Lotus root residue edible preservative film and preparation method thereof

Abstract

The invention belongs to the field of cellulose nano-films, and discloses an edible preservative film containing lotus root residues and a preparation method of the edible preservative film. The preparation method comprises the following steps: sequentially carrying out crushing, enzymolysis and centrifugation on lotus root residues to obtain a precipitate; mixing and reacting the precipitate with water and a bleaching agent to obtain a reaction product, washing the reaction product to be neutral, and sequentially performing water draining, crushing, water draining and freezing treatment to obtain frozen lotus root residues; mixing the frozen lotus root residues with water, and sequentially performing stirring and high-pressure homogenization treatment to obtain feed liquid; and carrying out suction filtration on the feed liquid to obtain a solid covered on a filter membrane for suction filtration, and carrying out air drying under natural conditions to obtain the edible preservative film for lotus root residues. According to the method, the agricultural product processing by-product lotus root residue is used as a raw material for producing the nano cellulose membrane, so that the production energy consumption and cost are reduced, and the problems of resource waste and environmental pollution are solved.

Description

Technical Field

[0001] The invention belongs to the field of cellulose nanofilms, and more specifically, relates to an edible cling film of lotus root residue and a preparation method thereof. Background Art

[0002] Cellulose is a macromolecular polysaccharide composed of glucose. It is widely found in terrestrial plants, a small number of animals and bacteria. It contains abundant hydroxyl groups on its surface, which can easily form strong intermolecular and intramolecular hydrogen bonds, which helps the matrix to form a dense structure and high strength. As the main component of plant cell walls, cellulose has the advantages of wide sources, biodegradability and low price. It is the largest natural polymer renewable resource on earth. In recent years, the main materials used for food preservation packaging are petroleum-based chemical materials such as polyethylene, polyethylene terephthalate, polyvinyl chloride, polystyrene and polypropylene of different densities. They have problems such as difficult degradation, recycling difficulties and single functions. In addition, the non-renewable fossil resources are increasingly depleted, and the plastic crisis caused by them has led to serious environmental pollution. Cellulose has broad application prospects in the fields of medical care, food preservation, and pharmaceutical packaging because of its advantages such as complete biodegradability, good biocompatibility and modifiability. Researchers have nano-sized cellulose to prepare nanocellulose materials with different nano-size effects. This is one of the most mature methods for efficient utilization of cellulose. The prepared nanocellulose materials are also widely used in energy conservation and environmental protection, food industry, new energy, biomedicine, adsorption and other fields.

[0003] Edible film is a film with good mechanical properties, selective permeability and dense network structure, which is made of natural edible biomacromolecules as the base material and cross-linked by covalent bonds or non-covalent bonds. According to the composition of the base material, edible films are divided into polysaccharides, proteins, lipids and composite edible films. Compared with traditional chemical packaging films, edible films have great development prospects in the packaging fields of food and medicine due to their biosafety and biodegradability, avoiding environmental pollution and other problems. The "Lepak" used by American researchers for frozen fish and meat packaging is an edible film made of acetylated glycerol esters and acetylated butyl cellulose as the main raw materials, which has good anti-fading, anti-dehydration and antibacterial effects. British researchers have prepared an edible film called "Semperfresh" with monoglycerides, diglycerides, sucrose and carboxymethyl cellulose as raw materials for fruit coating and preservation. It not only significantly extends its storage and freshness period, but also has the advantages of low price, antibacterial and moisture barrier. In addition, France, Japan, Germany and other countries have also carried out extensive research in the field of edible films. The systematic research and development of edible films in China started relatively late. In recent years, initial results have been achieved in the research of chitosan edible films, starch / protein edible films, and polysaccharide / lipid edible films. However, the world's leading cellulose nanofilm manufacturers mainly use wood and cotton (wood pulp) as raw materials, and the disadvantages of this type of raw materials are high cost. In addition, due to the high lignin content in wood pulp, the fibrillation efficiency is low and the energy consumption of the production process is high. In addition, most of the existing edible films have complex preparation processes, and the use of chemical reagents in the preparation process has problems such as low safety and high cost, which also has a certain adverse impact on the environment.

