Method for enhancing performance of gelatin-based film based on low-temperature plasma modified nanoparticles and application

Abstract

The invention discloses a method for enhancing the performance of a gelatin-based film based on low-temperature plasma modified nanoparticles and application. The zein-curcumin-resveratrol-chondroitin sulfate nano suspension is placed under the conditions of dielectric barrier discharge and low-temperature plasma to be modified, and a low-temperature plasma modified nanoparticle suspension is obtained; adding the low-temperature plasma modified nanoparticle suspension and glycerol into the gelatin solution, stirring, and ultrasonically defoaming to obtain a membrane solution; and uniformly pouring the prepared film liquid into a plate, and drying to form the gelatin-based film. The gelatin which is low in cost and biocompatible is used as a main film forming substrate, the low-temperature plasma modified nanoparticles are added to improve the mechanical property of the gelatin, the tensile strength of the prepared composite film is 33.43-76.99 MPa, and the elongation at break is 25.76-52.81%.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomaterials, and in particular relates to a method and application of enhancing the performance of gelatin-based films by modifying nanoparticles based on low-temperature plasma. Background Art

[0002] Gelatin-based films are widely used in food packaging and medical applications due to their biocompatibility, biodegradability, and excellent film-forming properties. However, pure gelatin films suffer from disadvantages such as low mechanical strength and poor water resistance. Currently, nanoparticles are often added to improve their performance, but these particles tend to agglomerate, resulting in poor dispersion and affecting the film's uniformity and mechanical properties.

[0003] Low-temperature plasma technology is a green and efficient surface modification method that can improve the surface properties of nanoparticles through physical or chemical effects and enhance their compatibility with the matrix.

[0004] However, there are few studies on the incorporation of low-temperature plasma-modified nanoparticles into gelatin-based films and their effects on the preservation of perishable foods. Summary of the Invention

[0005] The purpose of this section is to summarize some aspects of the embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of this application to avoid obscuring the purpose of this section, the abstract and the title of the invention, and such simplifications or omissions should not be used to limit the scope of the present invention.

[0006] In view of the above problems and / or the problems existing in the prior art, the present invention is proposed.

[0007] Therefore, the purpose of the present invention is to overcome the deficiencies in the prior art and provide a method for enhancing the performance of gelatin-based films based on low-temperature plasma-modified nanoparticles.

[0008] To solve the above technical problems, the present invention provides the following technical solutions: a method for enhancing the performance of gelatin-based films based on low-temperature plasma modified nanoparticles, comprising:

[0009] A zein-curcumin-resveratrol-chondroitin sulfate nanosuspension was modified under dielectric barrier discharge-low-temperature plasma to obtain a low-temperature plasma-modified nanoparticle suspension, wherein air was used as the working gas, the working current was 0.024 mA, the working voltage was 30 kV, the working time was 120 s, and the working frequency was 120 kHz;

[0010] Adding low-temperature plasma-modified nanoparticle suspension and glycerol to gelatin solution, stirring and ultrasonic defoaming to obtain membrane solution;

[0011] The prepared membrane solution was evenly poured into a petri dish and dried to form a gelatin-based film.

[0012] As a preferred embodiment of the method of the present invention, the preparation method of the zein-curcumin-resveratrol-chondroitin sulfate nanosuspension comprises:

[0013] Dissolving curcumin and zein in an ethanol solution, stirring the resulting solution, and injecting it into distilled water. Then, removing the ethanol using a rotary evaporator to obtain a curcumin-zein nanosuspension;

[0014] Adding the resveratrol solution dropwise to the curcumin-zein nanosuspension and stirring evenly to obtain a resveratrol-curcumin-zein nanosuspension;

[0015] The resveratrol-curcumin-zein nanosuspension is added dropwise to the chondroitin sulfate solution and stirred evenly to obtain the chondroitin sulfate-resveratrol-curcumin-zein nanosuspension.

