Edible film, preparation method thereof and edible seasoning bag

Abstract

The embodiment of the invention provides an edible film, a preparation method thereof and an edible seasoning bag, and relates to the technical field of edible packaging bags. The preparation method comprises the following steps: weighing the following raw materials: a phenolic acid-soybean polysaccharide grafted copolymer, water, gellan gum and glycerol; dissolving the phenolic acid-soybean polysaccharide grafted copolymer in water to obtain a phenolic acid-soybean polysaccharide grafted copolymer solution; adding gellan gum into the phenolic acid-soybean polysaccharide grafted copolymer solution at the temperature of 50-80 DEG C, and stirring for 20-40 minutes; adding glycerol into the solution at the temperature of 50-80 DEG C, and stirring for 10-30 minutes; and after ultrasonic defoaming treatment, the edible film is obtained by adopting a film casting mode. The edible film prepared by the preparation method provided by the embodiment of the invention not only can be eaten, but also has better barrier property, oxidation resistance and mechanical property.

Description

Technical Field

[0001] The present application relates to the technical field of edible packaging bags, and particularly relates to an edible film, a preparation method thereof, and an edible seasoning packet. Background Art

[0002] With the improvement of people's attention to food safety, the requirements for food packaging materials have also increased accordingly. Existing foods mainly use PP, PE, PVC, etc. as packaging materials. Such packaging materials cannot be biodegradable and are prone to causing pollution. Some packaging materials for chemical products also contain a small amount of toxic and harmful substances, which will cause certain pollution to foods.

[0003] In related technologies, it has been proposed to use edible materials such as natural edible biopolymer substances (such as proteins, lipids, saccharides, etc.) to prepare edible films to reduce the pollution to foods and the environment. However, the edible films in related technologies have problems of poor mechanical properties and barrier properties. When used as packaging materials for instant noodle seasoning packets or tea bags, etc., they are prone to breakage or extremely easy to deteriorate, resulting in poor user experience. Summary of the Invention

[0004] The embodiments of the present application provide an edible film, a preparation method thereof, and an edible seasoning packet, which are used to prepare an edible film with better barrier properties, antioxidant properties, and mechanical properties.

[0005] In a first aspect, the embodiments of the present application provide a preparation method of an edible film, including: weighing the following raw materials: phenolic acid-soybean polysaccharide graft copolymer, water, gellan gum, and glycerol; dissolving the phenolic acid-soybean polysaccharide graft copolymer in water to obtain a phenolic acid-soybean polysaccharide graft copolymer solution; adding gellan gum to the phenolic acid-soybean polysaccharide graft copolymer solution at 50°C - 80°C and stirring for 20 - 40 min; adding glycerol to the solution at 50 - 80°C and stirring for 10 - 30 min; after performing ultrasonic defoaming treatment, obtaining an edible film by means of casting film formation.

[0006] The edible film provided by the embodiments of the present application uses phenolic acid - soy polysaccharide graft copolymer and gellan gum as the main film - forming matrix, and glycerol as the plasticizer. Among them, soy polysaccharide itself has good film - forming properties and excellent stability, but its hydrophilicity limits the application range of soy polysaccharide. Phenolic acid can react with soy polysaccharide under certain conditions, reducing the content of its hydrophilic groups, increasing hydrophobicity, and expanding its application range. That is to say, phenolic acid - soy polysaccharide graft copolymer has good film - forming properties, excellent stability and hydrophobicity. Compounding the phenolic acid - soy polysaccharide graft copolymer can further improve the mechanical properties of the edible film. The obtained edible film can not only be directly edible without causing environmental pollution, but also has good barrier properties, antioxidant properties and mechanical properties, and can be used for directly packaging food.

[0007] Combined with the first implementation manner of the first aspect, weigh the following raw materials: phenolic acid - soy polysaccharide graft copolymer, water, gellan gum and glycerol. Specifically, weigh the following raw materials in parts by mass: 2 - 8 parts of phenolic acid - soy polysaccharide graft copolymer, 90 - 110 parts of water, 1 - 5 parts of gellan gum and 0.5 - 1.5 parts of glycerol.

[0008] Combined with the second implementation manner of the first aspect, before weighing the following raw materials: phenolic acid - soy polysaccharide graft copolymer, water, gellan gum and glycerol, the method further includes: weighing the following raw materials: soy polysaccharide, water, phenolic acid, ethanol solution, carbodiimide hydrochloride and N - hydroxysuccinimide; dissolving soy polysaccharide in water at 40 - 60 °C, and storing it refrigerated after dissolution to obtain a soy polysaccharide solution; under ice - bath conditions, uniformly mix phenolic acid in the ethanol solution, and add carbodiimide hydrochloride and N - hydroxysuccinimide to the ethanol solution, and continuously stir for 1 - 3 h; under light - shielding and refrigerated conditions, drop - add the soy polysaccharide solution and continuously stir; use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze - drying to obtain the phenolic acid - soy polysaccharide graft copolymer.

