阅读说明：本技术 一种壳聚糖-丝素蛋白可食膜及其制备方法 (Chitosan-silk fibroin edible film and preparation method thereof ) 是由 殷献华 钱静 张嘉帅 孟晶晶 于 2019-10-18 设计创作，主要内容包括：本发明涉及一种壳聚糖-丝素蛋白可食膜的制备方法,其特征在于,包括如下步骤：步骤S1、季铵化壳聚糖溶液的制备；步骤S2、丝素蛋白溶液的制备；步骤S3、壳聚糖-丝素蛋白的制备；步骤S4、壳聚糖-丝素蛋白可食膜的制备。本发明还公开了根据所述一种壳聚糖-丝素蛋白可食膜的制备方法制成的一种壳聚糖-丝素蛋白可食膜。本发明公开的壳聚糖-丝素蛋白可食膜阻湿性能好、能够有效地延缓果蔬的衰老和褐变,抑制果蔬中微生物的增长,提高果蔬的贮藏期和最大限度保持其原有品质和商品价值,使用安全、环保,具有较高的经济价值、社会价值和生态价值。(The invention relates to a preparation method of a chitosan-silk fibroin edible film, which is characterized by comprising the following steps: step S1, preparing a quaternized chitosan solution; step S2, preparing a silk fibroin solution; step S3, preparing chitosan-silk fibroin; and S4, preparing the chitosan-silk fibroin edible film. The invention also discloses a chitosan-silk fibroin edible film prepared by the preparation method of the chitosan-silk fibroin edible film. The chitosan-silk fibroin edible film disclosed by the invention has good moisture resistance, can effectively delay the aging and browning of fruits and vegetables, inhibits the growth of microorganisms in the fruits and vegetables, improves the storage period of the fruits and vegetables, keeps the original quality and commodity value of the fruits and vegetables to the maximum extent, is safe and environment-friendly to use, and has higher economic value, social value and ecological value.)

1. A preparation method of a chitosan-silk fibroin edible film is characterized by comprising the following steps:

step S1, preparation of quaternized chitosan solution: dissolving quaternized chitosan in deionized water, stirring for 15-30 minutes at 50-60 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 1-3% into the solution, continuing to perform heat preservation and mechanical stirring for 35-45 minutes at the rotation speed of 450-550rpm, and then standing to obtain a clear and transparent yellowish quaternized chitosan solution;

step S2, preparation of silk fibroin solution: dissolving nano silk fibroin in deionized water, stirring for 20-35 minutes at 55-65 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 0.5-1.5% into the solution, continuing to perform heat preservation and mechanical stirring for 25-35 minutes at the rotating speed of 500rpm, and then standing to obtain a silk fibroin solution;

step S3, preparation of chitosan-silk fibroin: mixing the quaternized chitosan solution prepared in the step S1 with the silk fibroin solution prepared in the step S2, uniformly stirring, adding glycerol, polyethylene glycol and a surfactant, stirring for 30-40 minutes on a magnetic stirrer, homogenizing for 3-5 times by using a homogenizer, vacuum-filtering, cooling for later use, and freeze-drying to obtain a sample;

step S4, preparing the chitosan-silk fibroin edible film: dissolving the chitosan-silk fibroin prepared in the step S3 in water, adding alginic acid, magnetically stirring for 2-3 hours in a water bath at 60-80 ℃ to obtain a mixed solution, then exhausting air by using a vacuum pump to remove air bubbles in the solution, pouring the solution on an acrylic plate, drying the acrylic plate at 60-80 ℃ to form a film, and finally uncovering the film for storage to obtain the chitosan-silk fibroin edible film.

2. The method for preparing the chitosan-silk fibroin edible film as claimed in claim 1, wherein the ratio of the quaternized chitosan, the deionized water and the glacial acetic acid in step S1 is 10g (1-1.5L) to (8-12 mL).

3. The method for preparing the chitosan-silk fibroin edible film as claimed in claim 1, wherein the ratio of the nano silk fibroin, the deionized water and the glacial acetic acid in step S2 is (9-11g), (1-1.5L) and (8-12 mL).

4. The preparation method of the chitosan-silk fibroin edible film as claimed in claim 1, wherein the mass ratio of the quaternized chitosan solution, the silk fibroin solution, glycerol, polyethylene glycol and the surfactant in step S3 is 1:1 (0.02-0.05):0.03: 0.02.

5. The method for preparing the chitosan-silk fibroin edible film according to claim 1, wherein the surfactant is at least one of tween 20 and tween 80.

6. The method for preparing the chitosan-silk fibroin edible film as claimed in claim 1, wherein the mass ratio of the chitosan-silk fibroin, water and alginic acid in step S4 is (2-5) to 100: 0.3.

7. The chitosan-silk fibroin edible film prepared by the preparation method of the chitosan-silk fibroin edible film as claimed in any one of claims 1-6.

Technical Field

The invention relates to the technical field of edible films, in particular to a chitosan-silk fibroin edible film and a preparation method thereof.

