A high-transparency, high-hydrophobicity fungal glassine paper based on liquid fermentation and its preparation method

Abstract

The present invention relates to a fungal glassine paper with high transparency and high hydrophobicity based on liquid fermentation and a preparation method thereof, belonging to the field of biomaterials. The present invention mainly solves the problems of low transparency and poor hydrophobicity of glassine paper. Five strains of enoki mushroom, oyster mushroom, shiitake mushroom, oyster mushroom and versicolor are used as starting strains. Through solid fermentation mycelium culture, liquid fermentation mycelium culture, deep expansion fermentation culture of liquid fermentation mycelium, extraction and purification of liquid fermentation mycelium, and paper preparation and forming steps, fungal glassine paper is prepared using mycelium of deep fermentation of different strains as raw materials. The glassine paper prepared by the present invention not only has high transparency and good hydrophobicity, but also adopts a simple preparation process and a short cycle, can achieve large-scale factory production, and can be used as food packaging paper.

Description

Technical Field

[0001] The invention relates to high-transparency and high-hydrophobicity fungal glassine paper based on liquid fermentation and a preparation method thereof, and belongs to the field of biomaterials. Background Art

[0002] Glassine paper is a translucent glassine made from plant cellulose, such as wood pulp and bamboo, through a series of processes including pulping, paper forming, pressing and drying, supercalendering, and coating. It boasts a dense and uniform texture, high light transmittance, high-temperature resistance, and excellent hydrophobicity, making it widely used in food packaging and labeling. The glassine paper manufacturing industry currently faces numerous challenges: Resources such as wood and bamboo have long growth cycles and are non-renewable; the production process is complex and poses significant risks to the environment and human health; and the unique properties of glassine paper require specialized processing. Developing new raw materials to replace traditional plant cellulose in the production of glassine paper is key to addressing these issues.

[0003] Studies have found that chitin has a similar molecular structure to plant cellulose and has been used in the papermaking industry. The general process for using chitin-rich marine shells for papermaking is as follows: Most high-chitin shrimp and crab shells undergo an acid demineralization step to remove the large amount of minerals they contain. They are then treated with alkali to remove protein and fat to obtain chitin. After deacetylation, chitosan is obtained and made into paper. Current research on fungal papermaking focuses on the fruiting bodies of common fungi, such as shiitake mushrooms, oyster mushrooms, and golden needle mushrooms. Chitin extracted from these fruiting bodies can be made into paper, and because it contains no minerals, demineralization is not required, making the process simpler and more environmentally friendly. However, using fruiting bodies to make paper presents challenges such as competing with humans for food, a long growing period, high costs, and unstable quality, making it unsuitable for factory-scale production of paper.

[0004] To address these practical challenges in fruiting body papermaking, our research team used Ganoderma lucidum mycelium, cultured through submerged fermentation in liquids with different fungi, as raw material. By adding additives such as catechins and citric acid for cross-linking and coating, they developed mycelium glassine paper with properties similar to commercially available glassine paper. This invention has been granted a patent (CN 119824713B). However, due to the inclusion of additives such as catechins, citric acid, and antioxidant food gum, the glassine paper preparation process is cumbersome, costly, and prone to environmental pollution and damage. Therefore, the development of food-grade glassine paper with a simple preparation process, low cost, biodegradability, and environmental friendliness is imperative. Summary of the Invention

[0005] A high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation and a preparation method thereof are provided to solve the problems existing in the background technology.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a method for preparing high-transparency and high-hydrophobicity fungal glassine paper based on liquid fermentation, comprising the following steps:

[0008] Step 1: solid fermentation mycelium culture:

[0009] The fungal strain is inoculated into a PDA plate for cultivation to obtain an activated fungal strain, and after the activated fungal strain has fully grown on the PDA plate, a hole is punched with a hole puncher to obtain a standby fungal block;

[0010] Step 2: Cultivation of liquid fermentation mycelium:

[0011] The spare fungus block obtained in step 1 is inoculated into a liquid culture medium for cultivation to obtain a secondary mother strain, and the secondary mother strain is expanded and cultured in a liquid culture medium to obtain fungal liquid fermentation mycelium;