[0004] In recent years, the agricultural product processing industry has developed rapidly, the processing conversion rate has increased, the industrial structure has been adjusted, and the system has been upgraded. Among agricultural products, lotus root is currently the aquatic vegetable with the largest planting area and the highest yield. Lotus root is a perennial plant of the Nymphaeaceae family. It has a cultivation history of more than 3,000 years in China and is an extremely rich edible and medicinal plant resource. At present, there is a complete lotus root processing and production system. However, many by-products such as lotus root skin and lotus root nodes will be produced during the lotus root processing process, accounting for about one-fifth of the fresh weight of lotus root. At present, the treatment methods of these by-products are relatively simple, mainly processed into animal feed and plant fertilizers, with low utilization rate, low economic benefits, serious losses and waste, short industrial chain, and random dumping of lotus root nodes, causing rot and deterioration, causing environmental problems, and increasing social disposal costs. These problems are becoming increasingly prominent, which has seriously restricted the market supply of agricultural products such as lotus root and the improvement of the quality and efficiency of the processing industry. Lotus root residue is rich in dietary fiber and is an ideal cheap, renewable and sustainable source of cellulose.

[0005] Therefore, the exploration of cellulose sources and the preparation of cellulose nanofilms are of great research significance. Summary of the invention

[0006] The purpose of the present invention is to provide a lotus root residue edible fresh-keeping film and a preparation method thereof in view of the deficiencies of the prior art. The present invention utilizes lotus root residue, a byproduct of agricultural product processing, as a raw material for producing nanocellulose film, thereby reducing production energy consumption and cost, and solving the problems of resource waste and environmental pollution.

[0007] In order to achieve the above object, the present invention provides a method for preparing an edible cling film of lotus root residue, the method comprising the following steps:

[0008] S1: crushing, enzymolysis and centrifugation of lotus root residue in sequence to obtain a precipitate;

[0009] S2: mixing the precipitate with water and a bleaching agent and reacting them to obtain a reaction product, washing the product with water until it is neutral, and sequentially subjecting the product to water control, crushing, water control and freezing to obtain a frozen lotus root residue material;

[0010] S3: mixing the frozen lotus root residue with water and subjecting the mixture to stirring and high-pressure homogenization in sequence to obtain a liquid;

[0011] S4: filtering the liquid to obtain a solid covered on the filter membrane for filtration, and air-drying the solid under natural conditions to obtain the lotus root residue edible preservative film.

[0012] In the present invention, the lotus root residue is prepared from lotus root peels and lotus root nodes which are byproducts of agricultural product processing by conventional means in the art.

[0013] According to the present invention, preferably, in step S1, the enzyme used in the enzymatic treatment is α-amylase.

[0014] According to the present invention, preferably, in step S1, the amount of enzyme used in the enzymatic hydrolysis treatment is 0.3-0.8% of the volume of the lotus root residue obtained by the pulverization treatment.

[0015] In the present invention, the equipment used in the pulverization process includes a pulverizer.

[0016] According to the present invention, preferably, in step S1, the enzymatic hydrolysis method comprises: mixing and stirring the enzyme used for the enzymatic hydrolysis with the lotus root residue obtained by the crushing treatment until the starch in the lotus root residue is completely decomposed to obtain an enzymatic hydrolysis mixture, and performing enzyme inactivation treatment and the centrifugal treatment to obtain the precipitate.

[0017] In the present invention, as a preferred embodiment, as shown in Figure 1(A)-(B), α-amylase is added to remove starch from the lotus root residue, and a brown precipitate is obtained after centrifugal washing, as shown in Figure 1(A); then the lotus root residue is bleached under the action of sodium hydroxide and hydrogen peroxide to remove lignin and hemicellulose, and the cellulose therein is retained, as shown in Figure 1(B). The frozen lotus root residue material after washing, bleaching and freezing is shown in Figure 2(A). The present invention destroys the hydrogen bonds between the cellulose chains of the lotus root residue through homogenization (high shear stirring, Figure 2(B)) and high-pressure homogenization (Figure 2(C)), so that the lotus root residue cellulose forms micron-sized fibers, which can be evenly dispersed in water and remain stable for a long time as shown in Figure 2(C).

[0018] According to the present invention, preferably, the temperature of the enzymatic hydrolysis treatment is 40-60°C.

[0019] According to the present invention, preferably, the temperature of the enzyme inactivation treatment is 80-100° C. and the time is 1-4 h.

[0020] According to the present invention, preferably, in step S1, the rotation speed of the centrifugal treatment is 4000-5000 r / min, and the time is 5-15 min.

[0021] According to the present invention, preferably, in step S2, the bleaching agent comprises hydrogen peroxide and sodium hydroxide.

