A kind of alcohol-soluble protein nanofiber membrane and preparation method thereof

Abstract

The invention belongs to the field of fiber material synthesis, and specifically relates to a prolamin nanofiber membrane and a preparation method thereof. In the invention, zein and highland barley prolamin are compounded in a certain ratio, and then cyclodextrin is added thereto, and the mechanical strength, sustained release performance and barrier performance of the nanofiber membrane formed after electrostatic spinning can be greatly improved.

Description

Technical Field

[0001] The invention belongs to the field of fiber material synthesis, and in particular relates to a prolamin nanofiber membrane and a preparation method thereof. Background Art

[0002] Packaging plays a key role in protecting food, extending its shelf life and reducing food waste. Although synthetic plastics are widely used in food packaging due to their high mechanical strength, high barrier properties and low cost, their toxicity, difficulty in degradation and raw material (petroleum) costs limit their application in the field of food packaging. Edible film, as a green packaging material, has a wide range of raw material sources and has advantages that other materials cannot match, such as safety and zero waste, and has good development prospects.

[0003] At present, the preparation of new degradable films is composed of proteins, lipids, polysaccharides or their composites. The inherent properties of proteins make them an excellent choice for the production of edible films. Nanofiber membranes have extremely high specific surface area, barrier properties and high sustained release properties of antibacterial substances. However, the biggest disadvantage of edible fiber membranes formed by polymers such as proteins and polysaccharides is low mechanical strength and poor water barrier properties, which greatly limits their application.

[0004] Zein is a degradable, water-insoluble protein that can form an ideal nanofiber membrane. Currently, most nanofiber materials are prepared by compounding with zein as the main raw material. However, its main characteristics are that the nanofiber membrane is brittle, has low mechanical strength, and its water resistance and sustained release properties are difficult to meet the requirements. Summary of the invention

[0005] In order to solve the above problems, the present invention provides a method for preparing highland barley alcohol-soluble protein, which comprises the following steps: drying highland barley lees in an electric heating blow drying box, crushing and sieving the dried sample; adding the sample powder into an ethanol aqueous solution, stirring with a magnetic stirrer, and then heating in a water bath for 120 minutes; centrifuging the solution, adding water to the supernatant, precipitating, centrifuging, collecting the precipitate and freeze-drying it to obtain the target product.

[0006] Furthermore, the sieving is a 40-mesh sieve.

[0007] Furthermore, the ethanol aqueous solution is 75% ethanol aqueous solution.

[0008] Furthermore, the water bath heating temperature is 30-50°C.

[0009] Furthermore, the centrifugation step is specifically centrifugation at 5000g for 15 minutes.

[0010] The invention also provides highland barley alcohol-soluble protein, which is prepared by the above preparation method.

[0011] The invention also provides a prolamin nanofiber membrane, which is composed of the following mass fractions: 15% to 20% zein, 5% to 10% highland barley prolamin, 2% to 3% glycerol, 3% to 7% cyclodextrin, and the balance is acetic acid.

[0012] Furthermore, the highland barley alcohol-soluble protein is the above-mentioned highland barley alcohol-soluble protein.

[0013] The present invention also provides a method for preparing the alcohol-soluble protein nanofiber membrane, wherein the components are uniformly mixed according to a proportion, the total protein content is 25%, and an electrostatic spinning membrane is prepared on an electrostatic spinning machine.

[0014] Furthermore, the voltage of the electrospinning machine is 17 kV, and the distance from the needle tip to the collector is maintained at 13 cm.

[0015] The present invention has the following beneficial effects:

[0016] After the zein, highland barley alcohol-soluble protein and cyclodextrin are compounded in the present invention, the elongation, mechanical strength, sustained-release performance and barrier performance are significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0018] Figure 1 Embodiment 1 fiber membrane;

[0019] Figure 2 Embodiment 2 fiber membrane;

[0020] Figure 3 Comparative Example 1 Fiber membrane;

[0021] Figure 4 Comparative Example 2 Fiber membrane;

[0022] Figure 5 Comparative Example 3 Fiber membrane. DETAILED DESCRIPTION

[0023] Now, various exemplary embodiments of the present invention are described in detail. The methods in the examples are conventional methods unless otherwise specified, and the reagents used are conventional commercially available reagents or reagents prepared by conventional methods unless otherwise specified. This detailed description should not be considered as a limitation of the present invention, but should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0024] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0025] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0026] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0027] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0028] Preparation of highland barley alcohol-soluble protein: Highland barley lees were dried in an electric heating blow dryer (DHG-9070B, Jinan, China) at 70°C to a fixed weight. The dried sample was crushed and passed through a 40-mesh sieve. 100 g of the powder was added to 1000 ml of 75% ethanol aqueous solution and stirred with a magnetic stirrer for 5 min [29, 30]. The sample was then heated in a 40°C water bath (HH-S6, Jinan, China) for 120 min. The solution was centrifuged at 5000 g for 15 min, the supernatant was poured into a 20 L stainless steel pot, and 8 L of water was added to precipitate highland barley alcohol-soluble protein. The mixture was centrifuged at 5000 g for 15 min, and the precipitate was collected and freeze-dried to a fixed weight.

[0029] Zein was purchased from Sigma; β-cyclodextrin was purchased from Aladdin Reagents.