[0016] As a preferred embodiment of the method of the present invention, the curcumin-zein nanosuspension has a curcumin concentration of 1-3 mg / mL and a zein concentration of 5-10 mg / mL.

[0017] As a preferred embodiment of the method of the present invention, the concentration of the resveratrol solution is 1-3 mg / mL.

[0018] As a preferred embodiment of the method of the present invention, the volume ratio of the resveratrol solution to the curcumin-zein nanosuspension is 10-20:80.

[0019] As a preferred embodiment of the method of the present invention, the concentration of the chondroitin sulfate solution is 1-3 mg / mL, and the volume ratio of the resveratrol-curcumin-zein nanosuspension to the chondroitin sulfate solution is 40-80:40-80.

[0020] As a preferred embodiment of the method of the present invention, the mass fraction of gelatin in the membrane solution is 2-4%, the mass fraction of nanoparticles in the active composite membrane solution is 1-5%, and the mass fraction of glycerol is 20-40%.

[0021] As a preferred embodiment of the method of the present invention, the drying forms a gelatin-based film, wherein the drying temperature is 35 to 50° C. and the drying time is 24 to 28 hours.

[0022] Another object of the present invention is to overcome the deficiencies in the prior art and provide a gelatin-based film.

[0023] Another object of the present invention is to overcome the deficiencies in the prior art and provide a gelatin-based film for use in fish freshness assessment, comprising:

[0024] Wrap the fresh fish to be tested with gelatin-based film and place it in a petri dish, then store or transport it at 4°C;

[0025] Regularly record the color or morphological changes of the packaging film through image acquisition equipment;

[0026] Combining color change data with preset freshness indicators, the freshness level of fish meat can be determined in real time.

[0027] Beneficial effects of the present invention:

[0028] (1) The present invention is the first to modify the zein-curcumin-resveratrol-chondroitin sulfate nanosuspension by dielectric barrier discharge (DBD) low-temperature plasma, significantly improving the stability of the nanoparticles and the synergistic effect of the antioxidant activity. The process is green and efficient, avoiding chemical residues, and its comprehensive performance far exceeds that of nanoparticles prepared by conventional ultrasonic emulsification or solvent evaporation methods. Low-cost and biocompatible gelatin is used as the main film-forming matrix, and low-temperature plasma-modified nanoparticles (NPs) are added to improve its mechanical properties. The prepared composite film has a tensile strength of 33.43 to 76.99 MPa and an elongation at break of 25.76 to 52.81%.

[0029] (2) The present invention uses gelatin as the base material, realizes efficient composite through the nucleophilic reaction between low-temperature plasma-modified nanoparticles and gelatin molecules, and adopts the cast film forming process to prepare an active packaging film with excellent mechanical properties and barrier properties. The film material is particularly suitable for preserving fresh aquatic products and shows significant application potential in the field of active packaging.

[0030] (3) During the refrigeration and preservation of fresh fish, the active membrane prepared by the present invention can effectively reflect the degree of spoilage of aquatic products through intuitive changes in measurement indicators, thereby achieving rapid and non-destructive freshness determination without the need for complex detection instruments.

[0031] (4) The preparation process of the present invention is simple, the parameters are easy to control, and it has good feasibility for industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. Those skilled in the art can also derive other drawings based on these drawings without inventive effort. Among them:

[0033] Figure 1Characterization of the nanoparticles of the present invention: A is SEM, B is particle size distribution, C is zeta potential, and D is FT-IR spectrum.

[0034] Figure 2 Comparison of the mechanical properties of different gelatin-based composite films prepared in the present invention (Gelatin: pure gelatin film; G-NPs: nanoparticle suspension-enhanced gelatin film; G-ACP-NPs: low-temperature plasma-modified nanoparticle-enhanced gelatin film).

[0035] Figure 3 Characterization of the optical properties of the composite film of the present invention: (A) transmittance curve, (B) opacity value, (C) comparison diagram of the actual appearance.

[0036] Figure 4 The microstructure and composition characterization of the composite film of the present invention: (A) SEM morphology, (B) ATR-FTIR spectrum, (C) X-ray diffraction pattern.

[0037] Figure 5 Thermal performance analysis of the composite film of the present invention: (A) DSC curve, (B) TG / DTG thermogravimetric curves of Gelatin, G-NPs and G-ACP-NPs respectively.

[0038] Figure 6 2 is a comparison chart of the antioxidant activity test results of the composite film of the present invention.

[0039] Figure 7 Evaluation of the effect of the gelatin-based film of the present invention on the preservation of tilapia at 4°C: (AH) are the change curves of pH value, moisture content, TBARS value, TVB-N value, hardness, elasticity, chewiness, and total bacterial count, respectively; (I) is a comparison of actual fish pieces at different storage periods. DETAILED DESCRIPTION

[0040] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the embodiments of the specification.

[0041] Low-temperature plasma modification equipment in the embodiment of the present invention:

[0042] Equipment model: BK130 / 36 dielectric barrier discharge (DBD) system, manufacturer: Phoenix Electric Co. Ltd. (USA), equipment type: atmospheric pressure low-temperature plasma generator.

[0043] The raw materials in the present invention are all common commercially available products.

[0044] Example 1

[0045] Preparation and characterization of low-temperature plasma modified nanoparticles:

[0046] (1) Preparation of nanoparticle suspension

[0047] 0.05 g of curcumin and 0.5 g of zein were dissolved in 50 mL of 70% ethanol aqueous solution and stirred magnetically for 6 h until completely dissolved;

[0048] The above solution was slowly injected into 60 mL of distilled water, and ethanol was removed using a rotary evaporator (40°C, 100 rpm) to prepare a curcumin / zein nanosuspension;

[0049] 10 mL of resveratrol solution (1 mg / mL) was added dropwise to the above suspension and stirred for 30 min to obtain a resveratrol / curcumin / zein nanosuspension;

[0050] 40 mL of the nanosuspension was added dropwise into 40 mL of chondroitin sulfate solution (2 mg / mL) and stirred for 60 min to form a core-shell nanoparticle suspension;

[0051] 10 mL of the nanosuspension was subjected to low-temperature plasma modification (parameters: current 0.024 mA, voltage 30 kV, treatment time 120 s, frequency 120 kHz) to obtain a modified nanoparticle suspension.

[0052] (2) Preparation of composite membrane solution

[0053] Dissolve gelatin in distilled water to prepare a 2 g / 100 mL gelatin solution;

[0054] 40 mL of the modified nanoparticle suspension and 20% glycerol (based on the mass of gelatin) were added to the gelatin solution, and the mixture was stirred for 1 hour and then ultrasonically degassed for 15 minutes to obtain a uniform and stable composite membrane solution.

[0055] (3) Film forming process

[0056] The composite film liquid was poured into a horizontal polytetrafluoroethylene mold and dried in a 40°C oven for 24 hours to obtain an active packaging film.

[0057] (4) Nanoparticle characterization

[0058] The particle size distribution and zeta potential were determined by laser particle size analyzer (25°C); the morphology was observed by SEM (acceleration voltage 10 kV); the functional group changes were analyzed by FT-IR (4000-500 cm -1 ).

[0059] SEM showed that the nanoparticles were spherical with smooth surface (see Figure 1A); the particle sizes before and after modification were 2067 nm and 273 nm, and the zeta potentials were -32.9 mV and -38.1 mV, respectively (see Figure 1 BC); found in infrared spectroscopy (see Figure 1 D), compared with the peak of zein, the peaks of hydroxyl and amide II groups in ZCRC NPs shifted from 3423 cm -1 Move to 1542cm -1 , then to 3301cm -1 and 1583cm -1 , indicating that strong hydrogen bonding and hydrophobic interactions were formed in ZCRC NPs. The peak position of hydroxyl stretching shifted from 3301 cm -1 Move slightly to 3303cm -1 , indicating that the hydrogen bonds in ZCRC NPs increased after ACP treatment, thereby promoting the formation of stable ZCRC NPs.

[0060] Example 2

[0061] Physical properties test analysis of composite films:

[0062] (1) Mechanical properties

[0063] The tensile strength (TS) and elongation at break (EAB) of the films were tested by a texture analyzer.The films were cut into 20 mm × 60 mm strips with a gap of 30 mm between the clamps.

[0064] from Figure 2 It can be seen that nanoparticles significantly improve the mechanical properties of the film, and the ACP-modified sample performs best, demonstrating its high potential as a packaging material.

[0065] (2) Barrier properties

[0066] ① Water content, water solubility and swelling degree

[0067] Weigh a 2 × 2 cm membrane piece (M0) and dry it at 105 °C for 24 h before weighing it (M1);

[0068] The dried film was then immersed in 50 mL of distilled water for 24 h, the surface water was removed with absorbent paper, and the weight of the film was measured (M2), and the film was dried in an oven at 105°C to a constant weight (M3).

[0069] The water content, water solubility and swelling values of the film are determined by the following formulas:

[0070]

[0071] The moisture barrier diagram of the film of the present invention is shown in Table 1. The gelatin film has the highest moisture barrier ability. The addition of nanoparticles can significantly reduce the moisture barrier ability of the film. The low-temperature plasma (ACP) modification effect is more significant. The reason for this phenomenon is that the nanoparticles interact with the gelatin matrix through hydrogen bonds, thereby blocking the binding of water molecules.

[0072] ② Water vapor transmission rate and oxygen transmission rate

[0073] The film (50 mm x 50 mm) was sealed in a beaker containing 3 g of calcium chloride and 3 g of deoxidizer and the cup was weighed after standing at 25°C and 75% relative humidity for 48 hours.

[0074] The water vapor transmission rate and oxygen transmission rate of the film were calculated:

[0075]

[0076] Where Δm is the mass increment (g), d is the film thickness (mm), and A is the permeation area (m 2 ), t is the time interval (s), and ΔP is the water vapor pressure difference across the film.

[0077] 2 g of gelatin and 20% (w / w) glycerol were dissolved in 100 mL of distilled water and thoroughly mixed using a water bath thermostated magnetic stirrer at 60°C for 1 h to obtain a gelatin solution;

[0078] The prepared ZCRC NPs solution and ACP-ZCRC NPs (ACP-modified NPs) solution were uniformly mixed with gelatin solution at a ratio of 1:1;

[0079] After vacuum defoaming, 40 mL of the solution was poured into a square plastic plate (100 mm × 100 mm) and dried at 40 °C for 24 h, which were respectively recorded as gelatin membranes with nanoparticles incorporated without low-temperature plasma treatment (G-NPs membranes) and gelatin membranes with nanoparticles incorporated with low-temperature plasma treatment (G-ACP-NPs membranes);

[0080] Gelatin membrane was used as a control;

[0081] Prior to testing, all films should be sealed and stored in a desiccating dish for subsequent performance testing.

[0082] The physical parameters of different films are shown in Table 1.

[0083] Table 1

[0084]

[0085] The water vapor transmission rate and oxygen transmission rate measurement experiments of the film (see Table 1) also confirmed that ACP modification can form a denser network structure and effectively inhibit the migration of water and oxygen molecules, indicating that the composite film is a potential food preservation and moisture-proof packaging material.

[0086] (3) Optical performance

[0087] The color of the films (10 mm x 30 mm) was measured using a colorimeter. The L* (lightness), a* (red-gray), and b* (yellow-blue) parameters were determined by reflectance measurements. Opacity was measured using a UV spectrophotometer.

[0088] Color changes of different films

[0089] Table 2

[0090]

[0091] As shown in Table 2, the addition of NPs significantly reduced the L* value while increasing a*, b*, and ΔE, which was attributed to the intrinsic colors of zein and curcumin, resulting in a red-yellow hue in the film. Figure 3 As shown in ABC, compared with the control gelatin film, the film without ACP-treated nanoparticles and the ACP-modified nanoparticle film resulted in lower transmittance and higher opacity, among which the ACP effect was more significant, indicating that the NPs-containing composite film exhibited excellent UV shielding properties and could effectively protect food from photooxidation and deterioration.

[0092] Example 3

[0093] Composite film structure characterization:

[0094] The microscopic morphology of the film was observed by scanning electron microscopy; the functional groups between the film components were analyzed by ATR-FTIR; and finally, the crystal structure of the film was determined by XRD.

[0095] like Figure 4 As shown in ABC, A is the micromorphology of the composite film, B is the ATR-FTIR spectrum of the composite film, and C is the XRD spectrum of the composite film.

[0096] As can be seen from the figure, SEM shows that the nanoparticles are uniformly dispersed in the gelatin matrix, promoting the formation of a more compact and uniform three-dimensional network; ATR-FTIR confirms that the gelatin-based and NPs components are bound by non-covalent bonds; XRD analysis shows that ACP modification does not change the crystal structure of the film, which is attributed to the good compatibility between the gelatin-based film and NPs, which leads to a decrease in the order of the molecular chain arrangement.

[0097] Example 4

[0098] Functional stability of composite films:

[0099] (1) Thermal stability

[0100] Approximately 3 to 10 mg of film fragments were placed in an aluminum crucible, with an empty crucible used as a reference and nitrogen as the transfer gas. The crucible was heated from 20°C to 200°C and from 30°C to 700°C at a heating rate of 10°C / min. Differential scanning calorimetry (DSC) and thermogravimetric (TG) curves were obtained, respectively. Derivative thermogravimetric (DTG) curves were calculated based on the first derivative of the TG data.

[0101] like Figure 5 As shown in ABCD, A is the DSC curve, B is the gelatin TG curve, C is the G-NPs TG curve, and D is the ACP-G-NPs curve.

[0102] As shown in the figure, the heat deformation temperature of the composite films increased to 151.13°C after ACP treatment, further confirming the enhanced thermal stability of the films due to the interaction between the NPs and the gelatin matrix. The weight of all films gradually decreased with increasing temperature, demonstrating three distinct stages of thermal decomposition. Compared to pure gelatin films, ACP treatment reduced film weight loss, which can be attributed to the higher thermal energy and hydrogen bonding during the modification process, which promotes the formation of a dense network between the NPs and the gelatin matrix, effectively suppressing the material's volatilization at high temperatures.

[0103] (2) Antioxidant activity

[0104] The film samples (50 mg) were immersed in distilled water (10 mL) for 1 hour and centrifuged. The supernatant (1 mL) was mixed with DPPH solution (1 mL, 0.05 mM), incubated in the dark for 30 minutes, and the absorbance was measured at 517 nm. For ABTS analysis, ABTS working solution was prepared by mixing 7 mM ABTS with 2.45 mM potassium persulfate and then incubating in the dark overnight. The film samples (50 mg) were reacted with 20 mL ABTS solution in the dark (25 ° C, 30 minutes) and the absorbance was recorded at 734 nm. The DPPH and ABTS radical scavenging activities of the films are shown in the equation:

[0105]

[0106] Where A0 and A1 are the absorbance values of the control and sample, respectively.

[0107] Antioxidant activity see Figure 6It can be seen that the addition of NPs significantly enhanced the antioxidant capacity of the film, while the antioxidant activity of the film after ACP treatment was also enhanced, which was attributed to the exposure of more free radicals and hydrophobic groups during ACP treatment, thereby interrupting the oxidation chain reaction. These results indicate that this nanocomposite film has high antioxidant activity and can be used in active packaging applications to prevent food oxidation, maintain food quality, and extend the shelf life of food.