[0009] Combined with the third implementation manner of the first aspect, weigh the following raw materials: soy polysaccharide, water, phenolic acid, ethanol solution, carbodiimide hydrochloride and N - hydroxysuccinimide. Specifically, weigh the following raw materials in parts by mass: 1 - 3 parts of soy polysaccharide, 90 - 110 parts of water, 1 - 4 parts of phenolic acid, 90 - 110 parts of ethanol solution, 1 - 4 parts of carbodiimide hydrochloride and 1 - 4 parts of N - hydroxysuccinimide.

[0010] Combined with the fourth implementation manner of the first aspect, after performing ultrasonic defoaming treatment, before obtaining the edible film by the casting film - forming method, the method further includes: reacting for 40 - 50 h under light - shielding conditions, and using centrifugation and dialysis to remove the residual reagents in the solution.

[0011] Combined with the fifth implementation manner of the first aspect, the phenolic acids include at least one of the following: gallic acid, cinnamic acid, ferulic acid, and catechin.

[0012] Combined with the sixth implementation manner of the first aspect, the gellan gum is low-acyl gellan gum.

[0013] In a second aspect, an edible film provided by an embodiment of the present application has components including: gellan gum, glycerol, and a phenolic acid-soybean polysaccharide graft copolymer.

[0014] Combined with the first implementation manner of the second aspect, the mass fraction of the gellan gum is 30 parts - 40 parts, the mass fraction of the glycerol is 10 parts - 20 parts, and the mass fraction of the phenolic acid-soybean polysaccharide graft copolymer is 40 parts - 60 parts.

[0015] In a third aspect, an edible seasoning packet provided by an embodiment of the present application uses the edible film provided by the second aspect and its possible implementation manners as a packaging material.

[0016] For the beneficial effects described in the second aspect to the third aspect of the present application, reference can be made to the analysis of the beneficial effects of the first aspect, and details are not elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The drawings are used to provide a further understanding of the technical solutions of the present invention, and constitute a part of the specification. Together with the embodiments of the present application, they are used to explain the technical solutions of the present invention and do not constitute a limitation to the technical solutions of the present invention.

[0018] Figure 1 It is a process flow of a preparation method of an edible film provided by an embodiment of the present application Figure 1 ;

[0019] Figure 2 It is a structural schematic diagram of gallic acid provided by an embodiment of the present application;

[0020] Figure 3 It is a structural change schematic diagram of gellan gum provided by an embodiment of the present application;

[0021] Figure 4 It is a structural schematic diagram of high-acyl gellan gum provided by an embodiment of the present application;

[0022] Figure 5 It is a structural schematic diagram of low-acyl gellan gum provided by an embodiment of the present application;

[0023] Figure 6 It is a process flow of a preparation method of an edible film provided by an embodiment of the present application Figure 2 ;

[0024] Figure 7Schematic diagram of an edible film provided by an embodiment of the present application;

[0025] Figure 8 Method flow of a preparation method of an edible film provided by an embodiment of the present application Figure 3 ;

[0026] Figure 9 Schematic diagram of the structure of ethanol provided by an embodiment of the present application;

[0027] Figure 10 Schematic diagram of an edible seasoning packet provided by an embodiment of the present application. Detailed implementation manners

[0028] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present application.

[0029] It should be noted that the terms "first" and "second" used in the embodiments of the present invention are only for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0030] In the embodiments of the present application, words such as "exemplary" or "for example" are used to indicate being used as an example, illustration or explanation. Any embodiment or design solution described as "exemplary" or "for example" in the embodiments of the present application should not be construed as being more preferred or having more advantages than other embodiments or design solutions. Exactly speaking, using words such as "exemplary" or "for example" aims to present relevant concepts in a specific manner.

[0031] With the improvement of people's attention to food safety, the requirements for food packaging materials have also increased accordingly. Existing foods mainly use PP, PE, PVC, etc. as packaging materials. Such packaging materials cannot be biodegradable, are prone to cause pollution, and some packaging materials of chemical products also contain a small amount of toxic and harmful substances, which will cause certain pollution to foods.

[0032] In the related art, edible films are prepared using edible materials such as natural edible biopolymeric substances (such as proteins, lipids, carbohydrates, etc.) to reduce pollution to food and the environment. However, the edible films in the related art have problems of poor instant solubility and barrier properties. When used as packaging materials for instant noodle seasoning packets or tea bags, etc., they are prone to breakage or easy deterioration, resulting in poor user experience.

[0033] Based on this, the embodiments of the present application provide an edible film, a preparation method thereof, and an edible seasoning packet. The edible film uses a phenolic acid-soybean polysaccharide graft copolymer and gellan gum as the main film-forming matrix, and glycerol as a plasticizer. The obtained edible film can not only be directly eaten without causing pollution to the environment, but also has good barrier properties, antioxidant properties, and mechanical properties, and can be used for directly packaging food.

[0034] Among them, soybean polysaccharide itself has good film-forming properties and excellent stability, but its hydrophilicity limits the application range of soybean polysaccharide. Phenolic acid can react with soybean polysaccharide under certain conditions to reduce the content of its hydrophilic groups, increase hydrophobicity, and expand its application range. That is to say, the phenolic acid-soybean polysaccharide graft copolymer has good film-forming properties, excellent stability, and hydrophobicity. Compositing the phenolic acid-soybean polysaccharide graft copolymer can further improve the mechanical properties of the edible film.

