Supramolecular hydrogel covering film capable of reversibly adhering to frozen food as well as production method and application of supramolecular hydrogel covering film

Abstract

The invention discloses a supramolecular hydrogel coating film reversibly adhering to frozen food and a production method and application thereof, belongs to the technical field of food packaging materials, and provides a production method of the supramolecular hydrogel coating film reversibly adhering to frozen food. The preparation method comprises the following steps: mixing 2, 3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, and carrying out an ice bath reaction to obtain a carboxylation modified araboxylan solution; adding dopamine hydrochloride into the arabinoxylan, stirring, dialyzing and freeze-drying to obtain an arabinoxylan-dopamine graft; adding acrylic acid and metal ions into an ethanol water solution, mixing with the araboxylan-dopamine graft, stirring, mixing with N, N '-methylene bisacrylamide and ammonium persulfate, and polymerizing to obtain the supramolecular hydrogel covering film. The supramolecular hydrogel coating film has the characteristics of light-operated reversible adhesion, high mechanical strength and degradability, and is suitable for various frozen foods.

Description

Technical Field

[0001] The invention belongs to the technical field of food packaging materials, and in particular relates to a supramolecular hydrogel coating capable of reversibly adhering to frozen food, and a production method and application thereof. Background Art

[0002] In the modern food industry, frozen food is gradually favored by consumers because of its convenience, stable quality and long shelf life. However, during long-term low-temperature storage, the quality of frozen food will inevitably decline. Reasonable packaging can effectively extend the shelf life of food and reduce food loss. This also requires high requirements for packaging materials. Ideal frozen food packaging should have excellent barrier properties to reduce the impact of oxygen and water vapor on food quality, thereby alleviating the negative effects of ice recrystallization and freeze-burn effects. At the same time, frozen packaging materials should also have sufficient mechanical strength to avoid damage during transportation and storage. Although traditional frozen packaging materials can provide a certain degree of protection, these materials often have the disadvantages of easy adhesion to food and difficulty in monitoring food quality. These disadvantages limit the further development of frozen food. The new intelligent material, light-controlled reversible adhesion hydrogel coating, has the characteristics of high mechanical strength, strong barrier properties and degradability. It can change its own structure under the irradiation of light of a specific wavelength to achieve packaging desorption, so that consumers can easily open the packaging without residue. It also provides a new way to monitor food quality and safety.

[0003] The patent with publication number CN110734557A discloses "a method for preparing a pH and temperature dual-responsive cellulose-based hydrogel for food preservation", which uses carboxymethyl cellulose and N-vinyl caprolactam to react to prepare a hydrogel, and then loads the preservative on the hydrogel. However, the hydrogel prepared by this technology is not easy to separate from food and easily causes food contamination. The patent with publication number CN115160570A discloses "a method for preparing a polylipoic acid material with light-regulated adhesion properties", which prepares a lipoic acid monomer containing azophenyl through esterification reaction, and further copolymerizes to obtain a polylipoic acid material containing azophenyl. However, this technology has problems such as high production cost, complex process, and low efficiency. Summary of the invention

[0004] In order to solve the above technical problems, the present invention proposes a supramolecular hydrogel film with reversible adhesion to frozen food, and a production method and application thereof. The supramolecular hydrogel film produced by the present invention has the characteristics of light-controlled reversible adhesion, simple preparation process, high mechanical strength, strong barrier properties and degradability, and is suitable for various types of frozen foods.

[0005] To achieve the above object, the present invention provides a method for producing a supramolecular hydrogel coating capable of reversibly adhering to frozen food, comprising the following steps:

[0006] (1) mixing an arabinoxylan solution with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, and reacting in an ice bath to obtain a carboxylated arabinoxylan solution;

[0007] (2) adding dopamine hydrochloride to the carboxylated arabinoxylan solution obtained in step (1), stirring, dialyzing, and freeze-drying to obtain an arabinoxylan-dopamine graft;

[0008] (3) adding acrylic acid and metal ions to an ethanol aqueous solution to obtain a mixed system, mixing the mixed system with the arabinoxylan-dopamine graft obtained in step (2), and stirring for a second time to obtain a premixed system; mixing the premixed system with N,N'-methylenebisacrylamide and ammonium persulfate, and performing a polymerization reaction to obtain a supramolecular hydrogel coating.

[0009] Preferably, the arabinoxylan solution in step (1) is prepared by dissolving arabinoxylan in water, and the arabinoxylan is extracted from wheat bran.

[0010] Preferably, the mass concentration of the arabinoxylan solution in step (1) is 1% to 2%; the arabinoxylan solution in step (1) is mixed with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1 to 2.5:1 to 2.5.