[0012] Step 3: Deep fermentation culture of liquid fermentation mycelium:

[0013] The fungal liquid fermentation mycelium obtained in step 2 is subjected to submerged expansion fermentation culture in a fermentation tank to obtain fungal liquid fermentation mycelium;

[0014] Step 4: Extraction and purification of liquid fermentation mycelium:

[0015] The fungal liquid fermentation mycelium obtained in step 3 is mixed with deionized water at a mass ratio of 1: (30-40) to obtain a fungal mycelium suspension, which is placed in a juicer and crushed and mixed multiple times to obtain a fungal mycelium suspension, which is placed in a 70-90°C water bath for extraction for 0.5-1h, then centrifuged and the supernatant is discarded to obtain a primary precipitate, the primary precipitate is mixed with 1M sodium hydroxide solution at a mass ratio of 1: (30-100) to prepare an alkaline fungal mycelium solution with a concentration of 1-3g / 100mL, the solution is placed in a 55-70°C water bath for extraction for 1.5-2h, then centrifuged and the supernatant is discarded to obtain a secondary precipitate, the secondary precipitate is washed with deionized water and centrifuged multiple times to obtain a tertiary precipitate with a pH of 7;

[0016] Step 5: Paper preparation and forming:

[0017] The tertiary precipitate obtained in step 4 and deionized water are mixed in a mass ratio of 1: (45-55) and then crushed and mixed using a juicer to obtain fungal mycelium pulp, which is poured into a mold and naturally air-dried outdoors to obtain fungal glassine paper.

[0018] Furthermore, the fungal strain in step 1 is selected from any one of enoki mushroom, oyster mushroom, shiitake mushroom, seafood mushroom and versicolor, and the culture conditions in step 1 are: culture at 25-30° C. in an incubator in the dark for 7-10 days, and the puncher is a 9 mm puncher.

[0019] Furthermore, after step 1, the step further includes transferring the spare mushroom blocks to the MYG plate, taking photos and recording using a mycelium phenotype instrument, and screening spare mushroom blocks with a mycelium growth rate greater than 3 mm / d.

[0020] Furthermore, in step 2, the formula of the liquid culture medium for culturing the spare bacterial block obtained in step 1 in the liquid culture medium is: maltose 8-15 g / L, glucose 3-7 g / L and yeast extract powder 3-7 g / L, the culture method is to use a 250 mL liquid shake flask, and the culture conditions are: 25-28 ° C, 150-170 rpm, and culture for 7-10 days; the formula of the liquid culture medium for expanding the secondary mother culture in the liquid culture medium is: maltose 8-15 g / L, glucose 3-7 g / L and yeast extract powder 3-7 g / L, the expansion culture method is to use a 1 L liquid shake flask, and the expansion culture conditions are: 25-28 ° C, 150-170 rpm, and culture for 7-14 days.

[0021] Furthermore, after step 2, the step further includes screening out fungal liquid fermentation mycelia with a biomass greater than 3 g / L; and screening out fungal liquid fermentation mycelia with a chitin content greater than 19%.

[0022] Furthermore, in step 3, the volume of the fermentation tank is 10 L, and the submerged fermentation culture uses a liquid culture medium. The formula of the liquid culture medium is: 8-15 g / L maltose, 3-7 g / L glucose, and 3-7 g / L yeast extract powder. The volume of the liquid culture medium is 7-7.5 L. The culture conditions of the submerged fermentation culture are: 25-28° C., 150-170 rpm, and culture in the liquid culture medium for 7-14 days.

[0023] Furthermore, after step 5, the step further includes measuring the elongation at break of the fungal glassine paper obtained in step 5 with reference to the national standard GB / T 12914-2018, and screening fungal glassine paper with an elongation at break of 1.5% or more; measuring the transmittance with a microplate reader with reference to the national standard GB / T 2410-2008, and screening fungal glassine paper with a transmittance of 20% or more; and measuring the static water contact angle θ using a sessile drop method, and screening fungal glassine paper with a water contact angle of 98°.