[0022] According to the present invention, preferably, in step S2, the usage ratio of the precipitate, hydrogen peroxide, sodium hydroxide and water is (2-5): (3-5): (2-6): 100 g / g / g / mL.

[0023] According to the present invention, preferably, in step S2, the reaction conditions include: water bath at 75-85°C, time 30-40min, the reaction product is observed to be obviously whitened, after the reaction is completed, the bleached product is washed with water to neutrality with a filter, and then processed by drying water, crushing, and drying water in sequence, and then stored in the freezer of a refrigerator to obtain frozen lotus root residue.

[0024] According to the present invention, preferably, in step S3, the usage ratio of the frozen lotus root residue material to water is (2-5): 100 g / mL.

[0025] According to the present invention, preferably, in step S3, the rotation speed of the stirring treatment is 7500-8500 r / min, and the time is 10-20 min;

[0026] According to the present invention, preferably, in step S3, the pressure of the high-pressure homogenization treatment is 95-105 bar, and the number of homogenization times is 6-8 times.

[0027] According to the present invention, preferably, in step S4, the suction filtration method includes injecting 75-85 mL of the feed solution onto the suction filtration membrane in batches.

[0028] Another aspect of the present invention provides the edible lotus root residue preservative film prepared by the preparation method of the edible lotus root residue preservative film.

[0029] The beneficial effects of the technical solution of the present invention are as follows:

[0030] The present invention utilizes lotus root residue, a by-product of agricultural product processing, as a raw material for producing nanocellulose membranes. This raw material, which is usually regarded as waste, represents a cheaper, sustainable and renewable source of cellulose. Compared with wood pulp, the lignin content in lotus root residue is lower, which effectively improves the cellulose separation efficiency and reduces production energy consumption and costs.

[0031] The invention can solve the problem that a large amount of lotus root residue generated in the lotus root processing process is discarded or burned, causing waste of resources, and the like.

[0032] The present invention can solve the "white pollution" problem caused by traditional fresh-keeping materials under the conditions of a sharp increase in global energy demand and a deteriorating environment.

[0033] Other features and advantages of the present invention will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The above and other objects, features and advantages of the present invention will become more apparent through a more detailed description of exemplary embodiments of the present invention in conjunction with the accompanying drawings, wherein like reference numerals generally represent like components throughout the exemplary embodiments of the present invention.

[0035] FIG1(A) shows a method for preparing an edible cling film of lotus root residue provided by the present invention, in which α-amylase is added to remove starch in the lotus root residue, and a brown precipitate is obtained after centrifugation and washing.

[0036] FIG. 1(B) shows a reaction product after bleaching in a method for preparing an edible cling film of lotus root residue provided by the present invention.

[0037] FIG. 2(A) shows a method for preparing an edible cling film for lotus root residue provided by the present invention, wherein the frozen lotus root residue is mixed with water after washing, bleaching and freezing.

[0038] FIG. 2(B) shows a diagram of the frozen lotus root residue material after being stirred in the method for preparing an edible cling film for lotus root residue provided by the present invention.

[0039] FIG. 2(C) shows a liquid obtained after the frozen lotus root residue material is stirred and subjected to high-pressure homogenization in a method for preparing an edible lotus root residue cling film provided by the present invention.

[0040] FIG3(A) shows a TGA (thermogravimetric analysis) graph of an edible cling film made from lotus root residues prepared by a method for preparing an edible cling film made from lotus root residues provided by the present invention.

[0041] FIG3(B) shows a DTG (thermogravimetric analysis) graph of an edible cling film made from lotus root residues by a method for making an edible cling film made from lotus root residues provided by the present invention.

[0042] FIG3(C) shows an infrared spectrum of an edible cling film made from lotus root residues prepared by the method for preparing an edible cling film made from lotus root residues provided by the present invention.

[0043] FIG3(D) shows an X-ray diffraction pattern of an edible cling film made from lotus root residues according to a method for making an edible cling film made from lotus root residues provided by the present invention.