[0030] Example 1: Zein and highland barley alcohol-soluble protein were added to acetic acid containing 2.5% glycerol and 5% cyclodextrin in a mass ratio of 6:4, wherein the total protein concentration was 25%. Magnetic stirring (500 rpm) was performed at room temperature for 30 min. Nanofibers were prepared on an electrospinning machine (HZ-11) at a voltage of 17 kV, and the distance from the needle tip to the collector was maintained at 13 cm. The electrospinning membrane was torn off and set aside for use.

[0031] Example 2: Zein and highland barley alcohol-soluble protein were added to acetic acid containing 2.5% glycerol and 8% cyclodextrin in a mass ratio of 8:2, wherein the total protein concentration was 25%. The nanofibers were prepared on an electrospinning machine (HZ-11) with a voltage of 17 kV and a distance from the needle tip to the collector electrode of 13 cm. The electrospinning membrane was torn off and set aside for use.

[0032] Comparative Example 1: Zein and highland barley alcohol-soluble protein were added to acetic acid containing 2.5% glycerol in a mass ratio of 6:4 to make the total protein concentration 25%. The nanofibers were prepared on an electrospinning machine (HZ-11) with a voltage of 17 kV and a distance from the needle tip to the collector electrode of 13 cm. The electrospinning membrane was torn off and set aside.

[0033] Comparative Example 2: Zein was added to acetic acid containing 2.5% glycerol, with a total protein concentration of 25%. The nanofibers were prepared on an electrospinning machine (HZ-11) with a voltage of 17 kV and a distance from the needle tip to the collector electrode of 13 cm. The electrospinning membrane was torn off and set aside for use.

[0034] Comparative Example 3: Zein and highland barley alcohol-soluble protein were added to acetic acid containing 2.5% glycerol in a mass ratio of 6:4, wherein the total protein concentration was 25%. The nanofibers were prepared on an electrospinning machine (HZ-11) at a voltage of 17 kV, and the distance from the needle tip to the collector was maintained at 13 cm. The electrospinning membrane was torn off and set aside for use.

[0035] Test example:

[0036] Mechanical properties test: The fiber membrane was cut into 5 mm × 30 mm specimens and tensile tested using a yarn fiber strength and elongation tester. The clamping length of the specimen was 10 mm and the tensile speed was 10 mm / min.

[0037] Morphology test: The observation was carried out using a HITACHT SU1510 scanning electron microscope produced by Hitachi, Japan.

[0038] Wettability test: The static contact angle of the fiber membrane was measured using an OCA25 contact angle meter, and the angle was used to characterize the surface hydrophobicity of the fiber web.

[0039] Antibacterial performance test after loading eugenol: 2.5 mg / mL eugenol was added to the fiber solution prepared above, stirred for 1 hour, and the electrospinning solution loaded with antibacterial substances was obtained. The spinning process was the same as that of the empty membrane. Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus were selected as research objects. The fiber membrane was made into a 5 mm diameter disc with a puncher and sterilized under ultraviolet light for 30 minutes. Take 100 μL of bacterial suspension (1×106 CFU / mL) and evenly spread it on the sterilized culture medium, then stick the fiber membrane to the surface of the culture medium, culture it in a constant temperature incubator at 37°C for 24 hours, and measure the diameter of the inhibition zone with a vernier caliper.

[0040] The test results of the nanofiber membrane performance are shown in Table 1. It can be seen from Table 1 that the mechanical properties, water barrier properties and antibacterial properties of the fiber membrane in the embodiment are significantly higher than those in the comparative example.

[0041] Table 1 Comparison of nanofiber membrane performance

[0042]

[0043] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A prolamin nanofiber membrane, characterized in that: The invention is composed of the following mass parts: 15% to 20% of zein, 5% to 10% of highland barley alcohol-soluble protein, 2% to 3% of glycerol, 3% to 7% of cyclodextrin, and the balance is acetic acid; the preparation method of the highland barley alcohol-soluble protein is as follows: drying highland barley lees in an electric heating blow drying box, crushing and sieving the dried sample; taking the sample powder and adding it to an ethanol aqueous solution, stirring it with a magnetic stirrer, and then heating it in a water bath for 120 minutes; then centrifuging the solution, taking the supernatant, adding water, precipitating, centrifuging, collecting the precipitate and freeze-drying; the preparation method of the alcohol-soluble protein nanofiber membrane is as follows: uniformly mixing the components according to the ratio, and forming an electrospinning membrane on an electrospinning machine; the voltage of the electrospinning machine is 17 kV, and the distance from the needle tip to the collector is maintained at 13 cm; the alcohol-soluble protein nanofiber membrane is used for food packaging.

2. The alcohol-soluble protein nanofiber membrane according to claim 1, characterized in that: The sieving is a 40-mesh sieve.

3. The alcohol-soluble protein nanofiber membrane according to claim 1, characterized in that: The ethanol aqueous solution is 75% ethanol aqueous solution.

4. The alcohol-soluble protein nanofiber membrane according to claim 1, characterized in that: The water bath heating temperature is 30-50°C.

5. The prolamin nanofiber membrane according to claim 1, characterized in that: The centrifugation step is specifically centrifugation at 5000g for 15 min.

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