Nano-micelle-containing composite film for food as well as preparation method and application of nano-micelle-containing composite film

Abstract

The invention is applicable to the technical field of food fresh-keeping materials, and provides a nano-micelle-containing composite film for food and a preparation method and application thereof.The nano-micelle-containing composite film comprises a film substrate, nano-micelles and a plasticizer, the addition amount of the nano-micelles is 1-10% of the addition amount of the film substrate, and the addition amount of the plasticizer is 20-60% of the addition amount of the film substrate; the nano-micelle comprises chitosan, an anti-inflammatory drug, 3-carboxyphenylboronic acid and antioxidant enzyme, and the anti-inflammatory drug is curcumin or luteolin. According to the embodiment of the invention, the nano-micelle is used as a carrier to carry the anti-inflammatory drug and the antioxidant enzyme, the nano-micelle can reduce the cytotoxicity of the anti-inflammatory drug and improve the availability of the antioxidant enzyme, and meanwhile, the nano-micelle can form a more compact and stable structure in the chitosan-based film due to the hydrogen-bond interaction, so that the anti-inflammatory drug is more stable. The composite film is endowed with stronger mechanical properties and thermal stability, so that the composite film can be better applied to food preservation, and oxidation and spoilage of food can be inhibited.

Description

Technical Field

[0001] The present invention belongs to the technical field of food preservation materials, and in particular relates to a food composite film containing nano-micelles, and a preparation method and application thereof. Background Art

[0002] Food spoilage occurs when multiple nutrients and enzymes interact in food, leading to a variety of degradative chemical changes that deteriorate its quality and shelf life. This phenomenon primarily occurs due to lipid oxidation, which triggers fatty acid degradation, producing harmful substances such as aldehydes and ketones, and enzymatic browning, which causes color loss in fruits and vegetables, leading to loss of commercial value. Therefore, preventing these problems during food processing, transportation, and storage has become a major research challenge.

[0003] Traditional preservation technologies rely on chemical preservatives and non-environmentally friendly materials such as polypropylene (PP), polyester (PET), polyethylene (PE) and polystyrene (PS). However, these materials may cause serious environmental pollution. With the increasing consumption of non-renewable resources, new environmentally friendly food packaging materials will inevitably replace traditional packaging. In addition, traditional packaging materials are limited to protecting packaged food from external influences and can no longer meet the requirements of food preservation and antiseptic functions, increasing food shelf life, etc. in existing technologies. Summary of the Invention

[0004] The purpose of the embodiments of the present invention is to provide a composite film for food containing nano-micelles, aiming to solve the problems raised in the above background technology.

[0005] The present invention is achieved by providing a composite food film containing nanomicelles, comprising a film matrix, nanomicelles, and a plasticizer, wherein the amount of the nanomicelles added is 1-10% of the amount of the film matrix added, more preferably 5%, 10%, or 15%, and the amount of the plasticizer added is 20-60% of the amount of the film matrix added, more preferably 40%, 45%, or 50%; The nanomicelles include chitosan, an anti-inflammatory drug, 3-carboxyphenylboronic acid and an antioxidant enzyme. The anti-inflammatory drug is curcumin (Cur) or luteolin (Lut), more preferably luteolin.

[0006] Preferably, the method for preparing the nanomicelles comprises the following steps: Chitosan (CS) and 3-carboxyphenylboronic acid (PBA) were dissolved in dimethyl sulfoxide (DMSO), and CS-PBA (CP) was obtained through amide bond reaction, dialyzed, and freeze-dried. CS-PBA and anti-inflammatory drugs are mixed and loaded with anti-inflammatory drugs through boronate bonds to form a hydrophilic and hydrophobic polymer carrier; During the self-assembly process of the hydrophilic and hydrophobic polymer carrier in water, antioxidant enzymes are added and encapsulated into the carrier through electrostatic adsorption. Nanomicelles are obtained through dialysis and freeze-drying.

[0007] Preferably, the molar ratio of the amino group of the chitosan to 3-carboxyphenylboronic acid is 1 to 6:1; more preferably 4:1 or 6:1; The mass ratio of CS-PBA to anti-inflammatory drug is 1 to 4:1; more preferably 3:1, 2:1 or 4:3; The mass ratio of the hydrophilic and hydrophobic polymer carrier to the antioxidant enzyme is 1:0.05-0.4; more preferably 1:0.1 or 1:0.2.

[0008] Preferably, the molecular weight of the chitosan is 2000-10000 Da; more preferably 3000-6000 Da or 10000 Da.

[0009] Preferably, the antioxidant enzyme is catalase (CAT) or superoxide dismutase (SOD); more preferably, superoxide dismutase.

[0010] Preferably, the film matrix is ​​chitosan or whey protein; more preferably chitosan.

[0011] Preferably, the plasticizer is glycerol or sorbitol; more preferably glycerol.

[0012] Another object of an embodiment of the present invention is to provide a method for preparing a composite film for food containing nanomicelles, comprising the following steps: adding the nanomicelles to a film matrix, thoroughly mixing in a magnetic stirrer, adding a plasticizer after mixing and removing bubbles in ultrasound, then pouring into a film mold, and drying to obtain the composite film.

[0013] Preferably, in the step of fully mixing in a magnetic stirrer, the mixing time of the magnetic stirrer is 10 to 40 minutes, more preferably 20 minutes; in the step of adding a plasticizer after mixing and removing bubbles in ultrasound, the working time of ultrasound is 20 to 60 minutes, more preferably 40 minutes; the drying temperature is 30 to 80°C, more preferably 40°C for 24 hours.

[0014] Another object of an embodiment of the present invention is to provide a use of a food composite film containing nanomicelles in inhibiting food oxidation and spoilage.

[0015] The present invention provides a composite food film containing nanomicelles. Nanomicelles are introduced into the composite film, wherein the amino groups of CS and the carboxyl groups of PBA react via an amide bond to form a CP. The boronic acid groups on the PBA in the CP then react with anti-inflammatory drugs (e.g., the 1,2-diol structure on luteolin) to form boronate ester bonds, thereby forming a hydrophilic and hydrophobic polymer carrier that can self-assemble into nanomicelles in an aqueous solution. During the self-assembly process, antioxidant enzymes are added and encapsulated into the nanomicelles via electrostatic adsorption. The product is finally obtained by dialysis and freeze-drying. In the embodiment of the present invention, nano-micelles are used as carriers to carry anti-inflammatory drugs and antioxidant enzymes. Nano-micelles can reduce the cytotoxicity of anti-inflammatory drugs and improve the utilization of antioxidant enzymes. By adding nano-micelles, the inherent limitations of ordinary films can be improved, and the composite film can be given antioxidant and antibacterial capabilities. At the same time, nano-micelles can form a denser and more stable structure in the chitosan-based film due to hydrogen bonding, giving the composite film stronger mechanical properties and thermal stability, making it better for use in food preservation and inhibiting food oxidation and spoilage. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a scanning electron microscope image of the CS-PBA-Lut / SOD nanomicelles prepared in Example 5 of the present invention; Figure 2 This is a scanning electron microscope image of the composite film prepared in Example 27 of the present invention; Figure 3 The cytotoxicity test results of the membrane-forming solution prepared in Example 27 of the present invention are as follows; Figure 4 The antioxidant test results of the composite film prepared in Example 27 of the present invention are as follows; Figure 5 The antibacterial test results of the composite film prepared in Example 27 of the present invention are shown; Figure 6 These are the food preservation test results of the composite film prepared in Example 27 of the present invention. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0018] The specific implementation of the present invention is described in detail below with reference to specific embodiments.

[0019] Example 1-24, a nanomicelle, the preparation method of which comprises the following steps: CS and PBA were dissolved in DMSO and stirred for 24 hours, then dialyzed in deionized water and freeze-dried to obtain a powdered product, CS-PBA. CS-PBA and Lut were reacted in DMSO for 12 hours to form a hydrophilic and hydrophobic polymer carrier. SOD was added during the self-assembly of the hydrophilic and hydrophobic polymer carrier in water and reacted for 12 hours to bind the negatively charged SOD to the positively charged polymer carrier. The product was then dialyzed in deionized water and freeze-dried to construct the nanomicelle CS-PBA-Lut / SOD. In Examples 1-24, the molecular weight of CS, the molar ratio of CS to PBA, the mass ratio of CS-PBA to Lut, and the mass ratio of the hydrophilic and hydrophobic polymer carrier to SOD are shown in Table 1: Table 1

[0020] The CS-PBA-Lut / SOD nanomicelles prepared in Example 5 were analyzed using a scanning electron microscope, and the scanning electron microscope images were as follows: Figure 1 As shown, it can be seen that the nanomicelles prepared in Example 5 present a uniform monodisperse spherical morphology with an average particle size of 150 nm.