[0024] On the other hand, the present invention also provides fungal glassine paper prepared by the method for preparing fungal glassine paper.

[0025] On the other hand, the present invention also provides the use of fungus glassine paper as food packaging paper.

[0026] The present invention has the following beneficial effects: Compared with glassine paper made from tree and bamboo resources, or glassine paper made from fruiting bodies, which has a production cycle of 1-3 months, the present invention utilizes submerged liquid fermentation, resulting in a shorter fungal mycelial cycle of only 7-10 days. Compared with papermaking processes using chitin from marine shells, the process is simpler and more environmentally friendly due to the reduced mineralization process. Compared with the 20-30% transmittance of glassine paper made from chitin from fungal fruiting bodies, the transmittance of the Flammulina enoki glassine paper produced using the present invention reaches 49.54%, more than double the transmittance. The water contact angle of the Flammulina enoki glassine paper is 102.4°, exceeding the 98.7° water contact angle of the most hydrophobic glassine paper currently available. Furthermore, the glassine paper produced using the present invention not only has high transparency and excellent hydrophobicity, but also employs a simple production process with a short production cycle, enabling large-scale factory production. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the growth process of Flammulina velutipes solid fermentation mycelium on a solid plate, where a represents 0 days, b represents 2 days, c represents 4 days, d represents 6 days, e represents 8 days, and f represents 10 days;

[0028] Figure 2 Diagram of the status of Flammulina velutipes liquid fermentation mycelium after 7 days of fermentation in a liquid shake flask;

[0029] Figure 3 A diagram showing the growth status of Flammulina velutipes liquid fermentation mycelium in a 10L large fermentation tank for 14 days;

[0030] Figure 4 State diagram of the tertiary precipitate obtained after extraction and purification;

[0031] Figure 5 Enoki mushroom mycelium pulp state diagram;

[0032] Figure 6 Schematic diagram comparing the transparency of Flammulina velutipes glassine paper and commercially available glassine paper, where: a is the Flammulina velutipes glassine paper, b is a schematic diagram of the pattern through the Flammulina velutipes glassine paper, c is a commercially available glassine paper, and d is a schematic diagram of the pattern through the commercially available glassine paper;

[0033] Figure 7 Morphological diagram of fungal glassine paper prepared in Examples 1-5, wherein: a is: Coriolus versicolor, b is: Lentinus edodes, c is: Pleurotus ostreatus, d is: Oyster mushroom, e is: Flammulina velutipes;

[0034] Figure 8 Schematic diagram of the growth curve of fungal solid fermentation mycelium on MYG plates in Examples 1-5;

[0035] Figure 9Schematic diagram of the biomass of fungal liquid fermentation mycelium in Examples 1-5;

[0036] Figure 10 Schematic diagram of chitin content of fungal liquid fermentation mycelia in Examples 1-5;

[0037] Figure 11 Schematic diagram of the elongation at break of the fungal glassine paper prepared in Examples 1-5 and commercially available glassine paper;

[0038] Figure 12 Transmittance curves of fungal glassine paper prepared in Examples 1-5 and commercially available glassine paper at 400-800 nm;

[0039] Figure 13 Comparison of water contact angles of Enoki mushroom glassine paper and commercially available glassine paper, where a represents commercially available glassine paper and b represents Enoki mushroom glassine paper. DETAILED DESCRIPTION

[0040] Example 1:

[0041] Step 1, solid fermentation mycelium culture:

[0042] 1.1 Select strain: Flammulina velutipes

[0043] 1.2 Activation of bacterial strains (primary mother strain culture):

[0044] Weigh 400g of peeled potatoes, cut into pieces, and bring to a boil. Continue cooking for 20 minutes, then filter and fill the volume with distilled water to 2000mL. Add 40g of agar and 40g of glucose, stir, and aliquot into sealed Erlenmeyer flasks. Autoclave the sealed flasks. After UV sterilizing the plates, pour the plates into the wells and seal them in a clean hood to obtain PDA solid plate medium (abbreviated as PDA plates). Use an inoculating needle to remove a 5mm-sized clump of Flammulina velutipes (i.e., primary stock) from a test tube. Place the clump in the center of the PDA plate and incubate in a dark, 28°C incubator for 7 days to obtain the activated Flammulina velutipes strain.

