Chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film and preparation method and application thereof
阅读说明：本技术 一种壳聚糖/纳米蒙脱土/三叶木通果皮提取物抗菌膜及其制备方法和应用 (Chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film and preparation method and application thereof ) 是由 邓云 江永利 尹浩 周学府 钟宇 王丹凤 于 2020-12-29 设计创作，主要内容包括：本发明提供了一种壳聚糖/纳米蒙脱土/三叶木通果皮提取物抗菌膜及其制备方法和应用,属于食品保鲜材料领域。本发明提供的壳聚糖/纳米蒙脱土/三叶木通果皮提取物抗菌膜的原料包括壳聚糖1.5％～2.5％、乙酸1.0％～1.5％、甘油0.25％～0.75％、吐温800.1％～0.2％、纳米蒙脱土0.05％～0.4％、三叶木通果皮提取物0.05％～0.4％和余量的水。本发明利用纳米蒙脱土提高抗菌膜的力学性能；三叶木通果皮提取物中的生物活性成分,提高膜的抗菌性和抗氧化活性。实验结果表明,本发明提供的抗菌膜的拉伸强度为13.28MPa,DPPH自由基清除率为19.56％,且具有优异的抗菌效果。(The invention provides a chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film and a preparation method and application thereof, belonging to the field of food fresh-keeping materials. The raw materials of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film provided by the invention comprise 1.5-2.5% of chitosan, 1.0-1.5% of acetic acid, 0.25-0.75% of glycerol, 800.1-0.2% of tween, 0.05-0.4% of nano montmorillonite, 0.05-0.4% of akebia trifoliate peel extract and the balance of water. The invention utilizes the nano-montmorillonite to improve the mechanical property of the antibacterial film; the bioactive component in the extract of the pericarp of akebia trifoliata improves the antibacterial property and the antioxidant activity of the membrane. Experimental results show that the tensile strength of the antibacterial film provided by the invention is 13.28MPa, the DPPH free radical clearance rate is 19.56%, and the antibacterial film has an excellent antibacterial effect.)
1. A chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film is prepared from the following raw materials in percentage by mass: 1.5 to 2.5 percent of chitosan, 1.0 to 1.5 percent of acetic acid, 0.25 to 0.75 percent of glycerol, 800.1 to 0.2 percent of Tween, 0.05 to 0.4 percent of nano montmorillonite, 0.05 to 0.4 percent of akebia trifoliata peel extract and the balance of water.
2. The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in claim 1, wherein the number average molecular weight of the chitosan is 4.0-5.0 KDa.
3. The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in claim 1 or 2, wherein the deacetylation degree of chitosan is 85-90%.
4. The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in claim 1, wherein the nano montmorillonite has a particle size of 100-200 nm.
5. The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in claim 1, wherein the particle size of akebia trifoliata peel extract is 0.1-0.5 mm.
6. The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in claim 1, wherein the water is sterile deionized water.
7. The method for preparing the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film as claimed in any one of claims 1 to 6, comprising the following steps:
(1) mixing chitosan with acetic acid, water, glycerol and tween 80 to obtain a chitosan solution;
(2) mixing the chitosan solution obtained in the step (1) with nano montmorillonite and akebia trifoliata peel extract to obtain a composite membrane solution;
(3) and (3) forming a film by using the composite film liquid obtained in the step (2) to obtain the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film.
8. The preparation method according to claim 7, wherein the temperature of the film forming in the step (3) is 45-55 ℃ and the humidity of the film forming is 30-50%.
9. The production method according to claim 7 or 8, wherein the film forming time in the step (3) is 15 to 20 hours.
10. The application of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by any one of claims 1 to 6 or the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by the preparation method of any one of claims 7 to 9 in fruit and vegetable preservative films.
Technical Field
The invention relates to the technical field of food preservation materials, in particular to a chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film and a preparation method and application thereof.
