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: adding chitosan and vanillin into an acetic acid solution, and stirring for more than 10 hours to obtain a first mixed membrane solution; preparing a curdlan solution at the temperature of 50-70 DEG C; mixing the first mixed membrane solution and the curdlan solution according to a preset proportion; the preset proportion is as follows: the first mixed membrane solution accounts for 20%-40%, and the curdlan solution accounts for 40%-70%; adding glycerol accounting for 1%-5% of the total mass of the first mixed membrane solution and the curdlan solution, and stirring for 2-5 hours to obtain a second mixed membrane solution; and drying the second mixed film liquid to obtain the edible film. The edible film prepared by the preparation method provided by the embodiment of the invention not only can be eaten, but also has better oxidation resistance and mechanical properties.

Description

Technical Field

[0001] This 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 food.

[0003] In related technologies, it has been proposed to use edible materials such as natural edible biopolymer substances (such as proteins, lipids, sugars, etc.) to prepare edible films to reduce pollution to food 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] Embodiments of this application provide an edible film, a preparation method thereof, and an edible seasoning packet, which are used to prepare an edible film with good barrier properties, antioxidant properties, and mechanical properties.

[0005] In a first aspect, embodiments of this application provide a preparation method of an edible film. The preparation method includes: adding chitosan and vanillin into an acetic acid solution, stirring for more than 10 hours to obtain a first mixed film solution; preparing a curdlan solution at 50°C - 70°C; mixing the first mixed film solution and the curdlan solution according to a preset ratio; the preset ratio is: the first mixed film solution accounts for 20% - 40%, and the curdlan solution accounts for 40% - 70%; adding glycerol accounting for 1% - 5% of the total mass of the first mixed film solution and the curdlan solution, stirring for 2 hours - 5 hours to obtain a second mixed film solution; drying the second mixed film solution to obtain an edible film.

[0006] The edible film provided by the embodiments of this application uses vanillin as a cross-linking agent to carry out a cross-linking reaction with chitosan, which can further enhance the mechanical properties of chitosan. At the same time, curdlan is used as a film-forming matrix and glycerol is used as a plasticizer. The obtained edible film can not only be directly edible without causing pollution to the environment, but also has good barrier properties and mechanical strength, and can be used to directly package food.

[0007] Combined with the first implementation manner of the first aspect, adding chitosan and vanillin into the acetic acid solution specifically means: adding chitosan accounting for 1% - 5% of the mass of the acetic acid solution, and vanillin accounting for 10% - 25% of the mass of the acetic acid solution into the acetic acid solution.

[0008] Combined with the second implementation manner of the first aspect, the mass fraction of the acetic acid solution is 1%.

[0009] Combined with the third implementation manner of the first aspect, chitosan and vanillin are added to the acetic acid solution and stirred for more than 10 hours to obtain a first mixed membrane solution, specifically: chitosan and vanillin are added to the acetic acid solution and stirred for more than 10 hours; tea polyphenols are added to the acetic acid solution and stirred for 2 to 3 hours to obtain a first mixed membrane solution; the second mixed membrane solution is dried to obtain an edible film, including: the second mixed membrane solution is dried at a low temperature to obtain an edible film.

[0010] Combined with the fourth implementation manner of the first aspect, chitosan and vanillin are added to the acetic acid solution and stirred for more than 10 hours to obtain a first mixed membrane solution, specifically: 1% - 5% by mass of chitosan based on the mass of the acetic acid solution and 10% - 25% by mass of vanillin based on the mass of the acetic acid solution are added to the acetic acid solution and stirred for more than 10 hours, and the mass fraction of the acetic acid solution is 1%; 10% - 20% by mass of tea polyphenols are added and stirred for 2 to 3 hours to obtain a first mixed membrane solution; the second mixed membrane solution is dried to obtain an edible film, including: the second mixed membrane solution is dried at a low temperature to obtain an edible film.

[0011] Combined with the fifth implementation manner of the first aspect, a curdlan solution is prepared at 50°C - 70°C, specifically: a curdlan solution with a mass fraction of 5% - 10% is prepared at 50°C - 70°C.

[0012] Combined with the sixth implementation manner of the first aspect, the preset ratio is: the first mixed membrane solution accounts for 30% and the curdlan solution accounts for 70%.

[0013] In a second aspect, an embodiment of the present application provides an edible film, and the components of the edible film include: chitosan, vanillin, tea polyphenols, curdlan, and glycerol.

[0014] Combined with the first implementation manner of the second aspect, the mass parts of chitosan are 5 - 9 parts, the mass parts of vanillin are 20 - 35 parts, the mass parts of tea polyphenols are 20 - 35 parts, the mass parts of curdlan are 15 - 35 parts, and the mass parts of glycerol are 15 - 20 parts.