[0045] 1.3 The formula of MYG solid plate medium (abbreviated as: MYG plate) is: maltose 10g / L, glucose 5g / L, yeast extract powder 5g / L and agar powder 15g / L.

[0046] 1.4 Solid fermentation culture process of strains:

[0047] After the activated Flammulina velutipes strains have fully grown on the PDA plate, a 9 mm diameter spare Flammulina velutipes colony disc (abbreviated as spare fungus block) containing Flammulina velutipes mycelium is taken from the PDA plate using a 9 mm borer.

[0048] Determination of bacterial strain plate growth rate:

[0049] The spare bacterial blocks were transferred to MYG plates and cultured in a dark incubator at 28°C for 12 days to obtain solid fermentation mycelia of Flammulina velutipes. Mycelia phenotype instrument was used to take photos and record the solid fermentation mycelia of Flammulina velutipes and measure the mycelia diameter every 48 hours. The growth process of solid fermentation mycelia of Flammulina velutipes was as follows: Figure 1 As shown, after the solid fermentation mycelium of Flammulina velutipes has fully grown the MYG plate, a growth curve is drawn and the average daily growth rate of the solid fermentation mycelium of Flammulina velutipes is obtained by calculation.

[0050] Step 2, cultivation of liquid fermentation mycelium:

[0051] 2.1 Liquid culture medium formula: maltose 10g / L, glucose 5g / L, yeast extract 5g / L.

[0052] 2.2 Cultivation and collection process of liquid fermentation mycelium:

[0053] The spare bacteria block obtained in step 1 was inoculated into the liquid culture medium prepared in step 2.1, and cultured in a 250 ml liquid shake flask at 25°C and 160 rpm for 7 days to obtain the secondary mother strain. The secondary mother strain was inoculated into the liquid culture medium prepared in step 2.1, and cultured in a 1 L liquid shake flask at 25°C and 160 rpm for 7 days to obtain the liquid fermentation mycelium of Flammulina velutipes. Its growth is shown in FIG. Figure 2 shown.

[0054] Determination of mycelial biomass in liquid fermentation:

[0055] The liquid fermentation mycelium obtained in step 2 was rinsed several times with distilled water until it turned completely white to obtain pure liquid fermentation mycelium of Flammulina velutipes (abbreviated as pure mycelium). 1% of the total mass of the pure mycelium was placed on a weighed plate. The plate was marked with the weight of the pure mycelium and the name of the strain. The remaining pure mycelium was stored in a refrigerator at 4°C until used. The plate containing the pure mycelium was then placed in a 60°C oven to a constant weight to obtain a mycelium precipitate. The precipitate was then weighed and the biomass (g / L) of the liquid fermentation mycelium of Flammulina velutipes was calculated and recorded. Each experiment was repeated three times and the average value was taken to obtain the biomass of the liquid fermentation mycelium of Flammulina velutipes.

[0056] Determination of chitin content in liquid fermentation mycelium:

[0057] 1) Sample Preparation: The purified Flammulina velutipes mycelia obtained in the liquid fermentation mycelial biomass determination step was freeze-dried in a freeze dryer and then ground into a powder using a mortar and pestle to obtain Flammulina velutipes mycelial powder. 0.5 g of Flammulina velutipes mycelial powder was weighed and dissolved in 4 mL of concentrated hydrochloric acid. The mixture was reacted at 25°C for 24 h, then adjusted to neutrality with 1 M NaOH solution. The solution was transferred to a 100 mL volumetric flask and brought to volume to obtain a Flammulina velutipes mycelial solution. After shaking, the solution was obtained as the sample to be tested.

[0058] 2) Standard Curve Preparation: Accurately measure different volumes of glucosamine standard solution (200 μL), add 400 μL of acetylacetone reagent to each volume, and shake thoroughly. Incubate in a 90°C water bath for 1 hour. Then, add 400 μL of p-dimethylaminobenzaldehyde reagent, dilute to 5.00 mL with anhydrous ethanol, and shake thoroughly. Incubate at room temperature for 1 hour. Measure the absorbance of the solution at 530 nm to obtain the regression equation for the standard curve.

[0059] 3) Determination of chitin content in the sample: Replace glucosamine with the sample to be tested. Follow the same steps as in step 2). Substitute the absorbance into the regression equation to calculate the glucosamine concentration. The chitin content in the sample can then be calculated using the formula.

[0060] The meaning of the letters in the formula is: C 样品 : glucosamine concentration obtained from the standard curve (μg / mL); V: fixed volume of the hydrolyzate of the sample to be tested (mL); D: dilution factor (if the hydrolyzate of the sample to be tested needs to be diluted before testing); m: mass of the sample to be tested (g).

[0061] Step 3: Deep fermentation of liquid fermentation mycelium:

[0062] A 10L large fermentation tank was used to further expand the deep fermentation culture of the liquid fermentation mycelium of the enoki mushroom obtained in step 2. The liquid culture medium was used for the expanded deep fermentation culture. The liquid culture medium formula was: 10g / L maltose, 5g / L glucose and 5g / L yeast extract powder. The volume of the liquid culture medium was: 7L. The conditions for the expanded deep fermentation culture were: 25°C, 160rpm, and the liquid culture medium was used for 14 days to obtain the liquid fermentation mycelium of the enoki mushroom. The fermentation status of the liquid fermentation mycelium of the enoki mushroom after growing in the fermentation tank for 14 days was as follows: Figure 3 shown.

[0063] Step 4: Extraction and purification of liquid fermentation mycelium:

[0064] The liquid fermentation mycelium of Enoki mushroom obtained in step 3 was mixed with deionized water in a mass ratio of 1:30 to obtain a mycelium suspension of Enoki mushroom, which was then crushed and mixed using a juicer. During the crushing process, a 15-second pause was required after every 30-second crushing, and the mixture was crushed 4 times to obtain a mycelium suspension of Enoki mushroom. The mycelium suspension of Enoki mushroom was extracted in a water bath at 85°C for 0.5h, and then centrifuged at 10,000 rpm for 0.5h at room temperature using a centrifuge. The supernatant in the centrifuge bottle was discarded and the precipitate was collected to obtain the first-level precipitation of Enoki mushroom mycelium (abbreviated as: first-level precipitation). The first-level precipitation was mixed with an alkaline solution of 1M sodium hydroxide in a mass ratio of 1:30 to prepare an alkaline mycelium solution with a concentration of 3g / 100mL. The alkaline mycelium solution was then reacted in a water bath at 65°C for 1.5h. The reaction mixture was then centrifuged. The alkaline mycelium solution after reaction is centrifuged at 10000rpm for 30min, the supernatant in the centrifuge bottle is removed, and the precipitate is retained. The precipitate is the secondary precipitate of Flammulina velutipes mycelium (abbreviated as: secondary precipitate); accurately weigh the secondary precipitate and deionized water with a mass ratio of 1:1, weigh and balance them, place them diagonally in the centrifuge and centrifuge at 9000rpm for 30min. After the centrifugation is completed, the supernatant is poured out and the precipitate is retained. Repeat the above centrifugation steps until the tertiary precipitate of Flammulina velutipes mycelium with a pH of 7 is obtained (abbreviated as: tertiary precipitate). The morphology of the tertiary precipitate is as follows Figure 4 shown.

[0065] Step 5, paper preparation and shaping:

[0066] The tertiary precipitate obtained in step 4 and deionized water were mixed in a mass ratio of 1:50 and crushed and mixed using a juicer to obtain a uniformly dispersed liquid fermented Flammulina velutipes mycelium pulp (abbreviated as Flammulina velutipes mycelium pulp). Figure 5 As shown, the paper is poured into a circular embroidery frame mold with a diameter of 9 cm, and an acrylic plate is pressed on top of the enoki mushroom mycelium pulp to prevent the enoki mushroom glassine paper from warping. Finally, the paper is naturally air-dried outdoors for 48 hours until the enoki mushroom glassine paper is completely dry and formed to obtain the enoki mushroom glassine paper.