Background
Most of the preservative films for traditional food packaging are plastic packaging products processed by using polyethylene, polyvinyl chloride and the like as raw materials, but the preservative films are difficult to decompose, can bring serious plastic waste pollution problems, can decompose harmful substances to human bodies after being heated, and simultaneously, the limited petroleum resources also limit the development of the plastic industry. Therefore, the preparation of biodegradable materials using natural polymer materials such as polysaccharide, starch and cellulose has attracted much attention. Among a plurality of natural substances, chitosan is a natural polymer obtained after deacetylation of chitin, has the characteristics of rich content, good safety, degradability, film-forming property and the like, and is an ideal material for food packaging and fresh keeping in the market at present.
But the single chitosan film has poor wettability, mechanical strength and oxidation resistance and unobvious preservation effect, so that the application of the chitosan film in food packaging and preservation is limited to a certain extent, and one or more film forming substances are generally added for mixing in order to improve the performance of the chitosan film, for example, starch, pectin and other film forming materials are added to form a blended film; however, the addition of film-forming materials is generally large and can greatly reduce the moisture permeability of the blended film. For example, in patent publication No. CN104610579A, plant starch and chitosan are added and blended to improve the mechanical properties of the blended film, but the moisture permeability of the film is obviously reduced; patent publication No. CN104610757A discloses that cereal prolamin is added and blended with chitosan to improve the mechanical properties of the blended film, but the moisture permeability of the film is significantly reduced. In addition, in order to improve the antibacterial effect of the chitosan film, a commercially available antibacterial additive and an antibacterial substance such as titanium dioxide or nano silver are generally required to be added, and for example, in the patent with the publication number of CN104479155A, titanium dioxide is added to prepare an antibacterial film; the patent with publication number CN102775646A adds silver-carrying nano titanium dioxide, so that the chitosan film has the dual antibacterial property of silver ions and titanium dioxide. But the above method is costly.
Therefore, how to improve the comprehensive properties of the chitosan film, such as mechanical property, water vapor permeability, antibacterial property, antioxidant activity and the like, and effectively reduce the cost becomes a key point of research.
Disclosure of Invention
The invention aims to provide a chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film and a preparation method and application thereof. The antibacterial film provided by the invention has the advantages of easily available raw materials, low cost and excellent mechanical property, water vapor permeability, antibacterial property and antioxidant activity.
The invention provides a chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film which is prepared from the following raw materials in percentage by mass: 1.5 to 2.5 percent of chitosan, 1.0 to 1.5 percent of acetic acid, 0.25 to 0.75 percent of glycerol, 800.1 to 0.2 percent of Tween, 0.05 to 0.4 percent of nano montmorillonite, 0.05 to 0.4 percent of akebia trifoliata peel extract and the balance of water.
Preferably, the number average molecular weight of the chitosan is 4.0-5.0 KDa.
Preferably, the degree of deacetylation of the chitosan is 85% to 90%.
Preferably, the particle size of the nano montmorillonite is 100-200 nm.
Preferably, the particle size of the akebia trifoliata peel extract is 0.1-0.5 mm.
Preferably, the water is sterile deionized water.
The invention provides a preparation method of a chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film in the technical scheme, which comprises the following steps:
(1) mixing chitosan with acetic acid, water, glycerol and tween 80 to obtain a chitosan solution;
(2) mixing the chitosan solution obtained in the step (1) with nano montmorillonite and akebia trifoliata peel extract to obtain a composite membrane solution;
(3) and (3) forming a film by using the composite film liquid obtained in the step (2) to obtain the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film.
Preferably, the temperature of the film forming in the step (3) is 45-55 ℃, and the humidity of the film forming is 30-50%.
Preferably, the film forming time in the step (3) is 15-20 h.
The invention also provides the application of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by the technical scheme or the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by the preparation method of the technical scheme in a fruit and vegetable preservative film.