[0035] Gellan gum is an extracellular linear polysaccharide secreted by Pseudomonas, composed of three monosaccharides: glucose, rhamnose, and glucuronic acid. It is an edible material with good film-forming properties. It can form a sol under heating conditions and can also form a transparent and strong gel after cooling. The film made of gellan gum has the characteristics of colorless transparency and high tensile strength.

[0036] As a plasticizer for the edible film, glycerol can weaken the secondary bonds, namely van der Waals forces, between the phenolic acid-soybean polysaccharide graft copolymer and the polymer of gellan gum, thereby increasing the mobility of the polymer molecular chains, reducing the crystallinity of the polymer molecular chains, that is, increasing the plasticity of the polymer, manifested as a decrease in the hardness, modulus, softening temperature, and embrittlement temperature of the polymer, while the elongation rate, flexibility, and flexibility, etc. are improved. And because the molecular weight of glycerol is small and it has certain hydrophilicity itself, it can further improve the dissolution performance of the edible film.

[0037] It should be understood that the edible film provided by the embodiments of the present application can not only be applied to packaging materials for dry materials such as tea bags and powders, but also can be used for packaging materials for liquids with low water content such as oils and sauces. The embodiments of the present application do not make any limitations on its usage scenarios.

[0038] Please refer to Figure 1 , Figure 1This is a flowchart of a method for preparing an edible film provided by an embodiment of the present application. As Figure 1 shown, the preparation method includes the following steps:

[0039] S101. Weigh the following raw materials: phenolic acid-soybean polysaccharide graft copolymer, water, gellan gum, and glycerol.

[0040] Among them, soybean polysaccharide is an acidic polysaccharide derived from soybean dregs. Its backbone is composed of acidic rhamnogalacturonic acid and α-1,4-galacturonic acid (the repeating unit is α-1,2-rhamnose and α-1,4-galacturonic acid), and then connected to β-1,4-galactan and α-1,3- or α-1,5-arabinose residues. Its components are mainly galactose, arabinose, galacturonic acid, rhamnose, fucose, xylose, glucose, etc. Soybean polysaccharide has good solubility, emulsifying property, emulsification stability, and anti-caking property. In addition, it is rich in dietary fiber, has good film-forming property, excellent adhesiveness, certain antibacterial property, and antioxidant property. The molecular structure of soybean polysaccharide is mainly composed of a main chain of acidic sugars (galacturonan, rhamnodigalacturonan) and side chains of neutral sugars (arabinan and galactan). Its main chain is short, the side chains are long, and the branching is complex. This high degree of branching results in a compact spherical structure of soybean polysaccharide; the molecular weight and degree of esterification of soybean polysaccharide will greatly affect its structure to a large extent. Soybean polysaccharide can form a film with certain antioxidant properties, but its mechanical properties and water resistance are poor, and the barrier property is weak.

[0041] Phenolic acid refers to phenolic compounds with a carboxylic acid group and is one of the main categories of plant phenolic compounds. It exists in various plant sources, such as fruits, vegetables, spices, etc., and has activities such as antioxidant, antibacterial, antiviral, and anticancer. Phenolic acid can not only greatly change the structure and physical and chemical properties of nanocellulose, such as hydrophilicity, crystallinity, and rheology, significantly improve the biological activity of nanocellulose, but also bring antibacterial and antioxidant effects to nanocellulose. Phenolic acid can react with polysaccharide molecules through an esterification reaction, reduce the content of hydrophilic groups in the film, and effectively improve the hydrophilic property of the polysaccharide film, thereby achieving the effects of hydrophobicity and antioxidant.

[0042] Among them, phenolic acid includes at least one of the following: gallic acid, cinnamic acid, ferulic acid, catechin. Exemplarily, Figure 2 shown is the structural schematic diagram of gallic acid.

[0043] Therefore, in the embodiment of the present application, phenolic acid-soybean polysaccharide graft copolymer is used, so that the obtained edible film has better hydrophobicity and antioxidant property. Among them, grafting refers to the reaction of chemically bonding appropriate side chains or functional side groups on a macromolecular chain, and the resulting product is called a graft copolymer. The phenolic acid-soybean polysaccharide graft copolymer is connected through an ester group (the hydroxyl group of phenolic acid and the carboxyl group of soybean polysaccharide).

[0044] Gellan gum is a kind of high molecular polysaccharide colloid with good tissue compatibility. It can be well compounded and compatible with other hydrophilic raw materials, and crosslinked to produce thickeners and stabilizers with excellent properties. The resulting compounded gum often produces new properties that the monomer gums themselves do not have, and can play a synergistic effect.

[0045] At low temperatures, the polymers in gellan gum exist in a double helix structure. When the double-stranded helix forms, gelation occurs, and then the helical aggregates are formed. Each chain is connected by internal secondary bonds (such as hydrogen bonds) to form two binding regions. The number of binding segments in each binding region changes with temperature. When the temperature rises, the segments separate, and the polymer exists in a single-chain form. When the temperature drops again, the polymer forms a double helix structure.

