A device and method for regulating fruit and vegetable ripening based on electrochemical CO2 reduction to generate ethylene

Abstract

The application relates to a fruit and vegetable ripening regulation device and method based on electrochemical CO2 reduction to generate ethylene, which comprises a CO2 storage bag (1), an electrolytic cell (2), an electrode (3), a power supply (4) and a sealed fruit and vegetable preservation box (5), wherein Cu2O (type I) nanoparticles are used as catalysts. In the application, the electrochemical catalytic CO2 technology is innovatively crossed with the discipline of food science, the CO2 gas mainly targeted by carbon neutralization is reused, ethylene generation is controlled through power regulation, the fruit and vegetable ripening efficiency is equivalent to or even better than that of commercial ripening agents (2% ethylene solution), and the application is a green, efficient and safe fruit and vegetable ripening regulation technology with great development prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemistry and food science and technology, and specifically provides a fruit and vegetable ripening regulation device and method based on electrochemical CO2 reduction to generate ethylene. BACKGROUND

[0002] Due to factors such as fruit and vegetable transportation, online group purchase, and online shopping, farmers often choose the sales method of "picking in advance and ripening on the ground". Therefore, in order to ensure the shelf life and commodity nature of fruits and vegetables, fruit and vegetable ripening regulation technology is particularly important.

[0003] Currently, the main fruit and vegetable ripening method is to spray, dip, and fumigate ethylene in a closed environment. Ethylene (ETH), also known as 2-chloroethyl phosphate, enters the plant tissue through the seed, leaf, or fruit, and then releases ethylene to accelerate ripening, shedding, and aging, with obvious ripening effect. However, ethylene is a strong acid aqueous solution, and most of the commercially available ETH ripening agents are 40% aqueous solutions with strong acidity and certain corrosivity. In addition, ETH is one of the most commonly used PDRs in the Pesticide Management Regulations, which can inhibit acetylcholine esterase and has a half-life of more than 1 day in food. Therefore, unscrupulous businessmen often misuse ETH in fruits and vegetables, causing pollution of agricultural products and the environment, and affecting human health, especially causing early puberty in children. A large number of studies have investigated the toxic effects of ethylene on rats or mice and found that it has reproductive toxicity, immunotoxicity, genetic toxicity, neurotoxicity, and liver toxicity. In addition to the potential harm to humans, the operation of applying ethylene is complex because different fruits and vegetables require different concentrations, sites, and temperatures. Therefore, the traditional fruit and vegetable ripening regulation method has the problems of multiple observations of fruit and vegetable conditions for ripening agent dosage adjustment, and the possibility of inconsistent ripening period and uneven ripening degree. Ethylene gas is not practically applied to fruit and vegetable ripening due to its flammability, explosiveness, difficulty in storage, and difficulty in concentration regulation.

[0004] Therefore, how to efficiently, safely, and accurately regulate the ripening of fruits and vegetables is a problem that needs to be solved. SUMMARY

[0005] In order to solve the safety problems and ethylene storage problems of existing ethylene application, the present application proposes a fruit and vegetable ripening regulation device and method based on electrochemical CO2 reduction to generate ethylene. The method innovatively combines electrochemical catalytic CO2 technology with food science, reuses CO2 gas which is the main target of carbon neutralization, and controls ethylene generation through a power source, which is a green, efficient, and safe fruit and vegetable ripening regulation technology with great development prospects.

[0006] The purpose of the present application is achieved as follows:

[0007] The first aspect of the present application provides a fruit and vegetable ripening control device based on electrochemical CO2 reduction to generate ethylene, comprising a CO2 storage bag, an electrolytic cell, an electrode, a power supply and a sealed fruit and vegetable preservation box.

[0008] The CO2 storage bag is connected to the electrolytic cell through a pipeline, and KHCO3 is used as the electrolyte in the electrolytic cell. The upper end of the electrolytic cell is open and connected to the sealed fruit and vegetable preservation box through a pipeline. The electrode is immersed in the electrolyte and comprises a working electrode and a counter electrode, which are respectively connected to the positive and negative electrodes of the power supply. The copper electrode uniformly coated with the catalyst cuprous oxide is the working electrode, and the platinum electrode is the counter electrode.

[0009] Further, the working electrode uses nanoscale cuprous oxide with space group Pn-3m (224) as the catalyst.

[0010] Further, the preparation of the working electrode comprises the following steps:

[0011] (1) In a system of 30 mL of pure water, weigh 1.0-3.0 g of cupric oxide dihydrate, 1.0-2.0 g of glucose and 0.5-1.0 g of sodium hydroxide, and add each component to pure water in turn. Stir the mixed solution at room temperature, and prepare it for use.

[0012] (2) Transfer the mixed solution to a round-bottom flask, and perform constant-temperature oil bath reaction under normal pressure.

[0013] (3) Transfer the reaction liquid to a centrifuge tube for centrifugation, take the precipitate, and then perform drying to obtain the nanocatalyst Cu2O.

[0014] (4) Weigh Cu2O and place it in a centrifuge tube, add anhydrous ethanol to fully dissolve Cu2O, then add Nafion solution, and shake to mix evenly to obtain a catalyst liquid.

[0015] (5) Uniformly apply the catalyst liquid to each side of a copper sheet, and dry it at room temperature to obtain the working electrode.

[0016] Further, the constant-temperature oil bath reaction in step (2) is performed at 100-120°C for 8-10 hours. The centrifugation in step (3) is performed at 3000 rpm for 10 minutes. The drying in step (3) is performed in a blast drying oven at a temperature of 70°C.

[0017] The second aspect of the present application provides a fruit and vegetable ripening control method based on electrochemical CO2 reduction to generate ethylene, which uses the fruit and vegetable ripening control device described above and comprises the following steps:

[0018] Step 1, fruit and vegetable pretreatment:

[0019] The unripe fruits and vegetables are washed and the surface moisture is dried, and they are placed in a closed fruit and vegetable preservation box at a suitable density;

[0020] Step 2, electrochemical reduction of CO2 to generate ethylene, ripening fruit and vegetable:

[0021] Open the switch connecting the CO2 storage bag to the electrolytic cell pipeline, allowing CO2 gas to continuously enter the KHCO3 electrolyte in the electrolytic cell; turn on the power supply, and connect the working electrode and the counter electrode to a constant voltage, thereby reducing CO2 to generate ethylene gas, which enters the closed fruit and vegetable preservation box through the pipeline, and the unripe fruits and vegetables are ripened. By controlling the power switch and the release time of ethylene through the regulating device, the ripeness of the fruits and vegetables can be controlled.

[0022] Further, the fruit and vegetable pretreatment also includes precooling the unripe fruits and vegetables under low temperature conditions for 3-5 hours. The purpose of precooling is to adapt the fruits and vegetables to the constant temperature during ripening, so that the biological activity of the unripe fruits and vegetables is stable after precooling for a period of time.

[0023] Further, the volume of the closed fruit and vegetable preservation box is 20-40 L, and the density of the unripe fruits and vegetables to be treated is 20-40 per box.

[0024] Further, the step 2 ripening fruit and vegetable is room temperature ripening for 3-5 days.

[0025] The advantages and beneficial effects of the present application are:

[0026] 1. In the fruit and vegetable ripening control device, non-nanoscale reagents, copper chloride dihydrate, glucose and sodium hydroxide, are innovatively used. According to the required proportion, under normal pressure and reaction conditions, nanoscale catalyst Cu2O (type I) nanoparticles can be synthesized. Compared with the currently commonly used catalysts (type II, type III, type IV), the reaction conditions of the nanocatalyst Cu2O are simpler and safer, and the generation of ethylene can be conveniently controlled. The reaction can be carried out under normal pressure, the particle size of Cu2O nanoparticles is uniform, the space group is Pn-3m (224), and the catalyst can achieve optimal ethylene generation and Faraday efficiency.

[0027] 2. The method for generating ethylene to control fruit and vegetable ripening using the fruit and vegetable ripening control device can effectively avoid the waste of fruits and vegetables and food safety problems caused by excessive use of ethylene.

[0028] 3. Using the fruit and vegetable ripening control device, only the power switch needs to be adjusted, and the fruits and vegetables can be uniformly ripened at a constant time, avoiding the problems of multiple application of ripening agents, complex operation and incomplete ripening in traditional ripening methods.

[0029] 4、The fruit and vegetable ripening regulation device product is small and convenient, and is suitable for a wide range of application environments (laboratories, families, factories, etc.); and it reduces CO2 to ethylene, which meets the current "carbon neutralization" requirement. BRIEF DESCRIPTION OF DRAWINGS

[0030] The application will be further described below in conjunction with the drawings and examples.

[0031] Figure 1 is a structural characterization schematic diagram of the catalyst Cu2O (type I) nanoparticles described in Example 1 of the application; wherein A is an XRD diagram of the catalyst, and B is an SEM diagram of the catalyst;

[0032] Figure 2 is a comparison result diagram of the ethylene production and Faraday efficiency of the four catalysts described in Example 1 and Comparative Examples 1-3 of the application within 24 hours of electrolytic catalysis of CO2 to generate ethylene; wherein A is ethylene production, and B is Faraday efficiency;

[0033] Figure 3 is a structural schematic diagram of the fruit and vegetable ripening regulation device described in Example 2 of the application; wherein 1 is a CO2 storage bag, 2 is an electrolytic cell, 3 is an electrode, 4 is a power supply, 5 is a fruit and vegetable preservation box, and 6 is an electrolyte;

[0034] Figure 4 is a diagram of the ethylene production and Faraday efficiency of the fruit and vegetable ripening regulation device under different voltages;

[0035] Figure 5 is a diagram of the appearance change of bananas by spraying a 2% ethephon solution and using the banana ripening regulation method of Example 4;

[0036] Figure 6 is a diagram of the texture influence of bananas by spraying a 2% ethephon solution and using the banana ripening regulation method of Example 4;

[0037] Figure 7 is a diagram of the sensory evaluation of bananas by spraying a 2% ethephon solution and using the banana ripening regulation method of Example 4;

[0038] Figure 8 is a diagram of the appearance change of persimmons by spraying a 2% ethephon solution and using the persimmon ripening regulation method of Example 5;

[0039] Figure 9 is a diagram of the texture influence of persimmons by spraying a 2% ethephon solution and using the persimmon ripening regulation method of Example 5;

[0040] Figure 10 is a diagram of the sensory evaluation of persimmons by spraying a 2% ethephon solution and using the persimmon ripening regulation method of Example 5. DETAILED DESCRIPTION

[0041] Example 1 - Preparation of catalyst Cu2O (Type I) nanoparticles

[0042] The present example provides a method for preparing Cu2O (Type I) nanoparticles, comprising the following steps:

[0043] With respect to a 30 mL pure water system, 1.0-3.0 g of copper oxide dihydrate, 1.0-2.0 g of glucose, and 0.5-1.0 g of sodium hydroxide are weighed, and the components are sequentially added to pure water. The solution is stirred at room temperature and mixed thoroughly, and then transferred to a round-bottom flask. The solution is reacted at 100-120°C under normal pressure for 8-10 hours, and then transferred to a centrifuge tube for high-speed centrifugation. The centrifugation time is 10 minutes, and the speed is 3000 rpm. The precipitate is taken and then dried in a 70°C air oven to obtain the catalyst Cu2O (Type I) nanoparticles.

[0044] Comparative Example 1 - Preparation of catalyst Cu2O (Type II) nanoparticles

[0045] With respect to a 30 mL pure water system, 2.0-4.8 g of copper sulfate, 2.0-2.5 g of glucose, and 5-10 g of sodium hydroxide are weighed, and the components are sequentially added to pure water. The solution is stirred at room temperature and mixed thoroughly, and then transferred to a round-bottom flask. The solution is reacted at 100-120°C in a high-pressure water reactor for 8-10 hours, and then transferred to a centrifuge tube for centrifugation. The precipitate is taken and then dried in a 70°C air oven to obtain the catalyst Cu2O (Type II) nanoparticles.

[0046] Comparative Example 2 - Preparation of catalyst CuO (Type III) nanoparticles

[0047] With respect to a 30 mL pure water system, 1M CuCl2 and 5M NaOH aqueous solution are mixed, and stirred at room temperature and mixed thoroughly. The solution is transferred to a round-bottom flask and reacted at 100-120°C under normal pressure for 8-10 hours. The reaction solution is transferred to a centrifuge tube for centrifugation. The precipitate is taken and then dried in a 70°C air oven to obtain the catalyst CuO (Type III) nanoparticles.

[0048] Comparative Example 3 - Preparation of catalyst CuO (Type IV) nanoparticles

[0049] With respect to a 30 mL pure water system, 1M CuSO4 and 5M NaOH aqueous solution are mixed, and stirred at room temperature and mixed thoroughly. The mixture is reacted at 100-120°C in a high-pressure water reactor for 8-10 hours. The reaction solution is transferred to a centrifuge tube for centrifugation. The precipitate is taken and then dried in a 70°C air oven to obtain the catalyst CuO (Type IV) nanoparticles.

[0050] Test Example 1

[0051] The catalysts prepared in Example 1 and Comparative Examples 1-3 and the preparation methods thereof are evaluated in this test example.

[0052] Firstly, Figure 1 The structural characterization of the Cu2O (type I) nanoparticles prepared in Example 1 is shown. The Cu2O (type I) nanoparticles have uniform particle sizes and a space group of Pn-3m (224). The space group refers to the lattice structure inside the crystal, which is related to the crystal faces of the metal catalyst, and the crystal faces directly affect the catalytic effect of the catalyst and the types of generated products.

[0053] Comparison from the perspective of space group: the Cu2O (type II) nanoparticles prepared in Comparative Example 1 have the same space group as the Cu2O (type I) nanoparticles prepared in Example 1, but Comparative Example 1 has more (222) crystal faces than Cu2O (type I). The space groups of the CuO (type III) and (type IV) nanoparticles prepared in Comparative Examples 2-3 are Cc (9) (i.e., monoclinic system) and C2 / c (15) (i.e., centrosymmetric monoclinic system), respectively.

[0054] Comparison from the perspective of the preparation method:

[0055] In the preparation method of the catalyst Cu2O (type I) nanoparticles of Example 1, non-nanoscale reagents (copper chloride dihydrate, glucose, and sodium hydroxide) are used, and the synthesis of the nano-catalyst can be stably carried out under mild reaction conditions (normal pressure conditions). Compared with the commonly used catalysts (type II, type III, and type IV) of Comparative Examples 1-3, the reaction conditions are simpler and safer, and the generation amount of ethylene can be conveniently controlled.

[0056] Specifically, in the preparation of the catalysts of Comparative Example 1 and Comparative Example 3, there is a large safety hazard due to the use of an autoclave, which is not suitable for non-laboratory, large-scale production, and the preparation conditions are relatively complex.

[0057] Comparison from the perspective of the generation amount of ethylene and Faraday efficiency:

[0058] Under the same conditions, the generation amount of ethylene and Faraday efficiency of the electrolytic catalysis of CO2 to generate ethylene within 24 hours using the four catalysts described in Example 1 and Comparative Examples 1-3 are compared. As shown in Table 1, the catalyst prepared in Example 1 has the highest generation amount of ethylene and Faraday efficiency. Figure 2As shown, the catalyst Cu2O (type I) nanoparticles described in Example 1 have the optimal ethylene production and Faraday efficiency within a 24-hour measurement time, and the ethylene production and Faraday efficiency of the Cu2O (type II) nanoparticles described in Comparative Example 1 are lower; the ethylene production and Faraday efficiency of the CuO (type III) nanoparticles and CuO (type IV) nanoparticles described in Comparative Examples 2 and 3 are very low, and it is found that the main gas product of the CuO (type III) nanoparticles described in Comparative Example 2 is CO and methane, which has adverse effects on the human body and fruits and vegetables and does not meet the food safety production requirements; the main gas product of the CuO (type IV) nanoparticles described in Comparative Example 3 is methane and ethane, which does not meet the food safety production requirements.

[0059] Example 2 - Fruit and vegetable ripening regulation device

[0060] This example provides a fruit and vegetable ripening regulation device based on electrochemical CO2 reduction to generate ethylene, as shown in Figure 3 The device includes a CO2 storage bag 1, an electrolytic cell 2, an electrode 3, a power supply 4, and a fruit and vegetable preservation box 5. The CO2 storage bag is connected to the electrolytic cell through a pipeline, and KHCO3 is used as the electrolyte 6 in the electrolytic cell. The electrolytic cell has an open upper end and is connected to the fruit and vegetable preservation box through a pipeline. The electrode is immersed in the electrolyte and includes a working electrode and a counter electrode, which are electrically connected to the positive and negative electrodes of the power supply, respectively. The copper electrode uniformly coated with the nano-catalyst cuprous oxide (type I) is the working electrode, and the platinum electrode is the counter electrode.

[0061] The preparation of the working electrode includes the following steps:

[0062] (1) 4-8 mg of the catalyst Cu2O (type I) nanoparticles prepared in Example 1 are weighed into a 1.5 mL centrifuge tube, 2.0-4.0 mL of anhydrous ethanol is added and ultrasonicated until the Cu2O is fully dissolved, then 5-10 μL of Nafion solution is added, and the mixture is shaken and mixed to prepare a catalyst solution;

[0063] (2) 20 μL of the catalyst solution is uniformly applied to each side of a 2-3 cm 2 copper sheet, which is then dried at room temperature to obtain the working electrode.

[0064] Example 3 - Optimization of reaction voltage of fruit and vegetable ripening regulation device

[0065] In this example, a copper sheet coated with the catalyst Cu2O (type I) nanoparticles described in Example 1 is used as the working electrode, and a platinum electrode is used as the counter electrode, to form the fruit and vegetable ripening regulation device described in Example 2. The fruit and vegetable ripening regulation device is measured at a constant voltage of 3 V, 4 V, and 5 V, respectively, and the ethylene production and Faraday efficiency are used as indicators for performance evaluation.

[0066] As shown in Figure 4 Figure 2, the fruit and vegetable ripening regulation device of Example 2 showed relatively stable performance at different voltages. However, at 4V, the fruit and vegetable ripening regulation device showed the optimal ethylene production and Faraday efficiency, which met the required ethylene concentration for regulating fruit and vegetable ripening. Therefore, 4V was selected as the optimal reaction voltage of the fruit and vegetable ripening regulation device, and subsequent fruit and vegetable ripening regulation research was carried out.

[0067] Example 4

[0068] In this example, immature bananas (variety: Guangxi Gaoshan Tainan) were selected as the treatment object, and a banana ripening regulation method based on electrochemical CO2 reduction to generate ethylene was provided. The method used the fruit and vegetable ripening regulation device as described in Example 2, and the specific steps were as follows:

[0069] Step 1, fruit and vegetable pretreatment:

[0070] The same batch of immature bananas were washed and dried to remove surface moisture, and then placed in a 4℃ refrigerator for 3-5h of precooling. The pre-cooled immature bananas were placed in a 40L cuboid airtight fruit and vegetable preservation box 5, and the experiment was carried out at 25-30℃.

[0071] Step 2, electrochemical CO2 reduction to generate ethylene and ripen fruit and vegetables:

[0072] Open the switch on the pipeline connecting the CO2 storage bag 1 and the electrolytic cell 2, so that CO2 gas is continuously introduced into the electrolytic cell and the 0.1M KHCO3 electrolyte 6; turn on the power supply 4, so that the working electrode and the counter electrode are connected to a constant voltage of 4V, thereby reducing CO2 to generate ethylene gas, which enters the airtight fruit and vegetable preservation box 5 through the pipeline, and the unripe fruit and vegetables are treated for ripening. By controlling the power switch and the release time of the regulation device, the ripeness of the fruit and vegetables can be controlled.

[0073] In this example, the airtight fruit and vegetable preservation box 5 was a 40L cuboid, and the density of the unripe fruit and vegetables to be treated was 20-40 per box. At 27℃, the power of the fruit and vegetable ripening regulation device was turned on, and the ripening time was 4 days.

[0074] Comparative Example 4

[0075] To compare the ripening effects of different methods, the method of Example 4 was used as the experimental group (CO2RR group), i.e. the banana group treated with the gas generated by the copper-based electrode with Cu2O (type I) nanoparticles under a constant voltage of 4V.

[0076] The control group (ETH group) was the banana group sprayed with 2% Guoguang ethylene solution.

[0077] The untreated group (CK group) consisted of bananas that were not subjected to any external interference.

[0078] Every two days, take three bananas from each of the above groups for fixed appearance observation and take photos to record the results.

[0079] like Figure 5 As shown, during the ripening process, the bananas ripened using the fruit and vegetable ripening control device of the present invention (experimental group) and the control group (ethephon-treated bananas) showed no significant difference in appearance color changes, both turning golden yellow on the fourth day. This demonstrates that the fruit and vegetable ripening control device of the present invention can achieve the same fruit and vegetable ripening effect as commercial ripening agents (2% ethephon solution) in terms of banana appearance changes.

[0080] To compare the effects of different ripening methods on banana texture, three bananas were randomly selected from each group every two days to determine titratable acidity, soluble solids, and changes in texture.

[0081] like Figure 6 As shown, during the ripening process, compared to untreated bananas, the bananas ripened by ethephon and the fruit and vegetable ripening control device of the present invention exhibited significant changes in firmness, titratable acidity, and soluble solids, which were 16.13N, 2.11%, and 14.28%, and 11.68N, 2.36%, and 14.48%, respectively. The ripening effect of the fruit and vegetable ripening control device was superior in terms of banana firmness, elasticity, and stickiness, indicating a better taste. Therefore, the fruit and vegetable ripening control device of the present invention can achieve the same or even better fruit and vegetable ripening effect as commercial ripening agents (2% ethephon solution) in ripening bananas.

[0082] Furthermore, sensory evaluation experiments were conducted on bananas treated with different ripening methods according to the sensory evaluation methods in Table 1.

[0083] Sensory evaluation tests were conducted on bananas from the ETH group and the CO2RR group, which had been ripened for 4 days. At this stage, the bananas had reached the 6th level of ripeness (yellowing and ripening). A 100-point evaluation method was used to conduct sensory analysis based on consumer preferences. Each group of bananas was pre-cut into uniform pieces and placed in paper cups, with random numbers recorded. Two samples were distributed to 10 evaluators familiar with the evaluation criteria by the host. Evaluators were spatially isolated from each other and rinsed their mouths with cool boiled water after tasting each sample before moving on to the next. After tasting, evaluators rated the bananas' color, softness, sweetness, aroma, and overall taste, recording their evaluations in the sensory evaluation record sheet shown in Table 2. The evaluation was conducted in three rounds, and the evaluation forms were collected and analyzed afterward.

[0084] Table 1. Sensory evaluation methods for bananas

[0085]

[0086]

[0087] Table 2 Banana sensory evaluation record table

[0088]

[0089] As Figure 7 shown, compared with untreated bananas and bananas treated with ethephon, persimmons ripened by the fruit and vegetable ripening control device of the present application were more favored by the evaluators in terms of softness, sweetness, aroma and overall taste, thus it can be seen that the fruit and vegetable ripening control device of the present application can achieve better fruit and vegetable ripening effect than commercial ripening agent (2% ethephon solution) in the sensory evaluation of ripened bananas.

[0090] Example 5

[0091] In this embodiment, immature persimmons (variety: Beijing Mopan persimmons) were selected as the treatment object, and a persimmon ripening control method based on electrochemical CO2 reduction to generate ethylene was provided, and the treatment methods were the same as in Example 4.

[0092] Comparative Example 5

[0093] In order to compare the ripening effects of different methods, the method of Example 5 was used as the experimental group (CO2RR group), i.e. the group of persimmons into which the gas generated by the copper-based electrode with attached Cu2O (type I) nanoparticles was passed at a constant voltage of 4V.

[0094] The control group (ETH group) was the group of persimmons sprayed with 2% Guoguang ethephon solution.

[0095] The untreated group (CK group) was the group of persimmons without any external factor interference.

[0096] Every 2 days, 2 persimmons for fixed appearance observation were taken for photographing and recording.

[0097] As Figure 8 shown, during the ripening process, there was no significant difference in the color change of persimmons ripened by the fruit and vegetable ripening control device of the present application and persimmons treated with ethephon, both of which turned orange on the fourth day, thus it can be seen that the fruit and vegetable ripening control device of the present application can achieve the same fruit and vegetable ripening effect as the commercial ripening agent (2% ethephon solution) in the appearance change of persimmons during ripening.

[0098] In order to compare the effects of different ripening methods on the texture of persimmons, the titratable acidity, soluble solids and texture changes of 2 randomly selected persimmons from each group every 2 days were determined.

[0099] As Figure 9As shown, compared with the untreated persimmons and the persimmons treated by ethylene, the titratable acidity and tannin of the persimmons ripened by the fruit and vegetable ripening regulation device of the present application are obviously lower, only 0.255% and 388.878 μmol / g, which indicates that the astringency of the persimmons in the device group is obviously reduced, the sour and sweet degree is closer to the requirement of commercialization, the elasticity and adhesion are relatively low, being 9.26 mm and 0.24 mJ respectively, which indicates that the taste of the persimmons in the device group is better. It can be seen that the fruit and vegetable ripening regulation device of the present application can achieve the same or even better ripening efficiency than the commercial ripening agent (2% ethylene solution) in banana ripening.

[0100] Further, according to the sensory evaluation method in Table 3, the persimmons treated by different ripening methods are subjected to sensory evaluation test. The ETH group persimmons and the CO2RR group persimmons ripened for 4 days are selected for sensory evaluation test, at this time, the color of the persimmons is yellow and the texture is soft. The 100-point evaluation method is used for consumer preference type sensory analysis. The persimmons in each group are uniformly cut in advance, loaded into paper cups and randomly numbered, and the evaluators (10 in total) who are familiar with the evaluation standard are distributed with 2 samples by the host, the evaluators are spatially isolated, and after tasting 1 sample, they rinse their mouths with cold boiled water before tasting the next sample. After tasting, the evaluators evaluate the color, softness, sweetness, astringency, aroma and overall taste of the persimmons, and fill in the sensory evaluation record table as shown in Table 4. The evaluation is conducted for 3 rounds, and after the evaluation, the evaluation table is collected for analysis.

[0101] Table 3 Sensory evaluation method of persimmons

[0102]

[0103] Table 4 Sensory evaluation record table of persimmons

[0104]

[0105] As Figure 10 shown, through sensory evaluation, compared with the untreated persimmons and the persimmons treated by ethylene, the persimmons ripened by the fruit and vegetable ripening regulation device of the present application are more loved by the evaluators in astringency, aroma and overall taste. It can be seen that the fruit and vegetable ripening regulation device of the present application can achieve better fruit and vegetable ripening effect than the commercial ripening agent (2% ethylene solution) in sensory evaluation of persimmon ripening.

[0106] In summary, the fruit and vegetable ripening control device based on electrochemical CO2 to generate ethylene of the present application can achieve the same or even better fruit and vegetable ripening efficiency than commercial ripening agent (2% ethylene solution). In addition, since the fruit and vegetable ripening device of the present application comprehensively utilizes CO2 to generate ethylene, it can be recycled, and the amount of ethylene released is controllable and the release process is continuous, therefore, the fruit and vegetable ripening device of the present application has better green and convenient, more safety and more stable ripening performance than traditional ripening technology.