Background

The fresh fruits and vegetables have high nutritive value and are deeply loved by consumers, but the fresh fruits and vegetables have short shelf life at room temperature and are easy to rot. With the improvement of the cognition degree of people on green food, how to improve the storage period of fruits and vegetables and keep the original quality and commodity value of the fruits and vegetables to the maximum degree becomes one of the focuses of research in the field of food science.

The edible film is an edible preservative film for short, has the characteristics of good preservation effect, convenient use, good practicability and the like, is simple in manufacturing process, low in cost, edible, easy to degrade and free of environmental pollution, is a food packaging material with great development potential, is a preservative material frequently used in a coating preservation technology, is usually coated on the surface of a fruit by a preservative with a film forming function, is formed on the surface of the fruit after standing for a period of time, and can block gas exchange between the fruit and air, so that the nutrient consumption is reduced, and the aging is delayed.

Although the edible preservative film used at present achieves remarkable results in fruit and vegetable preservation, the edible preservative film also has the problems that the polysaccharide has strong hydrophilicity, so that the film has poor moisture resistance and is easy to absorb moisture and become sticky in a high-humidity environment; the protein membrane has strong hydrophilicity and poor water resistance.

Tujie et al, in food and machinery, vol.26, No. 6, 11 months 2010, Chitosan-glycerol-fibroin blend film preparation and Performance research, Chitosan-glycerol-fibroin blend film was prepared by the sialorrhea method, and the influence of the blending ratio of each component on the film performance was examined with the elongation strength and elongation at break of the film as the index. The results show that: the chitosan can enhance the tensile strength of the film, but when the concentration of the chitosan is more than or equal to 10g/L, the elongation at break of the film is reduced; the tensile strength and the elongation at break of the film can be improved by adding the glycerol; the tensile strength of the membrane can be slightly increased by adding the silk fibroin, and the breaking elongation is obviously improved. Further adopting 10g/L chitosan, 10g/L glycerin and 0-10 g/L silk fibroin to form a film, and investigating the antibacterial performance. The results show that: the blended membrane containing 5g/L of silk fibroin can completely inhibit the growth of staphylococcus aureus, the blended membrane containing 20g/L of silk fibroin can completely inhibit the growth of escherichia coli, and the antibacterial performance of the chitosan blended membrane is greatly improved by adding the silk fibroin. In the paper, the mechanical property and the antibacterial property of the blend film are only researched, but the food fresh-keeping effect is not demonstrated; it is not an edible film; because no surfactant and plasticizer are added, the film formed by blending pure chitosan solution and silk fibroin solution is easy to age and crack and poor in moisture resistance.

Therefore, the development of the edible film which has good moisture resistance, can effectively delay the aging and browning of the fruits and vegetables, inhibits the growth of microorganisms in the fruits and vegetables, improves the storage period of the fruits and vegetables and keeps the original quality and commodity value of the fruits and vegetables to the maximum extent has very important significance for promoting the development of a coating preservation technology.

Disclosure of Invention

The invention aims to provide a chitosan-silk fibroin edible film for overcoming the defects of the prior art; the edible film has good moisture resistance, can effectively delay the aging and browning of fruits and vegetables, inhibits the growth of microorganisms in the fruits and vegetables, improves the storage period of the fruits and vegetables, keeps the original quality and commodity value of the fruits and vegetables to the maximum extent, is safe and environment-friendly to use, and has higher economic value, social value and ecological value; meanwhile, the invention also provides a preparation method of the chitosan-silk fibroin edible film.

In order to achieve the purpose, the invention adopts the technical scheme that:

a preparation method of a chitosan-silk fibroin edible film is characterized by comprising the following steps:

step S1, preparation of quaternized chitosan solution: dissolving quaternized chitosan in deionized water, stirring for 15-30 minutes at 50-60 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 1-3% into the solution, continuing to perform heat preservation and mechanical stirring for 35-45 minutes at the rotation speed of 450-550rpm, and then standing to obtain a clear and transparent yellowish quaternized chitosan solution;

step S2, preparation of silk fibroin solution: dissolving nano silk fibroin in deionized water, stirring for 20-35 minutes at 55-65 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 0.5-1.5% into the solution, continuing to perform heat preservation and mechanical stirring for 25-35 minutes at the rotating speed of 500rpm, and then standing to obtain a silk fibroin solution;

step S3, preparation of chitosan-silk fibroin: mixing the quaternized chitosan solution prepared in the step S1 with the silk fibroin solution prepared in the step S2, uniformly stirring, adding glycerol, polyethylene glycol and a surfactant, stirring for 30-40 minutes on a magnetic stirrer, homogenizing for 3-5 times by using a homogenizer, vacuum-filtering, cooling for later use, and freeze-drying to obtain a sample;

step S4, preparing the chitosan-silk fibroin edible film: dissolving the chitosan-silk fibroin prepared in the step S3 in water, adding alginic acid, magnetically stirring for 2-3 hours in a water bath at 60-80 ℃ to obtain a mixed solution, then exhausting air by using a vacuum pump to remove air bubbles in the solution, pouring the solution on an acrylic plate, drying the acrylic plate at 60-80 ℃ to form a film, and finally uncovering the film for storage to obtain the chitosan-silk fibroin edible film.