[0046] Please refer to Figure 3 , after gellan gum dissolves in water, the molecules will automatically aggregate to form a double helix structure. The force that stabilizes the double helix structure is mainly the intermolecular hydrogen bond. The further aggregation of the double helix can form a three-dimensional network structure, which is convenient for intercepting water molecules and generating a gel phenomenon. The gelation mechanism of gellan gum is considered to be the polymerization crosslinking between double helices induced by cations. Cations can promote the crosslinking within the molecule, stabilize the double helix structure, and accelerate the formation of a three-dimensional network structure of the double helix. The carboxyl side chains of gellan gum molecules repel each other due to electrostatic interaction, which hinders the close aggregation of the helix, and the intervention of cations can shield the electrostatic repulsion.

[0047] Gellan gum can be evenly dispersed by stirring in cold water or deionized water. When heated to 70 - 75 °C (or adding a small amount of chelating agents such as sodium citrate and sodium hexametaphosphate), it can be hydrated and dissolved into a transparent solution, and forms a transparent and firm gel after cooling to 40 - 45 °C. Therefore, when preparing the agarose solution, it needs to be prepared at a relatively high temperature (60 °C).

[0048] In some embodiments, gellan gum can be classified into two categories according to the number of acetate groups connected to the polymer: low acyl gellan gum and high acyl gellan gum. Referring to Figure 4 and Figure 5 as shown, high acyl gellan gum can also be called natural gellan gum, which can form a soft, elastic and adhesive gel; low acyl gellan gum is the material after removing the acyl group and glycerol group in the high acyl gellan gum molecule, and the formed gel has better hardness and mechanical strength.

[0049] Therefore, as a feasible implementation method, the gellan gum in the embodiments of the present application can be low acyl gellan gum.

[0050] In some embodiments, due to the too low concentration of the added gellan gum, it cannot effectively combine with other film-forming raw materials; when the concentration of gellan gum is too high, hydrogen bonds may form between it and other film-forming substances, which will instead hinder the dissolution performance of the edible film. Glycerol, as a plasticizer, has a relatively small molecular weight and certain hydrophilicity itself. It can improve the dissolution performance of the edible film; however, when the content of glycerol is too high, the interaction between film-forming substances will be weakened, and the dissolution time will be prolonged instead.

[0051] That is to say, within a certain range of the ratio between various substances, the cross-linking is relatively tight, and various properties of the film are improved; but when the content of a certain substance is relatively high, the viscosity of the film solution increases, the film-forming is uneven, and there may be a stacking phenomenon, resulting in a downward trend in the barrier performance, mechanical properties, etc. of the film.

[0052] Therefore, as a feasible implementation method, in the embodiment of the present application, S101 is specifically: weigh the following raw materials in parts by mass: 2 to 8 parts of phenolic acid-soybean polysaccharide graft copolymer, 90 to 110 parts of water, 1 to 5 parts of gellan gum, and 0.5 to 1.5 parts of glycerol.

[0053] It should be noted that the above "parts" can be expressed as mass measurement units such as g or kg, and are selected according to actual needs. The present application does not make specific limitations on this.

[0054] S102. Dissolve the phenolic acid-soybean polysaccharide graft copolymer in water to obtain a phenolic acid-soybean polysaccharide graft copolymer solution.

[0055] S103. Add gellan gum to the phenolic acid-soybean polysaccharide graft copolymer solution at 50°C - 80°C and stir for 20 - 40 min.

[0056] As can be seen from the above embodiments, at low temperatures, the polymer exists in a double helix structure in gellan gum. When the temperature rises, the segments will separate, and the polymer exists in a single-chain form. When the temperature drops again, the polymer will form a double helix structure again. Therefore, when preparing the agarose solution, in order to promote the uniform dispersion of gellan gum, it needs to be prepared at a relatively high temperature (50°C - 80°C) and continuously stirred for 20 - 40 min so that the gellan gum can be completely dispersed into the solution.

[0057] S104. Add glycerol to the solution at 50°C - 80°C and stir for 10 - 30 min.

[0058] Glycerol is added to the solution mixed with phenolic acid - soy polysaccharide graft copolymer and gellan gum, such that glycerol weakens the secondary bonds, i.e., van der Waals forces, between the polymers of phenolic acid - soy polysaccharide graft copolymer and gellan gum, thereby increasing the mobility of the polymer molecular chains, reducing the crystallinity of the polymer molecular chains, that is, increasing the plasticity of the polymer, manifested as a decrease in the hardness, modulus, softening temperature and embrittlement temperature of the polymer, while the elongation at break, flexibility and flexibility are improved. And because the molecular weight of glycerol is small and it has a certain hydrophilicity itself, it can further improve the dissolution performance of the edible film.

[0059] Since gellan gum will form a gel at a relatively low temperature, it is necessary to stir at a relatively high temperature, i.e., 50 - 80 °C, to avoid uneven diffusion after gel formation. Stir for 10 - 30 min to fully mix glycerol and the film - forming matrix.

[0060] S105. After ultrasonic defoaming treatment, an edible film is obtained by the casting film - making method.

[0061] Generally, there will be some bubbles in the solution prepared in the above steps. Part of them is brought by the raw materials themselves, and more are caused by air mixing during the batching process. Bubbles will cause defects in the edible film, such as apparent pits, missed coating, etc. Therefore, ultrasonic defoaming treatment is required before preparing the edible film.