[0108] Example 5

[0109] Evaluation of the application effect of tilapia preservation:

[0110] Fresh fish fillets were wrapped with composite film and placed in a culture dish and stored at 4°C for 8 days. The color changes of the film were photographed with a digital camera, and the changes in pH value, moisture content, TBARS value, TVB-N value, texture and total colony count of the fish fillets were measured.

[0111] Changes in fish meat when stored at 4°C Figure 7 ABCDEFGHI, where A represents pH change, B represents moisture content change, C represents TBARS value change, D represents TVB-N value change, E represents hardness change, F represents elasticity change, G represents chewiness change, H represents total colony count change, and I represents the appearance of fish meat.

[0112] The pH of fish meat showed a trend of first decreasing and then increasing, likely due to the production of lactic acid from protein and glycogen degradation, followed by the accumulation of alkaline compounds from endogenous enzyme autolysis or microbial enzyme activity. Simultaneously, the water content of all samples decreased, primarily due to the water absorption of the film, which facilitated the migration of water from the meat into the film. The TBARS value of fresh fish was 0.25 mg MAD / kg and did not change significantly during the first two days (P>0.05), but then gradually increased, indicating a progressive increase in lipid oxidation. The TVB-N value gradually increased with prolonged refrigeration, exceeding the spoilage threshold of 20 mg / 100 g in the control group on day 4, the PE, gelatin, and G-NPs groups on day 6, and the G-ACP-NPs group on day 8. This trend is consistent with the pH change, primarily due to the production of alkaline volatile compounds from protein degradation by endogenous enzymes and spoilage bacteria. Furthermore, the hardness, elasticity, and chewiness of each group decreased with prolonged storage, primarily due to protein degradation and myofibril rupture caused by muscle autolysis and microbial action. The total bacterial count increased in each group, but remained lower in the G-ACP-NPs group than in the other groups, demonstrating its excellent storage properties. Figure 7Figure 1 shows the packaging and appearance changes of fresh-cut fish. After 4 days of storage, the unpackaged fish and PE film showed obvious deterioration, while the fish packaged in G-NPs and G-ACP-NPs films effectively delayed the deterioration of fish quality due to the excellent UV-visible barrier, gas barrier, and antioxidant properties of the composite films.

[0113] The present invention has found that when using specific plasma parameters of 30 kV and 2 min, a hierarchical rough structure can be constructed on the surface of nanoparticles. This structure is achieved by:

[0114] ① Enhanced mechanical interlocking with gelatin (mechanical properties, tensile strength 33.43±1.50~76.99±2.48MPa, elongation at break 38.55±2.46 to 52.81±3.54%)

[0115] ② The formation of active oxygen slow-release micro-regions, thereby producing a synergistic effect, making the composite membrane:

[0116] The oxygen and water vapor barrier properties exceeded the theoretical predicted values (oxygen barrier property 3.61±0.05~1.82±0.03g / m·d, water vapor barrier property (7.45±0.76~2.63±0.86)×(10 -7 These nonlinear effects have not been revealed in the existing technology, and the parameter window is narrow, which is significantly unpredictable.

[0117] ③Specificity of shelf life extension (aquatic product comparison experiment)

[0118] Control group (untreated membrane): TVB-N exceeded the standard on day 4 (20.12 mg / 100 g);

[0119] The membrane of the present invention: maintained at 17.65 mg / 100 g on the 6th day and reached 22.06 mg / 100 g on the 8th day;

[0120] Commercially available antibacterial film: exceeded the standard on the 5th day (26.1 mg / 100 g).

[0121] In summary, the present invention significantly improves the mechanical strength, barrier properties, and antioxidant activity of gelatin films by modifying nanoparticles using low-temperature plasma. It is particularly suitable for fresh-keeping packaging of aquatic products, extending their shelf life by 2-3 days.