[0044] Figures 4(A)-(H) show microscopic images of the lotus root residue edible preservative film prepared by the preparation method of the lotus root residue edible preservative film provided by the present invention (Figure 4(A) is the surface of the untreated lotus root residue at a scale of 100μm; Figure 4(B) is the surface of the untreated lotus root residue at a scale of 2μm; Figure 4(C) is the surface of the 0.5wt.% lotus root residue edible film-forming liquid (i.e., the liquid of step S3) at a scale of 100μm; Figure 4(D) is the surface of the 0.5wt.% lotus root residue edible film-forming liquid (i.e., the liquid of step S3) at a scale of 2μm; Figure 4(E) is the surface of the lotus root residue edible film at a scale of 100μm; Figure 4(F) is the surface of the lotus root residue edible film at a scale of 2μm; Figure 4(G) is the cross-section of the lotus root residue edible film at a scale of 100μm; Figure 4(H) is the cross-section of the lotus root residue edible film at a scale of 2μm).

[0045] FIG5(A) shows a mechanical test result diagram of an edible cling film made from lotus root residue prepared by a method for preparing an edible cling film made from lotus root residue provided by the present invention.

[0046] FIG5(B) shows a degradation test result of an edible cling film made from lotus root residues prepared by the method for preparing an edible cling film made from lotus root residues provided by the present invention.

[0047] Figure 6 A graph showing the effect of the edible cling film of lotus root residue prepared by the method for preparing the edible cling film of lotus root residue provided by the present invention on the browning degree of cherries (Day is the number of days, the left is the control group, and the right is the experimental group). DETAILED DESCRIPTION

[0048] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to make the present invention more thorough and complete, and to fully convey the scope of the present invention to those skilled in the art.

[0049] Example 1

[0050] The present embodiment provides a method for preparing an edible cling film of lotus root residue, comprising the following steps:

[0051] S1: crushing lotus root residue with a pulverizer to obtain lotus root residue; stirring the lotus root residue with α-amylase at 40-60° C. until starch is completely decomposed to obtain an enzymatic hydrolysis mixture, then heating to 80-100° C. to react for 1-4 hours to inactivate the α-amylase, and then centrifuging to remove the supernatant to obtain a precipitate;

[0052] The amount of α-amylase used is 0.5% of the volume of the lotus root residue;

[0053] The speed of centrifugation was 4500 r / min and the time was 10 min;

[0054] S2: The precipitate is mixed with distilled water, hydrogen peroxide and sodium hydroxide and reacted in a water bath at 80° C. for 30-40 minutes. It is observed that the reaction product becomes obviously white. After the reaction is completed, the bleached product is washed with water to neutrality with a filter, and then the product is dried, crushed, and dried in sequence, and then stored in a refrigerator to obtain frozen lotus root residue;

[0055] The amount of the precipitate is 20 g, the amount of hydrogen peroxide is 40 g, the amount of sodium hydroxide is 40 g, and the amount of distilled water is 1000 mL;

[0056] S3: mixing the frozen lotus root residue with distilled water and stirring the mixture with a high shear mixer at 8000 r / min for 15 min to obtain a homogenate; and subjecting the homogenate to 7 high-pressure homogenization treatments at a pressure of 100 bar using a high-pressure homogenizer to obtain a liquid feed;

[0057] The usage ratio of the frozen lotus root residue material to water is 2:100 g / mL;

[0058] S4: Place a filter membrane in a suction filtration bottle, take the high-pressure homogenized liquid and shake it evenly, inject 80 mL of the liquid onto the filter membrane in batches with a syringe, and then air-dry under natural conditions after drying to obtain the lotus root residue edible preservative film.

[0059] Test Example 1

[0060] In this test example, the lotus root residue that has not been treated in step S1 of the present invention (hereinafter referred to as untreated lotus root residue) and the lotus root residue edible preservative film prepared by the present invention (hereinafter referred to as lotus root residue edible film) are physically and chemically characterized.

[0061] 1. TGA (thermogravimetric analysis) and DTG (thermogravimetric analysis):