[0062] Ultrasonic defoaming treatment can emit ultrasonic waves of a certain intensity. When the ultrasonic waves reach the solution, due to the action of the ultrasonic waves, the molecular substances in the foam in the solution also vibrate accordingly. The frequency of molecular vibration determines the speed of molecular vibration. The higher the frequency, the faster the speed. The energy obtained by the molecules due to vibration is related not only to the mass of the molecules but also to the speed of molecular vibration. Therefore, the higher the frequency of the ultrasonic waves, the higher the energy obtained by the molecules.

[0063] The mechanical energy of the ultrasonic waves causes the molecular substances to have a large acceleration. When the ultrasonic waves act on the liquid, the acceleration reached by the liquid particles may be more than a hundred thousand times greater than the gravitational acceleration. Such a huge acceleration will cause the liquid particles to move rapidly, causing the foam to break, that is, it can eliminate the foam in the solution.

[0064] The method of casting film - making is as follows: Weigh the film - forming solution, pour it onto the spreading board to fully spread, then place it flat and let it stand, or put it in an oven to dry into a film. The edible film produced by the casting film - making method has an orderly molecular arrangement and a fast cooling speed, which is beneficial to improving the transparency and gloss of the edible film, and the product texture is relatively soft, and its heat resistance and low - temperature adaptability are good.

[0065] As a feasible implementation method, please refer to Figure 6, before S105, the preparation method provided by the embodiments of the present application further includes:

[0066] S601. React for 40h - 50h under light - shielding conditions, and remove the residual reagents in the solution by centrifugation and dialysis.

[0067] Light will have a certain impact on the reaction of the reagents in the solution, and too short reaction time will lead to insufficient reaction. Therefore, before film - making, it is necessary to react for a relatively long time under light - shielding conditions to make the reagents react fully. Then, the residual reagents in the solution are removed by centrifugation and dialysis to avoid affecting subsequent film - forming.

[0068] It can be seen from the above embodiments that the edible film prepared by the preparation method provided by the embodiments of the present application has good barrier properties, mechanical properties, hydrophobicity and antioxidant properties. At the same time, the transparency and gloss of the prepared edible film are good.

[0069] Exemplarily, please refer to Figure 7 , the transparency and gloss of the edible film prepared by the embodiments of the present application are good.

[0070] In some embodiments, the preparation method provided by the embodiments of the present application can also prepare phenolic acid - soy polysaccharide graft copolymers.

[0071] As a feasible implementation manner, please refer to Figure 8 , before S101, the preparation method provided by the embodiments of the present application further includes:

[0072] S801. Weigh the following raw materials: soy polysaccharide, water, phenolic acid, ethanol solution, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide hydrochloride and N - hydroxysuccinimide.

[0073] Among them, 1 - ethyl - 3 - (3 - dimethylaminopropyl) carbodiimide hydrochloride (EDC) is a dehydrating agent with relatively high activity in the carbodiimide series. As the second - generation water - soluble condensing agent and coupling agent, it does not need to be carried out under anhydrous conditions, and the reagents do not need to be dried. It has the advantages of shorter reaction time, higher efficiency and easier operation. EDC is mainly used as a condensing agent and cross - linking agent for the synthesis of biological polysaccharides, polypeptides, proteins, nucleotides, polymer modification and organic synthesis, and its application in organic synthesis has received great attention.

[0074] EDC is used as a carboxyl - activating reagent in amide synthesis, and is also used for activating phosphate groups, cross - linking proteins and nucleic acids, and preparing immunoconjugates. The pH range for use is 4.0 - 6.0, and it is often used in combination with N - hydroxysuccinimide (NHS) to improve the coupling efficiency.

[0075] That is to say, EDC / NHS is selected as the coupling agent in the preparation process of phenolic acid - soy polysaccharide graft copolymers.

[0076] Please refer to Figure 9 , Figure 9 which shows the structural schematic diagram of ethanol. Ethanol is a very good solvent that can dissolve many inorganic substances as well as many organic substances. Therefore, ethanol is often used to dissolve plant pigments or their medicinal components, and is also commonly used as a reaction solvent to enable the organic and inorganic substances participating in the reaction to dissolve, increasing the contact area and enhancing the reaction rate. That is, ethanol is used as a reaction solvent in the preparation process of phenolic acid-soybean polysaccharide graft copolymer to improve the reaction rate between phenolic acid and soybean polysaccharide.

[0077] Since the grafting rate of the grafting reaction has a maximum value at a certain dosage of coupling agent or grafting monomer, in order to ensure the grafting rate of the grafting reaction, as a feasible implementation method, S401 can specifically be: Weigh the following raw materials in parts by mass: 1-3 parts of soybean polysaccharide, 90-110 parts of water, 1-4 parts of phenolic acid, 90-110 parts of ethanol solution, 1-4 parts of carbodiimide hydrochloride, and 1-4 parts of N-hydroxysuccinimide.

[0078] S802. Dissolve soybean polysaccharide in water at 40-60 °C, and store it refrigerated after dissolution to obtain a soybean polysaccharide solution.