[0107] Finally, it should be noted that the above is only used to illustrate the technical solutions of the present application and is not limiting. Although the present application has been described in detail with reference to the preferred arrangement, it should be understood by those skilled in the art that the technical solutions of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present application.

Claims

1. An electrochemical-based A fruit and vegetable ripening control device for reducing ethylene production, characterized in that, The device includes: The gas storage bag (1), electrolytic cell (2), electrode (3), power supply (4) and sealed fruit and vegetable preservation box (5); The The gas storage bladder is connected to the electrolytic cell via a pipeline, and the electrolytic cell contains... As the electrolyte (6), the upper end of the electrolytic cell is open and connected to the sealed fruit and vegetable preservation box through a pipeline; the electrode is immersed in the electrolyte, the electrode includes a working electrode and a counter electrode, which are electrically connected to the positive and negative poles of the power supply respectively, wherein the copper electrode with uniformly attached catalyst nano-sized cuprous oxide is the working electrode and the platinum electrode is the counter electrode. The working electrode uses nanoscale cuprous oxide with space group Pn-3m(224) as a catalyst, and the preparation of the working electrode includes the following steps; (1) Weigh 1.0 g to 3.0 g of copper oxide dihydrate, 1.0 g to 2.0 g of glucose and 0.5 g to 1.0 g of sodium hydroxide per 30 mL of pure water system. Add each component to pure water in sequence and stir magnetically at room temperature to mix thoroughly to obtain a mixed solution for later use. (2) Transfer the mixed solution to a round-bottom flask and react it in a constant-temperature oil bath under normal pressure; (3) Transfer the liquid obtained from the reaction to a centrifuge tube for centrifugation, collect the precipitate, and then dry it to obtain the catalyst nanoscale. ; (4) Weigh the catalyst nano-sized Place in a centrifuge tube, add anhydrous ethanol, and sonicate until the catalyst is at the nanoscale. After fully dissolving, Nafion solution is added, and the mixture is shaken to obtain the catalyst solution; (5) Apply the catalyst solution evenly to each surface of the copper sheet and dry it at room temperature to obtain the working electrode.

2. The fruit and vegetable ripening control device according to claim 1, characterized in that, The conditions for the constant temperature oil bath reaction in step (2) are: 100 ℃~120℃ for 8 h~10 h; the conditions for centrifugation in step (3) are: 3000 rpm for 10 min; the drying in step (3) is carried out by a forced-air drying oven at a temperature of 70 ℃.

3. An electrochemical-based A method for regulating the ripening of fruits and vegetables by reducing ethylene, characterized in that, The method employs the fruit and vegetable ripening control device as described in claim 1 or 2, and includes the following steps: Step 1, Fruit and Vegetable Pre-treatment: Wash the immature fruits and vegetables thoroughly and dry their surface moisture. Place them in a sealed fruit and vegetable preservation box (5) at an appropriate density. The volume of the sealed fruit and vegetable preservation box (5) is 20 L to 40 L, and the density of the immature fruits and vegetables to be processed is 20 to 40 per box. Step 2, Electrochemistry Reduction to produce ethylene, which ripens fruits and vegetables: Open The switch on the pipeline connecting the gas storage bag (1) and the electrolytic cell (2) enables... Gas is continuously fed into the electrolytic cell In the electrolyte (6); turn on the power supply (4) to connect the working electrode and the counter electrode to a constant voltage, thereby... Ethylene gas is generated by electrolysis and reduction. The ethylene enters the sealed fruit and vegetable preservation box (5) through the pipeline to ripen immature fruits and vegetables. The release time of ethylene in the device is controlled by controlling the power switch, thereby controlling the ripeness of the fruits and vegetables.

4. The method for regulating fruit and vegetable maturity according to claim 3, characterized in that, Fruit and vegetable pretreatment also includes pre-cooling unripe fruits and vegetables at 4°C for 3-5 hours.

5. The method for regulating fruit and vegetable maturity according to claim 3, characterized in that, Step 2: Ripen fruits and vegetables at room temperature for 3-5 days.

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