[0062] As shown in Figure 3(A), at 80-197°C, the lotus root residue edible film loses a small amount of weight, which is mainly due to the evaporation of free water and crystal water in cellulose and the mass loss of low molecular weight compounds; its main degradation temperature is 197-435°C, due to the dehydration and decomposition of glucose groups in cellulose, generating left-handed glucose. As can be seen from Figure 3(B), the corresponding main peak of weight loss within this temperature (197-435°C) is 336°C. At this time, the residual rate of the lotus root residue edible film is 53.7%, and that of the untreated lotus root residue is 46%. When the temperature reaches 664°C, the lotus root residue edible film is completely pyrolyzed, indicating that the processing technology of the lotus root residue edible film removes the components that are not easy to pyrolyze, and at the same time confirms that the impurities in the crude fiber of the lotus root residue are largely removed, and the cellulose purity of the lotus root residue edible film is relatively high. In addition, it can be seen from Figure 3 (A) that the main degradation temperature of the untreated lotus root residue is 110-450°C. It can be seen from Figure 3 (B) that the corresponding main peak of weight loss within this temperature (110-450°C) is 289°C. At this temperature, the residual rate of the edible film of the lotus root residue is 83%, and the untreated lotus root residue is 73%, indicating that the preparation process can improve the thermal stability of the product. This may be because the lignin and hemicellulose in the raw materials are removed in large quantities during the processing. At the same time, the increase in pyrolysis temperature also proves that the edible film of lotus root residue has higher heat resistance, which may be due to the film-making process to improve the purity of natural biomass and remove non-crystalline areas.

[0063] 2. Infrared spectrum analysis:

[0064] As shown in Figure 3(C), both the edible film of lotus root residue and the untreated lotus root residue were at 3420 cm -1 and 2925cm -1 There are characteristic absorption peaks of cellulose at 1726cm -1 There is a weak C=O stretching vibration peak at 1425cm, which belongs to the acetyl group of xylan in hemicellulose, but its peak is weak, indicating that the hemicellulose content in the edible film of lotus root residue is low. -1 The characteristic absorption peak at 1030 cm -1 The characteristic absorption peak at corresponds to the CO stretching vibration peak, which is attributed to the ether bonds in lignin or hemicellulose, which indirectly explains why the edible film of lotus root residue appears yellowish.

[0065] 3. X-ray diffraction analysis:

[0066] As can be seen from Figure 3(D), the untreated lotus root residue and the edible lotus root residue film mainly show three diffraction peaks at 2θ=15.22°, 21.57°, and 31.86°, which correspond to the diffraction of the (101), (002), and (110) planes of cellulose type I, respectively. This shows that the crystallinity of cellulose is not reduced under the processing technology of the lotus root residue edible film, and the hemicellulose, lignin, etc. in the lotus root residue edible film are removed in large quantities, and the cellulose content is relatively high.

[0067] 4. Hitachi Scanning Electron Microscope Image Analysis:

[0068] The scanning results of Figure 4 (A)-(H) show that:

[0069] The surface of untreated lotus root residue is smooth and dense, the cells are neatly arranged, the structure is complete, and the surface material is mainly cellulose, which is tightly connected.

[0070] The surface of the 0.5wt.% lotus root residue edible film-forming liquid (i.e., the liquid of step S3) obtained by the present invention is relatively rough, and an obvious fibrous structure can be seen at different magnifications. Dense micropores can be seen at different magnifications. This is because the cell wall is destroyed during the processing, and its contents flow out and are removed with treatments such as centrifugation. The collected cellulose is broken in large quantities under homogenization and high-pressure homogenization operations, and is evenly dispersed in the aqueous solution, with a reduced particle size and increased viscosity, and they are entangled with each other to form a network structure;

[0071] The surface structure of the edible film of lotus root residue is dense, the cross section is lamellar, and there are fewer micropores. This is because the film layers formed by cellulose in the film-forming process are stacked layer by layer under filtration to form a denser structure, which is beneficial to enhance its mechanical properties.

[0072] Test Example 2

[0073] The mechanical properties of the cling film are very important in practical applications. In this test example, a universal testing machine is used to perform a tensile test on the edible cling film of lotus root residue prepared by the present invention.

[0074] The results are shown in FIG5(A): The results show that the lotus root residue edible cling film prepared by the present invention has a good tensile strength of about 55.7 MPa, and a tensile strain of about 260%, which is higher than the existing common film materials, showing excellent mechanical properties and is suitable for the packaging of fruits and vegetables.

[0075] Test Example 3

[0076] Degradability is very important for cling film. In this test example, the lotus root residue edible cling film prepared by the present invention was degraded in soil to evaluate its potential as a sustainable material to replace some non-degradable plastic materials. It was also compared with commercial cling film (Miaojie PE polyethylene cling film, item number: M160DME, manufacturer: Top Daily Chemicals Co., Ltd.).

[0077] The results are as follows Figure 5B As shown: the weight of commercial cling film hardly changes under the action of soil, while the lotus root residue edible film (the lotus root residue edible cling film prepared by the present invention) slowly degrades in the soil. After being buried in the soil for about 60 days, the weight of the cling film loses 37%, and it has good degradability. It is believed that as time goes on, the cling film can eventually be completely degraded to achieve green recyclability.

