Non-woven fabric packaging bag with fresh-keeping and bacteriostatic effects and application thereof

Abstract

This invention belongs to the field of fruit and vegetable preservation technology, specifically relating to a preservation and antibacterial material and its preparation method. The non-woven packaging bag with preservation and antibacterial properties provided by this invention is characterized in that the packaging bag uses a dry modified non-woven fabric as a base layer, first coated with a coating solution A, then evenly sprinkled with a layer of ClO2 powder, and finally coated with a coating solution B. This invention coats the surface of the packaging bag with a film that has preservation and antibacterial properties, without directly contacting the fruit, thus improving consumer acceptability and avoiding the complex and cumbersome process of directly coating the fruit. Furthermore, it achieves continuous sterilization during fruit storage and transportation.

Description

Technical Field

[0001] This invention belongs to the field of fruit and vegetable preservation technology, specifically relating to a non-woven packaging bag with preservation and antibacterial effects and its application. Background Technology

[0002] Existing technologies disclose a common method for preserving fruits and vegetables by coating their surface with one or more layers of preservative and antibacterial film. This method can achieve longer-lasting preservation and better antibacterial effects. However, the disadvantages of this method are:

[0003] (1) It is difficult to apply on a large scale. Farmers or individual retailers need to purchase the corresponding coating solution first, and then coat the fruits one by one and dry them. In addition, it is difficult to control the amount of coating during the coating process. If the coating thickness is insufficient, the preservation effect will be reduced. If the coating thickness is too thick, the coating solution will be wasted, and it may also affect the normal respiration and metabolism of fruits and vegetables.

[0004] (2) In the minds of most consumers, even if the ingredients of the plastic wrap are relatively safe, they may still believe that the plastic wrap contains unknown chemical components and its safety cannot be guaranteed. Therefore, for most fruits, the use of preservative coating is difficult to promote in practical applications.

[0005] The inventor found that there are also cases of using non-woven fabric to preserve oranges. For example, some literature discloses that after soaking navel oranges in fennel extract and air-drying them, individual packaging of the navel oranges in non-woven fabric preservation bags treated with hydroxypropyl methylcellulose can reduce the weight loss and rot rate of navel oranges and extend their shelf life.

[0006] However, the aforementioned literature discloses that treating the non-woven bags with hydroxypropyl methylcellulose primarily aims to create a micro-modified atmosphere, reducing the respiration rate of navel oranges and maintaining quality, rather than directly coating the antibacterial film onto the non-woven fabric. If the antibacterial film were directly coated onto the non-woven fabric, what would its antibacterial effect be? Whether the active ingredients could volatilize and achieve the desired antibacterial effect for fruit preservation are also issues that need to be addressed. If the antibacterial components could be coated onto the non-woven packaging bag without direct contact with the fruit, it would not only make preservation more convenient but also significantly improve consumer acceptance, facilitating the promotion and large-scale application of this technology. Summary of the Invention

[0007] To solve the above-mentioned technical problems, the present invention provides a non-woven packaging bag with freshness preservation and antibacterial effect. The packaging bag is made of modified non-woven fabric as the base layer, coated with coating solution A, uniformly sprinkled with ClO2 powder layer, and finally coated with coating solution B.

[0008] A non-woven packaging bag with preservation and antibacterial properties. The packaging bag uses dry modified non-woven fabric as the base layer, first coated with coating solution A, then evenly sprinkled with ClO2 powder layer, and finally coated with coating solution B.

[0009] Coating solution A mainly comprises the following components: 1.5-2.0% chitosan by mass and 1.0-1.5% glacial acetic acid by volume; the degree of deacetylation of chitosan is greater than 95%, and the viscosity is 100-200 mPa·s; the balance is distilled water. A higher degree of deacetylation of chitosan enhances its inhibitory effect on bacteria and fungi, and highly deacetylated chitosan forms a colloid in water. When the degree of deacetylation is ≥95%, the solubility and viscosity of chitosan increase significantly. Chitosan with a viscosity in the range of 100-200 mPa·s typically has a higher molecular weight, resulting in higher viscosity and gelling ability. When the deacetylated viscosity is less than 95%, its solubility in dilute acid also decreases; less than 70% cannot be completely dissolved in dilute acid or dissolves extremely slowly. Viscosity below 100-200 mPa·s results in a relatively lower viscosity and gel-forming ability.

[0010] The coating solution B mainly comprises the following components: 1.0-2.0% carboxymethyl cellulose by mass; 1.0-2.0% plant essential oil and 0.5-0.8% surfactant by volume, with the balance being distilled water; the surfactant in the coating solution B is selected from at least one of Tween-80, Tween-20 and Sorbitol-20.

[0011] Preferably, the plant essential oil in the coating solution B is selected from at least one of cinnamaldehyde and lemon essential oil.

[0012] Based on the modified nonwoven fabric specification of 30cm×21cm, the coating amount of both coating solution A and coating solution B is 10-12mL; the amount of ClO2 powder layer is 0.5g.

[0013] The modified nonwoven fabric described above is obtained through the following steps:

[0014] (1) Preparation of polyvinyl alcohol mother liquor: Place polyvinyl alcohol particles in distilled water, stir to remove impurities, take out the polyvinyl alcohol particles after removing impurities, and dry them at 70°C for 12 hours.

[0015] The dried polyvinyl alcohol granules were added to deionized water at a material-to-liquid ratio of 1:9 and swelled at a constant temperature of 65°C for 2 hours. Then, a plasticizer was added until its mass fraction reached 1.5%. The mixture was then stirred at a constant temperature of 95°C for 4 hours until the polyvinyl alcohol was completely melted. Finally, the mixture was degassed at -0.1 MPa for 1 hour to obtain a polyvinyl alcohol mother liquor. The preferred plasticizer is glycerin.

[0016] (2) Non-woven fabric pretreatment: Soak the non-woven fabric in anhydrous ethanol, then shake to remove impurities, rinse with deionized water to remove anhydrous ethanol, and dry.

[0017] (3) Modification of nonwoven fabric: Fix the pretreated nonwoven fabric and coat it with polyvinyl alcohol mother liquor evenly to modify it, thereby obtaining modified nonwoven fabric; the amount of polyvinyl alcohol mother liquor coated on each 30cm×21cm nonwoven fabric is 10-12 mL.

[0018] The application of the aforementioned non-woven packaging bags with preservation and antibacterial properties in the preservation and antibacterial use of fruits and vegetables is also a key aspect of this invention.

[0019] The application method of non-woven packaging bags with preservation and antibacterial properties includes the following steps:

[0020] (1) Take two pieces of non-woven fabric prepared by the above method, take the coated side as the inner surface and their opposite side as the outer surface, press them into the shape of a cloth bag with a heat sealing machine, leave an opening in the cloth bag for putting fruit inside; the cloth bag can be a rectangular bag, or of course other shapes of cloth bags; generally speaking, the cloth bag is mostly rectangular, with a size of 30cm×21cm.

[0021] (2) Place the fruit to be preserved in the heat-sealed non-woven bag in (1); put 200-300g of fruit, such as blueberries or cherries, in each bag; of course, you can also put the appropriate amount according to the size of the fruit depending on the specific situation.

[0022] (3) Place the non-woven bag containing the fruit in a food storage box and store it at room temperature or at a low temperature, such as at -2~2℃ or 3~7℃.

[0023] Preferably, the surfactant is selected from at least one of Tween-80, polyoxyethylene (20) sorbitan monolaurate (also known as Tween-20) and sorbitan monolaurate (also known as Span-20).

[0024] The reason for coating the packaging bag of this invention with three layers—coating solution A, ClO2 powder layer, and coating solution B—is that the chitosan in coating solution A has good film-forming properties, biocompatibility, and biodegradability, thus acting as a physical barrier. The carboxymethyl cellulose in coating solution B has good solubility and film-forming properties, and also has a certain degree of water absorption, which can regulate the humidity of the coating and compensate for the shortcomings of the chitosan film.

[0025] To further enhance the antibacterial and preservation effects, this application also incorporates a ClO2 powder layer and cinnamaldehyde, which have a significant effect on improving the antibacterial and preservation effects.

[0026] Furthermore, the novel antibacterial film formed by electrostatic deposition of coating solution A and coating solution B exhibits improved uniformity, stability, and mechanical properties. When used together, the two films provide a better dispersion and carrying environment for the antibacterial components, such as chlorine dioxide in the middle of the two films and cinnamaldehyde in coating solution B, thus slowing down the release rate of volatile bactericidal substances and achieving continuous sterilization during the storage and logistics of fruits and vegetables.

[0027] Therefore, this invention first modifies the nonwoven fabric to improve its surface hydrophilicity, strength, and durability. Then, it treats the modified nonwoven fabric with coating solution A, ClO2, and coating solution B respectively to form preservation and antibacterial materials with different layers. The layer order of coating solution A, ClO2 powder coating, and coating solution B is coating solution A, ClO2 powder coating, and coating solution B, respectively. The principle of their function is as analyzed above. Their layer order cannot be changed, otherwise it will affect the antibacterial effect.

[0028] This invention also protects the application of the non-woven packaging bag with preservation and antibacterial properties prepared by the above method in the preservation and antibacterial use of fruits and vegetables. The fruits and vegetables mentioned above can be blueberries, figs, strawberries, cherries, or other fruits such as apples and citrus fruits.

[0029] The beneficial effects of this invention are as follows:

[0030] (1) The biggest improvement of this invention is that it breaks through the traditional method of coating the surface of the fruit with preservative and antibacterial agents. Instead, it coats the inner surface of the packaging bag with a film that has the function of preservative and antibacterial agents, without directly contacting the fruit. On the one hand, it improves the acceptance of consumers. On the other hand, it utilizes the slow-release effect of the preservative bag containing volatile bactericides to achieve continuous sterilization during the storage and transportation of the fruit. Through large-scale production and the production of active packaging bags, it reduces the spoilage loss of fruits and vegetables during the post-harvest storage and transportation process.

[0031] (2) In order to make the effective components in the coating on the non-woven fabric continuously volatilize and play a role in antibacterial preservation, the present invention uses a bilayer film of chitosan and carboxymethyl cellulose. There can be electrostatic interaction between the two to enhance the stability and integrity of the coating, provide a better dispersion and carrying environment for active antibacterial agents such as chlorine dioxide and cinnamaldehyde, delay the release rate of volatile bactericidal substances, and thus achieve the effect of continuous sterilization during the storage and logistics of fruits and vegetables.

[0032] (3) The non-woven packaging bag in this application is more convenient than the technical solution of coating the fruit surface. It avoids the complicated and tedious process of directly coating the fruit. Only the packaging bag with the coating is needed to achieve the effect of preserving the fruit and inhibiting bacteria. There is no need to coat each fruit individually. It is suitable for large-scale production and promotion. Compared with the traditional technology of coating the fruit surface, this is a significant improvement. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the coating sequence during the preparation of the packaging bag in Example 1;

[0034] Figure 2 The modified nonwoven fabric after coating in Example 1;

[0035] Figure 3 The images show the packaging effect of blueberries using the packaging material obtained in Comparative Example 1. Left: Comparative Example 1 stored for 0 days; Middle: Comparative Example 1 refrigerated for 6 days; Right: Comparative Example 1 refrigerated for 6 days + shelf life for 3 days.

[0036] Figure 4 The images show the packaging effect of blueberries using the packaging material obtained in Example 1. Left: Example 1, stored for 0 days; Middle: Example 2, refrigerated for 6 days; Right: Example 1, refrigerated for 6 days + shelf life for 3 days.

[0037] Figure 5 The colony plate conditions for each embodiment and comparative example are shown.

[0038] Figure 6 The total bacterial count for each example and comparative example is shown. Detailed Implementation

[0039] To enable those skilled in the art to better understand the present invention, the present invention will now be further described in conjunction with specific embodiments.

[0040] ClO2 powder layer, i.e., chlorine dioxide effervescent tablets (Beijing Hualong Xingyu Technology Development Co., Ltd.), can be crushed before use;

[0041] All other ingredients not mentioned are ordinary commercially available products.

[0042] Example 1

[0043] The steps for preparing nonwoven bags are as follows:

[0044] (1) Pretreatment of nonwoven fabric

[0045] Cut the nonwoven fabric into pieces measuring 30cm×21cm, soak them in anhydrous ethanol for 4 hours, then shake them in a shaker for 2 hours to remove impurities. Rinse them several times with deionized water to remove the anhydrous ethanol, and finally dry them at 60℃ for 6 hours until the nonwoven fabric is completely dry.

[0046] (2) Preparation of nonwoven fabric modification solution

[0047] Polyvinyl alcohol granules were placed in distilled water and stirred to remove impurities. The polyvinyl alcohol granules after impurity removal were taken out and dried in a drying oven at 70°C for 12 hours. The ratio of polyvinyl alcohol granules to deionized water was 1:9. The mixture was swollen at a constant temperature of 65°C for 2 hours. Then, plasticizer was added until its mass fraction reached 1.5%. The mixture was stirred at a constant temperature of 95°C for 4 hours until the polyvinyl alcohol was completely melted. Stirring was then stopped. The mixture was then degassed at -0.1 MPa for 1 hour to obtain polyvinyl alcohol mother liquor.

[0048] (3) Modification of nonwoven fabrics

[0049] Take about 12 mL of polyvinyl alcohol mother liquor from (2) and coat it onto the pretreated nonwoven fabric (30 cm × 21 cm) from (1) using a wire rod. The coating process should be slow to keep the coating uniform and flat. After coating, the modified nonwoven fabric is obtained and dried at 65°C for 15 min.

[0050] (4) Preparation of coating solution

[0051] Preparation of coating solution A: Dissolve 1.5g of chitosan and glacial acetic acid in distilled water to make the mass percentage of chitosan 1.5% and the volume percentage of glacial acetic acid 1.5%. Stir overnight at room temperature to obtain chitosan coating solution A; the degree of deacetylation of chitosan is greater than 95% and the viscosity is 100~200 mpa.s.

[0052] Preparation of coating solution B: Take 1.5g of carboxymethyl cellulose and slowly add it to distilled water while stirring to prevent the formation of a film on the surface of the carboxymethyl cellulose during dissolution, which would increase the difficulty of dissolution. After the carboxymethyl cellulose is completely dissolved, add cinnamaldehyde, then Tween-80, and add distilled water to make the mass percentage of carboxymethyl cellulose 1.5%, the volume percentage of cinnamaldehyde 1%, and the volume percentage of Tween-80 0.8%. Continue stirring until a stable emulsion is formed, thus obtaining coating solution B (coating sequence as attached). Figure 1 (as shown)

[0053] (5) Coating the modified nonwoven fabric with an antibacterial film

[0054] 12 mL of coating solution A was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; then 0.5 g of ClO2 powder was evenly sprinkled on top; finally, 12 mL of coating solution B was applied and dried at 65°C for 15 min; a nonwoven fabric with antibacterial and preservative properties was formed (the coated nonwoven fabric is shown in the attached image). Figure 2 (as shown)

[0055] Take two pieces of nonwoven fabric of the same size from (5), take the coated side as the inner surface and their opposite sides as the outer surface, and use a heat sealing machine to make a rectangular packaging bag with three closed sides and one open side.

[0056] The following are other embodiments and comparative examples. In each embodiment and comparative example 1-8, the nonwoven fabric is cut to the same specifications as in embodiment 1. Unless otherwise specified, the steps are the same as in embodiment 1.

[0057] Example 2

[0058] The difference from Example 1 is that in coating solution A, the mass percentage of chitosan is 1.5% and the volume percentage of glacial acetic acid is 1.5%.

[0059] In coating solution B, the mass percentage of carboxymethyl cellulose is 1.2%; the volume percentages are 1.0% lemon essential oil and 0.6% Tween-20.

[0060] Example 3

[0061] In coating solution B, the mass percentage of carboxymethyl cellulose is 1.8%; the volume percentages are 1.5% lemon essential oil and 0.6% sorbitan-20.

[0062] Example 4

[0063] In coating solution A, the mass percentage of chitosan is 2% and the volume percentage of glacial acetic acid is 2%.

[0064] Comparative Example 1

[0065] The difference from Example 1 is that the nonwoven fabric was not treated, as follows:

[0066] The nonwoven fabric is soaked in an ethanol solution for 4 hours, then shaken in a shaker for 2 hours to remove impurities. It is then rinsed multiple times with deionized water to remove the ethanol, and dried at 60°C. Finally, it is heat-sealed into rectangular packaging bags. That is, ordinary nonwoven bags only undergo pretreatment and are not coated with an antibacterial film layer.

[0067] Comparative Example 2

[0068] The difference from Example 1 is that ClO2 was not used to treat the nonwoven fabric, and the coating solution B does not contain cinnamaldehyde, as detailed below:

[0069] (4) Preparation of coating solution B: Take 1.5g of carboxymethyl cellulose and slowly add it to distilled water while stirring to prevent the formation of a film on the surface of carboxymethyl cellulose during the dissolution process, which would increase the difficulty of dissolution. After the carboxymethyl cellulose is completely dissolved, add Tween-80 and add distilled water to make the mass percentage of carboxymethyl cellulose 1.5% and the volume percentage of Tween-80 0.8%. Continue stirring until a stable emulsion is formed to obtain coating solution B.

[0070] (5) Coating the modified nonwoven fabric with an antibacterial film

[0071] 12 mL of coating solution A was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; then 12 mL of coating solution B was applied and dried at 65°C for 15 min; thus forming a nonwoven fabric with antibacterial and preservative properties.

[0072] Comparative Example 3

[0073] The difference from Example 1 is that ClO2 was not used to treat the nonwoven fabric, and the volume concentration of cinnamaldehyde in the coating solution B was 1.5%, as detailed below:

[0074] (4) Preparation of coating solution B: Take 1.5g of carboxymethyl cellulose and slowly add it to distilled water while stirring. After the carboxymethyl cellulose is completely dissolved, add cinnamaldehyde, then Tween-80, and add distilled water to make the mass percentage of carboxymethyl cellulose 1.5%, the volume percentage of cinnamaldehyde 1.5%, and the volume percentage of Tween-80 0.8%. Continue stirring until a stable emulsion is formed to obtain coating solution B.

[0075] (5) Coating the modified nonwoven fabric with an antibacterial film

[0076] 12 mL of coating solution A was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; finally, 12 mL of coating solution B was applied and dried at 65°C for 15 min; thus forming a nonwoven fabric with antibacterial and preservative properties.

[0077] Comparative Example 4

[0078] The difference from Example 1 is that the coating solution B does not contain cinnamaldehyde, as detailed below:

[0079] (4) Preparation of coating solution B: Take 1.5g of carboxymethyl cellulose and slowly add it to distilled water while stirring to prevent the formation of a film on the surface of carboxymethyl cellulose during the dissolution process, which would increase the difficulty of dissolution. After the carboxymethyl cellulose is completely dissolved, add Tween-80 and add distilled water to make the mass percentage of carboxymethyl cellulose 1.5% to obtain coating solution B.

[0080] Comparative Example 5

[0081] The difference from Example 1 lies in the coating sequence of the modified nonwoven fabric: coating B is applied first, followed by the application of ClO2 powder layer, and finally coating A, as detailed below:

[0082] 12 mL of coating solution B was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; then 0.5 g of ClO2 powder was evenly sprinkled on it; finally, 12 mL of coating solution A was applied and dried at 65°C for 15 min; thus forming a nonwoven fabric with antibacterial and preservation effects.

[0083] Comparative Example 6

[0084] The difference from Example 1 lies in the coating sequence of the modified nonwoven fabric: A is coated first, then B, and finally the ClO2 powder layer is coated, as detailed below:

[0085] 12 mL of coating solution A was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; then 12 mL of coating solution B was applied, and finally 0.5 g of ClO2 powder was evenly sprinkled on top, and dried at 65°C for 15 min; thus forming a nonwoven fabric with antibacterial and preservation effects.

[0086] Comparative Example 7

[0087] The difference from Example 1 is that the modified nonwoven fabric was not treated with coating solution A, as follows:

[0088] 0.5g of ClO2 powder was evenly sprinkled on the modified and dried nonwoven fabric in (3); finally, 12mL of coating solution B was applied and dried at 65℃ for 15min to form a nonwoven fabric with antibacterial and preservation effects.

[0089] Comparative Example 8

[0090] The difference from Example 1 is that the modified nonwoven fabric was not treated with coating solution B, as detailed below:

[0091] 12 mL of coating solution A was applied to the modified and dried nonwoven fabric in (3), and then dried at 65°C for 10 min; then 0.5 g of ClO2 powder was evenly sprinkled on it and dried at 65°C for 15 min; thus forming a nonwoven fabric with antibacterial and preservation effects.

[0092] Experimental Example 1: Testing the Postharvest Preservation Effect of Packaging Materials on Blueberries

[0093] (1) Select fresh blueberries that are free from external damage and pests and record the appearance of the fruit.

[0094] (2) After selection, the blueberries were placed in the packaging bags prepared in the examples and comparative examples, with 30 blueberries in each group, and the fruit quality indicators were recorded and tested.

[0095] (3) Store at 4-6℃ for 6 days, then place at shelf temperature for 3 days, and test the fruit’s rot index, weight loss rate and firmness.

[0096] The detection method is as follows:

[0097] (1) Hardness determination

[0098] Fruit firmness was measured using a GY-2 hardness tester. Three fruits were randomly selected from each group, and the average value of the results was taken. The unit is kg·cm. 2 ;

[0099] (2) Determination of weight loss rate

[0100] Fruit weight loss rate = (fruit weight before storage - fruit weight after storage) / fruit weight before storage × 100%;

[0101] (3) Determination of the corruption index

[0102] The blueberries are divided into 5 levels based on the area of ​​rot: 0 points for no rot, 2 points for rot between 0 and 1 / 4 of the blueberries, 2 points for rot between 1 / 4 and 1 / 2 of the blueberries, 3 points for rot between 1 / 2 and 3 / 4 of the blueberries, 4 points for rot between 3 / 4 and the whole blueberry, and 5 points for the whole blueberry rot.

[0103] Corruption Index = Number of blueberries in each grade × Grade score ÷ (5 × Total number of samples tested) × 100%;

[0104] Before the experiment, the blueberries collected were plump, disease-free, and had an average firmness of 0.99 kg / cm. 2

[0105] The quality indicators of blueberries packaged using the packaging bags prepared in the various embodiments and comparative examples are shown in Table 1:

[0106] Table 1 Fruit quality indicators

[0107] name <![CDATA[Hardness kg / cm 2 > Weight loss rate / % Decay Index / % Example 1 0.94±0.07 7.68±0.67 16.9±1.09 Example 2 0.92±0.04 7.46±0.13 17.0±0.95 Example 3 0.95±0.02 7.53±0.29 16.8±1.21 Example 4 0.94±0.05 7.61±0.44 17.0±1.16 Comparative Example 1 0.68±0.03 7.83±0.61 44.76±2.18 Comparative Example 2 0.73±0.05 7.21±0.65 17.62±1.80 Comparative Example 3 0.94±0.14 7.86±0.55 19.76±0.82 Comparative Example 4 0.94±0.07 7.8±0.73 41.43±2.15 Comparative Example 5 0.93±0.03 7.64±0.17 18.34±1.07 Comparative Example 6 0.90±0.04 7.80±0.15 25.35±4.24 Comparative Example 7 0.77±0.06 7.63±0.33 24.72±1.15 Comparative Example 8 0.89±0.04 7.71±0.31 22.05±1.06

[0108] As shown in Table 1, the decay index of Examples 1-4 was significantly lower than that of Comparative Examples 1-8, all ranging from 16-17%, while the decay index of Comparative Examples 1 and 4 was higher. Considering the fruit firmness and weight loss rate, Example 1 showed the best preservation effect on the fruit, followed by Examples 2-4.

[0109] As attached Figure 3 , 4As shown, when storing blueberries for different shelf lives, the packaging material used in this example demonstrates significantly better preservation results than the comparative method. Combined with... Figure 5 , 6 As can be seen, the total bacterial count of the packaging preservation method in this application is lower than that of the comparative method.

[0110] Experimental Example 2: Mechanical Property Testing of Nonwoven Bags

[0111] Test Example 2-1 Water Absorption Performance

[0112] Refer to GB / T1034—2008 Test for Water Absorption of Plastics. Testing the performance of nonwoven bags is essentially testing the mechanical properties of the nonwoven fabric blocks used to make the bags. Therefore, take the nonwoven fabric prepared according to the method in Example 1 (the nonwoven fabric obtained in step (5)). In the following tests, the above nonwoven fabric is used as the sample to be tested, with a size of 50mm × 50mm. Place it in an oven, adjust the temperature to 50℃, and periodically measure the weight of the sample until it reaches constant weight. Then, soak it in distilled water (500ml, 24℃) for 24 hours. Carefully remove the sample, gently absorb the surface moisture with filter paper, and weigh it. Calculate the water absorption rate according to the following formula:

[0113] η = (m1 - m0) / m0 × 100%,

[0114] Where m0 is the initial mass of the composite membrane, and m1 is the mass of the composite membrane after water absorption.

[0115] Experimental Example 2-2 Mechanical Properties of Nonwoven Bags

[0116] The mechanical properties of the sample, tensile strength F and elongation at break β, were measured using an intelligent electronic tensile testing machine. The non-woven fabric (size 10×1.5cm) from step (5) of Example 1 was used. The stretching rate was 300mm / min, the clamping distance was 80mm, the ambient temperature was 25℃, and the relative humidity of the sample environment was controlled at 50%. Three parallel samples were taken, and the results were expressed as the mean.

[0117] Experimental Example 2-3: Thickness of Nonwoven Fabric

[0118] For each sample, use vernier calipers to measure at least three different locations and take the average of the results.

[0119] Test Example 2-4 Water Vapor Transmission Rate

[0120] The thin film sample was cut into squares, weighed and the original mass was recorded. It was then used to seal a weighing cup (4 cm in diameter and 4 cm in depth) containing 3 g of CaCl2. The cup was then placed in a desiccator containing saturated potassium iodide (20°C, RH=70% relative humidity).

[0121] Weigh the cup every 6 hours for 2 days until a constant weight is reached. Record the time t before and after constant weight, and the mass difference M before and after weighing. Calculate the water vapor transmission rate (WVP) using the following formula:

[0122] Water vapor permeability = (M×x) / (t×A×Δp).

[0123] Where x is the membrane thickness (m), and A is the membrane permeation area (m²). 2 Δp is the vapor pressure difference over the permeation area (2339 Pa at 20℃), and t is the permeation time (s).

[0124] The results are shown in Table 2:

[0125] Table 2 Packaging Material Performance Tests

[0126] name Water absorption capacity / % Water vapor transmission rate / % Thickness / mm Elongation / % Tensile strength / MPa Example 1 52.56±5.84 3.56±0.38 0.61±0.03 115.83±8.3 4.68±0.15 Comparative Example 1 27.25±6.26 3.88±0.2 0.44±0.02 108.66±10.35 4.16±0.05 Comparative Example 2 16±5.55 5.5±1.46 0.55±0.02 106.91±6.29 4.42±0.21 Comparative Example 3 27.96±4.97 2.92±2.45 0.53±0.01 107.08±11.36 4.19±0.19 Comparative Example 4 61.04±11.26 3.33±0.4 0.56±0.02 107.16±0.82 4.33±0.13

[0127] As shown in Table 2, the water absorption performance of the packaging bag of Example 1 was increased by 0.9, 2.2, and 0.9 times compared with Comparative Examples 1, 2, and 3, respectively; the water vapor transmission rate of Example 1 was reduced by 35.3% compared with Comparative Example 2, which can effectively reduce the loss of moisture during fruit and vegetable storage as a fresh-keeping packaging; the tensile strength of Example 1 was increased compared with Comparative Examples 1, 2, 3, and 4, by 12.5%, 5.9%, 11.7%, and 8.1%, respectively.

Claims

1. A non-woven packaging bag with preservation and antibacterial properties, characterized in that, The packaging bag uses dry modified nonwoven fabric as the base layer, first coated with coating solution A, then evenly sprinkled with ClO2 powder layer, and finally coated with coating solution B; The modified nonwoven fabric is a modified nonwoven fabric obtained by coating polyvinyl alcohol mother liquor after treatment; Coating solution A comprises the following components: The composition is 1.5-2.0% chitosan by mass and 1.0-1.5% glacial acetic acid by volume; the degree of deacetylation of chitosan is greater than 95%, and the viscosity is 100-200 mPa·s; the balance is distilled water. Coating solution B comprises the following components: 1.0~2.0% carboxymethyl cellulose by mass; The coating solution contains 1.0-2.0% by volume of plant essential oil and 0.5-0.8% of surfactant, with the balance being distilled water; the surfactant in the coating solution B is selected from at least one of Tween-80, Tween-20, and Sorbitol-20; the plant essential oil is selected from at least one of cinnamaldehyde and lemon essential oil. Based on the modified nonwoven fabric with dimensions of 30cm×21cm, the coating amount of both coating solution A and coating solution B is 10-12mL; the amount of ClO2 powder layer is 0.5g.

2. The non-woven packaging bag with preservation and antibacterial effects as described in claim 1, characterized in that, Modified nonwoven fabrics are obtained through the following modification steps: (1) Preparation of polyvinyl alcohol mother liquor: Place polyvinyl alcohol particles in distilled water, stir to remove impurities, take out the polyvinyl alcohol particles after removing impurities, and dry them at 70°C for 12 hours. The dried polyvinyl alcohol granules were added to deionized water at a material-to-liquid ratio of 1:9 and swollen at a constant temperature of 65°C for 2 hours. Then, plasticizer was added until its mass fraction reached 1.5%. The mixture was then stirred at a constant temperature of 95°C for 4 hours until the polyvinyl alcohol was completely melted. Finally, the mixture was degassed at -0.1 MPa for 1 hour to obtain polyvinyl alcohol mother liquor. (2) Non-woven fabric pretreatment: Soak the non-woven fabric in anhydrous ethanol, then shake to remove impurities, rinse with deionized water to remove anhydrous ethanol, and dry. (3) Modification of nonwoven fabric: Fix the pretreated nonwoven fabric and coat it with polyvinyl alcohol mother liquor. The mixture is evenly coated on the nonwoven fabric to modify it and obtain modified nonwoven fabric. The amount of polyvinyl alcohol mother liquor coated on each 30cm×21cm nonwoven fabric is 10-12 mL.

3. The non-woven packaging bag with preservation and antibacterial effects as described in claim 2, characterized in that, The plasticizer is glycerin.

4. The application of the non-woven packaging bag with preservation and antibacterial function as described in claim 1 in the preservation and antibacterial use of fruits and vegetables.

5. The application method of the non-woven packaging bag with preservation and antibacterial effects as described in claim 1, comprising the following steps: (1) Take two pieces of nonwoven fabric as described in claim 1, take the coated side as the inner surface and their opposite sides as the outer surface; press them into the shape of a cloth bag using a heat sealing machine; (2) Place the fruit to be preserved into the heat-sealed non-woven bag in (1); (3) Place the non-woven bag containing the fruit in a food storage box and store it at room temperature or at -2~7℃.

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