The invention provides a chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film which is prepared from the following raw materials in percentage by mass: 1.5 to 2.5 percent of chitosan, 1.0 to 1.5 percent of acetic acid, 0.25 to 0.75 percent of glycerol, 800.1 to 0.2 percent of Tween, 0.05 to 0.4 percent of nano montmorillonite, 0.05 to 0.4 percent of akebia trifoliata peel extract and the balance of water. The antibacterial film provided by the invention utilizes a two-dimensional sheet-shaped structure of nano-montmorillonite, the thickness of the sheet-shaped structure is in a nano scale, so that chitosan molecular chains can be inserted into a montmorillonite sheet layer to form a composite material in an intercalation or stripping structure form, the nano-montmorillonite is uniformly dispersed into the chitosan, and load can be uniformly distributed when the nano-montmorillonite is acted by external force, so that the mechanical property of the material is improved; the akebia trifoliata peel extract contains rich bioactive components such as hederagenin, pectin, polyphenol and the like, can improve the antibacterial property and the antioxidant activity of the chitosan membrane, and has the advantages of wide source, easily obtained raw materials and low cost; meanwhile, the addition of the nano montmorillonite and the akebia trifoliata peel extract destroys hydrogen bond action in and among chitosan molecules and forms new hydrogen bond action, thereby improving the performances of the membrane such as water vapor permeability and the like; by controlling the dosage of each component, the problems of nonuniform distribution, agglomeration and the like in the chitosan can be avoidedThereby improving the performance of the chitosan film. The experimental result shows that the film thickness of the antibacterial film provided by the invention is 56.25 +/-2.58 mu m, the tensile strength is 13.28 +/-0.18 MPa, the elongation at break is 42.11 +/-0.90%, and the water vapor transmission rate is 28.00 +/-4.13 g.mm.m-2d-1·kPa-1The DPPH free radical clearance rate is 19.56 +/-1.01%, and the compound has excellent antibacterial effect (the inhibition zone is larger than 12mm) on escherichia coli and staphylococcus aureus.
Drawings
FIG. 1 is a photomicrograph of the films prepared in example 1 and comparative examples 1-3;
FIG. 2 is a comparison of the antimicrobial performance of the films of example 1 and comparative examples 1-3.
Detailed Description
The invention provides a chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film which is prepared from the following raw materials in percentage by mass: 1.5 to 2.5 percent of chitosan, 1.0 to 1.5 percent of acetic acid, 0.25 to 0.75 percent of glycerol, 800.1 to 0.2 percent of Tween, 0.05 to 0.4 percent of nano montmorillonite, 0.05 to 0.4 percent of akebia trifoliata peel extract and the balance of water.
The present invention is not particularly limited as far as the sources of the above components are concerned, unless otherwise specified, and any commercially available product or product prepared by a conventional preparation method known to those skilled in the art may be used.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises 1.5-2.5% of chitosan by mass, and the preferred content is 2%. The invention limits the mass content of the chitosan within the range, can enable the chitosan molecular chains to have stronger acting force, enables the composite membrane liquid to have more proper viscosity and fluidity, improves the membrane forming property of the composite membrane liquid, and enables the membrane to have better strength and smoothness.
In the invention, the number average molecular weight of the chitosan is preferably 4.0-5.0 KDa, and more preferably 4.4 KDa; the deacetylation degree of the chitosan is preferably 85-90%, and more preferably 88.1%. The molecular weight and the deacetylation degree of the chitosan are limited within the range, the chitosan has better solubility, the formed antibacterial film is more compact and has better antibacterial performance, and meanwhile, the interaction between the chitosan and the extracts of the peel of the nano montmorillonite and the peel of the akebia trifoliata can be improved, so that the chitosan can be uniformly dispersed in the antibacterial film, and the comprehensive performances of the antibacterial film, such as mechanical property, antibacterial property and the like, are further improved.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises, by mass, 1.0-1.5% of acetic acid, and preferably 1.25%. In the present invention, the acetic acid is used to dissolve chitosan. The invention limits the mass content of the acetic acid within the range, and the acetic acid can combine with free amino groups in the chitosan to destroy hydrogen bonds in and among chitosan molecules, and keep the molecular weight of the chitosan within a larger range, so that the chitosan is dissolved more fully, and further the comprehensive performances such as the mechanical property and the like of the antibacterial film are improved.