Slow-release fruit fumigation preservative based on natural preservative and preparation method thereof

Abstract

The invention provides a slow-release fruit fumigation preservative based on a natural preservative and a preparation method thereof, and belongs to the technical field of fruit bacteriostasis and preservation, the slow-release fruit fumigation preservative comprises the following raw material components by weight: 27-35% of a deoxidant, 1.5-2% of calcium chloride, 60-70% of plant essential oil microcapsules, and 1.5-3% of modified calcium peroxide. A humidity response release mechanism is achieved through the chitosan-sodium alginate microcapsules, and the slow release effect of the plant essential oil is achieved; the deoxidant is used for rapidly reducing the initial oxygen concentration in the fruit package and weakening the aerobic respiration of the fruit package; the modified calcium peroxide slowly releases oxygen and absorbs carbon dioxide, so that anaerobic respiration is avoided. The preservative has the advantages of being non-contact, controllable in slow release, friendly in component and the like, and can effectively prolong the storage period of the fruits and maintain the quality of the fruits.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of fruit bacteriostatic preservation technology, in particular to a slow-release fruit fumigation preservative based on natural preservatives and a preparation method thereof. BACKGROUND

[0002] Fruits are fresh and live commodities, high in water content and rich in nutrients, and are prone to rot and deterioration. Moreover, fruits are usually planted far away from cities. Therefore, how to preserve fruits and extend the storage and transportation cycle is very important for the market supply and demand of fruits.

[0003] The main reasons for the rotting of fresh fruits during postharvest processing are the combined action of the following factors: physiology (decay caused by normal physiological functions after fruit picking), pathology (rot caused by pathogenic microorganisms), physics (mechanical damage), and environment (unsuitable temperature and humidity). In pathological rot, fungi are the main rot-causing pathogenic bacteria of fruits.

[0004] With the increasing awareness of food safety among consumers, the hazards of chemical preservatives have gradually attracted people's attention. Therefore, the current market tends to use safe and efficient natural preservatives. At present, there are various preservation products based on natural preservatives, but there are still the following significant defects:

[0005] Firstly, most of the existing fruit preservation products are contact type, such as soaking and coating, and there are few non-contact fumigation type preservatives. Non-contact preservatives are more convenient and safer to use. Secondly, although slow-release preservatives are widely used, most of them rely solely on the physical adsorption of the carrier matrix for slow release, and it is difficult to change the release rate of the preservative according to environmental changes. In addition, most of the existing fruit preservatives focus on preventing and controlling rot caused by pathogenic microorganisms, and generally ignore the control of physiological decay.

[0006] Therefore, it is necessary to develop a fumigation type fruit preservative based on natural preservatives and having controllable and slow-release preservation effect. SUMMARY

[0007] The purpose of the present application is to provide a slow-release fruit fumigation preservative based on natural preservatives and a preparation method thereof, to solve the problems raised in the background art.

[0008] To achieve the above purpose, the present application provides the following technical solution:

[0009] A slow-release fruit fumigation preservative based on natural preservatives, comprising the following raw material components in percentage by weight: oxygen scavenger 27-35%, calcium chloride 1.5-2%, plant essential oil microcapsule 60-70%, and modified calcium peroxide 1.5-3%;

[0010] The oxygen scavenger is composed of activated carbon powder and sodium L-ascorbate.

[0011] The plant essential oil microcapsule is a microcapsule coated with thyme essential oil and cassia bark essential oil.

[0012] The modified calcium peroxide is PEG-modified calcium peroxide.

[0013] The thyme essential oil and the cassia bark essential oil are commercially available products, and are purchased from Shanghai Yuanye Biotechnology Co., Ltd., with product numbers S26577 and S33677, respectively.

[0014] Preferably, the preservative is used in an amount of 8-12 g / L.

[0015] Preferably, the fruit is a non-respiratory climacteric fruit.

[0016] The application also discloses a preparation method of the slow-release fruit fumigation preservative based on the natural preservative.