[0011] Preferably, the temperature of the ice bath reaction in step (1) is 0° C., and the time of the ice bath reaction is 0.5 to 2 h.

[0012] Preferably, dopamine hydrochloride is added to the carboxylated modified arabinoxylan solution in step (2) to a mass concentration of 0.05% to 0.2%; the temperature of the first stirring in step (2) is 15 to 25°C, and the time of the first stirring in step (2) is 12 to 24 hours; the dialysis in step (2) is carried out in water, and the dialysis time is 72 hours; the freeze-drying temperature in step (2) is -80°C, and the freeze-drying time is 48 hours.

[0013] Preferably, the volume concentration of the ethanol aqueous solution in step (3) is 60% to 80%, acrylic acid is added to the ethanol aqueous solution in step (3) to a final mass concentration of 0.2% to 0.4%, and metal ions are added to a final mass concentration of 0.3% to 0.5%.

[0014] Preferably, the mass ratio of the mixed system in step (3) to the arabinoxylan-dopamine graft obtained in step (2) is 97-99:1-3; the temperature of the second stirring in step (3) is 40-60°C, the speed of the second stirring is 150-250rpm, and the time of the second stirring is 40-60min.

[0015] Preferably, the mass ratio of the premixed system, N,N'-methylenebisacrylamide and ammonium persulfate in step (3) is 99.3-99.75:0.2-0.5:0.05-0.2, the polymerization reaction temperature in step (3) is 70-90°C, and the polymerization reaction time is 30-60 min.

[0016] The invention also provides the supramolecular hydrogel coating prepared by the production method.

[0017] The invention also provides application of the supramolecular hydrogel coating prepared by the production method in frozen food packaging.

[0018] Compared with the prior art, the present invention has the following advantages and technical effects:

[0019] The present invention uses wheat bran as a raw material, extracts arabinoxylan (AX), performs carboxyl modification, and grafts dopamine to obtain modified AX; through metal ion coordination and acrylic acid crosslinking, light-controlled reversible adhesion of supramolecular hydrogel is achieved to prepare a supramolecular hydrogel coating specially used for frozen food. AX, which is rich in wheat bran, is a degradable polysaccharide with good application prospects, and has the advantages of large yield and low cost. AX has good surface adhesion after dopamine grafting, and can be tightly adsorbed on the surface of the target material through non-covalent action. The carboxyl group of the AX-dopamine graft can chelate and coordinate with metal ions, and a Fenton-like reaction will occur under ultraviolet light irradiation, thereby causing a change in the valence state of the metal ion, resulting in the breaking of the coordination bond, and then inducing supramolecular network reconstruction, so that the adhesion behavior of the hydrogel coating changes.

[0020] The present invention realizes light-controlled reversible adhesion through dopamine grafting, metal ion chelation and other methods, and is easier to separate from food. By grafting carboxylated AX with dopamine, utilizing metal ion chelation coordination and acrylic acid oxidation cross-linking, the mechanical strength and barrier properties of the hydrogel in a low temperature environment are improved; through the coordination of metal ions, the change of the valence state of metal ions and the dissociation of coordination compounds are induced under ultraviolet light irradiation, thereby realizing the reconstruction of the supramolecular network and light-regulated desorption. DETAILED DESCRIPTION

[0021] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but should be understood as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0022] It should be understood that the terms described in the present invention are only for describing special embodiments and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. Each smaller range between the intermediate value in any stated value or stated range and any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0023] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0024] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to the skilled artisan. The present invention description and examples are exemplary only.

[0025] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0026] Example 1

[0027] Wheat bran is subjected to conventional methods such as de-starch, alkali extraction, deproteinization, enzyme treatment, dialysis and alcohol precipitation to obtain arabinoxylan.

[0028] (1) Arabinoxylan is dissolved in water to prepare an arabinoxylan solution with a mass concentration of 2%, the arabinoxylan solution is mixed with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1.5:1.5, and reacted in an ice bath at 0°C for 0.5h to obtain a carboxylated arabinoxylan solution;

[0029] (2) adding dopamine hydrochloride to the carboxylated arabinoxylan solution to a mass concentration of 0.1%, stirring at 20° C. for 24 h, dialyzing in water for 72 h, and freeze-drying at -80° C. for 48 h to obtain arabinoxylan-dopamine grafted product;

[0030] (3) Acrylic acid and metal ions are added to an ethanol aqueous solution with a volume concentration of 60%, and acrylic acid is added to a final mass concentration of 0.4%, and metal ions are added to a final mass concentration of 0.4% to obtain a mixed system. The mixed system is mixed with arabinoxylan-dopamine grafted material in a mass ratio of 98:2, and a second stirring is performed at 50°C and 200 rpm for 50 minutes to obtain a premixed system; the premixed system is mixed with N,N'-methylenebisacrylamide and ammonium persulfate in a mass ratio of 99.55:0.3:0.15, and a polymerization reaction is carried out at 80°C for 50 minutes to obtain a supramolecular hydrogel coating.

[0031] The adhesion strength of the hydrogel coating was measured using a micro tensile tester equipped with a fixture. Before testing, all samples were cut into rectangular strips (50×15 mm) and attached to the substrate to ensure that there were no bubbles or impurities. The sample was fixed on the fixture of the micro tensile tester, the test speed was set to 100 mm / min, and the test was repeated 5 times.

[0032] The tensile strength of the hydrogel film was measured using an automatic tensile texture analyzer equipped with a tensile fixture. All samples were cut into rectangular strips (50×15 mm) before testing. The test speed was 1 mm / s, the initial distance was 40 mm, the test was repeated 5 times, and the thickness of the film was measured by a vernier caliper, and the average value was taken from 6 random measurements.

[0033] The prepared supramolecular hydrogel film has an adhesion strength of more than 500 kPa and a tensile strength of 54.74 kPa, and desorption can be achieved under ultraviolet irradiation at a wavelength of 365 nm for 180 s.

[0034] Example 2

[0035] Wheat bran is subjected to de-starch, alkali extraction, deproteinization, enzyme treatment, dialysis and alcohol precipitation according to a known method to obtain arabinoxylan.

[0036] (1) Arabinoxylan is dissolved in water to prepare an arabinoxylan solution with a mass concentration of 2%, the arabinoxylan solution is mixed with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1:1, and reacted in an ice bath at 0°C for 0.5h to obtain a carboxylated arabinoxylan solution;

[0037] (2) adding dopamine hydrochloride to the carboxylated arabinoxylan solution to a mass concentration of 0.05%, stirring at 20° C. for 24 h, dialyzing in water for 72 h, and freeze-drying at -80° C. for 48 h to obtain arabinoxylan-dopamine grafted product;

[0038] (3) Acrylic acid and metal ions are added to an ethanol aqueous solution with a volume concentration of 70%, and acrylic acid is added to a final mass concentration of 0.2%, and metal ions are added to a final mass concentration of 0.3% to obtain a mixed system. The mixed system is mixed with arabinoxylan-dopamine grafted material at a mass ratio of 99:1, and the mixture is stirred for a second time at 50°C and 200 rpm for 50 minutes to obtain a premixed system; the premixed system is mixed with N,N'-methylenebisacrylamide and ammonium persulfate in a mass ratio of 99.75:0.2:0.05, and the mixture is polymerized at 80°C for 50 minutes to obtain a supramolecular hydrogel coating.

[0039] The adhesion strength of the hydrogel coating was measured using a micro tensile tester equipped with a fixture. Before testing, all samples were cut into rectangular strips (50×15 mm) and attached to the substrate to ensure that there were no bubbles or impurities. The sample was fixed on the fixture of the micro tensile tester, the test speed was set to 100 mm / min, and the test was repeated 5 times.

[0040] The tensile strength of the hydrogel film was measured using an automatic tensile texture analyzer equipped with a tensile fixture. All samples were cut into rectangular strips (50×15 mm) before testing. The test speed was 1 mm / s, the initial distance was 40 mm, the test was repeated 5 times, and the thickness of the film was measured by a vernier caliper, and the average value was taken from 6 random measurements.

[0041] The prepared supramolecular hydrogel film has an adhesion strength of over 430 kPa and a tensile strength of 47.33 kPa, and can be desorbed by irradiation with ultraviolet light at a wavelength of 365 nm for 210 s.

[0042] Example 3

[0043] Wheat bran is subjected to de-starch, alkali extraction, deproteinization, enzyme treatment, dialysis and alcohol precipitation according to a known method to obtain arabinoxylan.

[0044] (1) Arabinoxylan was dissolved in water to prepare an arabinoxylan solution with a mass concentration of 2%, and the arabinoxylan solution was mixed with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:2.5:2.5, and reacted in an ice bath at 0°C for 0.5h to obtain a carboxylated arabinoxylan solution;

[0045] (2) adding dopamine hydrochloride to the carboxylated arabinoxylan solution to a mass concentration of 0.2%, stirring at 20° C. for 24 h, dialyzing in water for 72 h, and freeze-drying at -80° C. for 48 h to obtain arabinoxylan-dopamine grafted product;

[0046] (3) Acrylic acid and metal ions are added to an ethanol aqueous solution with a volume concentration of 80%, and acrylic acid is added to a final mass concentration of 0.4%, and metal ions are added to a final mass concentration of 0.5% to obtain a mixed system. The mixed system is mixed with arabinoxylan-dopamine grafted material in a mass ratio of 97:3, and a second stirring is performed at 50°C and 200 rpm for 50 minutes to obtain a premixed system; the premixed system is mixed with N,N'-methylenebisacrylamide and ammonium persulfate in a mass ratio of 99.3:0.5:0.2, and a polymerization reaction is carried out at 80°C for 50 minutes to obtain a supramolecular hydrogel coating.

[0047] The adhesion strength of the hydrogel coating was measured using a micro tensile tester equipped with a fixture. Before testing, all samples were cut into rectangular strips (50×15 mm) and attached to the substrate to ensure that there were no bubbles or impurities. The sample was fixed on the fixture of the micro tensile tester, the test speed was set to 100 mm / min, and the test was repeated 5 times.

[0048] The tensile strength of the hydrogel film was measured using an automatic tensile texture analyzer equipped with a tensile fixture. All samples were cut into rectangular strips (50×15 mm) before testing. The test speed was 1 mm / s, the initial distance was 40 mm, the test was repeated 5 times, and the thickness of the film was measured by a vernier caliper, and the average value was taken from 6 random measurements.

[0049] The prepared supramolecular hydrogel film has an adhesion strength of over 470 kPa and a tensile strength of 51.29 kPa, and can be desorbed by irradiation with ultraviolet light at a wavelength of 365 nm for 195 s.

[0050] The embodiments described above are only descriptions of the preferred modes of the present invention, and are not intended to limit the scope of the present invention. Without departing from the design spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should all fall within the protection scope determined by the claims of the present invention.

Claims

1. A method for producing a supramolecular hydrogel coating capable of reversibly adhering to frozen food, characterized in that: The following steps are involved: (1) mixing an arabinoxylan solution with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide, and reacting in an ice bath to obtain a carboxylated arabinoxylan solution; (2) adding dopamine hydrochloride to the carboxylated arabinoxylan solution obtained in step (1), stirring, dialyzing, and freeze-drying to obtain an arabinoxylan-dopamine graft; (3) adding acrylic acid and metal ions to an ethanol aqueous solution to obtain a mixed system, mixing the mixed system with the arabinoxylan-dopamine graft obtained in step (2), and stirring for a second time to obtain a premixed system; mixing the premixed system with N,N'-methylenebisacrylamide and ammonium persulfate, and performing a polymerization reaction to obtain a supramolecular hydrogel coating.

2. The production method according to claim 1, characterized in that: The arabinoxylan solution in step (1) is prepared by dissolving arabinoxylan in water, and the arabinoxylan is extracted from wheat bran.

3. The production method according to claim 1, characterized in that: The mass concentration of the arabinoxylan solution in step (1) is 1% to 2%; the arabinoxylan solution in step (1) is mixed with 1,3-dimethylaminopropyl-3-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide in a molar ratio of 1:1 to 2.5:1 to 2.

5.

4. The production method according to claim 1, characterized in that: The temperature of the ice bath reaction in step (1) is 0° C., and the time of the ice bath reaction is 0.5 to 2 h.

5. The production method according to claim 1, characterized in that: In step (2), dopamine hydrochloride is added to the carboxylated modified arabinoxylan solution to a mass concentration of 0.05% to 0.2%; in step (2), the first stirring temperature is 15 to 25° C., and the first stirring time is 12 to 24 hours; in step (2), the dialysis is performed in water, and the dialysis time is 72 hours; in step (2), the freeze-drying temperature is -80° C., and the freeze-drying time is 48 hours.

6. The production method according to claim 1, characterized in that: The volume concentration of the ethanol aqueous solution in step (3) is 60% to 80%. Acrylic acid is added to the ethanol aqueous solution in step (3) to a final mass concentration of 0.2% to 0.4%, and metal ions are added to a final mass concentration of 0.3% to 0.5%.

7. The production method according to claim 1, characterized in that: The mass ratio of the mixed system in step (3) to the arabinoxylan-dopamine graft obtained in step (2) is 97-99:1-3; the temperature of the second stirring in step (3) is 40-60°C, the speed of the second stirring is 150-250rpm, and the time of the second stirring is 40-60min.

8. The production method according to claim 1, characterized in that: The mass ratio of the premixed system, N,N'-methylenebisacrylamide and ammonium persulfate in step (3) is 99.3-99.75:0.2-0.5:0.05-0.2, the polymerization reaction temperature in step (3) is 70-90°C, and the polymerization reaction time is 30-60min.

9. The supramolecular hydrogel film prepared by the production method according to any one of claims 1 to 8.

10. Use of the supramolecular hydrogel film prepared by the production method according to any one of claims 1 to 8 in frozen food packaging.