[0078] Test Example 4

[0079] Browning refers to the phenomenon that polyphenol oxidase oxidizes phenolic substances into brown pigment in the presence of oxygen. This test example tests the effect of the lotus root residue edible preservative film prepared by the present invention on the browning degree of cherries.

[0080] In the experimental group, 0.5 wt.% of the lotus root residue edible film-forming liquid (i.e., the liquid in step S3) obtained in the present invention was coated on the surface of the cherry.

[0081] The control group was left with the cherries naturally without any treatment.

[0082] The results are as follows Figure 6 As shown:

[0083] The browning degree of cherries after coating treatment (experimental group) is much lower than that of the control group, and the increase rate of the overall browning value fluctuates less, and the rate of change is more stable than that of the control group, indicating that with the increase of storage time, the preservation effect of the experimental group is relatively stable, and the lotus root residue edible film-forming liquid has good preservation performance for cherries.

[0084] As the storage time increased, the appearance of the cherries in both the control and experimental groups gradually shrunk and darkened. From the appearance, it can be seen that the cherries in the control group rotted on the fourth day, and the color became significantly darker. On the fifth day, the cherries' skin shrunk severely. The experimental group began to rot slightly from the seventh day.

[0085] From the observation phenomena, it can be seen that the edible film-forming liquid of lotus root residue can effectively delay the decay and decay of cherries, extend the shelf life of cherries and improve their storage performance. This is mainly because the edible film-forming liquid of lotus root residue forms a relatively stable network structure, which reduces the evaporation loss of water in cherries, weakens cell respiration, and improves the preservation effect of cherries.

[0086] The embodiments of the present invention have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. A method for preparing an edible cling film of lotus root residue, characterized in that: The preparation method comprises the following steps: S1: crushing, enzymolysis and centrifugation of lotus root residue in sequence to obtain a precipitate; S2: mixing the precipitate with water and a bleaching agent and reacting them to obtain a reaction product, washing the product with water until it is neutral, and sequentially subjecting the product to water control, crushing, water control and freezing to obtain a frozen lotus root residue material; S3: mixing the frozen lotus root residue with water and subjecting the mixture to stirring and high-pressure homogenization in sequence to obtain a liquid; S4: filtering the liquid to obtain a solid covered on the filter membrane for filtration, and air-drying the solid under natural conditions to obtain the lotus root residue edible preservative film.

2. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S1: The enzyme used in the enzymatic treatment is α-amylase; The amount of enzyme used in the enzymatic hydrolysis treatment is 0.3-0.8% of the volume of the lotus root residue obtained by the crushing treatment; The enzymatic hydrolysis method comprises: mixing and stirring the enzyme used in the enzymatic hydrolysis with the lotus root residue obtained by the pulverization treatment until the starch in the lotus root residue is completely decomposed to obtain an enzymatic hydrolysis mixture, and performing enzyme inactivation treatment and the centrifugal treatment to obtain the precipitate.

3. The method for preparing the edible cling film of lotus root residue according to claim 2, wherein: The temperature of the enzymatic treatment is 40-60°C; The temperature of the enzyme inactivation treatment is 80-100° C. and the time is 1-4 hours.

4. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S1, the rotation speed of the centrifugal treatment is 4000-5000 r / min, and the time is 5-15 min.

5. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S2: The bleaching agent includes hydrogen peroxide and sodium hydroxide; The dosage ratio of the precipitate, hydrogen peroxide, sodium hydroxide and water is (2-5): (3-5): (2-6): 100 g / g / g / mL.

6. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S2, the reaction conditions include: water bath at 75-85°C, time 30-40 min.

7. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S3: The usage ratio of the frozen lotus root residue material to water is (2-5): 100 g / mL; The stirring process is performed at a rotation speed of 7500-8500 r / min and for a time of 10-20 min.

8. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S3, the pressure of the high-pressure homogenization treatment is 95-105 bar, and the number of homogenization times is 6-8 times.

9. The method for preparing the edible cling film of lotus root residue according to claim 1, wherein: In step S4, the suction filtration method includes injecting 75-85 mL of the feed solution onto the suction filtration membrane in batches.

10. The edible cling film for lotus root residue prepared by the method for preparing the edible cling film for lotus root residue according to any one of claims 1 to 9.

Images