Banana preservation method and application

Abstract

The invention relates to the technical field of agricultural product preservation, in particular to a banana preservation method and application. According to the method provided by the invention, the polyethyleneimine-sulfur quantum dot composite material is prepared into a 0.8-1.5 g / L solution, and the solution is sprayed on the surfaces of banana fruits, so that the effect of prolonging the storage period of bananas is realized. The polyethyleneimine-sulfur quantum dot has the characteristics of simple synthesis method, small particle size, low toxicity, low price, simple preparation, suitability for large-scale production, good water solubility, good biocompatibility and the like; when the solution is sprayed to the surfaces of banana fruits, excessive active oxygen and ethylene in banana fruit bodies can be relieved and removed, and the storage time after harvesting is prolonged; the invention has the advantages of simple use method, obvious action effect and the like; when the method provided by the invention is applied to other fruit and vegetable products, the effects of sterilizing and reducing the fruit rot risk can also be achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of agricultural product preservation, in particular to a banana preservation method and application. Background Art

[0002] Bananas, a core tropical fruit worldwide, possess high nutritional value. Driven by population growth and rising health awareness, bananas are experiencing significant market demand and the industry's potential continues to be unleashed. However, as a typical climacteric fruit, bananas undergo extremely intense postharvest metabolic activity. Once off the plant, endogenous ethylene levels surge rapidly, triggering a sharp increase in respiration. This accelerates the hydrolysis of starch into soluble sugars, rapidly softens the flesh, and turns the peel from green to yellow. This irreversible ripening process significantly shortens the natural storage period of bananas. Breeding storage-resistant varieties is a key strategy for postharvest banana preservation. By selecting varieties with excellent storage-resistant properties and combining these storage-resistant genes with other desirable traits through hybridization, these traits can be stably transmitted to future generations through artificial hybridization, creating new varieties. However, the process of breeding storage-resistant varieties is labor-intensive and time-consuming, requiring extensive field trials and years of observation to ensure that the selected varieties exhibit stable storage-resistant properties under diverse environments and conditions. Furthermore, genetic recombination and trait segregation during hybridization add to the complexity of the breeding process.

[0003] In recent years, the development of chemical preservation technologies has enabled bananas to slow spoilage by inhibiting pathogens and regulating ethylene metabolism. These methods include three key approaches: First, fruit soaking with fungicides, such as benzimidazoles like carbendazim, thiabendazole, or prochloraz (at a concentration of 0.1%-0.2%), can reduce the incidence of anthracnose and Fusarium rot by over 40% by disrupting fungal cell membranes or inhibiting spore germination. Second, ethylene activity intervention involves impregnating porous carriers (such as vermiculite and perlite) with a saturated potassium permanganate solution to create adsorption packs. These packs are then placed inside packaging to decompose ethylene gas. Combined with modified atmosphere packaging, this can extend the shelf life at room temperature to 25-30 days. Third, barrier coating technology involves forming a micron-sized protective film using sucrose fatty acid esters (at a concentration of 0.5%-2%) or chitosan solutions to block oxygen penetration and reduce water evaporation. Combined with fungicides (such as 0.1% thiabendazole), this further inhibits surface microbial activity. It's worth noting that compounding chemical agents significantly enhances their effectiveness—for example, combining 0.1% benzyl alcohol with an ethylene absorber can maintain a 95% yield of good fruit during a 205-day storage period. However, residual risks and environmental compatibility remain key concerns for the industry during long-term use. Therefore, seeking more environmentally friendly and sustainable control methods is key to future development.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] In view of the technical problems existing in the background technology, the present invention provides a method for preserving bananas, which uses a polyethyleneimine-sulfur quantum dot composite material as a preservative to extend the storage period of bananas.

[0006] In a first aspect, the present invention provides a method for preserving bananas, comprising spraying a polyethyleneimine-sulfur quantum dot composite material solution with a concentration of 0.8-1.5 g / L on the surface of the fruit.

[0007] Preferably, the polyethyleneimine-sulfur quantum dot composite material is obtained by reacting sulfur quantum dots with polyethyleneimine.

[0008] Preferably, the preparation method of the polyethyleneimine-sulfur quantum dot composite material comprises: uniformly mixing sulfur quantum dots and polyethyleneimine in an aqueous solution, and reacting at 40-100° C. for 1-6 hours.

[0009] Preferably, the preparation method of the sulfur quantum dots comprises: dissolving sulfur powder, sodium hydroxide and polyethylene glycol in water, reacting at 40-100° C. for 24-108 hours; lowering the temperature to below 50° C., adding hydrogen peroxide, and fully reacting.

[0010] Preferably, the usage ratio of sulfur powder, sodium hydroxide and polyethylene glycol is: 1.4±0.2g: 4.0±0.5g: 3±0.4ml; the usage ratio of sulfur powder and polyethyleneimine is: 1.4±0.2g: 1.11±0.2g.

[0011] Preferably, the banana preservation method of the present invention comprises the following steps: dissolving sulfur powder, sodium hydroxide and polyethylene glycol in water, reacting at 40-100° C. for 24-108 hours; reducing the temperature to below 50° C., adding hydrogen peroxide, and transferring to a 4° C. environment for standing after sufficient reaction to obtain sulfur quantum dots; uniformly mixing the sulfur quantum dots with an aqueous solution of polyethyleneimine, reacting at 40-100° C. for 1-6 hours, and purifying to obtain a polyethyleneimine-sulfur quantum dot composite material; and configuring the polyethyleneimine-sulfur quantum dot composite material into a 0.8-1.5 g / L solution, and spraying the solution on the surface of banana fruit.

[0012] Preferably, the polyethyleneimine-sulfur quantum dot composite material is uniformly dispersed in the aqueous solution, and the average particle size of the sulfur quantum dots is 2.4±1 nm, and the lattice gap is 0.21±0.01 nm.

[0013] Preferably, the in vitro clearance rate of hydrogen peroxide of the polyethyleneimine-sulfur quantum dot composite material is 23.37±2.01%; the in vitro clearance rate of hydroxyl radicals is 35.17±3.23%; and the in vitro clearance rate of superoxide anions is 31.03±1.44%.

[0014] Preferably, the storage period of bananas reaches more than 13 days.

[0015] In a second aspect, the present invention provides an application of the aforementioned banana preservation method in preserving other fruits and vegetables, wherein a polyethyleneimine-sulfur quantum dot composite material solution having a concentration of 0.8-1.5 g / L is sprayed on the surface of other fruits and vegetables.

[0016] Beneficial effects:

[0017] The present invention provides a method for preserving bananas. The method provided by the present invention first prepares sulfur quantum dots from sulfur powder, sodium hydroxide, and polyethylene glycol, then mixes the sulfur quantum dots with an aqueous solution of polyethyleneimine to prepare a polyethyleneimine-sulfur quantum dot composite material, and finally configures the polyethyleneimine-sulfur quantum dot composite material into a 0.8-1.5g / L solution, which is sprayed on the surface of banana fruits to extend the storage period of bananas. Polyethyleneimine-sulfur quantum dots have the characteristics of simple synthesis method, small particle size, low toxicity, low price, simple preparation, suitability for large-scale production, good water solubility, and good biocompatibility. Spraying the solution onto the surface of banana fruits can alleviate and remove excessive active oxygen and ethylene in the banana fruits, thereby extending the storage time after harvest. The present invention has the advantages of simple use and obvious effect. The method provided by the present invention can also be applied to other fruit and vegetable products to sterilize and reduce the risk of fruit rot. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be described below.

[0019] Figure 1 1 is the material characterization result of PEI-SQDs in Example 6. Figure A is a TEM image of PEI-SQDs; Figure B is an infrared spectrum of PEI-SQDs; and Figure C is a fluorescence spectrum of PEI-SQDs.

[0020] Figure 2 This is the banana phenotype 13 days after PEI-SQDs spraying in Example 7.

[0021] Figure 3 This is the degradation curve of the reaction between PEI-SQDs and ethylene in Example 7.

[0022] Figure 4 These are the results of banana firmness measurement 13 days after PEI-SQDs spraying in Example 7.

[0023] Figure 5 This is the banana color measurement result 13 days after PEI-SQDs spraying in Example 7.

[0024] Figure 6 This is the result of measuring the soluble sugar content in bananas 13 days after spraying PEI-SQDs in Example 7.

[0025] Figure 7 This is the result of measuring the soluble solids content of banana 13 days after spraying PEI-SQDs in Example 7. DETAILED DESCRIPTION

[0026] The present invention provides a method for preserving bananas. Sulfur quantum dots are first prepared from sulfur powder, sodium hydroxide, and polyethylene glycol. The sulfur quantum dots are then mixed with an aqueous solution of polyethyleneimine to produce a polyethyleneimine-sulfur quantum dot composite material. Finally, the polyethyleneimine-sulfur quantum dot composite material is prepared into a 0.8-1.5 g / L solution and sprayed on the surface of bananas to extend the storage life of the bananas. The use of sulfur quantum dots overcomes the shortcomings of the prior art. They have the advantages of small size, high surface energy, ease of application, and environmental friendliness. They can remove active oxygen and ethylene from the fruit, as well as sterilize it, thereby extending the storage life of bananas after harvest.

[0027] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are also within the scope of protection of the present invention.

[0028] The endpoints and any values ​​of the ranges disclosed in this specification are not limited to the exact ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0029] In the description of this specification, the reference terms "one embodiment", "some embodiments", "specific implementation methods", or "some specific implementation methods" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0030] Unless otherwise specified, the materials and reagents used in the following examples are all commercially available. Experimental methods without specific conditions specified in the examples are generally performed under conventional conditions or the conditions recommended by the manufacturer.

[0031] Example 1

[0032] This embodiment provides a method for preserving bananas, which comprises spraying a 1g / L PEI-SQDs solution on the surface of the banana fruit. The PEI-SQDs (i.e., polyethyleneimine-sulfur quantum dot composite material) is prepared by the following method: 1.4g sulfur powder, 4.0g sodium hydroxide and 3ml polyethylene glycol are dissolved in water, reacted at 70°C for 72h, and then the temperature of the reaction system is lowered to below 50°C, hydrogen peroxide is added, and after sufficient reaction, the mixture is transferred to a 4°C environment and allowed to stand to obtain 83.3mL of sulfur quantum dot stock solution. 30mL of sulfur quantum dot stock solution is mixed with 2mL of 20% polyethyleneimine (PEI 1800 ) in aqueous solution were mixed evenly, then reacted at 70°C for 4 h, and then dialyzed and purified using a 2000Da dialysis bag for 6 h.

[0033] Example 2

[0034] This embodiment provides a method for preserving bananas, which involves spraying a 1g / L PEI-SQDs solution on the surface of the banana fruit. The PEI-SQDs (i.e., polyethyleneimine-sulfur quantum dot composite material) is prepared by the following method: 1.4g sulfur powder, 4.0g sodium hydroxide, and 3ml polyethylene glycol are dissolved in water, reacted at 40°C for 108h, and then the temperature of the reaction system is lowered to below 50°C, hydrogen peroxide is added, and after sufficient reaction, the mixture is transferred to a 4°C environment and allowed to stand to obtain 83.3mL of sulfur quantum dot stock solution. Take 30mL of sulfur quantum dot stock solution and 1.5mL of 20% polyethyleneimine (PEI 1800 ) in aqueous solution were mixed evenly, then reacted at 100°C for 1 h, and then dialyzed and purified using a 2000Da dialysis bag for 6 h.

[0035] Example 3

[0036] This embodiment provides a method for preserving bananas, which comprises spraying a 1g / L PEI-SQDs solution on the surface of the banana fruit. The PEI-SQDs (i.e., polyethyleneimine-sulfur quantum dot composite material) is prepared by the following method: 1.4g sulfur powder, 4.0g sodium hydroxide and 3ml polyethylene glycol are dissolved in water, reacted at 100°C for 24h, and then the temperature of the reaction system is lowered to below 50°C, and hydrogen peroxide is added. After sufficient reaction, the mixture is transferred to a 4°C environment and allowed to stand to obtain 83.3mL of sulfur quantum dot stock solution. Take 30mL of sulfur quantum dot stock solution and 2.5mL of 20% polyethyleneimine (PEI1800 ) in aqueous solution were mixed evenly, then reacted at 40° C. for 6 h, and then dialyzed and purified using a 2000 Da dialysis bag for 6 h.

[0037] Example 4

[0038] This embodiment provides a method for preserving bananas, wherein a 1.5 g / L PEI-SQDs solution is sprayed on the surface of the banana fruit. The PEI-SQDs are prepared in the same manner as in Example 1.

[0039] Example 5

[0040] This embodiment provides a method for preserving bananas, wherein a 0.8 g / L PEI-SQDs solution is sprayed on the surface of the banana fruit. The PEI-SQDs are prepared in the same manner as in Example 1.

[0041] Example 6

[0042] This example characterizes the PEI-SQDs material obtained in Example 1, including transmission microscope imaging and potential measurement, ultraviolet spectrophotometer and fluorescence spectrophotometer measurement, and Fourier transform infrared spectrometer FTIR measurement. Figure 1 .

[0043] (1) The morphology of PEI-SQDs was characterized using transmission electron microscopy (TEM). Figure 1 As shown in the TEM image of Figure A, PEI-SQDs are uniformly dispersed in the aqueous solution, and the particle size distribution histogram shows that the average particle size of SQDs is 2.4 nm and the lattice gap is 0.21 nm.

[0044] (2) Figure 1 The FT-IR spectrum of Figure B shows that NH (3352 cm -1 and 1582cm -1 ), -CH2(2950cm -1 and 2820cm -1 )(Dong et al 2012, Zeng et al 2017), with an absorption peak at 1450 cm -1 There are obvious peaks corresponding to the in-plane bending vibration of CH and the stretching vibration of CN (1112 cm -1 )(Guo et al 2019), which indicates that PEI is successfully capped on the surface of SQDs. -1 The new absorption peak at 775 cm is attributed to SNS bonding. -1 The SN stretching at 660 cm -1This is attributed to SO stretching vibration (Yan et al 2022). The presence of S-N bonds indicates that sulfur may have reacted chemically with the amino groups on PEI, and PEI-SQDs were successfully synthesized.

[0045] (3) Figure 1 The fluorescence spectrum of Figure C shows that the fluorescence emission spectra of sulfur dots at different excitation wavelengths indicate that PEI-SQDs are excitation wavelength dependent.

[0046] Example 7

[0047] In this example, the PEI-SQDs material obtained in Example 1 was used as a test material to evaluate its ability to improve the storage capacity of bananas.

[0048] (1) Banana Treatment: Bananas sprayed with a 1g / L PEI-SQD solution served as the treatment group, while those sprayed with the aqueous solution served as the control group. After spraying with PEI-SQDs, the bananas were placed in the dark for 3 hours to allow the PEI-SQDs to be completely absorbed by the fruit. The bananas were then placed in a sealed box to begin the storage test.

[0049] Figure 2 The phenotype of banana fruits treated with PEI-SQDs for 13 days was compared with that of untreated fruits. The results showed that the degree of surface browning of bananas treated with PEI-SQDs was significantly lower than that of the control.

[0050] (II) Identification of the ability to scavenge reactive oxygen species in vitro:

[0051] (1) Determination of Hydrogen Peroxide (H2O2) Content: The "Hydrogen Peroxide Content Determination Kit" (A064-1-1, Nanjing Jiancheng Biological Co., Ltd.) was used according to the instructions. PEI-SQDs were prepared into an optimal concentration solution, and reagent 1 (preheated at 37°C for 10 min) and reagent 2 were added. In the blank tube, the supernatant was replaced with distilled water, and in the standard tube, the supernatant was replaced with H2O2 standard application solution. After mixing, the absorbance at 405 nm was measured.

[0052] (2) Superoxide anion (·O2 - ) content was determined using the "Total SOD Activity Assay Kit WST-8 Method" (Biyuntian Biotechnology Co., Ltd.) according to the manufacturer's instructions. PEI-SQDs were prepared into an optimal concentration, and SOD assay buffer and WST-8 / enzyme working solution were added. Then, the reaction starter solution was added. The solution was heated in a 37°C water bath for 30 minutes. After mixing, the absorbance at 450 nm was measured. The calculation formula was: Percent Inhibition = (A blank control 1 - A sample) / (A blank control 1 - A blank control 2) * 100%.

[0053] (3) Using the principle of Fenton reaction, Fe 2+ The solution was mixed with H2O2 reagent to generate hydroxyl radicals, and the PEI-SQDs were added to the system. The absorbance change per unit time was measured at 240 nm to calculate the hydroxyl radical scavenging efficiency of the sulfur-containing quantum dots.

[0054] The in vitro ROS scavenging ability test demonstrates that PEI-SQDs can directly react with ROS, thereby reducing their content and mimicking the activity of enzymes to scavenge ROS in vitro. The results of the in vitro ROS scavenging ability test of PEI-SQDs are shown in Table 1.

[0055] Table 1 In vitro scavenging efficiency of reactive oxygen species by PEI-SQDs

[0056]

[0057] As shown in Table 1, the scavenging rates of hydrogen peroxide, hydroxyl radicals, and superoxide anions were 23.37±2.01%, 35.17±3.23%, and 31.03±1.44%, respectively, indicating that PEI-SQDs can act as a kind of nanoenzyme mimic.

[0058] (III) Identification of ethylene scavenging ability in vitro:

[0059] A solution containing 0.2g of sulfur quantum dots was placed in a 6cm glass Petri dish and slowly evaporated and concentrated in a 40°C oven to obtain dried sulfur quantum dots. The glass Petri dish containing the sulfur quantum dots was placed in a 250ml photoreactor. A certain amount of ethylene gas was injected through the valves at both ends and evenly dispersed, then sealed. A 1ml syringe was used to extract gas and inject it into a gas chromatograph (Agilent Technologies 6790B). The initial peak area of ​​ethylene in the photocatalyst before catalysis was measured as T0. The photocatalyst was placed under a mercury lamp, and 1ml of gas was extracted every 30 minutes using a gas chromatograph. The residual peak area of ​​ethylene in the photocatalyst was measured as T1. The detection parameters were: fuel gas flow rate 45ml / min, utility gas flow rate 350ml / min, pre-detection gas temperature 180°C, and measurement was performed using an FID detector. Degradation rate = (T0 - T1) / T1 * 100%.

[0060] The results of the in vitro ethylene scavenging ability test of PEI-SQDs are shown in Figure 3 .Depend on Figure 3 It can be seen that PEI-SQDs have a high efficiency in catalyzing ethylene degradation in vitro, and the ethylene content in the photoreactor gradually decreases over time, indicating that PEI-SQDs have the ability to remove ethylene.

[0061] (4) Banana hardness test:

[0062] (1) Sample preparation: Place the banana flat on a stage and mark test points on the peel at intervals of 2 cm. Five points are measured on a single banana finger, and each group is repeated three times to eliminate local differences.

[0063] (2) Measurement setup: Use a 6mm diameter cylindrical probe (P / 6) and TPA (Texture Profile Analysis) double compression mode. After calibrating the instrument, align the probe with the marked point and press vertically downward. The software plots the force-time curve in real time. The first compression peak force is directly read as the hardness value, and the average of multiple measurements is taken.

[0064] Figure 4 The results of banana firmness testing 13 days after PEI-SQDs application compared to the control group show that the firmness of bananas in the PEI-SQDs treatment group was significantly improved, proving that PEI-SQDs can extend the post-harvest storage time of bananas.

[0065] (5) Banana maturity (color) determination: Use a colorimeter to measure the color deviation of the banana peel to determine the banana's maturity. For the whole banana, mark three fixed test points: the head, middle, and tail (avoiding the ridges and stalks). During the test, vertically fit the probe to the peel surface and press the measurement button to capture the data. Each set of samples should be repeated three times and the average value should be taken to eliminate local differences. A single measurement takes approximately 1 to 2 seconds. The values ​​L*, a*, and b* obtained represent: brightness / browning degree, red-green bias, and yellow-blue bias, respectively. The reference values ​​queried are used as calculation indicators: L0*=64, a0*=1, and b0*=40.

[0066] Total color difference

[0067] Figure 5 The banana color test results 13 days after PEI-SQDs application compared with the control group showed that the banana color of the PEI-SQDs-treated group was less brown than that of the control group.

[0068] (6) Determination of soluble sugar content in bananas: Take samples of the fruit homogenate and use a saccharimeter to determine the soluble sugar content.

[0069] Figure 6 The results of the soluble sugar content test of bananas 13 days after PEI-SQDs application compared with the control group show that the soluble sugar content of bananas treated with PEI-SQDs is higher than that of the control group, indicating that the PEI-SQDs-treated bananas consume less sugar through respiration and are more storable.

[0070] (VII) Banana Soluble Solids Determination: 250 g of fresh banana pulp of uniform maturity should be selected and chopped. The pulp should be homogenized using a high-speed tissue blender and filtered through a double layer of gauze to obtain a clear juice. Prior to measurement, the refractometer should be calibrated to 20°C with distilled water. Two to three drops of the filtrate should then be added to the prism surface. After closing the cover, the scale value corresponding to the light-dark boundary (% Brix) should be read.

[0071] Figure 7 The results of the soluble solids content test of bananas 13 days after PEI-SQDs application compared with the control group showed that the soluble solids content of bananas in the PEI-SQDs treatment group was higher than that in the control group.

[0072] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A method for preserving bananas, characterized in that: A polyethyleneimine-sulfur quantum dot composite material solution with a concentration of 0.8-1.5 g / L is sprayed on the fruit surface.

2. The method for preserving bananas according to claim 1, wherein: The polyethyleneimine-sulfur quantum dot composite material is obtained by reacting sulfur quantum dots with polyethyleneimine.

3. The method for preserving bananas according to claim 2, wherein: The preparation method of the polyethyleneimine-sulfur quantum dot composite material comprises: uniformly mixing sulfur quantum dots and polyethyleneimine in an aqueous solution, and reacting at 40-100° C. for 1-6 hours.

4. The method for preserving bananas according to claim 2, wherein: The preparation method of the sulfur quantum dots comprises: dissolving sulfur powder, sodium hydroxide and polyethylene glycol in water, reacting at 40-100° C. for 24-108 hours; lowering the temperature to below 50° C., adding hydrogen peroxide and allowing for sufficient reaction.

5. The method for preserving bananas according to claim 4, wherein: The usage ratio of sulfur powder, sodium hydroxide and polyethylene glycol is: 1.4±0.2g:4.0±0.5g:3±0.4 ml; the usage ratio of sulfur powder and polyethyleneimine is: 1.4±0.2g:1.11±0.2g.

6. The method for preserving bananas according to any one of claims 1 to 5, characterized in that: The method comprises the following steps: dissolving sulfur powder, sodium hydroxide and polyethylene glycol in water, reacting at 40-100°C for 24-108 hours; lowering the temperature to below 50°C, adding hydrogen peroxide, and transferring the mixture to a 4°C environment for standing after sufficient reaction to obtain sulfur quantum dots; uniformly mixing the sulfur quantum dots with an aqueous solution of polyethyleneimine, reacting at 40-100°C for 1-6 hours, and purifying the mixture to obtain a polyethyleneimine-sulfur quantum dot composite material; and configuring the polyethyleneimine-sulfur quantum dot composite material into a 0.8-1.5 g / L solution, and spraying the solution on the surface of banana fruits.

7. The method for preserving bananas according to claim 6, characterized in that: The polyethyleneimine-sulfur quantum dot composite material is uniformly dispersed in the aqueous solution, and the average particle size of the sulfur quantum dots is 2.4±1 nm and the lattice gap is 0.21±0.01 nm.

8. The method for preserving bananas according to claim 6, characterized in that: The in vitro clearance rate of hydrogen peroxide, hydroxyl radicals and superoxide anions of polyethyleneimine-sulfur quantum dot composite materials was 23.37±2.01% and 35.17±3.23% respectively.

9. The method for preserving bananas according to claim 6, wherein: The storage period of bananas is more than 13 days.

10. Application of the banana preservation method according to any one of claims 1 to 9 in the preservation of other fruits and vegetables, characterized in that: Spray a polyethyleneimine-sulfur quantum dot composite material solution with a concentration of 0.8-1.5 g / L on the surface of other fruits and vegetables.

Images