[0021] Examples 25-33. A composite film for food containing nanomicelles, the preparation method comprising the following steps: incorporating the nanomicelles prepared in Example 5 into a chitosan matrix, thoroughly mixing the mixture in a magnetic stirrer, adding glycerol after mixing, and removing bubbles by ultrasound to obtain a film-forming solution; finally, pouring the film-forming solution into a film mold and drying the mixture to obtain a composite film; In Examples 25-33, the amount of nanomicelles added and the amount of glycerol added are shown in Table 2: Table 2

[0022] The composite film prepared in Example 27 was analyzed using a scanning electron microscope, and the scanning electron microscope image was obtained as shown in FIG. Figure 2 As shown, it can be seen that the surface of the composite membrane prepared in Example 27 is relatively smooth and flat.

[0023] Comparative Example 1: A pure chitosan film, the preparation method of which is different from that of Example 27 except that no nanomicelles are added.

[0024] Performance Analysis: 1. Cytotoxicity analysis of film-forming solution: Cell culture: RAW264.7 cell line (from the Department of Biochemistry, School of Basic Medical Sciences, Jilin University) was cultured in DMEM medium supplemented with 10% fetal bovine serum in an incubator with 5% CO2 at 37°C. Cytotoxicity experiment: RAW264.7 cells were seeded into a 96-well plate at 5000 cells per well and cultured overnight. The membrane-forming solution prepared in Example 27 was prepared at different concentrations and co-cultured with the cells for 24 hours. The culture medium was removed, and 200 μL of normal culture medium containing MTT (0.5 mg / mL) was added to each well and incubated for a further 4 hours. After removing the culture medium, 150 μL of DMSO was added to each well. The absorbance of each well was measured at 492 nm using a microplate reader, and the cell viability was calculated. The calculation formula for the cell viability was: Cell viability (%) = (A sample / A blank) × 100; The experimental results are as follows Figure 3 As shown, it can be seen that the membrane-forming solution prepared in the embodiment of the present invention exhibits a cell growth-promoting effect at a low concentration. At a concentration of 1 mg / mL, the cell survival rate exceeds 80%.

[0025] 2. Effect of composite membrane on scavenging DPPH free radicals: The composite film prepared in Example 27 and the pure chitosan film prepared in Comparative Example 1 were dissolved in 1% acetic acid solution to prepare sample solutions. 500 μL of the sample solution was mixed with 500 μL of a 1 mM DPPH solution and reacted at room temperature in the dark for 30 min. The absorbance was measured at 517 nm using an ultraviolet spectrophotometer and the DPPH free radical inhibition rate was calculated. The calculation formula for the DPPH free radical inhibition rate is: DPPH free radical inhibition rate (%) = (1-A sample / A blank) × 100; The experimental results are as follows Figure 4 As shown, it can be seen that the composite film prepared in the embodiment of the present invention has excellent free radical scavenging ability compared with the pure chitosan film.

[0026] 3. Composite membrane for Escherichia coli ( E. coli ), Staphylococcus aureus ( S. aureus ) and Bacillus subtilis ( B. subtilis ) (from the Department of Biochemistry, School of Basic Medical Sciences, Jilin University) Inhibitory Effect: Colony culture: The selected bacterial strain was streaked onto LB solid medium and cultured at 37°C for 14 h. Subsequently, a single colony was inoculated into LB liquid medium and cultured at 37°C with shaking until the logarithmic growth phase. Finally, the bacteria in the logarithmic growth phase were transferred to fresh LB liquid medium and cultured at 37°C with shaking until the OD 600 The value reaches 1 (i.e. 2×10 9 CFU / mL); Antibacterial experiment: dilute the bacterial solution to 1×10 8 CFU / mL of bacterial suspension; then, the composite film solution prepared in Example 27 (1 mg / mL) and the pure chitosan film solution prepared in Comparative Example 1 (1 mg / mL) were added in a ratio of 1:1, and incubated at 37 ° C for 12 h; after centrifugation of the bacterial incubation solution, it was stained with SYTO 9 and propidium iodide (PI) stain at 37 ° C in the dark for 20 min, then washed three times with PBS and resuspended, and the live / dead bacteria were observed under a fluorescent inverted microscope; the results showed that Figure 5 As shown, it can be seen that the composite film prepared in Example 27 of the present invention has a more obvious antibacterial effect than the pure chitosan film.

[0027] 4. Application of composite film in food preservation: Green grapes were washed with sterile water, and grapes with poor appearance were removed. The surfaces of the green grapes were then coated with the composite film (CLS film) prepared in Example 27, commercial food preservative film (Xinyue PVC preservative film from Lexin Company), and the pure CS film prepared in Comparative Example 1. Uncoated grapes were used as a control group. The green grapes were cultured at room temperature, and their weight and morphological changes were observed and recorded daily for 7 days. The results are shown in FIG. Figure 6 As shown, it can be seen that on the 7th day of the experiment, the control group, the plastic wrap group and the pure CS film group all showed varying degrees of browning and peel wrinkling, among which the control group and the CS film group showed more obvious phenomena, while the composite film group showed less obvious browning and the fruit was fuller, indicating that the composite film prepared in the embodiment of the present invention has excellent ability in food preservation.

[0028] In summary, the morphological characteristics, structure, physicochemical properties and application functions of the composite films prepared in the embodiments of the present invention were evaluated. The results showed that the introduction of nanomicelles significantly improved the density, light-shielding properties, waterproof properties and other properties of the film. In addition, the composite films synergistically inhibited food oxidation and microbial spoilage by integrating antioxidant enzymes with polymer matrices, and had great potential in food transportation and preservation.

[0029] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A food composite film containing nano-micelles, characterized in that: The invention comprises a film matrix, nano micelles and a plasticizer, wherein the amount of the nano micelles added is 1-10% of the amount of the film matrix added, and the amount of the plasticizer added is 20-60% of the amount of the film matrix added; The nano micelles include chitosan, anti-inflammatory drugs, 3-carboxyphenylboronic acid and antioxidant enzymes, and the anti-inflammatory drugs are curcumin or luteolin.

2. The food composite film containing nano micelles according to claim 1, characterized in that The preparation method of the nano micelles comprises the following steps: Chitosan and 3-carboxyphenylboronic acid were dissolved in dimethyl sulfoxide, and CS-PBA was obtained through amide bond reaction, dialysis and freeze-drying. CS-PBA and anti-inflammatory drugs are mixed and loaded with anti-inflammatory drugs through boronate bonds to form a hydrophilic and hydrophobic polymer carrier; During the self-assembly process of the hydrophilic and hydrophobic polymer carrier in water, antioxidant enzymes are added and encapsulated into the carrier through electrostatic adsorption. Nanomicelles are obtained through dialysis and freeze-drying.

3. The food composite film containing nano micelles according to claim 2, characterized in that The molar ratio of the amino group of the chitosan to 3-carboxyphenylboronic acid is 1-6:1; The mass ratio of CS-PBA to anti-inflammatory drugs is 1-4:1; The mass ratio of the hydrophilic and hydrophobic polymer carrier to the antioxidant enzyme is 1:0.05-0.

4.

4. The food composite film containing nano micelles according to claim 1, characterized in that The molecular weight of the chitosan is 2000-10000 Da.

5. The food composite film containing nano micelles according to claim 1, characterized in that The antioxidant enzyme is catalase or superoxide dismutase.

6. The food composite film containing nano micelles according to claim 1, characterized in that The film matrix is ​​chitosan or whey protein.

7. The food composite film containing nano micelles according to claim 1, characterized in that The plasticizer is glycerol or sorbitol.

8. A method for preparing a food composite film containing nanomicelles according to any one of claims 1 to 7, characterized in that: The following steps are involved: The nano-micelles are added to the film matrix, and the mixture is fully mixed in a magnetic stirrer. After mixing, a plasticizer is added and bubbles are removed in ultrasound. The mixture is then poured into a film mold and dried to obtain the composite film.

9. The method for preparing a food composite film containing nano-micelles according to claim 8, wherein: In the step of fully mixing in a magnetic stirrer, the mixing time of the magnetic stirrer is 10 to 40 minutes; in the step of adding a plasticizer after mixing and removing bubbles in ultrasound, the working time of ultrasound is 20 to 60 minutes; and the temperature of the drying is 30 to 80°C.

10. Use of the food composite film containing nanomicelles according to any one of claims 1 to 7 in inhibiting food oxidation and spoilage.

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