[0015] In a third aspect, an embodiment of the present application provides an edible seasoning packet, and the edible seasoning packet 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, which will not be elaborated here. Description of the Drawings

[0017] The accompanying drawings are used to provide a further understanding of the technical solution 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 solution of the present invention, and do not constitute a limitation to the technical solution of the present invention.

[0018] Figure 1 The method flow of a method for preparing an edible film provided in an embodiment of the present application Figure 1 ;

[0019] Figure 2 The schematic structural diagram of a chitosan provided in an embodiment of the present application;

[0020] Figure 3 The schematic structural diagram of a vanillin provided in an embodiment of the present application;

[0021] Figure 4 The method flow of a method for preparing an edible film provided in an embodiment of the present application Figure 2 ;

[0022] Figure 5 The method flow of a method for preparing an edible film provided in an embodiment of the present application Figure 3 ;

[0023] Figure 6 The schematic structural diagram of a catechin provided in an embodiment of the present application;

[0024] Figure 7 The method flow of a method for preparing an edible film provided in an embodiment of the present application Figure 4 ;

[0025] Figure 8 The method flow of a method for preparing an edible film provided in an embodiment of the present application Figure 5 ;

[0026] Figure 9 The schematic diagram of an edible film provided in an embodiment of the present application;

[0027] Figure 10 The schematic diagram of an edible seasoning packet provided in 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 construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, 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 examples, illustrations, or explanations. 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. Rather, the use of words such as "exemplary" or "for example" is intended to present relevant concepts in a specific manner.

[0031] With the increasing attention of people 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 causing pollution, and some packaging materials for chemical products also contain a small amount of toxic and harmful substances, which will cause certain pollution to food.

[0032] In related technologies, it has been proposed to use edible materials such as natural edible biopolymer substances (such as proteins, lipids, sugars, etc.) to prepare edible films to reduce pollution to food and the environment. However, the edible films in related technologies have problems of poor instant solubility and barrier performance. 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.

[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 chitosan, vanillin, and curdlan 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 antioxidant properties and mechanical properties, and can be used for directly packaging food.

[0034] Among them, chitosan, also known as deacetylated chitin, soluble chitin, polyglucosamine, has the chemical name of β-(1,4)-2-amino-2-deoxy-D-glucan, and is obtained by deacetylating chitin and removing the acetyl group on C2. Since there are many hydroxyl groups, amino groups, and some N-acetylamino groups distributed on its macromolecular chain, they will form intramolecular and intermolecular hydrogen bonds, thus forming a stable three-dimensional network structure during the film-forming process. The mechanical strength of the film prepared with chitosan can be almost comparable to that of polymeric materials.

[0035] Vanillin (3-methoxy-4-hydroxybenzaldehyde), also known as vanillin or vanillol, is an important component in vanilla. It not only contains an aldehyde group but also has a phenol structure, with 8 carbon atoms. These structural features indicate its strong antibacterial properties and can effectively inhibit the growth and reproduction of microorganisms. Moreover, the aldehyde of vanillin and the amino part of chitosan will form a Schiff base interaction, which can effectively enhance the mechanical properties of the chitosan film.

[0036] Curdlan, also known as heat gel and coagulating polysaccharide, is a water-insoluble glucan produced by microorganisms and composed of β-1,3-glycosidic bonds. It is a general term for a class of polysaccharides that can form both hard and elastic thermally irreversible gels and thermoreversible gels when their suspensions are heated. Curdlan has good fluidity and maintains extremely strong stability in the dry state. Curdlan has good film-forming properties. The prepared film can not only be directly edible but also has the advantages of being insoluble in water, biodegradable, and oxygen-impermeable. Therefore, it can be used as the main film-forming matrix of edible films.

[0037] Glycerol, as a plasticizer for edible films, can weaken the secondary bonds between polymers, namely van der Waals forces, thereby increasing the mobility of polymer molecular chains, reducing the crystallinity of 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, flexibility, and flexibility are improved. And because of the relatively small molecular weight of glycerol and its inherent hydrophilicity, it can further improve the dissolution properties of edible films.

[0038] 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 be used for packaging materials of 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.

[0039] Please refer to Figure 1 , Figure 1 which is a process flow chart of a method for preparing an edible film provided by the embodiments of the present application. As Figure 1 shown, the preparation method includes the following steps:

[0040] S101. Add chitosan and vanillin to an acetic acid solution and stir for more than 10 hours to obtain a first mixed film solution.