[0122] Through plasma-specific interface engineering, the present invention has effects that have not been reported in the prior art in terms of stabilization mechanism (hydrogen bonding to form a covalent network) and process parameters (nonlinear parameter effects). It significantly improves the stability of nanoparticles, synergizes antioxidant activity, and makes the process green and efficient, avoiding chemical residues. Its comprehensive performance far exceeds that of nanoparticles prepared by conventional ultrasonic emulsification or solvent volatilization methods. These effects have not been reported in existing literature and are non-obvious.

[0123] The innovations of this invention are as follows: (1) for the first time, two natural antioxidants, curcumin and resveratrol, are co-encapsulated in core-shell nanoparticles, achieving synergistic enhancement of the active ingredients; (2) low-temperature plasma surface modification technology significantly improves the dispersibility and interfacial bonding strength of the nanoparticles in the gelatin matrix; and (3) the prepared active packaging film not only has excellent mechanical and barrier properties but also can reflect changes in fish freshness in real time through an intelligent response mechanism. Experimental results show that this packaging film can extend the shelf life of refrigerated fish by 2-3 days, and has broad application prospects in the field of intelligent packaging of fresh food.

[0124] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, and all of these should be included in the scope of the present invention.

Claims

1. A method for enhancing the performance of gelatin-based films based on low-temperature plasma-modified nanoparticles, characterized in that: include, A zein-curcumin-resveratrol-chondroitin sulfate nanosuspension was modified under dielectric barrier discharge-low-temperature plasma to obtain a low-temperature plasma-modified nanoparticle suspension, wherein air was used as the working gas, the working current was 0.024 mA, the working voltage was 30 kV, the working time was 120 s, and the working frequency was 120 kHz; Adding low-temperature plasma-modified nanoparticle suspension and glycerol to gelatin solution, stirring and ultrasonic defoaming to obtain membrane solution; The prepared membrane solution was evenly poured into a petri dish and dried to form a gelatin-based film.

2. The method according to claim 1, wherein: The preparation method of the zein-curcumin-resveratrol-chondroitin sulfate nanosuspension comprises: Dissolving curcumin and zein in an ethanol solution, stirring the resulting solution, and injecting it into distilled water. Then, removing the ethanol using a rotary evaporator to obtain a curcumin-zein nanosuspension; Adding the resveratrol solution dropwise to the curcumin-zein nanosuspension and stirring evenly to obtain a resveratrol-curcumin-zein nanosuspension; The resveratrol-curcumin-zein nanosuspension is added dropwise to the chondroitin sulfate solution and stirred evenly to obtain the chondroitin sulfate-resveratrol-curcumin-zein nanosuspension.

3. The method according to claim 2, wherein: The curcumin-zein nanosuspension has a curcumin concentration of 1-3 mg / mL and a zein concentration of 5-10 mg / mL.

4. The method according to claim 2 or 3, wherein: The concentration of the resveratrol solution is 1-3 mg / mL.

5. The method according to claim 4, wherein: The volume ratio of the resveratrol solution to the curcumin-zein nanosuspension is 10-20:

80.

6. The method according to claim 5, wherein: The concentration of the chondroitin sulfate solution is 1-3 mg / mL, and the volume ratio of the resveratrol-curcumin-zein nanosuspension to the chondroitin sulfate solution is 40-80:40-80.

7. The method according to claim 1, wherein: The membrane liquid contains gelatin at a mass fraction of 2-4%, nanoparticles at a mass fraction of 1-5%, and glycerol at a mass fraction of 20-40%.

8. The method according to claim 1 or 7, wherein: The drying forms a gelatin-based film, wherein the drying temperature is 35 to 50° C. and the drying time is 24 to 28 hours.

9. A gelatin-based film obtained by the method according to any one of claims 1 to 8.

10. Use of the gelatin-based film according to claim 9 in evaluating the freshness of fish, characterized in that: include, Wrap the fresh fish to be tested with gelatin-based film and place it in a petri dish, then store or transport it at 4°C; Regularly record the color or morphological changes of the packaging film through image acquisition equipment; Combining color change data with preset freshness indicators, the freshness level of fish meat can be determined in real time.

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