[0067] Determination of elongation at break of Flammulina velutipes glassine paper:

[0068] The enoki mushroom glassine paper obtained in step 5 was measured for elongation at break according to the national standard GB / T 12914-2018 "Paper and board - Determination of tensile strength - Constant rate of extension method": the enoki mushroom glassine paper was evenly cut into 20×50 mm rectangles, clamped on a fixture, and stretched at a constant elongation rate until the specimen broke. The elongation at break value calculated by the software was then recorded.

[0069] Determination of light transmittance of Flammulina velutipes glassine paper:

[0070] The enoki mushroom glassine paper obtained in step 5 was punched with a hole punch and placed in a 96-well plate. The absorption spectrum of the paper at a wavelength of 400-800 nm was then measured using a microplate reader. The transmittance of the paper was calculated based on the functional relationship between transmittance and absorbance. Figure 6 shown.

[0071] Determination of water contact angle of Flammulina velutipes glassine paper:

[0072] The static water contact angle θ of the Enoki mushroom glassine paper obtained in step 5 was measured over 60 s using the sessile drop method on a 10 μL droplet deposited on the surface of the Enoki mushroom glassine paper.

[0073] Example 2: Example 2 is the same as Example 1 in all steps, except that the enoki mushroom strain is replaced by the shiitake mushroom strain.

[0074] Example 3: Example 3 is the same as Example 1 in all steps, except that the Enoki mushroom strain is replaced by the Pleurotus ostreatus strain.

[0075] Example 4: Example 4 is the same as Example 1 in all steps, except that the enoki mushroom strain is replaced by the seafood mushroom strain.

[0076] Example 5: Example 5 is the same as Example 1 in all steps, except that the Enoki mushroom strain is replaced by the Versicolor versicolor strain.

[0077] The fungal strains used in Examples 1-5 of the present invention are all fungal strains available to the public through conventional channels.

[0078] The fungus glassine paper obtained in Examples 1-5 has the following morphology: Figure 7 shown.

[0079] (1) Growth rate determination

[0080] The growth curves of the fungal solid fermentation mycelia of Examples 1-5 on the MYG plate are as follows: Figure 8 As shown, Tv1 is Coriolus versicolor, Po1 is Pleurotus ostreatus, L1 is Shiitake mushroom, J1 is Enoki mushroom, and H1 is Oyster mushroom.

[0081] The average daily growth rates of the fungal solid fermentation mycelia of Examples 1-5 were measured and shown in Table 1.

[0082] Table 1: Average daily growth rate of fungal solid fermentation mycelia in Examples 1-5.

[0083]

[0084] Among them, Yunzhi mushroom grows the fastest and can fill the board in 6 days. Shiitake mushroom, Oyster mushroom and Enoki mushroom grow slower and need 10 days to fill the board. Seafood mushroom grows the slowest and needs 12 days to fill the board.

[0085] (2) Biomass determination:

[0086] The biomass of the fungal liquid fermentation mycelia of Examples 1-5 was measured and shown in Table 2.

[0087] Table 2: Biomass of mycelia from fungal liquid fermentation of Examples 1-5.

[0088]

[0089] Among them, the three strains of Flammulina velutipes, Pleurotus ostreatus and Coriolus versicolor have higher biomass and are suitable for use as test strains for paper preparation. The biomass results of the fungal liquid fermentation mycelium in Examples 1-5 are as follows: Figure 9 As shown, Tv1 is Coriolus versicolor, Po1 is Pleurotus ostreatus, L1 is Shiitake mushroom, J1 is Enoki mushroom, and H1 is Oyster mushroom.

[0090] (III) Chitin content determination:

[0091] The biomass of the fungal liquid fermentation mycelia of Examples 1-5 was measured and shown in Table 3.