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises 0.25-0.75% of glycerol, and preferably 0.5% of glycerol. In the present invention, the glycerin is used as a plasticizer, which can improve the mechanical properties of the antibacterial film. The invention limits the mass content of the glycerol within the range, can better weaken the acting force among chitosan molecules, increase the mobility of chitosan molecular chains, and reduce the crystallinity of the molecular chains, and simultaneously, the glycerol and the Tween 80 have synergistic effect, thereby improving the mechanical property of the antibacterial film.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises 800.1-0.2% of tween, and preferably 0.15% by mass. In the present invention, tween 80 is used as an emulsifier. According to the invention, the mass content of the Tween 80 is limited within the range, so that the composite membrane liquid can form a uniform and stable dispersion, the appearance and the structure of the membrane are improved, the Tween and the glycerol have a synergistic effect, and the mechanical property of the antibacterial membrane is improved.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises 0.05-0.4% of nano montmorillonite, and preferably 0.2% of nano montmorillonite. In the invention, the nano montmorillonite is a two-dimensional lamellar structure, the thickness of the lamellar structure is in a nano scale, a chitosan molecular chain can be inserted into a montmorillonite layer to form a composite material with an intercalation or peeling structure, the nano montmorillonite is uniformly dispersed into the chitosan, meanwhile, the hydrogen bond action in chitosan molecules and among the chitosan molecules can be destroyed, a new hydrogen bond action is formed, the crosslinking degree and compactness are improved, and the mechanical property of the antibacterial film and the like are improved. The invention limits the mass content of the nano montmorillonite in the range, can enable the nano montmorillonite to be more uniformly dispersed in the antibacterial film, avoids agglomeration, and thus improves the performance of the antibacterial film.
In the invention, the particle size of the nano montmorillonite is preferably 100-200 nm, and more preferably 150 nm. The invention limits the grain diameter of the nano montmorillonite in the range, and can enable the nano montmorillonite to be more uniformly dispersed in the antibacterial film, thereby further improving the comprehensive properties of the antibacterial film, such as mechanics and the like.
The raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises 0.05-0.4% of akebia trifoliate peel extract, and preferably 0.2% of akebia trifoliate peel extract. In the invention, the akebia trifoliata peel extract contains rich bioactive components such as hederagenin, pectin, polyphenol and the like, so that the antibacterial property and the antioxidant activity of the chitosan membrane can be improved, and meanwhile, the akebia trifoliata peel extract has wide sources, easily-obtained raw materials and low cost; and the hydrogen bond action in the chitosan molecule and among the molecules can be destroyed, a new hydrogen bond action is formed, the crosslinking degree and the compactness are improved, and the mechanical property of the antibacterial film and the like are improved. The mass content of the akebia trifoliata peel extract is limited within the range, so that the antibacterial performance of the antibacterial film can be improved, the akebia trifoliata peel extract is uniformly dispersed in the antibacterial film, and agglomeration is avoided, so that the performance of the antibacterial film is improved.
In the invention, the particle size of the akebia trifoliata peel extract is preferably 0.1-0.5 mm, and more preferably 0.2 mm. The particle size of the akebia trifoliata peel extract is limited within the range, so that the akebia trifoliata peel extract can be more uniformly dispersed in the antibacterial film, the antibacterial performance of the antibacterial film is further improved, agglomeration of the akebia trifoliata peel extract can be avoided, and the comprehensive performance of the antibacterial film is further improved.
The source of the akebia trifoliata peel extract is not particularly limited in the invention, and the akebia trifoliata peel extract can be prepared by adopting a commercial product or a product prepared by a conventional preparation method which is well known to a person skilled in the art. In the embodiment of the invention, the preparation method of the akebia trifoliata peel extract comprises the following steps: (1) adding 10g of akebia trifoliata peel dry powder into a sealed chamber at 25 ℃, adding 50% ethanol solution by volume fraction, and mixing to obtain a mixed solution, wherein the liquid-material ratio is 20:1 mL/g; (2) performing ultrasonic treatment on the obtained mixed solution for 50min under the condition of 50Hz, and then centrifuging the mixed solution for 20min under the condition of 3500 r/min; (3) collecting supernatant, concentrating under reduced pressure at 40 deg.C and-0.08 MPa for 1 hr, and freeze drying the concentrated supernatant to obtain caulis Akebiae pericarp extract.
According to the mass content, the raw material of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film comprises the balance of water. In the present invention, the water is a solvent. In the present invention, the water is preferably sterile deionized water. In the invention, the sterile deionized water can avoid the substances such as bacteria, impurities and the like in the water from generating adverse effects on the performance of the antibacterial film.
The invention utilizes the nano montmorillonite to be evenly dispersed into the chitosan, thereby improving the mechanical property of the material; the akebia trifoliata peel extract contains rich bioactive components such as hederagenin, pectin, polyphenol and the like, so that the antibacterial property and the antioxidant activity of the chitosan film are improved, and meanwhile, the source is wide, the raw materials are easily available, and the cost is low; the components are uniformly distributed in the chitosan by controlling the composition and the dosage of the components, so that the performance of the chitosan film is improved.
The invention provides a preparation method of a chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film in the technical scheme, which comprises the following steps:
(1) mixing chitosan with acetic acid, water, glycerol and tween 80 to obtain a chitosan solution;
(2) mixing the chitosan solution obtained in the step (1) with nano montmorillonite and akebia trifoliata peel extract to obtain a composite membrane solution;
(3) and (3) forming a film by using the composite film liquid obtained in the step (2) to obtain the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film.
The invention mixes chitosan with acetic acid, water, glycerol and tween 80 to obtain chitosan solution.
The operation of mixing the chitosan with acetic acid, water, glycerol and tween 80 is not particularly limited, and the technical scheme of mixing materials, which is well known to those skilled in the art, can be adopted. In the present invention, it is preferred to first add acetic acid to the water, and then add chitosan, glycerol and tween 80. According to the invention, acetic acid is added into water to prepare an acetic acid solution, and then chitosan is added, so that the chitosan can fully and uniformly interact with the acetic acid and can be dissolved more fully, and the performance of the antibacterial film is further improved.
In the present invention, the mixing of the chitosan with acetic acid, water, glycerol and tween 80 is preferably performed under stirring conditions; the stirring is preferably mechanical stirring; the rotating speed of the stirring is preferably 200-300 r/min, and more preferably 250 r/min; the stirring time is preferably 20-40 min, and more preferably 30 min; the stirring temperature is preferably 20-30 ℃, and more preferably 25 ℃.
After the chitosan solution is obtained, the chitosan solution is mixed with the nano montmorillonite and the akebia trifoliata peel extract to obtain a composite membrane liquid.
The operation of mixing the chitosan solution with the nano montmorillonite and the akebia trifoliata peel extract is not particularly limited, and the technical scheme of mixing materials, which is well known by the technical personnel in the field, is adopted. In the invention, the chitosan solution is preferably mixed with the nano montmorillonite and the akebia trifoliata peel extract under the stirring condition; the stirring is preferably mechanical stirring; the rotating speed of the stirring is preferably 200-300 r/min, and more preferably 250 r/min; the stirring time is preferably 20-40 min, and more preferably 30 min; the stirring temperature is preferably 20-30 ℃, and more preferably 25 ℃.
After the composite membrane liquid is obtained, the invention carries out membrane forming on the composite membrane liquid to obtain the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial membrane.
In the present invention, the composite film liquid is preferably subjected to degassing treatment before film formation. In the present invention, the degassing treatment is preferably ultrasonic degassing; the frequency of the ultrasonic wave is preferably 20-70 Hz, and more preferably 50 Hz; the ultrasonic treatment time is preferably 20-40 min, and more preferably 30 min. In the invention, the degassing treatment is used for removing bubbles in the composite membrane liquid, so that holes are avoided after membrane forming, and the performance of the antibacterial membrane is reduced.
In the invention, the film forming of the composite film liquid is preferably dry film forming; the drying temperature is preferably 45-55 ℃, and more preferably 50 ℃; the drying humidity is preferably 30-50%, and more preferably 40%; the drying time is preferably 15-20 h, and more preferably 18 h. In the present invention, the dry film formation treatment is preferably performed in a glass film formation vessel of 20X 20 cm. The invention limits the temperature and humidity of the dried film in the above range, can make the water evaporation rate moderate, the chitosan molecules can be orderly arranged in the forming process of the film matrix, the density is high, and the film has better performance and appearance.