[0017] S1. Preparation of the oxygen scavenger:

[0018] The activated carbon powder is added into the sodium L-ascorbate aqueous solution under stirring at room temperature, and stirring is continuously performed for 90-120 min; then, centrifugation, vacuum drying at 60 DEG C and grinding are performed, so as to obtain the oxygen scavenger.

[0019] S2. Preparation of the plant essential oil microcapsule:

[0020] S2-1. A small amount of Tween 80 is added into the thyme essential oil and the cassia bark essential oil, and then the mixture is slowly added into a 1.5% sodium alginate aqueous solution, and high-pressure homogenization is performed, so as to obtain a sodium alginate-essential oil primary emulsion.

[0021] S2-2. Calcium chloride is dissolved in a 1% acetic acid solution, so as to obtain a 3% calcium chloride-acetic acid solution; and chitosan is dissolved in the calcium chloride-acetic acid solution, so as to obtain a chitosan solution.

[0022] S2-3. The primary emulsion in step S2-1 is added dropwise into the chitosan solution in step S2-2, pH is adjusted to 4-5, and stirring is performed for 20-30 min; then, centrifugation, washing and freeze-drying are performed, so as to obtain the plant essential oil microcapsule.

[0023] S3. Preparation of the modified calcium peroxide:

[0024] Calcium chloride and PEG1000 are weighed and dissolved in deionized water; after complete dissolution, concentrated ammonia water is added to the reaction solution until the pH value is 9.5; after stirring for 3 h, a 30% hydrogen peroxide solution is slowly added; stirring reaction is performed for 5 h; the pH value is adjusted to 12; the precipitate is separated by centrifugation; the precipitate is washed with distilled water until the pH value of the filtrate is between 8-8.5; and vacuum drying is performed at 50 DEG C, so as to obtain the modified calcium peroxide.

[0025] S4. Vacuum drying the oxygen scavenger, calcium chloride, plant essential oil microcapsules of step S2 and modified calcium peroxide of step S3 at 40℃ for 2h;

[0026] S5. Filling the above dried raw materials into a polypropylene non-woven fabric separated into two parts by a heat-sealed non-woven fabric, the oxygen scavenger and calcium chloride are filled into the same layer, and the plant essential oil microcapsules and modified calcium peroxide are filled into the other layer, and then sealed, to obtain a fruit fumigation preservative.

[0027] Preferably, in step S1, the mass concentration of the sodium L-ascorbate aqueous solution is 25%, and the solid-liquid ratio of the activated carbon powder and the sodium L-ascorbate aqueous solution is 1:3 (g:mL).

[0028] Preferably, in step S2-1, the volume ratio of thyme essential oil: cinnamon bark essential oil: sodium alginate aqueous solution is (0.6-1):(0.5-0.9):5, and the amount of Tween 80 added is 0.2-0.5% of the total volume.

[0029] Preferably, in step S2-2, the molecular weight of chitosan is 10-30 kDa, the degree of deacetylation is not less than 90%, and the mass concentration of chitosan in the chitosan solution is 1%.

[0030] Preferably, in step S2-3, the mass ratio of the chitosan solution to the primary emulsion is 3:1.

[0031] Preferably, in step S3, the solid-liquid ratio of calcium chloride: PEG1000: deionized water: concentrated ammonia: 30% hydrogen peroxide solution is 1:10:50:5:7 (g:g:mL:mL:mL).

[0032] The beneficial effects of the above technical solutions of the present application are as follows:

[0033] 1. The microcapsules prepared by coating plant essential oil with chitosan-sodium alginate have a humidity response mechanism: in a low humidity environment, the shell material structure is dense and strong, and has excellent barrier properties, which can effectively prevent the leakage of internal essential oil; in a high humidity environment, the shell material will absorb water and swell, thereby "opening" the channel for essential oil release. In the early stage of storage and transportation, the humidity in the packaging box is low, and with the plant transpiration and respiration, the humidity quickly rises, at which time the plant essential oil in the microcapsules is released through humidity response, ensuring that the plant essential oil plays a role in inhibiting bacteria and preserving freshness at the time when the fruit is breathing actively and the risk of microbial growth is high.

[0034] 2. In order to reduce the aerobic respiration of fruits, sodium L-ascorbate consumes oxygen, and the high humidity environment generated by fruit respiration and transpiration triggers the synergistic effect of free sodium L-ascorbate in the powder and activated carbon, rapidly consuming the oxygen in the package at the initial stage, while reducing the aerobic respiration intensity of the fruits; calcium chloride, as a food-grade moisture absorbent, can accelerate the triggering of the sodium L-ascorbate oxygen absorption reaction.

[0035] 3. Thyme essential oil and cinnamon bark essential oil have broad-spectrum antibacterial properties and good fumigation antibacterial effect, and have good fumigation inhibition effect on various pathogenic bacteria; using microcapsule encapsulation can reduce the influence of essential oil odor on fruits, improve the stability of essential oil, prevent essential oil effective components from volatilizing or deteriorating, and at the same time realize intelligent slow release.

[0036] 4. Calcium peroxide can generate hydrogen peroxide and calcium hydroxide in a high humidity environment, and hydrogen peroxide can further react to generate oxygen, which, together with the deoxidizer, maintains a low oxygen environment in the closed fumigation environment, reducing the aerobic respiration of fruits while preventing anaerobic respiration of fruits; secondly, hydrogen peroxide is also a strong reducing agent that can oxidize ethylene released by fruits during storage, reducing the ethylene concentration; in addition, the generated calcium hydroxide can also absorb carbon dioxide in the closed space.

[0037] 5. PEG modification of calcium peroxide can increase its hydrophobicity, slow down the oxygen release rate, so that the preservative mainly reacts as a deoxidizer at the initial stage of storage, quickly reducing the oxygen concentration; then slowly release oxygen to maintain a low oxygen environment. BRIEF DESCRIPTION OF DRAWINGS

[0038] The above and other objects, features and advantages of the exemplary embodiments of the present application will be more apparent from the following detailed description taken in conjunction with the accompanying drawings. In which:

[0039] Figure 1 Release curve of the plant essential oil microcapsule prepared for Example 1. DETAILED DESCRIPTION

[0040] The preferred embodiments of the present application are described below, and it should be understood that the preferred embodiments described herein are only used to illustrate and explain the present application, and are not used to limit the present application.

[0041] If the specific experimental steps or conditions are not specified in the present scheme, the operation or conditions can be carried out according to the conventional experimental steps described in the literature in the art. If the reagents or instruments used are not specified by the manufacturer, they are all conventional reagent or instrument products that can be obtained by market purchase.

[0042] Example 1

[0043] A slow-release fruit fumigation preservative based on natural preservatives, comprising the following raw material components in percentage by weight: oxygen scavenger 33%, calcium chloride 1.5%, plant essential oil microcapsule 63%, modified calcium peroxide 2.5%;

[0044] A preparation method of a slow-release fruit fumigation preservative based on natural preservatives, comprising the following steps:

[0045] S1. Oxygen scavenger preparation:

[0046] The activated carbon powder is added into a 25% sodium L-ascorbate aqueous solution under stirring at room temperature, the solid-liquid ratio of the activated carbon powder and the sodium L-ascorbate aqueous solution is 1:3 (g:mL), the stirring is continued for 100 min, then centrifugation, vacuum drying at 60°C, grinding after drying, and the oxygen scavenger is obtained;

[0047] S2. Plant essential oil microcapsule preparation:

[0048] S2-1. A small amount of Tween 80 is added to the thyme essential oil and the cinnamon bark essential oil, and then slowly added into a 1.5% sodium alginate aqueous solution, and high-pressure homogenization is performed to obtain a sodium alginate-essential oil primary emulsion; wherein the volume ratio of the thyme essential oil, the cinnamon bark essential oil and the sodium alginate aqueous solution is 0.8:0.7:5, and the amount of Tween 80 added is 0.4% of the total volume;