[0079] The solubility of soybean polysaccharide increases with the increase of temperature. When the temperature rises to about 80 °C, the temperature will not continue to rise. Therefore, soybean polysaccharide needs to be dissolved at a relatively high temperature (40-60 °C). And during the grafting reaction, temperature will have a corresponding impact on the grafting rate. The grafting rate is relatively high within a certain temperature range. Therefore, the soybean polysaccharide solution needs to be stored refrigerated to keep it at a relatively low temperature.

[0080] S803. Under ice bath conditions, uniformly mix phenolic acid in the ethanol solution, and add carbodiimide hydrochloride and N-hydroxysuccinimide to the ethanol solution, and continuously stir for 1-3 h.

[0081] S804. Drop the soybean polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir.

[0082] Both light and temperature will affect the grafting rate of the grafting reaction. Therefore, in order to further improve the grafting rate, under light-shielded and refrigerated conditions, the soybean polysaccharide is dropped into the solution, so that the soybean polysaccharide and phenolic acid undergo a grafting reaction under the action of the coupling agent, enabling the hydroxyl group of phenolic acid to connect with the carboxyl group of soybean polysaccharide.

[0083] S805. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soybean polysaccharide graft copolymer.

[0084] After the grafting reaction, there may be some unreacted reagents in the solution. To avoid their impact on the subsequent process, centrifugation and dialysis were used to remove the residual reagents in the solution, followed by lyophilization to obtain the phenolic acid-soybean polysaccharide graft copolymer.

[0085] It can be seen that in the preparation method provided by the embodiments of the present application, the EDC / NHS condensation system is selected as the coupling agent in the preparation process of the graft copolymer, effectively avoiding the introduction of difficult-to-remove organic solvents and catalysts in the traditional method, and having a relatively high grafting rate. It can connect the hydroxyl group of phenolic acid with the carboxyl group of soybean polysaccharide, mutually improve the properties of phenolic acid and soybean polysaccharide, improve the properties of a single raw material, and obtain a more excellent film-forming material.

[0086] The embodiments of the present application also provide an edible film, and the components of the edible film include: gellan gum, glycerol, and phenolic acid-soybean polysaccharide graft copolymer.

[0087] It should be understood that the edible film can be prepared by the preparation method provided in the above embodiments, and the present application will not elaborate here.

[0088] As a feasible implementation method, the mass fraction of gellan gum in the edible film is 30 parts - 40 parts, the mass fraction of glycerol is 10 parts - 20 parts, and the mass fraction of phenolic acid-soybean polysaccharide graft copolymer is 40 parts - 60 parts.

[0089] The embodiments of the present application also provide an edible seasoning packet, which uses the edible film provided in the above embodiments as the packaging material.

[0090] Exemplarily, the prepared edible film can be used to package the powder, sealed with a heat sealer to make a 5×6 cm packaging bag, and the made powder packet is as Figure 10 shown.

[0091] To make the present application easier to understand, the following will combine specific examples to detail the effects of the edible film provided by the present application.

[0092] Example 1:

[0093] Dissolve 2 g of soy polysaccharide in water at 50 °C, and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, and sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir. React for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 4 g of phenolic acid-soy polysaccharide in 100 mL of water, then add 3 g of low-acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the membrane solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0094] Example 2:

[0095] Dissolve 4 g of soy polysaccharide in 100 mL of water, then add 3 g of low-acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the membrane solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0096] Example 3:

[0097] Dissolve 2 g of soy polysaccharide in water at 50 °C, and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, and sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir. React for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 2 g of phenolic acid-soy polysaccharide in 100 mL of water, then add 3 g of low-acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the membrane solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0098] Example 4:

[0099] Dissolve 2 g of soy polysaccharide in water at 50 °C, and store it in the refrigerator after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, and successively add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir. React for 48 h under light-shielded conditions. Remove the residual reagents in the solution by centrifugation and dialysis, and then perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 10 g of phenolic acid-soy polysaccharide in 100 mL of water, and then add 3 g of low-acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under a vacuum state.

[0100] Then, perform barrier property tests on the edible films prepared in Example 1, Example 2, Example 3, and Example 4. Among them, the barrier property tests include: testing the water vapor transmission rate of the film according to the gravimetric method at room temperature. Tightly cover the thin film sample on a centrifuge tube filled with pre-dried silica gel 3 mm from the tube mouth. After weighing, place it in a desiccator filled with saturated sodium chloride (RH = 75%) in a sealed state, and weigh it every 24 h for a total of one week. Calculate the water vapor transmission amount of the edible film through the following formula:

[0101]

[0102] where, WVP is the water vapor transmission amount of the specimen, with the unit of [g·mm / (m 2 ·Pa·d)]; d is the film thickness, with the unit of mm; Δm is the change in the mass of the centrifuge tube within the t time period, with the unit of g; A is the area of the specimen through which water vapor permeates, with the unit of m 2 ; t is the difference in the two interval times after the mass change stabilizes, with the unit of d; P is the water vapor pressure difference across the film, with the unit of Pa.

[0103] The water vapor transmission amount of the film prepared in Example 1 is 0.25×10 -9 g·mm / (m 2 ·Pa·d); the water vapor transmission amount of the film prepared in Example 2 is 1.56×10 -8 g·mm / (m 2 ·Pa·d); the water vapor transmission amount of the film prepared in Example 3 is 3.48×10 -9 g·mm / (m 2 ·Pa·d); the water vapor transmission amount of the film prepared in Example 4 is 8.69×10 -9 g·mm / (m 2·Pa·d).

[0104] It can be seen that when gellan gum is not added, the water vapor transmission rate of the prepared film is relatively high, that is, the barrier performance of the film is poor. When the ratio of gellan gum to phenolic acid-soybean polysaccharide is within a certain range, the water vapor transmission rate of the prepared film is relatively low, that is, the barrier performance is good. Therefore, for the edible film provided in the embodiments of the present application, the mass fraction of gellan gum is 30 parts - 40 parts, and the mass fraction of the phenolic acid-soybean polysaccharide graft copolymer is 40 parts - 60 parts.

[0105] Example 5:

[0106] Dissolve 2 g of soybean polysaccharide in water at 50 °C, and store it in the refrigerator after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, and sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soybean polysaccharide solution under light-shielding and refrigeration conditions, and continuously stir. React for 48 h under light-shielding conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soybean polysaccharide graft copolymer. Dissolve 10 g of phenolic acid-soybean polysaccharide in 100 mL of water, and then add 3 g of low acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under a vacuum state.

[0107] Example 6:

[0108] Dissolve 4 g of soybean polysaccharide in 100 mL of water, and then add 3 g of low acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under a vacuum state.

[0109] Example 7:

[0110] Dissolve 2 g of soy polysaccharide in water at 50 °C and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions and continuously stir, and react for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 2 g of phenolic acid-soy polysaccharide in 100 mL of water, then add 3 g of low acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0111] Example 8:

[0112] Dissolve 2 g of soy polysaccharide in water at 50 °C and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions and continuously stir, and react for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 10 g of phenolic acid-soy polysaccharide in 100 mL of water, then add 3 g of low acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then perform ultrasonic defoaming; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0113] Then, perform the DPPH radical scavenging rate test on the edible films prepared in Example 5, Example 6, Example 7, and Example 8 to test the antioxidant properties of the films.

[0114] Among them, the DPPH radical scavenging rate test of the film includes: fully mix 2 mL of the reconstituted supernatant of the film sample with 2.5 mL of a 0.1 mM DPPH-ethanol solution, place it in the dark at room temperature for 30 min, then centrifuge for 5 min (8000 rpm) to obtain the supernatant. At a wavelength of 517 nm, record the absorbance of the supernatant, measure it in three parallels, and calculate the DPPH radical scavenging ability of the sample as follows.

[0115]

[0116] Among them, As represents the absorbance of the sample, Ab represents the absorbance of the mixture of the sample and ultrapure water, and Ac represents the absorbance of the mixture of ultrapure water and the DPPH solution.

[0117] The DPPH radical scavenging rate of the film prepared in Example 5 was 82%; the DPPH radical scavenging rate of the film prepared in Example 6 was 42%; the DPPH radical scavenging rate of the film prepared in Example 7 was 63%; the DPPH radical scavenging rate of the film prepared in Example 8 was 86%.

[0118] It can be seen that when only soy polysaccharide and gellan gum are used as the main film-forming matrix, the DPPH radical scavenging rate of the obtained film is relatively low, that is, the antioxidant ability of the film is poor. While using a certain proportion of phenolic acid-soy polysaccharide and gellan gum as the main film-forming matrix, the obtained edible film has a relatively high antioxidant ability, that is, it has good antioxidant properties.

[0119] Example 9:

[0120] Dissolve 2 g of soy polysaccharide in water at 50 °C and store it in the refrigerator after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, and sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions and continuously stir, and react for 48 h under light-shielded conditions. Remove the residual reagents in the solution by centrifugation and dialysis, and perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 4 g of phenolic acid-soy polysaccharide in 100 mL of water, and then add 3 g of low-acyl gellan gum to the solution and stir to dissolve it at 50 °C - 80 °C; then add 1 g of glycerol to the solution and stir for 15 min at 50 °C - 80 °C; then ultrasonically defoam; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0121] Example 10:

[0122] Dissolve 2 g of soy polysaccharide in water at 50 °C, and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir. React for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and then perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 4 g of phenolic acid-soy polysaccharide in 100 mL of water, then add 1 g of glycerol to the solution, and stir at 50 °C - 80 °C for 15 min; then use ultrasonic waves to defoam; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0123] Example 11:

[0124] Dissolve 2 g of soy polysaccharide in water at 50 °C, and store it refrigerated after dissolution. Under an ice bath, uniformly mix 3 g of phenolic acids (such as gallic acid, cinnamic acid, ferulic acid, catechin, etc.) in an ethanol solution, sequentially add the same mass of EDC (1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), and continuously stir for 2 h. Dropwise add the soy polysaccharide solution under light-shielded and refrigerated conditions, and continuously stir. React for 48 h under light-shielded conditions. Use centrifugation and dialysis to remove the residual reagents in the solution, and then perform freeze-drying to obtain the phenolic acid-soy polysaccharide graft copolymer. Dissolve 4 g of phenolic acid-soy polysaccharide in 100 mL of water, and add 8 g of low acyl gellan gum to the solution and stir to dissolve at 50 °C - 80 °C; then add 1 g of glycerol to the solution, and stir at 50 °C - 80 °C for 15 min; then use ultrasonic waves to defoam; finally, cast the film solution onto a glass plate, dry it at room temperature, and store it under vacuum conditions.

