid;

s2, preparation of protocatechuic acid improvement solution: dissolving protocatechuic acid powder in water under stirring to obtain 3 wt% protocatechuic acid modified solution;

s3, preparation of plasticizing liquid: dissolving a plasticizer glycerol in water by stirring to obtain 1.25 wt% of plasticizing liquid;

(2) Ultrasonic mixing and degassing: and (2) carrying out ultrasonic treatment on the modified fish scale collagen matrix film forming solution obtained in the step (1), wherein the ultrasonic frequency is 25KHz, the ultrasonic time is 18min, and fully mixing and degassing to obtain an ultrasonic mixed degassing solution.

(3) Preparing the collagen edible film: the ultrasonic mixed degassing liquid obtained in the step (2) is mixed according to the volume of 20L/m²Uniformly pouring the collagen edible film on the organic silicon resin, then placing the organic silicon resin at the temperature of 25 ℃ and the humidity of 50% for drying for 24h, cooling to room temperature after drying is finished, and uncovering the film to obtain the collagen edible film.

Example 3

(1) Preparing a film forming solution:

s1, preparing a fish scale collagen matrix liquid: dissolving the crude scale collagen powder in 65 ℃ water under stirring to obtain 5wt% scale collagen matrix liquid;

s2, preparation of protocatechuic acid improvement solution: dissolving protocatechuic acid powder in water under stirring to obtain 4 wt% protocatechuic acid modified solution;

s3, preparation of plasticizing liquid: stirring and dissolving a plasticizer sorbitol in water to obtain 1.25 wt% plasticizing liquid;

(2) Ultrasonic mixing and degassing: and (2) carrying out ultrasonic treatment on the modified fish scale collagen matrix film forming solution obtained in the step (1), wherein the frequency of ultrasonic treatment is 30KHz, the ultrasonic treatment time is 20min, and fully mixing and degassing to obtain ultrasonic mixed degassing liquid.

(3) Preparing the collagen edible film: the ultrasonic mixed degassing liquid obtained in the step (2) is mixed according to the volume of 20L/m²Uniformly pouring the collagen edible film on the organic silicon resin, then placing the organic silicon resin at the temperature of 30 ℃ and the humidity of 50% for drying for 24h, cooling to room temperature after drying is finished, and uncovering the film to obtain the collagen edible film.

Comparative example 1

An edible collagen film was prepared according to the method of example 1, except that protocatechuic acid was replaced with the same weight part of water to obtain a reference edible collagen film.

Comparative example 2

An edible collagen film was prepared according to the method of example 2, except that protocatechuic acid was replaced with the same parts by weight of water to obtain a reference edible collagen film.

Comparative example 3

An edible collagen film was prepared according to the method of example 3, except that protocatechuic acid was replaced with the same parts by weight of water to obtain a reference edible collagen film.

Test example

(1) And (3) detecting the thickness and transparency of the collagen edible film:

in order to evaluate the change of protocatechuic acid on the thickness and transparency of the edible collagen film, the thickness and transparency of the prepared edible collagen film were measured using a micrometer and an ultraviolet-visible spectrophotometer, respectively. For the thickness, the thickness of the edible film was measured at 10 randomly selected points, and then the average value was taken as the thickness of the edible film to the accuracy of 0.001 mm. For clarity, edible films of the corresponding size were placed in a cuvette for wavelength measurement (600nm), and clarity was calculated according to the following formula:

logT₆₀₀representing the transmittance of the edible film at 600 nm; x represents the thickness of the edible film.

The results obtained are shown in table 1.