[0049] S2-2. The calcium chloride is dissolved in a 1% acetic acid solution to obtain a 3% calcium chloride-acetic acid solution, and the chitosan is dissolved in the calcium chloride-acetic acid solution to obtain a chitosan solution; wherein the molecular weight of the chitosan is 20 kDa, the degree of deacetylation is not less than 90%, and the mass concentration of the chitosan in the chitosan solution is 1%;

[0050] S2-3. The primary emulsion in step S2-1 is added dropwise into the chitosan solution in step S2-2, the mass ratio of the chitosan solution to the primary emulsion is 3:1, the pH is adjusted to 4.5, and stirring is performed for 20 min, and then centrifugation, washing, and freeze-drying are performed to obtain the plant essential oil microcapsule;

[0051] S3. Modified calcium peroxide preparation:

[0052] The calcium chloride and PEG1000 are weighed and dissolved in deionized water, after complete dissolution, concentrated ammonia water is added to the reaction solution until the pH is 9.5, stirring is performed for 3 h, then a 30% hydrogen peroxide solution is slowly added, stirring is performed for 5 h, the pH value is adjusted to 12, the precipitate is separated by centrifugation, the precipitate is washed with distilled water until the pH value of the filtrate is between 8-8.5, and vacuum drying is performed at 50°C to obtain the modified calcium peroxide; wherein the solid-liquid ratio of the calcium chloride, the PEG1000, the deionized water, the concentrated ammonia water and the 30% hydrogen peroxide solution is 1:10:50:5:7 (g:g:mL:mL:mL).

[0053] S4. Vacuum drying the oxygen scavenger, calcium chloride, plant essential oil microcapsules and modified calcium peroxide of step S1 at 40°C for 2h;

[0054] S5. Filling the above dried raw materials into a polypropylene nonwoven cloth which is divided into two parts by a heat-sealed nonwoven cloth, the oxygen scavenger and calcium chloride are filled into one part, and the plant essential oil microcapsules and modified calcium peroxide are filled into the other part, and then sealing, to obtain a fruit fumigation preservative.

[0055] Example 2

[0056] The difference from Example 1 is that:

[0057] Raw material components: oxygen scavenger 35%, calcium chloride 2%, plant essential oil microcapsules 60%, modified calcium peroxide 3%;

[0058] In step S1, stirring for 90 min;

[0059] In step S2-1, the volume ratio of thyme essential oil: cinnamon bark essential oil: sodium alginate aqueous solution is 0.6:0.9:5, and the amount of Tween 80 added is 0.2% of the total volume;

[0060] In step S2-2, the molecular weight of chitosan is 10 kDa;

[0061] In step S2-3, the pH is adjusted to 5.

[0062] Example 3

[0063] The difference from Example 1 is that:

[0064] Raw material components: oxygen scavenger 27%, calcium chloride 1.5%, plant essential oil microcapsules 70%, modified calcium peroxide 1.5%;

[0065] In step S1, stirring for 120 min;

[0066] In step S2-1, the volume ratio of thyme essential oil: cinnamon bark essential oil: sodium alginate aqueous solution is 1:0.5:5, and the amount of Tween 80 added is 0.5% of the total volume;

[0067] In step S2-2, the molecular weight of chitosan is 30 kDa;

[0068] In step S2-3, the pH is adjusted to 4, and stirring for 30 min.

[0069] Comparative Example 1

[0070] The difference from Example 1 is that no oxygen scavenger is added.

[0071] Comparative Example 2

[0072] The difference from Example 1 is that no calcium chloride is added.

[0073] Comparative Example 3

[0074] The difference from Example 1 is that no plant essential oil microcapsules are added.

[0075] Comparative Example 4

[0076] The difference from Example 1 is that no modified calcium peroxide is added.

[0077] Comparative Example 5

[0078] The difference from Example 1 is that unmodified calcium peroxide is added.