[0125] Perform mechanical property tests on the edible films prepared in Example 9, Example 10, and Example 11. Among them, the mechanical property tests include: using a universal tensile testing machine to test the tensile strength (TS) and elongation at break (E) of the film. Before the test, cut the film into rectangular strips (10 mm × 50 mm), set the initial tensile strength to be 30 mm, and the tensile speed to be 20 mm / min, and record the tensile strength. Each film sample is subjected to 5 parallel tests, and the average value is taken.

[0126] The tensile strength of the film prepared in Example 9 is 15 MPa; the tensile strength of the film prepared in Example 10 is 6 MPa; the tensile strength of the film prepared in Example 11 is 10 MPa.

[0127] It can be seen that when gellan gum is not added, the tensile strength of the prepared edible film is low, that is, the mechanical properties are poor; while using a certain proportion of phenolic acid-soybean polysaccharide and gellan gum as the main film-forming matrix, the obtained edible film has a high tensile strength, that is, good mechanical properties.

[0128] As can be seen from the above examples, the edible film prepared by the preparation method provided by the embodiments of the present application has good barrier properties, antioxidant properties and mechanical properties, has a good effect when used for packaging food, can extend the shelf life of food, and is not easy to break at the same time.

[0129] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for preparing an edible film, characterized in that, The preparation method includes: Weigh the following raw materials: phenolic acid - soy polysaccharide graft copolymer, water, gellan gum, and glycerol; Dissolve the phenolic acid - soy polysaccharide graft copolymer in water to obtain a phenolic acid - soy polysaccharide graft copolymer solution; Add the gellan gum to the phenolic acid - soy polysaccharide graft copolymer solution at 50°C - 80°C and stir for 20 - 40 min; Add the glycerol to the solution at 50°C - 80°C and stir for 10 - 30 min; After performing ultrasonic defoaming treatment, obtain an edible film by the casting film - making method.

2. The preparation method according to claim 1, characterized in that, The weighing of the following raw materials: phenolic acid - soy polysaccharide graft copolymer, water, gellan gum, and glycerol is specifically as follows: Weigh the following raw materials in parts by mass: 2 - 8 parts of the phenolic acid - soy polysaccharide graft copolymer, 90 - 110 parts of water, 1 - 5 parts of gellan gum, and 0.5 - 1.5 parts of glycerol.

3. The preparation method according to claim 1, wherein Before the weighing of the following raw materials: phenolic acid - soy polysaccharide graft copolymer, water, gellan gum, and glycerol, the method further includes: Weigh the following raw materials: soy polysaccharide, water, phenolic acid, ethanol solution, carbodiimide hydrochloride, and N - hydroxysuccinimide; Dissolve the soy polysaccharide in water at 40 - 60°C, and store it refrigerated after dissolution to obtain a soy polysaccharide solution; Under ice - bath conditions, uniformly mix the phenolic acid in the ethanol solution, and add the carbodiimide hydrochloride and the N - hydroxysuccinimide to the ethanol solution, and continuously stir for 1 - 3 h; Drop - add the soy polysaccharide solution under light - avoiding and refrigerated conditions and continuously stir; Remove the residual reagents in the solution by centrifugation and dialysis, and perform freeze - drying to obtain the phenolic acid - soy polysaccharide graft copolymer.

4. The preparation method according to claim 3, characterized in that, The weighing of the following raw materials: soy polysaccharide, water, phenolic acid, ethanol solution, carbodiimide hydrochloride, and N - hydroxysuccinimide is specifically as follows: Weigh the following raw materials in parts by mass: 1 - 3 parts of the soy polysaccharide, 90 - 110 parts of water, 1 - 4 parts of the phenolic acid, 90 - 110 parts of the ethanol solution, 1 - 4 parts of the carbodiimide hydrochloride, and 1 - 4 parts of the N - hydroxysuccinimide.

5. The preparation method according to any one of claims 1-4, characterized in that, Before the ultrasonic defoaming treatment and then obtaining an edible film by the casting film - making method, the method further includes: React under light - avoiding conditions for 40 h - 50 h, and remove the residual reagents in the solution by centrifugation and dialysis.

6. The preparation method according to any one of claims 1 to 4, characterized in that The phenolic acid includes: gallic acid, cinnamic acid, ferulic acid, catechin.

7. The preparation method according to any one of claims 1-4, characterized in that, The gellan gum is low - acyl gellan gum.

8. An edible film, characterized in that, The components of the edible film include: gellan gum, glycerol, and phenolic acid - soy polysaccharide graft copolymer.

9. The edible film according to claim 8, wherein, The mass fraction of the gellan gum is 30 - 40 parts, the mass fraction of the glycerol is 10 - 20 parts, and the mass fraction of the phenolic acid - soy polysaccharide graft copolymer is 40 - 60 parts.

10. An edible seasoning packet, characterized in that, The edible seasoning packet uses the edible film as claimed in claim 8 or 9 as the packaging material.

Images