As can be seen from the results in Table 1, the edible collagen films of examples 1 to 3 had a thickness of 0.036 to 0.046 mm. Compared with the thickness (0.035-0.036mm) of the collagen edible film of the comparative examples 1-3, the thickness of the collagen edible film is not increased significantly after the protocatechuic acid is compounded. When the protocatechuic acid concentration is 4 wt%, the thickness of the collagen edible film is 0.046 mm. In addition, the edible films of collagen of examples 1 to 3 had a transparency of 1.45 to 3.89. Compared with the transparency (4.43-4.56) of the collagen edible films of comparative examples 1-3, the transparency of the collagen edible film is obviously increased after the protocatechuic acid is compounded. When the concentration of protocatechuic acid is 2 wt%, the transparency of the collagen edible film is 1.45; and when the protocatechuic acid concentration is 4 wt%, the transparency of the collagen edible film is 3.89. Therefore, protocatechuic acid is creatively added into the preparation formula of the edible collagen film, so that the limitation of the thickness of the edible collagen film on the use aspect is not influenced, and the increased transparency is more beneficial to the application of the edible collagen film on the food aspect.

(2) Detecting the ductility of the collagen edible film:

in order to evaluate the change of protocatechuic acid in ductility of the edible collagen film, elongation at break of the prepared edible collagen film was measured using a texture analyzer with reference to the method of ASTM standard method D882-97. The edible film has a gauge of 35 x 50mm, an initial effective marking portion (between the two clamps) length of 30mm, and an elongation at break as a percentage of the effective marking portion (between the two clamps) length when snapped off to the initial effective marking portion (between the two clamps). The results are shown in Table 1.

As is clear from the results in Table 1, the edible films of collagen of examples 1 to 3 had an elongation at break of 90.23 to 118.04%. Compared with the elongation at break (11.32-13.98%) of the edible collagen films of comparative examples 1-3, after the protocatechuic acid is compounded, the elongation at break of the edible collagen films is remarkably increased. When the protocatechuic acid concentration is 3 wt%, the ultimate elongation of the edible collagen film is 118.04% at the maximum. Therefore, protocatechuic acid is creatively added into the preparation formula of the collagen edible film, so that the breaking elongation of the collagen edible film can be obviously improved, and the ductility of the collagen edible film is enhanced.

(3) And (3) detecting the ultraviolet blocking performance of the collagen edible film:

in order to evaluate the change of protocatechuic acid in the ultraviolet ray blocking property of the edible collagen film, the ultraviolet ray blocking property of the prepared edible collagen film was measured using an ultraviolet spectrophotometer. The edible films of the corresponding size were placed in a cuvette for wavelength scanning (200-. The ultraviolet ray blocking rate of the collagen edible film is characterized by the transmittance of ultraviolet rays. The results are shown in Table 1.

As is clear from the results in Table 1, the edible films of collagen of examples 1 to 3 had UV blocking ratios of 99.10 to 99.71%. Compared with the ultraviolet ray blocking rate (38.47-40.21%) of the collagen edible films of the comparative examples 1-3, after the protocatechuic acid is compounded, the ultraviolet ray blocking rate of the collagen edible films is obviously increased. When the protocatechuic acid concentration is 4 wt%, the ultraviolet ray blocking rate of the collagen edible film is 99.71% of the maximum value. Therefore, protocatechuic acid is creatively added into the preparation formula of the collagen edible film, so that the ultraviolet ray blocking rate of the collagen edible film can be obviously enhanced.

(4) Detecting the water vapor barrier property of the collagen edible film:

in order to evaluate the change of protocatechuic acid on the water vapor barrier property of the edible collagen film, the water vapor barrier property of the prepared edible collagen film is determined by referring to the national standard GB/T1037-1988 cup method for testing the water vapor permeability of plastic films and sheets. The method comprises the following specific steps: the edible membrane is fixed on the mouth of a small test cup containing anhydrous silica gel, the weighed test cup is put into a dryer filled with aqueous solution (25 ℃, 3169Pa), a certain steam pressure difference is kept between the inner side and the outer side of the membrane, and the membrane is taken out and weighed once every 1 hour until the weight change is less than 0.001 g. The results are shown in Table 1.

As is clear from the results in Table 1, the water vapor barrier properties of the edible films of collagen of examples 1 to 3 were 0.78 to 0.87X 10^-10·gm^-1·s^-1·Pa^-1. Water vapor barrier property (1.01-1.05X 10) of the edible collagen film compared to comparative examples 1-3^-10·gm^-1·s^-1·Pa^-1) After protocatechuic acid is compounded, the water vapor barrier property of the collagen edible film is obviously improved. When the protocatechuic acid concentration is 4 wt%, the water vapor barrier property of the collagen edible film is 0.78 multiplied by 10 at the maximum value^-10·gm^-1·s^-1·Pa^-1. Therefore, protocatechuic acid is creatively added into the preparation formula of the collagen edible film, so that the water vapor barrier property of the collagen edible film can be obviously enhanced.

TABLE 1

In addition, the collagen edible film prepared by the invention also has good oxidation resistance and antibacterial performance, can adjust and improve the immunity of an organism and the intestinal barrier function after being eaten, is beneficial to the health of the organism, and better realizes the active packaging function of the edible film and the effect of being beneficial to the health of the organism.

Compared with the edible film produced by the prior art, the edible collagen film prepared by the invention has the advantages of better transparency, higher ductility, stronger ultraviolet ray barrier property and water vapor barrier property, simple process and no pollution, and has the technical effect which cannot be achieved by the prior art.

Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made in the above embodiments by those of ordinary skill in the art without departing from the principle and spirit of the present invention.

Claims

1. A method for preparing an edible collagen film, comprising the steps of:

2. The method for preparing an edible collagen film according to claim 1,

the concentration of the scale collagen matrix liquid is 5-10 wt%, and the scale collagen matrix liquid is obtained by stirring and dissolving crude scale collagen powder in water with the temperature of 60-70 ℃;

the protocatechuic acid modified solution has a concentration of 1-4 wt%, and is obtained by dissolving protocatechuic acid powder in water under stirring;

the concentration of the plasticizing liquid is 1-2.5wt%, and the plasticizing liquid is obtained by stirring and dissolving a plasticizing agent in water;

the modified fish scale collagen matrix film-forming solution is obtained by uniformly mixing a fish scale collagen matrix solution, a protocatechuic acid modified solution and a plasticizing solution in a volume ratio of 2:1: 2.

3. The method for preparing the edible collagen film according to claim 2, wherein the crude extract fish scale collagen powder is prepared by leaching fish scales at 70-90 ℃ for 1-3h and drying; the fish scale is at least one of grass carp scale, silver carp scale and carp scale.

4. The method for preparing the edible collagen film according to claim 2, wherein the effective concentration of the protocatechuic acid powder is 95-99%.

5. The method for preparing an edible collagen film according to claim 1, wherein the plasticizer is at least one selected from glycerol, sorbitol and ethylene glycol.

6. The method for preparing the edible collagen film according to claim 1, wherein the ultrasonic treatment conditions comprise an ultrasonic frequency of 20-30KHz and an ultrasonic time of 15-20 min.

7. The method for preparing the edible collagen film according to claim 1, wherein the ultrasonic mixing degassing liquid is 18-25L/m²Poured evenly over the silicone resin.

8. The preparation method of the edible collagen film according to claim 1, wherein the drying conditions include a temperature of 25-40 ℃, a humidity of 50-60% and a time of 20-24 h.

9. The method for preparing an edible collagen film according to any one of claims 1 to 8, comprising the steps of:

(1) preparing a film forming solution:

s1, preparing a fish scale collagen matrix liquid: dissolving the crude scale collagen powder in water of 60-70 ℃ under stirring to obtain 5-10 wt% of scale collagen matrix liquid;

s4, preparing a modified fish scale collagen matrix film forming solution: uniformly stirring and mixing the scale collagen matrix liquid, the protocatechuic acid improvement liquid and the plasticizing liquid in a volume ratio of 2:1:2 to obtain a modified scale collagen matrix film forming liquid;

10. An edible collagen film made by the method of any one of claims 1-9.