[0079] Test 1: Determination of the embedding rate of plant essential oil microcapsules

[0080] The characteristic absorption peak of the compound essential oil with a volume ratio of thyme essential oil: cinnamon bark essential oil of 0.8:0.7 was determined by ultraviolet full-band scanning after dilution 10 times with anhydrous ethanol. The compound essential oil was diluted with anhydrous ethanol to prepare a gradient concentration solution, and the absorbance at the characteristic absorption peak was tested. The linear regression equation of the absorbance value y versus the concentration C (x) of the compound essential oil was drawn to prepare a standard curve of the compound essential oil. 0.05 g of the plant essential oil microcapsules prepared in Example 1 was dissolved in 20 mL of anhydrous ethanol, and ultrasonic, magnetic stirring and centrifugation were performed. 1 mL of the supernatant was diluted to 10 mL with anhydrous ethanol, and the absorbance was measured. The total oil content m 总 (g) in the microcapsules was calculated by substituting into the standard curve of the compound essential oil. 0.05 g of the plant essential oil microcapsules prepared in Example 1 was dissolved in 20 mL of anhydrous ethanol, and only centrifugation was performed. 1 mL of the supernatant was diluted to 10 mL with anhydrous ethanol, and the absorbance was measured. The oil content m 表 (g) on the surface of the microcapsules was calculated by substituting into the standard curve of the compound essential oil.

[0081] Embedding rate (%) = (m 总 -m 表 ) * 100% / m 总 .

[0082] The characteristic absorption peak of the compound essential oil is at 282 nm, and the standard curve equation is y = 0.012x + 0.038, R 2 = 0.9981, and the linear relationship is good. The embedding rate of the plant essential oil microcapsules prepared in Example 1 is calculated to be 67.5%.

[0083] Test 2: Test of the release performance of plant essential oil

[0084] Three portions of the plant essential oil microcapsules prepared in Example 1 were weighed and placed in Petri dishes, and then placed in a constant temperature (25°C) and dark environment. The total mass of the plant essential oil microcapsules and the Petri dishes was measured every day for the first 8 days, and then measured every two days. The cumulative release rate of the plant essential oil microcapsules was calculated according to the formula, and each group was measured three times.

[0085] The release rate (%) = (m 初 -m t ) * 100% / m 初 ;

[0086] In the formula, m 初 is the total mass of the initial plant essential oil microcapsules and the Petri dishes; m t is the total mass of the plant essential oil microcapsules and the Petri dishes on the tth day.

[0087] The release curve of the complex essential oil in the plant essential oil microcapsules is shown in Figure 1 . The results show that the release rate of the essential oil in the microcapsules increases slowly with time. The release rate increases slowly for the first 7 days, and then tends to be flat on the 8th day, with a cumulative release rate of about 33.4%, indicating that the essential oil microcapsules have a certain slow-release effect.

[0088] Test three: antibacterial performance test of plant microcapsules

[0089] The plant essential oil microcapsules prepared in Example 1 were added to sterilized potato glucose agar medium. After the medium solidified, a bacterial cake (4 mm in diameter) was inoculated in the middle of the medium. The Petri dish was sealed and inverted and cultured in a 28°C incubator for 5 days. The mycelial growth diameter was measured using a vernier caliper (cross method). The experiment was repeated three times, and the average value was taken. The test strains were two common pathogenic bacteria in fruits: Botrytis cinerea and Aspergillus niger.

[0090] The results show that the plant essential oil has good inhibition effect on the two pathogenic bacteria. The inhibition zone diameter of Botrytis cinerea is 35 mm, and the inhibition zone diameter of Aspergillus niger is 31 mm.

[0091] Test four: evaluation of the fresh-keeping effect of strawberries

[0092] Fresh strawberries after harvest, select no disease, no injury, uniform size, maturity and color consistent and similar to the strawberry, will be randomly divided into 1 control group and 8 test group packaging in about 1L (150mm x 135mm x 50mm, about 1.5mm thick) sealed transparent preservation box, flat 9 strawberries, 8 test group into the preparation of the preservative 12g of example 1-3 and comparative example 1-5, placed at the bottom of the fruit, the control group is not treated. Stored at room temperature (20℃), relative humidity 50%~60% conditions under the condition of sealed for 7 days, then open the preservation cover, change into PE preservative film, continue to store for 7 days, analysis of the 0th, 7th, 10th and 14th day of the rot rate, weight loss rate, hardness and soluble solids content, the results are summarized in table 1.