After the film forming is finished, the film forming product is preferably sequentially cooled and uncovered, and the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film is obtained. In the present invention, the cooling is preferably performed in a room temperature environment; the cooling time is preferably 6-10 h, and more preferably 8 h. In the present invention, the cooling can avoid unevenness of the film surface caused by peeling the film at a higher temperature.
After the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film is obtained, the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film is preferably stored in a drying container with the temperature of 25 +/-0.5 ℃ and the relative humidity of 50 +/-5%.
The invention also provides the application of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by the technical scheme or the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film prepared by the preparation method of the technical scheme in a food preservative film. The application of the chitosan/nano montmorillonite/akebia trifoliate peel extract antibacterial film in the food preservative film is not particularly limited, and the food preservative film well known to the technical personnel in the field can be applied.
The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film is prepared from the following raw materials in percentage by mass: 1.5 percent of chitosan (the number-average molecular weight is 4.4KDa, the deacetylation degree is 88.1 percent), 1 percent of acetic acid, 0.5 percent of glycerol, 800.1 percent of Tween, 0.2 percent of nano montmorillonite (the particle size is 150nm), 0.2 percent of akebia trifoliata peel extract (the particle size is 0.2mm) and 96.5 percent of sterile deionized water.
The preparation method of the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film comprises the following steps:
(1) dissolving 1g acetic acid in 96.5g sterile deionized water to obtain acetic acid solution, adding 1.5g chitosan, 0.5g glycerol and 0.1g tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) adding 0.2g of nano montmorillonite and 0.2g of akebia trifoliata peel extract into the chitosan solution, and stirring for 30min at a speed of 250r/min to obtain a composite membrane solution;
(3) placing the composite membrane liquid in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(4) slowly pouring the degassed composite membrane liquid into a 20 x 20cm glass membrane forming container for drying and membrane forming, wherein the drying temperature is 50 ℃, the drying humidity is 40%, and the drying time is 18 h;
(5) and (3) cooling the dried and film-formed container for 6 hours at room temperature, and removing the prepared film to obtain the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film.
Example 2
The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film is prepared from the following raw materials in percentage by mass: 1.5 percent of chitosan (the number average molecular weight is 4.4KDa, the deacetylation degree is 88.1 percent), 1.5 percent of acetic acid, 0.5 percent of glycerol, 800.1 percent of Tween, 0.2 percent of nano montmorillonite (the particle size is 150nm), 0.1 percent of akebia trifoliata peel extract (the particle size is 0.2mm) and 96.1 percent of sterile deionized water.
The preparation method of the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film comprises the following steps:
(1) dissolving 1.5g acetic acid in 96.1g sterile deionized water to obtain acetic acid solution, adding 1.5g chitosan, 0.5g glycerol, and 0.1g tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) adding 0.2g of nano montmorillonite and 0.1g of akebia trifoliata peel extract into the chitosan solution, and stirring for 30min at a speed of 250r/min to obtain a composite membrane solution;
(3) placing the composite membrane liquid in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(4) slowly pouring the degassed composite membrane liquid into a 20 x 20cm glass membrane forming container for drying and membrane forming, wherein the drying temperature is 45 ℃, the drying humidity is 40%, and the drying time is 15 h;
(5) and (3) cooling the dried and film-formed container for 6 hours at room temperature, and removing the prepared film to obtain the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film.
Example 3
The chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film is prepared from the following raw materials in percentage by mass: 2.0 percent of chitosan (the number average molecular weight is 4.4KDa, the deacetylation degree is 88.1 percent), 1.5 percent of acetic acid, 0.75 percent of glycerol, 800.1 percent of Tween, 0.2 percent of nano montmorillonite (the particle size is 150nm), 0.2 percent of akebia trifoliata peel extract (the particle size is 0.2mm) and 95.25 percent of sterile deionized water.
The preparation method of the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film comprises the following steps:
(1) dissolving 1.5g acetic acid in 95.25g sterile deionized water to obtain acetic acid solution, adding 2.0g chitosan, 0.75g glycerol and 0.1g tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) adding 0.2g of nano montmorillonite and 0.2g of akebia trifoliata peel extract into the chitosan solution, and stirring for 30min at a speed of 250r/min to obtain a composite membrane solution;
(3) placing the composite membrane liquid in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(4) slowly pouring the degassed composite membrane liquid into a 20 x 20cm glass membrane forming container for drying and membrane forming, wherein the drying temperature is 45 ℃, the drying humidity is 40%, and the drying time is 15 h;
(5) and (3) cooling the dried and film-formed container for 6 hours at room temperature, and removing the prepared film to obtain the chitosan/nano montmorillonite/akebia trifoliata peel extract antibacterial film.
Comparative example 1
The chitosan membrane is prepared from the following raw materials in percentage by mass: chitosan 1.5% (number average molecular weight 4.4KDa, degree of deacetylation 88.1%), acetic acid 1.0%, glycerol 0.5%, tween 800.1% and sterile deionized water 96.9%.
The preparation method of the chitosan film comprises the following steps:
(1) dissolving 1.0g acetic acid in 96.9g sterile deionized water to obtain acetic acid solution, adding 1.5g chitosan, 0.5g glycerol, and 0.1g Tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) placing the chitosan solution in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(3) slowly pouring the degassed chitosan membrane solution into a 20 × 20cm glass membrane forming container for drying at 50 deg.C and 40% humidity for 18h to form a membrane;
(4) and (3) placing the dried and film-formed container in a room-temperature environment for cooling for 6h, and removing the prepared film to obtain the chitosan film.
Comparative example 2
The chitosan/nano montmorillonite composite membrane is prepared from the following raw materials in percentage by mass: chitosan 1.5% (number average molecular weight 4.4KDa, degree of deacetylation 88.1%), acetic acid 1%, glycerol 0.5%, tween 800.1%, nano montmorillonite 0.2% (particle size 150nm) and sterile deionized water 96.7%.
The preparation method of the chitosan/nano montmorillonite composite membrane comprises the following steps:
(1) dissolving 1g acetic acid in 96.7g sterile deionized water to obtain acetic acid solution, adding 1.5g chitosan, 0.5g glycerol and 0.1g tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) adding 0.2g of nano-montmorillonite into the chitosan solution, and stirring for 30min at a speed of 250r/min to obtain a composite membrane liquid;
(3) placing the composite membrane liquid in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(4) slowly pouring the degassed composite membrane liquid into a 20 x 20cm glass membrane forming container for drying and membrane forming, wherein the drying temperature is 50 ℃, the drying humidity is 40%, and the drying time is 18 h;
(5) and (3) cooling the dried and film-formed container for 6 hours at room temperature, and removing the prepared film to obtain the chitosan/nano montmorillonite composite film.
Comparative example 3
The chitosan/akebia trifoliata peel extract composite membrane is prepared from the following raw materials in percentage by mass: chitosan 1.5% (number average molecular weight 4.4KDa, degree of deacetylation 88.1%), acetic acid 1%, glycerol 0.5%, tween 800.1%, akebia trifoliata peel extract 0.2% (particle size 0.2mm) and sterile deionized water 96.7%.
The preparation method of the chitosan/akebia trifoliata peel extract composite membrane comprises the following steps:
(1) dissolving 1g acetic acid in 96.7g sterile deionized water to obtain acetic acid solution, adding 1.5g chitosan, 0.5g glycerol and 0.1g tween 80, stirring at 25 deg.C and 250r/min for 30min to obtain chitosan solution;
(2) adding 0.2g of akebia trifoliata peel extract into the chitosan solution, and stirring at 250r/min for 30min to obtain a composite membrane solution;
(3) placing the composite membrane liquid in an ultrasonic instrument, ultrasonically degassing and removing bubbles, wherein the ultrasonic power is 50Hz, and the ultrasonic time is 30 min;
(4) slowly pouring the degassed composite membrane liquid into a 20 x 20cm glass membrane forming container for drying and membrane forming, wherein the drying temperature is 50 ℃, the drying humidity is 40%, and the drying time is 18 h;
(5) and (3) placing the dried and film-formed container in a room temperature environment for cooling for 6h, and removing the prepared film to obtain the chitosan/akebia trifoliata peel extract composite film.