[0092] Table 3: Chitin content of fungal liquid fermentation mycelia of Examples 1-5.

[0093]

[0094] Among them, the chitin content of the liquid fermentation mycelium of Flammulina velutipes is the highest, and chitin plays a role in giving the material rigidity in the composite material, which also lays the foundation for its good mechanical properties. The chitin content results of the fungal liquid fermentation mycelium of Examples 1-5 are as follows: Figure 10 As shown, Tv1 is Coriolus versicolor, Po1 is Pleurotus ostreatus, L1 is Shiitake mushroom, J1 is Enoki mushroom, and H1 is Oyster mushroom.

[0095] (IV) Determination of elongation at break:

[0096] The elongation at break of the fungus glassine paper of Examples 1-5 was measured and shown in Table 4.

[0097] Table 4: Elongation at break of the fungus glassine papers of Examples 1-5 and the commercially available glassine papers of the comparative example.

[0098]

[0099] Compared with the elongation at break of commercial glassine paper of 2.37±0.13%, the elongation at break of Flammulina velutipes glassine paper is better than that of commercial glassine paper. The other fungal glassine papers also have good mechanical properties. This is because chitin plays an important role in them. The elongation at break of the fungal glassine paper of Examples 1-5 and the commercial glassine paper of the comparative example are shown in the following table. Figure 11As shown, Tv1 is Coriolus versicolor, Po1 is Pleurotus ostreatus, L1 is Lentinus edodes, J1 is Enoki mushroom, H1 is Hokkaido mushroom, and glassine paper is commercially available glassine paper.

[0100] (V) Determination of light transmittance:

[0101] The calculated light transmittance of the fungus glassine paper of Examples 1-5 is shown in Table 5.

[0102] Table 5: Light transmittance of the fungus glassine paper of Examples 1-5 and the commercially available glassine of the comparative example.

[0103]

[0104] Compared with the 21.12% of commercial glassine paper, the transmittance of the other fungal glassine papers, except for the oyster mushroom glassine paper, is higher than that of the commercial glassine paper. Figure 12 As shown, Tv1 is Coriolus versicolor, Po1 is Pleurotus ostreatus, L1 is Lentinus edodes, J1 is Enoki mushroom, H1 is Hokkaido mushroom, and glassine paper is commercially available glassine paper.

[0105] (6) Water contact angle measurement:

[0106] The water contact angles of the fungus glassine papers of Examples 1-5 were measured and shown in Table 6.

[0107] Table 6: Water contact angles of the fungus glassine papers of Examples 1-5 and commercial glassine papers of the comparative example.

[0108]

[0109] The water contact angle of Flammulina velutipes glassine paper was measured to be , and the water contact angle of commercially available glassine paper Compared with the other two, the Flammulina velutipes glassine paper has better performance. Figure 13 shown.

[0110] The steps in the method of the embodiment of the present invention can be adjusted in order, combined and deleted according to actual needs. In the scheme of the present invention, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, please refer to the relevant description of other embodiments. The various technical features of the technical solution of the present invention can be combined arbitrarily. In order to make the description concise, not all possible combinations of the various technical features in the embodiment are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the description of the present invention.

[0111] The above is only a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications should also be regarded as the scope of protection of the present application.

Claims

1. A method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation, characterized in that: The method comprises the following steps: Step 1: solid fermentation mycelium culture: The fungal strain is inoculated into a PDA plate for cultivation to obtain an activated fungal strain, and after the activated fungal strain has fully grown on the PDA plate, a hole is punched with a hole puncher to obtain a standby fungal block; Step 2: Cultivation of liquid fermentation mycelium: The spare fungus block obtained in step 1 is inoculated into a liquid culture medium for cultivation to obtain a secondary mother strain, and the secondary mother strain is expanded and cultured in a liquid culture medium to obtain fungal liquid fermentation mycelium; Step 3: Deep fermentation culture of liquid fermentation mycelium: The fungal liquid fermentation mycelium obtained in step 2 is subjected to submerged expansion fermentation culture in a fermentation tank to obtain fungal liquid fermentation mycelium; Step 4: Extraction and purification of liquid fermentation mycelium: The fungal liquid fermentation mycelium obtained in step 3 is mixed with deionized water at a mass ratio of 1: (30-40) to obtain a fungal mycelium suspension, which is placed in a juicer and crushed and mixed multiple times to obtain a fungal mycelium suspension, which is placed in a 70-90°C water bath for extraction for 0.5-1h, then centrifuged and the supernatant is discarded to obtain a primary precipitate, the primary precipitate is mixed with 1M sodium hydroxide solution at a mass ratio of 1: (30-100) to prepare an alkaline fungal mycelium solution with a concentration of 1-3g / 100mL, the solution is placed in a 55-70°C water bath for extraction for 1.5-2h, then centrifuged and the supernatant is discarded to obtain a secondary precipitate, the secondary precipitate is washed with deionized water and centrifuged multiple times to obtain a tertiary precipitate with a pH of 7; Step 5: Paper preparation and forming: The tertiary precipitate obtained in step 4 and deionized water are mixed at a mass ratio of 1: (45-55) and then crushed and mixed using a juicer to obtain fungal mycelium pulp, which is poured into a mold and naturally air-dried outdoors to obtain fungal glassine paper; The fungal strain in step 1 is selected from any one of enoki mushroom, oyster mushroom, shiitake mushroom, seafood mushroom and versicolor. The culture conditions in step 1 are: culture at 25-30° C. in an incubator in the dark for 7-10 days, and the puncher is a 9mm puncher.

2. The method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to claim 1, characterized in that: The step 1 further includes transferring the spare mushroom blocks to the MYG plate, taking photos and recording using a mycelium phenotype instrument, and screening the spare mushroom blocks with a mycelium growth rate greater than 3 mm / d.

3. The method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to claim 2, characterized in that: In step 2, the liquid culture medium in which the spare bacterial block obtained in step 1 is inoculated and cultured has a formula of 8-15 g / L maltose, 3-7 g / L glucose, and 3-7 g / L yeast extract powder, and the culture is carried out in a 250 mL liquid shake flask, and the culture conditions are: 25-28° C., 150-170 rpm, and culture for 7-10 days; the liquid culture medium in which the secondary mother culture is expanded and cultured in the liquid culture has a formula of 8-15 g / L maltose, 3-7 g / L glucose, and 3-7 g / L yeast extract powder, and the expansion culture is carried out in a 1 L liquid shake flask, and the expansion culture conditions are: 25-28° C., 150-170 rpm, and culture for 7-14 days.

4. The method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to claim 3, characterized in that: The step 2 further comprises screening out fungal liquid fermentation mycelia with a biomass greater than 3 g / L; and screening out fungal liquid fermentation mycelia with a chitin content greater than 19%.

5. The method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to claim 4, characterized in that: In step 3, the volume of the fermentation tank is 10 L, and the submerged fermentation culture uses a liquid culture medium. The formula of the liquid culture medium is: 8-15 g / L maltose, 3-7 g / L glucose, and 3-7 g / L yeast extract powder. The volume of the liquid culture medium is 7-7.5 L. The conditions of the submerged fermentation culture are: 25-28° C., 150-170 rpm, and culture in the liquid culture medium for 7-14 days.

6. The method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to claim 5, characterized in that: The step 5 further includes measuring the elongation at break of the fungal glassine paper obtained in step 5 with reference to the national standard GB / T 12914-2018, and screening fungal glassine paper with an elongation at break of 1.5% or more; measuring the transmittance using a microplate reader with reference to the national standard GB / T 2410-2008, and screening fungal glassine paper with a transmittance of 20% or more; and measuring the static water contact angle θ using a sessile drop method, and screening fungal glassine paper with a water contact angle of 98°.

7. Fungal glassine paper prepared by the method for preparing high-transparency and high-hydrophobic fungal glassine paper based on liquid fermentation according to any one of claims 1 to 6.

8. Use of the fungus glassine paper as claimed in claim 7 as food packaging paper.

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