[0041] Chitosan is the only natural basic polysaccharide in nature, and its storage amount is second only to cellulose. Chitosan is derived from the natural polymer chitin. Its molecular structure contains many hydroxyl groups and amino groups, and it has excellent antibacterial properties, strong adsorption properties, strong moisture absorption and water retention properties, and can be spun and formed into films. In addition, chitosan also has excellent biodegradability, biocompatibility, biosafety, non-immunogenicity and bioadhesion. Therefore, it has wide application value in many industrial fields such as food packaging engineering, biomaterial development, papermaking, cosmetics, agriculture, environment and medicine, so that people's attention to chitosan is getting higher and higher, and the research is getting deeper and deeper.

[0042] Chitosan is a natural polymer with the characteristics of being safe, non-toxic, biodegradable, good biocompatibility and broad-spectrum antibacterial properties. Chitosan has good film-forming properties. However, pure chitosan films are brittle, have poor mechanical properties and water resistance, and are easily swollen in acidic media, thus limiting its application.

[0043] Please refer to Figure 2 , Figure 2 As shown in the structural schematic diagram of chitosan, the chitosan molecule contains hydroxyl groups and amino groups, and different groups can be introduced on the repeating units by chemical modification methods to improve the properties of chitosan. In a neutral medium, the amino groups on chitosan are very easy to react with aldehydes or ketones to form Schiff bases, thus generating aldehyde and ketone imine polysaccharides.

[0044] Therefore, the mechanical properties, water resistance, barrier properties, acid resistance and thermal stability of chitosan films can be improved through cross-linking reactions. Among them, the cross-linking reaction refers to the reaction in which two or more molecules (generally linear molecules) are bonded to each other to form a more stable network structure molecule (three-dimensional molecule). This reaction transforms linear or slightly branched macromolecules into a three-dimensional network structure, thereby improving properties such as strength, heat resistance, wear resistance, and solvent resistance, and can be used for foamed or non-foamed products.

[0045] Please refer to Figure 3 , Figure 3 As shown in the structural schematic diagram of vanillin. Vanillin contains an aldehyde group and is a selective natural cross-linking agent. It is a very attractive bio-based monomer with broad practical application prospects.

[0046] Therefore, in the preparation method provided by the embodiments of this application, chitosan and vanillin are added to an acetic acid solution and stirred for more than 10 hours, so that a cross-linking reaction occurs between chitosan and vanillin, further enhancing the mechanical properties of chitosan.

[0047] As a feasible implementation method, S101 can be specifically: adding chitosan accounting for 1%-5% of the mass of the acetic acid solution and vanillin accounting for 10%-25% of the mass of the acetic acid solution to the acetic acid solution.

[0048] Acetic acid is a saturated carboxylic acid containing two carbon atoms in its molecule and is an important oxygen-containing derivative of hydrocarbons. Its molecular formula is C2H4O2, the structural formula is CH3COOH, and HAC is an abbreviated form. The structural formula functional group is a carboxyl group, and the CAS number is 64-19-7. Since it is the main component of vinegar, it is also called acetic acid.

[0049] The acetic acid solution is a good solvent for chitosan. When the concentration of the acetic acid solution increases, the interaction between chitosan molecules and vanillin will increase, and the interaction between polymers will decrease. Therefore, as a feasible implementation method, the mass fraction of the acetic acid solution is 1%.

[0050] S102. A curdlan solution can be prepared at 50°C - 70°C.

[0051] Curdlan is a polysaccharide produced by soil bacteria through glucose fermentation. It has a unique form of forming a gel under heating conditions and is also called a thermogel. It is a water-insoluble glucan composed of α-1,3-glycosidic bonds. The gel strength of curdlan increases with the increase of the heating temperature until it is heated to 130°C, and its gel strength will still continue to increase.

[0052] It should be noted that curdlan can dissolve in alkaline aqueous solutions but not in water. Although curdlan is insoluble in water, it is easily dispersed in cold water and can form a more homogeneous dispersion through high-speed stirring treatment. That is to say, the curdlan solution in the embodiments of the present application can also be called an aqueous dispersion of curdlan.

[0053] Curdlan has the following properties:

[0054] Thermal reversibility: When the aqueous dispersion of curdlan is heated to 55°C - 65°C and then cooled to below 40°C, a thermally reversible low-level gel can be formed. When this low-level gel is heated to 60°C, it can return to the original aqueous dispersion state.

[0055] Thermal irreversibility: When the aqueous dispersion of curdlan is heated to about 80°C or above, a strong and thermally irreversible high-level gel can be formed.

[0056] Film-forming property: It has good film-forming properties. The prepared film can not only be directly edible but also has the advantages of being insoluble in water, biodegradable, and oxygen-impermeable.

[0057] Therefore, for the edible film provided by the embodiments of the present application, a curdlan solution is prepared at 50°C - 70°C, so that curdlan can form a uniform dispersion, which is convenient for subsequent preparation of the edible film.

[0058] It should be understood that the concentration of curdlan has a certain influence on the gel strength. As the concentration of curdlan increases, its gel strength increases. However, when the concentration of curdlan is too high, it cannot be evenly dispersed in water.

[0059] Therefore, as a feasible implementation method, please refer to Figure 4 , S102 can be specifically: S1021. Prepare a curdlan solution with a mass fraction of 5%-10% at 50°C - 70°C.

[0060] S103. Mix the first mixed membrane solution and the curdlan solution according to a preset ratio.

[0061] Among them, the preset ratio is: the first mixed membrane solution accounts for 20%-40%, and the curdlan solution accounts for 40%-70%.

[0062] As can be seen from the above embodiments, the addition of curdlan can improve the mechanical properties of the edible film, and at the same time can accelerate the dissolution of the edible film at high temperature, that is, improve the dissolution performance of the edible film; however, when the concentration of curdlan is too high, hydrogen bonds may be formed between curdlan and other film-forming substances, which will instead hinder the dissolution performance of the film. When the contents of chitosan and vanillin are low, the cross-linking between various substances is relatively tight, and the various properties of the film are improved; however, when the content of a certain substance is high, the viscosity of the membrane solution increases, the film formation is uneven, and there may be a stacking phenomenon, resulting in a downward trend in the barrier performance, mechanical properties, etc. of the film.

[0063] Therefore, the preset ratio in the embodiments of the present application is: the first mixed membrane solution accounts for 20%-40%, and the curdlan solution accounts for 40%-70%. In this way, it can be ensured that the prepared edible film is relatively uniform, and the mechanical properties and barrier properties are good.

[0064] Further, as a feasible implementation method, the preset ratio is: the first mixed membrane solution accounts for 30%, and the curdlan solution accounts for 70%.

[0065] S104. Add glycerol accounting for 1%-5% of the total mass of the first mixed membrane solution and the curdlan solution, and stir for 2 hours - 5 hours to obtain a second mixed membrane solution.

[0066] Glycerol is used as a plasticizer. It has a small molecular weight and has certain hydrophilicity itself. It can improve the dissolution performance of the edible film; however, when the content of glycerol is too high, it will weaken the interaction between film-forming substances, and instead will prolong the dissolution time. Therefore, glycerol accounting for 1%-5% of the total mass of the agarose solution, gellan gum solution and sodium carboxymethylcellulose solution can be directly added, so that glycerol can increase the mobility of polymer molecular chains, increase the plasticity of the polymer, and at the same time improve the dissolution performance of the edible film.

[0067] Stir for 2 to 5 hours after adding glycerol to fully mix glycerol with other film-forming matrices, obtaining the second mixed film solution.

[0068] S105. Dry the second mixed film solution to obtain an edible film.

[0069] After all the film-forming raw materials are evenly mixed, dry them to obtain an edible film.

[0070] It can be seen from S101 - S105 that for the edible film provided in the embodiment of the present application, through using vanillin as a cross-linking agent to carry out a cross-linking reaction with chitosan, the mechanical properties of chitosan can be further enhanced. At the same time, curdlan is used as a film-forming matrix and glycerol is used as a plasticizer. The obtained edible film can not only be directly edible without causing pollution to the environment, but also has good barrier properties and mechanical strength, and can be used for directly packaging food, such as being used as the packaging material for instant noodle seasoning packets, etc.

[0071] In some embodiments, as one of the most important components of food, oil is an indispensable substance in human nutrition. It can not only promote the digestion and absorption of vitamins, but also is an important source of polyunsaturated fatty acids in the human body. However, during the production and transportation stages, oils and their products will undergo oxidation and rancidity, resulting in a series of changes, manifested as the deterioration of sensory characteristics, the decline of nutritional value, the increase of health risks and economic losses. During the oxidation process of oil, hydroperoxides will continue to oxidize to produce secondary oxidation products, which are difficult to metabolize in the human body and will cause damage to the liver.

[0072] Therefore, when packaging foods containing oil, the packaging material is required to have certain barrier properties and antibacterial and antioxidant properties. In order to improve the antioxidant property of the edible film and extend the shelf life of the food packaged inside the edible film, it is necessary to further improve the barrier property of the edible film, that is, the antioxidant property.

[0073] As a feasible implementation method, please refer to Figure 5 , S101 may specifically include the following steps:

[0074] S501. Add chitosan and vanillin to an acetic acid solution and stir for more than 10 hours.

[0075] S502. Add tea polyphenols to the acetic acid solution and stir for 2 to 3 hours to obtain the first mixed film solution.

[0076] Among them, tea polyphenols (TP) are the general term for polyphenolic substances in tea leaves, which have strong antioxidant activity and antibacterial properties. At the same time, tea polyphenols contain multiple hydroxyl groups and have the ability to form stable hydrogen bonds with polymers, thereby changing the network structure of polymers. The antioxidant ability of TP is 2-20 times that of vitamin E (VE), vitamin A (VA), and BHA. The catechins in TP are mainly gallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC), and their molecular structures are as Figure 1 shown. The antioxidant active sites of TP are located in the B and C rings of catechins. The phenolic hydroxyl groups on the rings can provide hydrogen atoms to fatty free radicals to inactivate them, and can react with oxygen free radicals during the oxidation process to generate stable biphenolquinone and o-quinone substances, thereby terminating the chain reaction of free radicals. At the same time, TP has an elimination rate of more than 98% for superoxide anions and hydrogen peroxide free radicals, and shows an obvious dose-effect relationship. However, TP is easily deteriorated by light, high heat, and the surrounding environment.

[0077] Exemplarily, please refer to Figure 6 , Figure 6 which is a schematic structural diagram of the main catechins in tea polyphenols.

[0078] Tea polyphenols have strong antioxidant effects, especially the ester-type catechin EGCG, whose reducing ability can even reach 100 times that of L-ascorbic acid. Among the four main catechin compounds, the antioxidant ability is EGCG > EGC > ECG > EC > BHA, and the antioxidant performance increases with the increase of temperature. In addition to the antioxidant effect, tea polyphenols also have antibacterial effects, such as inhibiting Staphylococcus, Escherichia coli, Bacillus subtilis, etc. Tea polyphenols can adsorb the peculiar smell in food, so it has a certain deodorizing effect. It has a protective effect on the pigments in food. It can not only act as a natural pigment but also prevent food from fading. Tea polyphenols also have the effect of inhibiting the formation and accumulation of nitrite.

[0079] However, the hydroxyl groups in tea polyphenols are very active and are prone to oxidation, polymerization, condensation and other reactions under conditions such as light, high temperature, and alkalinity, thereby losing their antioxidant properties. Therefore, to solve this problem, microencapsulation technology can be used to encapsulate tea polyphenols, thereby changing the solubility, photosensitivity, and thermosensitivity of tea polyphenols, etc. In the embodiments of the present application, chitosan microcapsules are prepared using vanillin as a cross-linking agent to encapsulate tea polyphenols, which can improve the stability of tea polyphenols, effectively extend the oxidation of oils and fats, and inhibit the growth and reproduction of microorganisms.

[0080] In an appropriate range, increasing the content of tea polyphenols can improve the microencapsulation effect; however, when exceeding the appropriate range and continuing to increase the solid content, it will instead have a slightly negative effect on the microencapsulation effect. This is because appropriately increasing the total solid content is beneficial for the formation of the capsule wall and improving its compactness. At the same time, due to the increase in the viscosity of the system and the improvement of stability, the migration of tea polyphenols to the surface of chitosan is reduced, enabling better encapsulation of tea polyphenols. However, if the solid content is too high, the viscosity of the feed liquid will be too large, easily causing serious wall sticking and nozzle blockage phenomena.

[0081] Therefore, as a feasible implementation method, the mass of tea polyphenols added is 10%-20% of the mass of the acetic acid solution.

[0082] Please refer to Figure 7 , S105 can be specifically: low-temperature drying of the second mixed film solution to obtain an edible film.

[0083] Since tea polyphenols are prone to deterioration under high heat, after adding tea polyphenols to the acetic acid solution, when drying the second mixed film solution, low-temperature drying needs to be selected to avoid the deterioration of tea polyphenols under high heat, which may affect the antioxidant property of the edible film.

[0084] As another feasible implementation method, please refer to Figure 8 , S101 can be implemented as the following steps:

[0085] S801: Add chitosan accounting for 1%-5% of the mass of the acetic acid solution and vanillin accounting for 10%-25% of the mass of the acetic acid solution to the acetic acid solution, and stir for more than 10 hours.

[0086] Among them, the mass fraction of the acetic acid solution is 1%.

[0087] S802: Add tea polyphenols accounting for 10%-20% of the mass of the acetic acid solution and stir for 2-3 hours to obtain the first mixed film solution.

[0088] It can be understood that reducing the ratio of the core material to the wall material, that is, reducing the content of tea polyphenols and increasing the content of chitosan, will increase the film-forming speed of droplets during the drying process, increase the film thickness, and at the same time, tea polyphenols are more evenly dispersed in the chitosan solution, reducing the amount of tea polyphenols remaining on the surface of the capsule wall, so the encapsulation rate increases. However, if the core-wall ratio is too small, the content of tea polyphenols will be too low.

[0089] Therefore, in this embodiment, after adding chitosan accounting for 1%-5% of the mass of the acetic acid solution and vanillin accounting for 10%-25% of the mass of the acetic acid solution to the acetic acid solution and stirring for more than 10 hours, then add tea polyphenols accounting for 10%-20% of the mass of the acetic acid solution.

[0090] Please continue to refer to Figure 8, S105 may specifically be: performing low-temperature drying on the second mixed membrane solution to obtain an edible film.

[0091] Since tea polyphenols are prone to deterioration under high heat, after adding tea polyphenols to the acetic acid solution, when drying the second mixed membrane solution, low-temperature drying needs to be selected to avoid the deterioration of tea polyphenols under high heat, which affects the antioxidant property of the edible film.

[0092] The embodiment of the present application also provides an edible film, and the components of the edible film include: chitosan, vanillin, tea polyphenols, curdlan gum, and glycerol.

[0093] It should be understood that the edible film can be prepared by using the preparation method provided in the above embodiment, and the present application will not elaborate herein.

[0094] As a feasible implementation manner, the mass fraction of chitosan in the edible film is 5 parts - 9 parts, the mass fraction of vanillin is 20 parts - 35 parts, the mass fraction of tea polyphenols is 20 parts - 35 parts, the mass fraction of curdlan gum is 15 parts - 35 parts, and the mass fraction of glycerol is 15 parts - 20 parts.

[0095] Exemplarily, please refer to Figure 9 , Figure 9 is a schematic diagram of an edible film provided by an embodiment of the present application.

[0096] The embodiment of the present application also provides an edible seasoning packet, and the edible seasoning packet uses the edible film provided in the above embodiment as a packaging material.

[0097] Exemplarily, the prepared edible film can be used to package powder materials, sealed with a heat sealer to form a packaging bag of 5×6 cm, and the formed powder packet is as Figure 10 shown.

[0098] 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.

[0099] Example 1:

[0100] At room temperature, chitosan (3%) and vanillin (20%) are added to a 1% acetic acid solution, magnetically stirred for 18 h, 10% tea polyphenols are added, and stirring continues for 3 h. Impurities in the solution are removed in a vacuum state using a nylon filter. Curdlan gum (8%) is dissolved at 50°C - 70°C; the two solutions are mixed (the chitosan solution accounts for 30% and the curdlan gum solution accounts for 70%), 3% glycerol is added, stirred at 30°C for 3 h, spread on a glass plate, and then dried at room temperature, and stored under vacuum drying conditions after drying.

[0101] Example 2:

[0102] At room temperature, chitosan (3%) and vanillin (20%) were added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols were added and stirring continued for 3 h. Impurities in the solution were removed using a nylon filter under vacuum. Curdlan (8%) was dissolved at 50 °C - 70 °C; the two solutions were mixed (the chitosan solution accounted for 50% and the curdlan solution accounted for 50%), then 3% glycerol was added, and stirred at 30 °C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it was stored under vacuum drying conditions.

[0103] Example 3:

[0104] At room temperature, chitosan (3%) and vanillin (20%) were added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols were added and stirring continued for 3 h. Impurities in the solution were removed using a nylon filter under vacuum. Curdlan (8%) was dissolved at 50 °C - 70 °C; the two solutions were mixed (the chitosan solution accounted for 10% and the curdlan solution accounted for 90%), then 3% glycerol was added, and stirred at 30 °C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it was stored under vacuum drying conditions.

[0105] Example 4:

[0106] At room temperature, chitosan (3%) and vanillin (20%) were added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols were added and stirring continued for 3 h. Impurities in the solution were removed using a nylon filter under vacuum. Curdlan (8%) was dissolved at 50 °C - 70 °C; the two solutions were mixed (the chitosan solution accounted for 70% and the curdlan solution accounted for 30%), then 3% glycerol was added, and stirred at 30 °C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it was stored under vacuum drying conditions.

[0107] Then, mechanical property tests were carried out on the edible films prepared in the above examples. Among them, the mechanical property tests included: using a universal tensile machine to test the tensile strength (TS) and elongation at break (E) of the film. Before the test, the film was cut into rectangular strips (10 mm × 50 mm), the initial tensile strength was set to 30 mm, the tensile speed was 30 mm / min, and the tensile strength was recorded. Each film sample was subjected to 5 parallel tests and the average value was taken.

[0108] The tensile strength of the edible film prepared in Example 1 was 20 MPa; the tensile strength of the edible film prepared in Example 2 was 17 MPa; the tensile strength of the edible film prepared in Example 3 was 10 MPa; the tensile strength of the edible film prepared in Example 1 was 4 MPa.

[0109] It can be seen that when the ratio of the chitosan solution to the curdlan solution is within a certain range, the tensile strength of the prepared edible film is relatively high, that is, the mechanical properties are relatively good. Therefore, in the preparation method provided in the embodiments of the present application, the preset ratio includes: the chitosan solution accounts for 20%-40%, and the curdlan accounts for 40%-70%.

[0110] Example 5:

[0111] At room temperature, chitosan (3%) and vanillin (20%) are added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols are added and stirring is continued for 3 h. A nylon filter is used to remove impurities in the solution under vacuum. Curdlan (10%) is dissolved at 50°C - 70°C; the two solutions are mixed (the chitosan solution accounts for 30% and the curdlan solution accounts for 70%), then 3% glycerol is added, and stirred at 30°C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it is stored under vacuum drying conditions.

[0112] Example 6:

[0113] At room temperature, chitosan (3%) and vanillin (5%) are added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols are added and stirring is continued for 3 h. A nylon filter is used to remove impurities in the solution under vacuum. Curdlan (5%) is dissolved at 50°C - 70°C; the two solutions are mixed (the chitosan solution accounts for 30% and the curdlan solution accounts for 70%), then 3% glycerol is added, and stirred at 30°C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it is stored under vacuum drying conditions.

[0114] Example 7:

[0115] At room temperature, chitosan (3%) and vanillin (30%) are added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols are added and stirring is continued for 3 h. A nylon filter is used to remove impurities in the solution under vacuum. Curdlan (10%) is dissolved at 50°C - 70°C; the two solutions are mixed (the chitosan solution accounts for 30% and the curdlan solution accounts for 70%), then 3% glycerol is added, and stirred at 30°C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it is stored under vacuum drying conditions.

[0116] Then, the DPPH free radical scavenging rate of the edible films prepared in Example 5, Example 6 and Example 7 is tested to test the antioxidant properties of the films.

[0117] Among them, the test of the DPPH free radical scavenging rate of the film includes: mixing 2 mL of the supernatant of the reconstituted film sample with 2.5 mL of a 0.1 mM DPPH-ethanol solution thoroughly, placing it in the dark at room temperature for 30 min, and then centrifuging for 5 min (8000 rpm) to obtain the supernatant. At a wavelength of 517 nm, record the absorbance of the supernatant, measure it in triplicate, and calculate the DPPH free radical scavenging ability of the sample as follows.

[0118]

[0119] 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.

[0120] The DPPH free radical scavenging rate of the film prepared in Example 5 was 89%; the DPPH free radical scavenging rate of the film prepared in Example 6 was 65%; the DPPH free radical scavenging rate of the film prepared in Example 7 was 72%.

[0121] It can be seen that the content of vanillin can have a certain impact on the antioxidant properties of the edible film. Therefore, in the preparation method provided in the embodiments of the present application, adding 10%-25% of vanillin to the acetic acid solution can make the prepared edible film have good antioxidant properties.

[0122] Example 8:

[0123] At room temperature, add chitosan (3%) and vanillin (30%) to 1% acetic acid solution, stir magnetically for 18 h, add 25% tea polyphenols, and continue stirring for 3 h. Use a nylon filter to remove impurities in the solution under vacuum. Dissolve curdlan (10%) at 50°C - 70°C; mix the two solutions (the chitosan solution accounts for 30% and the curdlan solution accounts for 70%), add 3% glycerol, stir at 30°C for 3 h, spread it on a glass plate, and then dry it at room temperature. After drying, store it under vacuum drying conditions.

[0124] Example 9:

[0125] At room temperature, add chitosan (3%) and vanillin (20%) to 1% acetic acid solution, stir magnetically for 18 h, add 25% tea polyphenols, and continue stirring for 3 h. Use a nylon filter to remove impurities in the solution under vacuum. Dissolve curdlan (10%) at 50°C - 70°C; mix the two solutions (the chitosan solution accounts for 30% and the curdlan solution accounts for 70%), add 3% glycerol, stir at 30°C for 3 h, spread it on a glass plate, and then dry it at room temperature. After drying, store it under vacuum drying conditions.