Performance testing
Film thickness test: randomly taking 5 points on the membrane by using a digital micrometer screw to measure;
tensile strength and elongation at break measurements: cutting the film into strips of 1.5 × 10cm according to GB1040-79, and measuring by using a texture analyzer;
and (3) measuring the water vapor transmission rate: adopting a cup-like method, wherein the relative humidity difference between the inner side and the outer side of the film is 0/100%;
and (3) water solubility determination: drying the membrane at 105 ℃ to constant weight, immersing the membrane in distilled water for 48h, wherein the using amount of the distilled water is less than that of the membrane, taking out the residual membrane, drying the residual membrane at 105 ℃ to constant weight, and the water solubility is the mass loss percentage of the membrane;
and (3) determination of antibacterial activity: escherichia coli and Staphylococcus aureus were inoculated into LB liquid medium and TSB liquid medium, respectively, and activated at 37 deg.C and 200rpm for 12 h. Sucking 200 mu L of bacterial culture solution, uniformly smearing in a PCA culture medium, cutting a sterile paper sheet into a circular sheet with the diameter of 6mm by using a puncher, soaking the sterile paper in the composite membrane solution for 3h, draining, and then putting the circular sheet on the surface of the inoculated culture medium. And (3) putting the prepared escherichia coli and staphylococcus aureus experimental group into a constant-temperature incubator at 37 ℃, observing the size of a bacteriostatic zone after 24 hours, recording the change of the size of the bacteriostatic zone by using a cross method, and analyzing the bacteriostatic performance of the antibacterial composite membrane. Each set of tests was done in 3 replicates.
And (3) testing the oxidation resistance: the oxidation resistance of the membrane is characterized by DPPH radical scavenging. Accurately weighing 0.5g of membrane sample, placing the membrane sample into 10mL of deionized water, oscillating for 4h, and then carrying out 2000r/mCentrifuging for 5min under in condition; adding 1.0mL methanol into 1mL supernatant, adding 1.0mL DPPH methanol solution (DPPH concentration is 0.3mmol/L), mixing, standing in the dark for 30min, and measuring the light absorption A at 517nmS(ii) a Simultaneously, the supernatant is replaced by 1.0mL of distilled water, and then the absorbance A is measuredC(ii) a The DPPH free radical clearance is calculated by the formula:
the performance test data for the films of examples 1-3 and comparative examples 1-3 are set forth in Table 1, with different lower case letters in the same column of Table 1 indicating significant differences at the 95% confidence interval.
TABLE 1 data for various performance tests of films in examples 1-3 and comparative examples 1-3
As can be seen from Table 1, the tensile strength and elongation at break of the pure chitosan membrane and the composite membrane obtained by only adding the nano-montmorillonite or akebia trifoliata peel extract are both low, and the mechanical property is poor; DPPH free radical clearance rate is low, and antioxidant activity is poor; the tensile strength and the elongation at break of the antibacterial film prepared by adding the nano montmorillonite and the akebia trifoliata peel extract are increased, the mechanical property of the antibacterial film is improved, the water solubility is enhanced, the DPPH free radical clearance rate is increased, the antioxidant activity is enhanced, the water vapor transmission rate is not obviously reduced and is slightly increased, the water loss of fruits and vegetables can be well prevented, excessive water cannot be left, and the preservation effect is better improved; the addition of nano montmorillonite and caulis Akebiae pericarp extract can greatly improve the membrane performance.
The appearance of each of the films of example 1 and comparative examples 1 to 3 is shown in fig. 1, and the films of comparative example 1, comparative example 2, comparative example 3 and example 1 are sequentially arranged from top to bottom in fig. 1. As can be seen from fig. 1, the film prepared in example 1 has a smooth surface and a dark color.
The bacteriostatic effect of each film in example 1 and comparative examples 1 to 3 is shown in fig. 2. As can be seen from fig. 2, the antibacterial film prepared in example 1 has excellent antibacterial performance, particularly, has better antibacterial performance against staphylococcus aureus.
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.