Furthermore, in step S1, the mixture ratio of the quaternized chitosan, the deionized water and the glacial acetic acid is 10g (1-1.5L): 8-12 mL.

Furthermore, in step S2, the ratio of the nano silk fibroin, the deionized water and the glacial acetic acid is (9-11g): (1-1.5L): 8-12 mL.

Preferably, the mass ratio of the quaternized chitosan solution, the silk fibroin solution, the glycerol, the polyethylene glycol and the surfactant in the step S3 is 1:1 (0.02-0.05):0.03: 0.02.

Preferably, the surfactant is at least one of tween 20 and tween 80.

Further, in step S4, the mass ratio of chitosan-silk fibroin, water and alginic acid is (2-5):100: 0.3.

The invention also aims to provide the chitosan-silk fibroin edible film prepared by the preparation method of the chitosan-silk fibroin edible film.

Further, the chitosan-silk fibroin edible film is used as a fruit and vegetable coating fresh-keeping material.

Due to the application of the technical scheme, compared with the prior art, the invention has the following advantages: the edible film has good moisture resistance, can effectively delay the aging and browning of fruits and vegetables, inhibits the growth of microorganisms in the fruits and vegetables, improves the storage period of the fruits and vegetables, keeps the original quality and commodity value of the fruits and vegetables to the maximum extent, is safe and environment-friendly to use, and has higher economic value, social value and ecological value; the preparation method of the chitosan-silk fibroin edible film is simple and easy to operate, the reaction condition is mild, and the dependence on equipment is not high.

Detailed Description

The invention relates to a preparation method of a chitosan-silk fibroin edible film, which is characterized by comprising the following steps:

step S1, preparation of quaternized chitosan solution: dissolving quaternized chitosan in deionized water, stirring for 15-30 minutes at 50-60 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 1-3% into the solution, continuing to perform heat preservation and mechanical stirring for 35-45 minutes at the rotation speed of 450-550rpm, and then standing to obtain a clear and transparent yellowish quaternized chitosan solution;

step S2, preparation of silk fibroin solution: dissolving nano silk fibroin in deionized water, stirring for 20-35 minutes at 55-65 ℃ to form a solution, then adding glacial acetic acid with the mass percentage concentration of 0.5-1.5% into the solution, continuing to perform heat preservation and mechanical stirring for 25-35 minutes at the rotating speed of 500rpm, and then standing to obtain a silk fibroin solution;

step S3, preparation of chitosan-silk fibroin: mixing the quaternized chitosan solution prepared in the step S1 with the silk fibroin solution prepared in the step S2, uniformly stirring, adding glycerol, polyethylene glycol and a surfactant, stirring for 30-40 minutes on a magnetic stirrer, homogenizing for 3-5 times by using a homogenizer, vacuum-filtering, cooling for later use, and freeze-drying to obtain a sample;

step S4, preparing the chitosan-silk fibroin edible film: dissolving the chitosan-silk fibroin prepared in the step S3 in water, adding alginic acid, magnetically stirring for 2-3 hours in a water bath at 60-80 ℃ to obtain a mixed solution, then exhausting air by using a vacuum pump to remove air bubbles in the solution, pouring the solution on an acrylic plate, drying the acrylic plate at 60-80 ℃ to form a film, and finally uncovering the film for storage to obtain the chitosan-silk fibroin edible film.

Further, the mixture ratio of the quaternized chitosan, the deionized water and the glacial acetic acid in the step S1 is 10g (1-1.5L): 8-12 mL); in the step S2, the ratio of the nano silk fibroin, the deionized water and the glacial acetic acid is (9-11g): (1-1.5L): 8-12 mL); in the step S3, the mass ratio of the quaternized chitosan solution to the silk fibroin solution to the glycerol to the polyethylene glycol to the surfactant is 1:1 (0.02-0.05) to 0.03: 0.02; the surfactant is at least one of Tween 20 and Tween 80; in the step S4, the mass ratio of the chitosan-silk fibroin, the water and the alginic acid is (2-5) to 100: 0.3.

The invention also aims to provide the chitosan-silk fibroin edible film prepared by the preparation method of the chitosan-silk fibroin edible film.

Further, the chitosan-silk fibroin edible film is used as a fruit and vegetable coating fresh-keeping material; the edible film has good moisture resistance, can effectively delay the aging and browning of fruits and vegetables, inhibits the growth of microorganisms in the fruits and vegetables, improves the storage period of the fruits and vegetables, keeps the original quality and commodity value of the fruits and vegetables to the maximum extent, is safe and environment-friendly to use, and has higher economic value, social value and ecological value; the preparation method of the chitosan-silk fibroin edible film is simple and easy to operate, the reaction condition is mild, and the dependence on equipment is not high.

The invention will be further described with reference to specific examples, but the scope of protection of the invention is not limited thereto: