Bamboo fiber-based food preservation wrapping paper and preparation method thereof

Abstract

The application relates to a bamboo fiber-based food fresh-keeping packaging paper and a preparation method thereof. The preparation method comprises the following steps: bleached sulfite tender bamboo fibers and bamboo root fibers are respectively subjected to grinding and pulping treatment, and then are dispersed and mixed to obtain NBF / BRF mixed pulp; then modified bamboo fiber cellulose nanocrystals are added to obtain NBF / BRF / BNC composite pulp; the NBF / BRF / BNC composite pulp is then papermaking, shaping, dewatering and drying to obtain a bamboo paper sample A; bamboo vinegar liquid is uniformly sprayed on the outer surface of the bamboo paper sample A; finally, the bamboo paper sample A is hot-pressed and dried to obtain the bamboo fiber-based food fresh-keeping packaging paper. The bamboo fiber-based food fresh-keeping packaging paper is prepared by using bamboo fiber raw materials with different characteristics, and the bamboo fiber-based food fresh-keeping packaging paper has excellent mechanical strength, barrier performance, hydrophobic performance, antibacterial and mildew resistance, and can be used in the field of fruit and vegetable fresh-keeping packaging materials.

Description

Technical Field

[0001] This invention relates to the field of food preservation packaging materials, specifically to a bamboo fiber-based food preservation packaging paper and its preparation method. Background Technology

[0002] Bamboo is a fast-growing plant that can mature and regrow in a short time, allowing it to quickly supplement and replace plastics, thus reducing dependence on plastics and petroleum. Furthermore, bamboo absorbs large amounts of carbon dioxide during its growth and is completely biodegradable after use, causing no long-term pollution and minimizing the environmental impact of bamboo products. More importantly, China possesses abundant bamboo resources, widely distributed and with a large planting area, providing ample raw material for the "bamboo-for-plastics" industry. In addition, bamboo has relatively low planting and processing costs, which helps reduce costs and improve economic efficiency. Moreover, bamboo has excellent plasticity and hardness, allowing it to be made into raw bamboo packaging, bamboo woven products, and bamboo fiber packaging, which can replace some plastic products. Therefore, in the context of a global ban on plastics, replacing plastics with bamboo not only helps reduce plastic pollution and address climate change but also promotes the development of green industries and improves economic efficiency, making it an environmentally friendly and sustainable development choice.

[0003] Bamboo fiber is a cellulose fiber extracted from naturally grown bamboo. Bamboo fiber itself possesses excellent air permeability, water absorption, strong abrasion resistance, and good dyeability, and has natural antibacterial, bacteriostatic, mite-repellent, and deodorizing functions. Due to increased public awareness of environmental protection and the continued implementation of national plastic restriction measures, plant fiber-based environmentally friendly packaging is becoming increasingly popular. With the release of the "Three-Year Action Plan for Accelerating the Development of 'Bamboo-for-Plastic' Development," bamboo fiber-based packaging paper is receiving significant attention from packaging companies, and various research institutes are also exploring the use of bamboo fiber to prepare packaging paper. However, research and application of bamboo fiber packaging paper for food preservation are scarce. Therefore, developing a new type of bamboo fiber-based food preservation packaging paper is an urgent problem that needs to be solved. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the first objective of the present invention is to provide a method for preparing bamboo fiber-based food preservation packaging paper.

[0005] The second objective of this invention is to provide bamboo fiber-based food preservation packaging paper obtained by the above preparation method.

[0006] The third objective of this invention is to provide the application of the above-mentioned bamboo fiber-based food preservation packaging paper.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] A method for preparing bamboo fiber-based food preservation packaging paper includes the following steps:

[0009] (1) Bleached sulfate tender bamboo fiber and bamboo root fiber were respectively subjected to pulping treatment to obtain NBF pulp with a freeness of 35-40°SR and BRF pulp with a freeness of 45-50°SR.

[0010] (2) Disperse the NBF slurry and the BRF slurry in step (1) to obtain NBF dispersion and BRF dispersion;

[0011] (3) Mix the NBF dispersion and the BRF dispersion in step (2) evenly to obtain an NBF / BRF mixed slurry;

[0012] (4) The modified bamboo cellulose nanocrystals are added to the NBF / BRF mixed slurry obtained in step (3) under stirring conditions and mixed evenly to obtain NBF / BRF / BNC composite slurry;

[0013] (5) The NBF / BRF / BNC composite pulp described in step (4) is paper-made, shaped, dehydrated and dried to obtain bamboo paper sample A;

[0014] (6) The outer surface of the bamboo paper sample A described in step (5) is uniformly sprayed with bamboo vinegar solution and dried to obtain bamboo paper sample B;

[0015] (7) The bamboo paper sample B described in step (6) is hot-pressed and dried to obtain bamboo fiber-based food preservation packaging paper.

[0016] Preferably, the bleached sulfate tender bamboo fiber in step (1) has a length of 2-20 mm and a diameter of 10-25 μm; the bamboo root fiber has a length of 5-30 mm and a diameter of 28-40 μm.

[0017] Preferably, the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber in step (1) is 5:5 to 7:3.

[0018] Preferably, the tender bamboo in step (1) is a 1-year-old tender bamboo.

[0019] Preferably, the pulping process in step (1) is performed using a dual-disc pulper;

[0020] Preferably, the amount of modified bamboo fiber nanocrystals added in step (4) is 4.0 to 7.0% of the mass of NBF / BRF / BNC composite slurry.

[0021] Preferably, the slurry concentration of the NBF / BRF / BNC composite slurry in step (4) is 0.2% to 1.0% by mass.

[0022] Preferably, the concentration of the bamboo vinegar in step (6) is 3.5 to 5.0% by mass.

[0023] Preferably, the amount of bamboo vinegar solution sprayed onto the outer surface of the bamboo paper sample A in step (6) is 2.0–5.0 g / m². 2 .

[0024] Preferably, the pulping conditions for the bleached sulfate tender bamboo fiber in step (1) are: pulping speed of 500-750 r / min and pulping concentration of 4.0-5.0 wt%; the pulping conditions for the bamboo root fiber are: pulping speed of 600-980 r / min and pulping concentration of 2.5-3.5 wt%.

[0025] Preferably, the stirring speed in step (4) is 4000 to 7000 r / min.

[0026] Preferably, the stirring in step (4) is done using an electric mixer.

[0027] Preferably, the length of the modified bamboo cellulose nanocrystals in step (4) is 50-200 nm and the diameter is 2-30 nm. The modified bamboo cellulose nanocrystals are prepared by the following method: bleached sulfate bamboo pulp is hydrolyzed with organic acid, dialyzed, centrifuged, and then acetylated to obtain modified bamboo cellulose nanocrystals.

[0028] Preferably, the modified bamboo cellulose nanocrystals are prepared by the following method: 3.0–4.0 g of bleached sulfate bamboo pulp is slowly added to 50–70 mL of a 55–60% maleic acid solution, and the mixture is stirred and hydrolyzed in a water bath at 45–50 °C for 45–50 minutes. The acid hydrolysis reaction is then terminated by adding deionized water, and the solid is repeatedly centrifuged and washed for purification. Finally, the purified solid is dialyzed and centrifuged again to obtain a light blue solution. This solution is concentrated by rotary evaporation to obtain aqueous suspensions of bamboo cellulose nanocrystals of different concentrations. These suspensions are then freeze-dried in a freeze-drying oven for 48–72 hours to obtain bamboo cellulose nanocrystals of different concentrations. 5–10 g of the bamboo cellulose nanocrystals are placed in a flask containing 50–80 mL of glacial acetic acid, heated to 50–60 °C, and 10–20 mL of acetic anhydride reagent and 500 μL of dicyclohexylcarbodiimide are added. The reaction is carried out for 60–80 minutes. After a few minutes, the mixture was poured into ethanol to precipitate a white flocculent precipitate. The precipitate was then centrifuged, washed 3-5 times with ethanol, and then washed 2-3 times with deionized water. Finally, an aqueous suspension of acetylated bamboo cellulose nanocrystals was obtained. The suspension was then freeze-dried in a freeze-drying oven for 48-72 hours to obtain acetylated bamboo cellulose nanocrystals.

[0029] Preferably, the paper forming in step (5) is performed using a slanted wire paper machine.

[0030] Preferably, the bamboo vinegar solution described in step (5) is sprayed onto the upper and lower surfaces of the bamboo paper sample A.

[0031] Preferably, the drying method in step (6) is: infrared drying at 100-180°C for 30-50 minutes.

[0032] Preferably, the hot pressing conditions in step (7) are: temperature of 88-98℃, pressure of 28-36MPa, and time of 15-30min.

[0033] Preferably, the drying method in step (7) is: infrared drying at 82-90°C for 10-20 minutes.

[0034] A bamboo fiber-based food preservation packaging paper is obtained by the above preparation method.

[0035] The performance indicators of the bamboo fiber-based food preservation packaging paper are as follows: basis weight: 54-60 g / m³ 2 Tensile strength: 2.95~3.48kN / m; Tear strength: 658.4~737.2mN; Oxygen permeability: 446~523cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 118~157 g / m 2 • Day; Water contact angle: 106–128°; Cobb water absorption value: 6.7–13.5 g / m³ 2 Antibacterial rate: 90-96%; Anti-mildew grade: Level I.

[0036] The above-mentioned bamboo fiber-based food preservation packaging paper is used in food preservation packaging materials.

[0037] Preferably, the food preservation packaging material is a preservation packaging material used for packaging fruits and vegetables.

[0038] Preferably, the fruits and vegetables include apricots, lychees, strawberries, tomatoes, and bamboo shoots, etc.

[0039] The present invention has the following advantages:

[0040] 1. This invention uses moso bamboo as the basic raw material. Moso bamboo is a large bamboo material with advantages such as fast growth rate, wide distribution range, excellent fiber quality and strong regeneration ability. Food preservation packaging paper prepared from different raw materials such as bamboo fiber, bamboo root, bamboo nanocellulose, and bamboo vinegar from the same bamboo can be naturally biodegradable and belongs to environmentally friendly packaging materials. It can realize the use of bamboo instead of plastic in the field of food preservation packaging materials, which is in line with the dual carbon development goal.

[0041] 2. The bamboo fiber-based food preservation packaging paper prepared by this invention is made from a reasonable blend of two types of fiber raw materials from moso bamboo, making full use of the advantages of bamboo fibers from different parts of the bamboo: the roots of moso bamboo are long and strong, which can significantly improve the physical strength of the bamboo-based packaging paper; the main stem fibers of young moso bamboo are fine and soft, with good fiber morphology, which can ensure tight bonding between fibers; in addition, bamboo fibers contain flavonoids, waxes and other substances, which have good air permeability and wear resistance, and have natural antibacterial, anti-mite and deodorizing effects. Bamboo vinegar is a by-product obtained from the pyrolysis of bamboo. It is a liquid (pH value 2.5-3) made by burning moso bamboo that is over 5 years old. It contains organic acids, alcohols, phenols, esters and trace amounts of alkaline components, which have anti-mildew, antibacterial, antioxidant and deodorizing properties. These are all beneficial to improving the food preservation effect of the packaging paper. Among them, the esters in bamboo vinegar can also help improve the hydrophobic effect.

[0042] 3. This invention utilizes nanoscale-modified bamboo cellulose nanocrystals added to the pulp. The acetylated bamboo cellulose nanocrystals not only serve as a paper reinforcing filler but also exhibit excellent moisture-proof and water-blocking effects. Acetylation improves the hydrophobicity, thermal stability, and chemical stability of the nanocellulose while retaining its original biocompatibility and nanoscale advantages. Acetylation modification alters the properties and surface characteristics of the nanocellulose, allowing BNC to form strong covalent and hydrogen bonds with the hydroxyl groups on the bamboo cellulose surface. This increases the mechanical strength of the packaging paper and improves its pore structure, enhancing its barrier properties. The addition of bamboo nanocellulose improves the interfacial bonding between bamboo fibers, resulting in packaging paper exhibiting excellent mechanical strength and barrier performance.

[0043] 4. The bamboo fiber, bamboo root fiber, bamboo nanocellulose, and bamboo vinegar used in this invention are all derived from moso bamboo, realizing the full utilization of one bamboo. The prepared bamboo fiber-based food preservation packaging paper has good mechanical properties, barrier properties, hydrophobic properties, and antibacterial properties. It can be used in the field of food preservation packaging materials, which will promote the high-quality development of the bamboo industry and realize the high-value utilization of bamboo instead of plastic in the food packaging field. Attached Figure Description

[0044] Figure 1 This is a schematic flowchart of the preparation method of the bamboo fiber-based food preservation packaging paper of the present invention.

[0045] Figure 2 This is a schematic diagram of the structure of the bamboo fiber-based food preservation packaging paper of the present invention.

[0046] Figure 3 This is a scanning electron microscope image of the surface of the bamboo fiber-based food preservation packaging paper obtained in Example 1 of the present invention.

[0047] Among them, 1 is bamboo paper base and 2 is bamboo vinegar coating. Detailed Implementation

[0048] The present invention will be further described in detail below with reference to embodiments, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the reagents, methods and equipment used in the present invention are conventional reagents, methods and equipment in this technical field. Test methods in the following embodiments that do not specify specific experimental conditions are generally performed under conventional experimental conditions. Unless otherwise specified, the reagents and raw materials used in the present invention are all commercially available.

[0049] 1. The bleached sulfate-treated young bamboo fiber (NBF) involved in the embodiments and comparative examples of this invention was obtained from the State Key Laboratory of Pulp and Paper Engineering, with a length of 2–20 mm and a diameter of 10–25 μm; the bamboo root fiber (BRF) was obtained from the State Key Laboratory of Pulp and Paper Engineering, with a length of 5–30 mm and a diameter of 28–40 μm. Bamboo vinegar was purchased from Shijiazhuang Hongsen Activated Carbon Co., Ltd., with a concentration of 20%.

[0050] 2. The modified bamboo cellulose nanocrystals (BNC) involved in the embodiments and comparative examples of this invention are prepared from bleached sulfate bamboo pulp as raw material through organic acid hydrolysis, dialysis, centrifugation, and acetylation modification. Specifically, 50-70 mL of a 55-60% maleic acid solution is placed in a water bath (water bath temperature: 45-50 ℃). 3.0-4.0 g of bleached sulfate bamboo pulp is accurately weighed and slowly added to the 55-60% maleic acid solution. The mixture is stirred and hydrolyzed at 45-50 ℃ for 45-50 min. Then, 10-15 times the volume of deionized water is added to terminate the acid hydrolysis reaction. The solids are then washed by centrifugation. The upper layer is removed, and the lower solid sediment is washed with water. This centrifugation and washing process is repeated several times until the upper layer becomes turbid. The lower solid layer was collected, placed in a dialysis bag, and dialyzed in water. The solid and liquid in the dialysis bag were then centrifuged again, and the upper pale blue solution was collected. Rotary evaporation was used to concentrate the solution, yielding aqueous suspensions of acetylated modified bamboo cellulose nanocrystals of varying concentrations for later use. These suspensions were then freeze-dried in a freeze-drying oven for 48–72 hours to obtain moso bamboo cellulose nanocrystals. The organic acids in these nanocrystals are mild and can be recycled. 5–10 g of bamboo cellulose nanocrystals were placed in a flask containing 50–80 mL of glacial acetic acid. The temperature was raised to 50–60 °C, and 10–20 mL of acetic anhydride reagent and 500 μL of dicyclohexylcarbodiimide were added. After reacting for 60–80 min, the mixture was poured into ethanol to precipitate a white flocculent precipitate. The precipitate was then centrifuged, washed 3–5 times with ethanol, and then centrifuged and washed 2–3 times with deionized water. Finally, an aqueous suspension of acetylated bamboo cellulose nanocrystals was obtained. This suspension was then freeze-dried in a freeze-drying oven for 48–72 h to obtain acetylated bamboo cellulose nanocrystals.

[0051] 3. The detection of various parameters involved in the embodiments of this invention is carried out in accordance with national standard testing methods and industry standards, specifically as follows:

[0052] ① Quantitative (GB / T 451.2-2002);

[0053] ②Tensive strength (GB / T 453-2002);

[0054] ③ Tear strength (GB / T 455-2002);

[0055] ④Oxygen transmission rate (GB / T 19789-2005);

[0056] ⑤ Water vapor transmission rate (GB / T 22921-2008);

[0057] ⑥ Water contact angle (GB / T 30447-2013);

[0058] ⑦ Cobb water absorption value (GB / T 1540-2002): The lower the Cobb water absorption value, the better the paper's water resistance.

[0059] ⑧ Antibacterial rate (GB15979-2002): The colonies selected were Staphylococcus aureus (ATCC29213) and Escherichia coli (ATCC8099), both purchased from Shanghai Center for Preservation of Biotechnology.

[0060] ⑨ Anti-mildew rating test (GB / T 4768-2008). The anti-mildew rating is divided into four levels: I, II, III and IV. The order of anti-mildew ability is: I > II > III > IV.

[0061] Figure 1 The preparation process of the bamboo fiber barrier packaging paper of the present invention is shown, specifically as follows: Pulping treatment: Bleached sulfate tender bamboo fiber and bamboo root fiber are respectively pulped to obtain NBF pulp and BRF pulp; Dispersion treatment: The NBF pulp and BRF pulp are dispersed to obtain NBF dispersion and BRF dispersion; Uniform mixing: The NBF dispersion and BRF dispersion are mixed uniformly to obtain NBF / BRF mixed pulp; Stirring and mixing: Modified bamboo cellulose nanocrystals are added to the NBF / BRF mixed pulp under stirring conditions and mixed uniformly to obtain NBF / BRF / BNC composite pulp; Forming, dehydration and drying: The NBF / BRF / BNC composite pulp is formed, dehydrated and dried to obtain bamboo paper sample A; Surface spraying: Bamboo vinegar is uniformly sprayed onto the outer surface of bamboo paper sample A and dried to obtain bamboo paper sample B, wherein, as... Figure 2 As shown, bamboo vinegar was evenly sprayed onto the upper and lower surfaces of bamboo paper sample A; hot pressing and drying: bamboo paper sample B was hot-pressed and dried to obtain bamboo fiber-based food preservation packaging paper.

[0062] Example 1

[0063] This embodiment provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0064] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 500 r / min and a pulping concentration of 4.0 wt% to obtain NBF pulp with a freeness of 35°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 600 r / min and a pulping concentration of 2.5 wt% to obtain BRF pulp with a freeness of 45°SR.

[0065] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0066] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 5:5 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0067] (4) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to the NBF / BRF mixed slurry under stirring (speed 4000r / min). The amount of modified bamboo fiber nanocrystals added was 4.0% of the oven-dry mass of the NBF / BRF / BNC composite slurry. The mixture was stirred evenly to obtain the NBF / BRF / BNC composite slurry.

[0068] (5) The NBF / BRF / BNC composite pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 0.2% to obtain bamboo paper sample A.

[0069] (6) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with bamboo vinegar solution with a mass concentration of 3.5%, and the spraying amount is 2.0 g / m². 2 Then, the paper sample was dried with infrared light at 100°C for 30 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0070] (7) Bamboo paper sample B was hot-pressed for 15 min at a temperature of 88℃ and a pressure of 28MPa, and then dried in the infrared at 82℃ for 10 min to obtain bamboo fiber-based food preservation packaging paper.

[0071] The cross-sectional scanning electron microscope image of the bamboo fiber-based food preservation packaging paper prepared in this embodiment is shown below. Figure 3 As shown, the performance indicators of this bamboo fiber-based food preservation packaging paper are as follows: Basis weight: 54 g / m³ 2 Tensile strength: 2.95 kN / m; Tear strength: 658.4 mN; Oxygen permeability: 523 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 157 g / m 2 • day; Water contact angle: 106°; Cobb water absorption value: 13.5 g / m³ 2 Antibacterial rate: 90%; Anti-mildew grade: Level I.

[0072] Example 2

[0073] This embodiment provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0074] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 600 r / min and a pulping concentration of 4.4 wt% to obtain NBF pulp with a freeness of 37°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 750 r / min and a pulping concentration of 2.8 wt% to obtain BRF pulp with a freeness of 47°SR.

[0075] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0076] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 6:4 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0077] (4) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to the NBF / BRF mixed slurry under stirring (speed 5000r / min). The amount of modified bamboo fiber nanocrystals added was 5.0% of the oven-dry mass of the NBF / BRF / BNC composite slurry. The mixture was stirred evenly to obtain the NBF / BRF / BNC composite slurry.

[0078] (5) The NBF / BRF / BNC composite pulp was formed, dehydrated and dried on a slanted wire paper machine with a pulp mass concentration of 0.5% to obtain bamboo paper sample A.

[0079] (6) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with bamboo vinegar solution with a mass concentration of 4.0%, and the spraying amount is 3.0 g / m². 2 Then, the paper sample was dried with infrared light at 140°C for 38 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0080] (7) Bamboo paper sample B was hot-pressed for 20 min at a temperature of 92℃ and a pressure of 30MPa, and then dried in the infrared at 85℃ for 14 min to obtain bamboo fiber-based food preservation packaging paper.

[0081] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this embodiment are as follows: Basis weight: 56 g / m³ 2 Tensile strength: 3.16 kN / m; Tear strength: 687.3 mN; Oxygen permeability: 501 cm³ 3 / m 2• Day • 0.1 MPa; Water vapor transmission rate: 143 g / m 2 • day; Water contact angle: 111°; Cobb water absorption value: 10.4 g / m³ 2 Antibacterial rate: 92%; Anti-mildew grade: Level I.

[0082] Example 3

[0083] This embodiment provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0084] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 700 r / min and a pulping concentration of 4.8 wt% to obtain NBF pulp with a freeness of 38°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 850 r / min and a pulping concentration of 3.2 wt% to obtain BRF pulp with a freeness of 48°SR.

[0085] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0086] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 7:4 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0087] (4) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to the NBF / BRF mixed slurry under stirring (speed 6000r / min). The amount of modified bamboo fiber nanocrystals added was 6.0% of the oven-dry mass of the NBF / BRF / BNC composite slurry. The mixture was stirred evenly to obtain the NBF / BRF / BNC composite slurry.

[0088] (5) The NBF / BRF / BNC composite pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 0.7% to obtain bamboo paper sample A.

[0089] (6) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with bamboo vinegar solution with a mass concentration of 4.5%, and the spraying amount is 4.0 g / m². 2 Then, the paper sample was dried with infrared light at 160°C for 45 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0090] (7) Bamboo paper sample B was hot-pressed for 25 min at a temperature of 95℃ and a pressure of 33MPa, and then dried in the infrared at 88℃ for 17 min to obtain bamboo fiber-based food preservation packaging paper.

[0091] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this embodiment are as follows: Basis weight: 58 g / m³ 2 Tensile strength: 3.31 kN / m; Tear strength: 705.6 mN; Oxygen permeability: 472 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 127 g / m 2 • day; Water contact angle: 117°; Cobb water absorption value: 8.3 g / m³ 2 Antibacterial rate: 95%; Anti-mildew grade: Level I.

[0092] Example 4

[0093] This embodiment provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0094] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 750 r / min and a pulping concentration of 5.0 wt% to obtain NBF pulp with a freeness of 40°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 980 r / min and a pulping concentration of 3.5 wt% to obtain BRF pulp with a freeness of 50°SR.

[0095] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0096] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 7:3 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0097] (4) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to the NBF / BRF mixed slurry under stirring (speed 7000r / min). The amount of modified bamboo fiber nanocrystals added was 7.0% of the oven-dry mass of the NBF / BRF / BNC composite slurry. The mixture was stirred evenly to obtain the NBF / BRF / BNC composite slurry.

[0098] (5) The NBF / BRF / BNC composite pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 1.0% to obtain bamboo paper sample A.

[0099] (6) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with bamboo vinegar solution with a mass concentration of 5.0%, and the spraying amount is 5.0 g / m². 2 Then, the paper sample was dried with infrared light at 180°C for 50 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0100] (7) Bamboo paper sample B was hot-pressed for 30 min at a temperature of 98℃ and a pressure of 36MPa, and then dried in the infrared at 90℃ for 20 min to obtain bamboo fiber-based food preservation packaging paper.

[0101] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this embodiment are as follows: Basis weight: 60 g / m³ 2 Tensile strength: 3.48 kN / m; Tear strength: 737.2 mN; Oxygen permeability: 446 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 118 g / m 2 • day; Water contact angle: 128°; Cobb water absorption value: 6.7 g / m³ 2 Antibacterial rate: 96%; Anti-mildew grade: Level I.

[0102] Comparative Example 1

[0103] This comparative example provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0104] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a speed of 500 r / min and a pulp concentration of 4.0 wt% to obtain NBF pulp with a freeness of 35°SR.

[0105] (2) Disperse the NBF slurry to obtain NBF fiber slurry.

[0106] (3) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to NBF fiber slurry under stirring (speed 4000r / min). The amount of modified bamboo fiber nanocrystals added was 4.0% of the oven-dry mass of NBF / BNC composite slurry. The mixture was stirred evenly to obtain NBF / BNC composite slurry.

[0107] (4) The NBF / BNC composite pulp was formed, dehydrated and dried on a slanted wire paper machine with a pulp mass concentration of 0.2% to obtain bamboo paper sample A.

[0108] (5) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with a bamboo vinegar solution with a mass concentration of 3.5%, and the spraying amount is 2.0 g / m². 2 Then, the paper sample was dried with infrared light at 100°C for 30 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0109] (6) Bamboo paper sample B was hot-pressed for 15 min at a temperature of 88℃ and a pressure of 28MPa, and then dried in the infrared at 82℃ for 10 min to obtain bamboo fiber-based food preservation packaging paper.

[0110] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this comparative example are as follows: Basis weight: 54 g / m³ 2 Tensile strength: 1.84 kN / m; Tear strength: 513.6 mN; Oxygen permeability: 735 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 324 g / m 2 • day; Water contact angle: 92°; Cobb absorbance: 33.1 g / m³ 2 Antibacterial rate: 82%; Anti-mildew grade: Level I.

[0111] Comparative Example 2

[0112] This comparative example provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0113] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 500 r / min and a pulping concentration of 4.0 wt% to obtain NBF pulp with a freeness of 35°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 600 r / min and a pulping concentration of 2.5 wt% to obtain BRF pulp with a freeness of 45°SR.

[0114] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0115] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 5:5 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0116] (4) The NBF / BRF mixed pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 0.2% to obtain bamboo paper sample A.

[0117] (5) The upper and lower surfaces of bamboo paper sample A are uniformly sprayed with a bamboo vinegar solution with a mass concentration of 3.5%, and the spraying amount is 2.0 g / m². 2 Then, the paper sample was dried with infrared light at 100°C for 30 minutes using an electric infrared generator to obtain bamboo paper sample B.

[0118] (6) Bamboo paper sample B was hot-pressed for 15 min at a temperature of 88℃ and a pressure of 28MPa, and then dried in the infrared at 82℃ for 10 min to obtain bamboo fiber-based food preservation packaging paper.

[0119] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this comparative example are as follows: Basis weight: 54 g / m³ 2 Tensile strength: 1.73 kN / m; Tear strength: 503.8 mN; Oxygen permeability: 752 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 316 g / m 2 • day; Water contact angle: 72°; Cobb water absorption value: 42.4 g / m³ 2 Antibacterial rate: 78%; Anti-mildew grade: Level I.

[0120] Comparative Example 3

[0121] This comparative example provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0122] (1) Bleached sulfate tender bamboo fiber (NBF, length 2-20 mm, diameter 10-25 μm) was pulped in a double disc refiner at a refining speed of 500 r / min and a pulping concentration of 4.0 wt% to obtain NBF pulp with a freeness of 35°SR; bamboo root fiber (BRF, length 5-30 mm, diameter 28-40 μm) was pulped in a double disc refiner at a refining speed of 600 r / min and a pulping concentration of 2.5 wt% to obtain BRF pulp with a freeness of 45°SR.

[0123] (2) Disperse the NBF slurry and the BRF slurry to obtain NBF dispersion and BRF dispersion.

[0124] (3) Mix the NBF dispersion and BRF dispersion at an oven-dry mass ratio of 5:5 (i.e., the mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber) to obtain NBF / BRF mixed slurry.

[0125] (4) Modified bamboo cellulose nanocrystals (BNC, length 50-200nm, diameter 2-30nm) were added to the NBF / BRF mixed slurry under stirring (speed 4000r / min). The amount of modified bamboo fiber nanocrystals added was 4.0% of the oven-dry mass of the NBF / BRF / BNC composite slurry. The mixture was stirred evenly to obtain the NBF / BRF / BNC composite slurry.

[0126] (5) The NBF / BRF / BNC composite pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 0.2% to obtain bamboo paper sample A.

[0127] (6) Bamboo paper sample A was hot-pressed for 15 min at a temperature of 88℃ and a pressure of 28MPa, and then dried in the infrared at 82℃ for 10 min to obtain bamboo fiber-based food preservation packaging paper.

[0128] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this comparative example are as follows: Basis weight: 54 g / m³ 2 Tensile strength: 2.36 kN / m; Tear strength: 612.5 mN; Oxygen permeability: 673 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 468 g / m 2 • day; Water contact angle: 65°; Cobb water absorption value: 51.2 g / m³ 2 Antibacterial rate: 71%; Anti-mildew level: Grade III.

[0129] Comparative Example 4

[0130] This comparative example provides a method for preparing bamboo fiber-based food preservation packaging paper. The specific preparation steps are as follows:

[0131] (1) Bleached sulfate bamboo fiber (BF, length 2-15 mm, diameter 27-52 μm) was pulped in a double disc refiner at a refining speed of 500 r / min and a pulping concentration of 4.0 wt% to obtain BF pulp with a freeness of 35°SR; bamboo shoot shell fiber (SF, length 5-20 mm, diameter 30-45 μm) was pulped in a double disc refiner at a refining speed of 600 r / min and a pulping concentration of 2.5 wt% to obtain SF pulp with a freeness of 45°SR.

[0132] (2) Disperse the BF slurry and the SF slurry to obtain BF dispersion and SF dispersion.

[0133] (3) Mix the BF dispersion and SF dispersion at an oven-dry mass ratio of 5:5 (i.e., the mass ratio of bleached sulfate bamboo fiber and bamboo shoot shell fiber) to obtain BF / SF mixed slurry.

[0134] (4) Add nano-grade antibacterial bamboo powder (BP, particle diameter 50-500 nm) to BF / SF mixed slurry under stirring (speed 4000 r / min). The amount of nano-grade antibacterial bamboo powder added is 4.0% of the oven-dry mass of BF / SF / BP composite slurry. Mix evenly to obtain BF / SF / BP composite slurry.

[0135] (5) The BF / SF / BP composite pulp was formed, dewatered and dried on a slanted wire paper machine with a pulp mass concentration of 0.2% to obtain bamboo paper sample A.

[0136] (6) A composite solution of 3.5% (by mass) of quaternary ammonium salt chitosan and bamboo nanocellulose was uniformly sprayed onto the upper and lower surfaces of bamboo paper sample A. The oven-dry mass ratio of quaternary ammonium salt chitosan and bamboo nanocellulose was 5:5, and the spraying amount was 2.0 g / m². 2 Then, the paper sample was dried with infrared light at 100 °C for 30 min using an electric infrared generator to obtain bamboo paper sample B.

[0137] (7) Bamboo paper sample B was hot-pressed for 15 min at a temperature of 88℃ and a pressure of 28MPa, and then dried in the infrared at 82℃ for 10 min to obtain bamboo fiber-based food preservation packaging paper.

[0138] The performance indicators of the bamboo fiber-based food preservation packaging paper prepared in this comparative example are as follows: Basis weight: 54 g / m³ 2 Tensile strength: 2.65 kN / m; Tear strength: 616.8 mN; Oxygen permeability: 562 cm³ 3 / m 2 • Day • 0.1 MPa; Water vapor transmission rate: 183 g / m 2 • day; Water contact angle: 69°; Cobb absorbance: 46.7 g / m³ 2 Antibacterial rate: 87%; Anti-mildew level: IV.

[0139] Fruit and vegetable preservation experiment

[0140] The bamboo fiber-based packaging papers prepared in Examples 1, 2, 3, and 4, and Comparative Examples 1, 2, 3, and 4 were sealed and made into packaging bags. Yellow apricots of similar color, size, and shape, without mechanical damage, were selected, washed with clean water, and air-dried before being packed into various types of paper-based packaging bags. Three parallel samples were prepared for each group and stored at room temperature for 9 days. The packaging bags were opened and tested every 2 days (1, 3, 5, 7, and 9 days), and the preservation effect indicators of the packaging bags were recorded. The preservation effect indicators were the mass loss rate, rot rate, and hardness. The test methods are as follows:

[0141] (1) Determination of mass loss rate: The mass loss was measured by weighing method. The mass of the apricot sample was weighed once before and once after storage. The mass loss rate (R) was calculated according to the following formula: R=(m1-m2) / m1×100%, where: m1 is the mass of the apricot before storage, g; m2 is the mass of the apricot after storage, g.

[0142] (2) Determination of rot rate: The yellow apricot is considered rotten when the fruit has obvious rot or mold on its appearance. The rot rate F is calculated according to the following formula: F = (number of rotten fruits / total number of fruits) × 100%.

[0143] (3) Hardness test: The hardness index of the yellow apricot was tested using a texture analyzer. The test parameters were: speed before test 1.0 mm / s, test speed 2.0 mm / s, speed after test 2.0 mm / s, trigger type was pressure, and trigger value was 5.0 gf.

[0144] The results of mass loss rate (%), decay rate (%), and hardness (g) are shown in Tables 1, 2, and 3, respectively.

[0145] Table 1

[0146]

[0147] Table 2

[0148]

[0149] Table 3

[0150]

[0151] As can be seen from the data in Tables 1-3, the bamboo fiber-based food preservation packaging paper in Examples 1-4 has a better overall preservation effect than the packaging paper in Comparative Examples 1-4. Specifically, compared to the packaging paper in Comparative Example 4, the preservation packaging paper in Examples 1-4 has a better preservation effect on freshly picked apricots, reducing the spoilage rate and quality loss rate, slowing down the decrease in hardness, delaying softening, and maximizing the preservation of apricot quality. Therefore, the analysis of apricot quality indicators during storage shows that the bamboo fiber-based food preservation packaging paper in Examples 1-4 has a certain preservation effect on apricots, effectively inhibiting quality loss, improving sensory quality, and thus delaying spoilage and achieving a longer shelf life. The bamboo fiber-based food preservation packaging paper of this invention can improve the storage quality of apricots and greatly reduce the spoilage rate and nutritional value loss.

[0152] Experiment on the hydrophobic properties of modified bamboo cellulose nanocrystals

[0153] This experiment compares the hydrophobic properties of modified bamboo cellulose nanocrystals obtained by the preparation method of this invention with those obtained by conventional preparation methods.

[0154] Comparative experimental procedure: Place 50–70 mL of 55–60% sulfuric acid solution in a water bath (water bath temperature: 45–50 ℃). Accurately weigh 3.0–4.0 g of bleached sulfate bamboo pulp and slowly add it to the 55–60% sulfuric acid solution. Stir and hydrolyze at 45–50 ℃ for 45–50 min. Then add 10–15 times the volume of deionized water to terminate the acid hydrolysis reaction. Next, wash the solids using centrifugation. Discard the supernatant and continue washing the lower solid sediment with water. Repeat this centrifugation washing process several times until the supernatant becomes cloudy. Collect the lower solids, place them in a dialysis bag, and dialyze them in distilled water. Finally, centrifuge the solid and liquid in the dialysis bag again, collecting the upper light blue solution. Concentrate by rotary evaporation to obtain aqueous suspensions of bamboo cellulose nanocrystals of different concentrations for later use. The mixture was freeze-dried in a freeze-drying oven for 48–72 h to obtain bamboo cellulose nanocrystals. Then, 5–10 g of the bamboo cellulose nanocrystals were placed in a flask containing 50–80 mL of glacial acetic acid, heated to 50–60 °C, and 10–20 mL of acetic anhydride reagent and 500 μL of perchloric acid were added. After reacting for 60–80 min, the mixture was poured into ethanol to precipitate a white flocculent precipitate. The precipitate was then centrifuged, washed 3–5 times with ethanol, and then centrifuged and washed 2–3 times with deionized water to obtain an acetylated bamboo cellulose nanocrystal aqueous suspension. This suspension was then freeze-dried in a freeze-drying oven for 48–72 h to obtain an acetylated bamboo cellulose nanocrystal solid powder.

[0155] Test data show that the water contact angle of the modified bamboo cellulose nanocrystals obtained by this invention is 90.3°, while the water contact angle of the modified bamboo cellulose nanocrystals obtained in the comparative experiment is only 67.5°. Therefore, the hydrophobic properties of the modified bamboo cellulose nanocrystals obtained by the preparation method of this invention are superior to those of conventional preparation methods. Sulfuric acid is a corrosive acid, toxic, and non-recyclable.

[0156] In summary, this invention uses moso bamboo as the basic raw material. Moso bamboo is a large bamboo species with advantages such as rapid growth, wide distribution, excellent fiber quality, and strong regeneration ability. Food preservation packaging paper prepared from different raw materials such as bamboo fiber, bamboo root, bamboo nanocellulose, and bamboo vinegar from the same bamboo stalk is naturally biodegradable and belongs to environmentally friendly packaging materials. It can realize the replacement of plastic with bamboo in the field of food preservation packaging materials, which is in line with the dual-carbon development goals. The bamboo fiber-based food preservation packaging paper prepared by this invention is made by rationally compounding two types of fiber raw materials from moso bamboo, making full use of the advantages of bamboo fibers from different parts of the bamboo: the long and strong fibers of moso bamboo roots can significantly improve the physical strength of bamboo-based packaging paper; the fine and soft fibers of the main stem of young moso bamboo have excellent fiber morphology, ensuring a tight bond between fibers; in addition, bamboo fibers contain flavonoids, waxes, and other substances, which have good air permeability and wear resistance, and possess natural antibacterial, anti-mite, and deodorizing effects. Bamboo vinegar is a byproduct of bamboo pyrolysis, a liquid (pH 2.5-3) produced by burning bamboo aged 5 years or more. It contains organic acids, alcohols, phenols, esters, and trace amounts of alkaline components, possessing anti-mildew, antibacterial, antioxidant, and deodorizing properties, all of which contribute to improving the food preservation effect of packaging paper. The esters in bamboo vinegar also help enhance its hydrophobic effect. This invention utilizes nano-sized modified bamboo cellulose nanocrystals added to the pulp. Acetylated bamboo cellulose nanocrystals not only serve as paper reinforcement fillers but also exhibit excellent moisture-proof and water-blocking effects. Acetylation improves the hydrophobicity, thermal stability, and chemical stability of nanocellulose while retaining its original biocompatibility and nano-size advantages. Acetylation modification alters the properties and surface characteristics of nanocellulose, allowing BNC to form strong covalent and hydrogen bonds with the hydroxyl groups on the bamboo cellulose surface. This increases the mechanical strength of the packaging paper and improves its pore structure, enhancing its barrier properties. The addition of bamboo nanocellulose improves the interfacial bonding between bamboo fibers, resulting in packaging paper exhibiting excellent mechanical strength and barrier properties. The bamboo fiber, bamboo root fiber, bamboo nanocellulose, and bamboo vinegar used in this invention are all derived from moso bamboo, achieving full utilization of a single bamboo plant. The prepared bamboo fiber-based food preservation packaging paper possesses excellent mechanical properties, barrier properties, hydrophobic properties, and antibacterial properties, making it suitable for use in food preservation packaging materials. This will promote the high-quality development of the bamboo industry and realize the high-value utilization of bamboo in the food packaging field, replacing plastic with bamboo.

[0157] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for preparing bamboo fiber-based food preservation packaging paper, characterized in that: Includes the following steps: (1) Bleached sulfate tender bamboo fiber and bamboo root fiber were respectively subjected to pulping treatment to obtain NBF pulp with a freeness of 35-40°SR and BRF pulp with a freeness of 45-50°SR. (2) Disperse the NBF slurry and the BRF slurry in step (1) to obtain NBF dispersion and BRF dispersion; (3) Mix the NBF dispersion and the BRF dispersion in step (2) evenly to obtain an NBF / BRF mixed slurry; (4) The modified bamboo cellulose nanocrystals are added to the NBF / BRF mixed slurry obtained in step (3) under stirring conditions and mixed evenly to obtain NBF / BRF / BNC composite slurry; (5) The NBF / BRF / BNC composite pulp described in step (4) is paper-made, shaped, dehydrated and dried to obtain bamboo paper sample A; (6) The outer surface of the bamboo paper sample A described in step (5) is uniformly sprayed with bamboo vinegar solution and dried to obtain bamboo paper sample B; (7) The bamboo paper sample B described in step (6) is hot-pressed and dried to obtain bamboo fiber-based food preservation packaging paper; The bleached sulfate tender bamboo fiber mentioned in step (1) has a length of 2-20 mm and a diameter of 10-25 μm; the bamboo root fiber has a length of 5-30 mm and a diameter of 28-40 μm. The mass ratio of bleached sulfate tender bamboo fiber and bamboo root fiber in step (1) is 5:5 to 7:3; The amount of modified bamboo fiber nanocrystals added in step (4) is 4.0% to 7.0% of the mass of the NBF / BRF / BNC composite slurry; The slurry concentration of the NBF / BRF / BNC composite slurry mentioned in step (4) is 0.2% to 1.0% by mass. The concentration of the bamboo vinegar solution in step (6) is 3.5% to 5.0% by mass. In step (6), the amount of bamboo vinegar solution sprayed onto the outer surface of the bamboo paper sample A is 2.0–5.0 g / m². 2 ; The drying method described in step (6) is: infrared drying at 100-180℃ for 30-50 minutes; The hot pressing conditions described in step (7) are: temperature of 88-98℃, pressure of 28-36MPa, and time of 15-30min; The drying method described in step (7) is: infrared drying at 82-90℃ for 10-20 minutes; The modified bamboo cellulose nanocrystals mentioned in step (4) have a length of 50–200 nm and a diameter of 2–30 nm; the modified bamboo cellulose nanocrystals are prepared by the following method: Bleached sulfate bamboo pulp was hydrolyzed with organic acid, dialyzed, centrifuged, and then acetylated to obtain modified bamboo cellulose nanocrystals.

2. The method for preparing bamboo fiber-based food preservation packaging paper according to claim 1, characterized in that: The pulping conditions for bleached sulfate-treated young bamboo fiber in step (1) are: pulping speed of 500-750 r / min and pulping concentration of 4.0-5.0 wt%; the pulping conditions for bamboo root fiber are: pulping speed of 600-980 r / min and pulping concentration of 2.5-3.5 wt%. The stirring speed in step (4) is 4000-7000 r / min.

3. The method for preparing bamboo fiber-based food preservation packaging paper according to claim 1, characterized in that: The modified bamboo cellulose nanocrystals were prepared by the following method: 3.0–4.0 g of bleached sulfate bamboo pulp was slowly added to 50–70 mL of maleic acid solution with a concentration of 55–60%. The mixture was stirred and hydrolyzed in a water bath at 45–50 °C for 45–50 minutes. The acid hydrolysis reaction was then terminated by adding deionized water, and the solid was washed by centrifugation several times for purification. Finally, the purified solid was dialyzed and centrifuged again to obtain a light blue solution. The solution was concentrated by rotary evaporation to obtain aqueous suspensions of bamboo cellulose nanocrystals of different concentrations. These suspensions were then freeze-dried in a freeze-drying oven for 48–72 hours to obtain bamboo cellulose nanocrystals of different concentrations. 5–10 g of bamboo cellulose nanocrystals were placed in a flask containing 50–80 mL of glacial acetic acid. The temperature was raised to 50–60 °C, and 10–20 mL of acetic anhydride reagent and 500 μL of dicyclohexylcarbodiimide were added. After reacting for 60–80 min, the mixture was poured into ethanol to precipitate a white flocculent precipitate. The precipitate was then centrifuged, washed 3–5 times with ethanol, and then centrifuged and washed 2–3 times with deionized water. Finally, an aqueous suspension of acetylated bamboo cellulose nanocrystals was obtained. This suspension was then freeze-dried in a freeze dryer for 48–72 h to obtain acetylated bamboo cellulose nanocrystals.

4. A bamboo fiber-based food preservation packaging paper, characterized in that: It is obtained by the preparation method described in any one of claims 1 to 3.

5. The application of the bamboo fiber-based food preservation packaging paper according to claim 4 in food preservation packaging materials.

6. The application according to claim 5, characterized in that: The food preservation packaging material is a packaging material used for packaging fruits and vegetables.

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