[0126] Example 10:

[0127] At room temperature, chitosan (3%) and vanillin (20%) were added to a 1% acetic acid solution, and magnetically stirred for 18 h. Then 10% tea polyphenols were added and stirring was continued for 3 h. Impurities in the solution were removed under vacuum using a nylon filter. Curdlan (10%) was dissolved at 50 °C - 70 °C; the two solutions were mixed (the chitosan solution accounted for 30% and the curdlan solution accounted for 70%), then 3% glycerol was added, and stirred at 30 °C for 3 h, spread on a glass plate, and then dried at room temperature. After drying, it was stored under vacuum drying conditions.

[0128] Then, the DPPH free radical scavenging rate of the edible films prepared in Example 8, Example 9, and Example 10 was tested to test the antioxidant properties of the films. The DPPH free radical scavenging rate of the film prepared in Example 8 was 80%; the DPPH free radical scavenging rate of the film prepared in Example 9 was 75%; the DPPH free radical scavenging rate of the film prepared in Example 10 was 89%.

[0129] It can be seen from the above examples that when the contents of both vanillin and tea polyphenols are relatively high, the antioxidant property of the prepared edible film is not the best, while when the contents of vanillin and tea polyphenols are within a certain range, the antioxidant property of the prepared edible film is better.

[0130] Therefore, in the preparation method provided in the embodiments of the present application, the mass of vanillin accounts for 10% - 25% of the acetic acid solution, and the mass of tea polyphenols accounts for 10% - 20% of the acetic acid solution, which can ensure the antioxidant property of the edible film.

[0131] It can be seen from Examples 1 - 10 that the preparation method provided in the embodiments of the present application can prepare edible films with good mechanical properties and antioxidant properties, which can be used for packaging food and can prevent the oxidative rancidity of fats and oils in food, and extend the shelf life of food.

[0132] 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 comprises: adding chitosan and vanillin into the acetic acid solution and stirring for more than 10 hours to obtain a first mixed membrane solution; Prepare a curdlan solution at 50°C-70°C; The first mixed membrane liquid and the curdlan solution are mixed according to a preset ratio; the preset ratio is: the first mixed membrane liquid accounts for 20%-40%, and the curdlan solution accounts for 40%-70%; Adding glycerol accounting for 1% to 5% of the total mass of the first mixed membrane solution and the curdlan solution, stirring for 2 hours to 5 hours to obtain a second mixed membrane solution; The second mixed film liquid is dried to obtain an edible film.

2. The preparation method according to claim 1, characterized in that, The step of adding chitosan and vanillin to the acetic acid solution is specifically as follows: The chitosan accounting for 1%-5% of the mass of the acetic acid solution and the vanillin accounting for 10%-25% of the mass of the acetic acid solution are added into the acetic acid solution.

3. The preparation method according to claim 1, characterized in that, The mass fraction of the acetic acid solution is 1%.

4. The preparation method according to claim 1, characterized in that, The chitosan and vanillin are added to the acetic acid solution and stirred for more than 10 hours to obtain a first mixed membrane solution, which is specifically: Adding the chitosan and the vanillin into the acetic acid solution and stirring for more than 10 hours; adding tea polyphenols to the acetic acid solution and stirring for 2 hours to 3 hours to obtain the first mixed membrane solution; The step of drying the second mixed film liquid to obtain an edible film comprises: The second mixed film liquid is dried at low temperature to obtain the edible film.

5. The preparation method according to claim 1, characterized in that, The chitosan and vanillin are added to the acetic acid solution and stirred for more than 10 hours to obtain a first mixed membrane solution, which is specifically: Adding 1%-5% of the chitosan by mass of the acetic acid solution and 10%-25% of the vanillin by mass of the acetic acid solution to the acetic acid solution, stirring for more than 10 hours, wherein the mass fraction of the acetic acid solution is 1%; adding tea polyphenols accounting for 10% to 20% of the mass of the acetic acid solution, stirring for 2 hours to 3 hours, to obtain the first mixed membrane solution; The step of drying the second mixed film liquid to obtain an edible film comprises: The second mixed film liquid is dried at low temperature to obtain the edible film.

6. The preparation method according to claim 1, characterized in that, The curdlan solution is prepared at 50°C-70°C, specifically: The curdlan solution with a mass fraction of 5% to 10% is prepared at 50° C. to 70° C.

7. The preparation method according to claim 1, characterized in that, The preset ratio is: the first mixed membrane solution accounts for 30%, and the curdlan solution accounts for 70%.

8. An edible film, characterized in that, The components of the edible film include chitosan, vanillin, tea polyphenols, curdlan and glycerol.

9. The edible film according to claim 8, characterized in that, The mass fraction of the chitosan is 5-9 parts, the mass fraction of the vanillin is 20-35 parts, the mass fraction of the tea polyphenols is 20-35 parts, the mass fraction of the curdlan is 15-35 parts, and the mass fraction of the glycerol is 15-20 parts.

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

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