[0093] Table 1 strawberry preservation effect evaluation

[0094]

[0095] From table 1, the rot rate and weight loss rate of example 1-3 are significantly lower than the control group and comparative example; the rot rate and weight loss rate of comparative example 1 (without oxygen scavenger) and comparative example 3 (without plant oil microcapsule) are higher in 14 days of storage, which shows that oxygen scavenging and bacteriostasis are the key to preservation; the rot rate of comparative example 4 (without modified calcium peroxide) and comparative example 5 (without modified calcium peroxide) is also higher than example, which shows that modified calcium peroxide plays an important role in delaying aging.

[0096] Example 1-3 can effectively maintain the hardness of strawberry, and the hardness of comparative example 1-5 decreases rapidly, especially comparative example 3 (without plant oil microcapsule) decreases to 1.1, which shows that the bacteriostatic effect of plant oil is essential to maintain the structure of fruit.

[0097] The soluble solids content of example 1-3 is significantly higher than that of the control group, and the soluble solids content of comparative example 1, 3, 4 and 5 decreases obviously, which shows that the preservative of the application can effectively delay the degradation of fruit nutrients.

[0098] In summary, the preservative of the application generates a high humidity environment through the respiration and transpiration of fruits, triggers the reaction of oxygen scavenger and the release of microcapsule, reduces the consumption of nutrients by the respiration of fruits itself, at the same time, the plant oil microcapsule slowly releases oil to form fumigation bacteriostatic effect; calcium peroxide generates hydrogen peroxide and calcium hydroxide with water, decomposes ethylene generated by fruits and absorbs carbon dioxide generated; in addition, hydrogen peroxide further reacts to generate oxygen, which maintains a low oxygen environment with oxygen scavenger. The synergistic effect of each component significantly inhibits the rot and quality deterioration of strawberry, and prolongs the preservation period. The data of comparative example further verifies the indispensability of oxygen scavenger, plant oil microcapsule and modified calcium peroxide in the preservation process.

[0099] Finally, it is to be explained that the above embodiments are only used to illustrate the technical solutions of the present application but not to limit the present application, and other modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art should be covered in the scope of claims of the present application as long as they do not depart from the spirit and scope of the technical solutions of the present application.

Claims

1. A natural preservative based slow release fruit fumigant preservative agent, characterized in that, The raw material components include the following in terms of weight percentage: oxygen scavenger 27-35%, calcium chloride 1.5-2%, plant essential oil microcapsule 60-70%, modified calcium peroxide 1.5-3%; The oxygen scavenger is composed of activated carbon powder and sodium L-ascorbate; The plant essential oil microcapsule is a microcapsule coated with thyme essential oil and cinnamon bark essential oil; The modified calcium peroxide is PEG-modified calcium peroxide.

2. The fruit fumigant preservative according to claim 1, characterized in that, The preservative is used in an amount of 8-12 g / L.

3. The fruit fumigation preservative according to claim 1, characterized in that, The fruit is a non-respiratory climacteric fruit.

4. The method of preparing the fruit fumigation preservative according to claim 1, characterized in that, The method comprises the following steps: S1. Oxygen scavenger preparation: The activated carbon powder is added to the sodium L-ascorbate aqueous solution under stirring at room temperature, and the stirring is continued for 90-120 min, followed by centrifugation and vacuum drying at 60°C. After drying, the product is ground to obtain the oxygen scavenger; S2. Plant essential oil microcapsule preparation: S2-1. A small amount of Tween 80 is added to the thyme essential oil and cinnamon bark essential oil, and then slowly added to a 1.5% sodium alginate aqueous solution to obtain a sodium alginate-essential oil primary emulsion; S2-2. Calcium chloride is dissolved in a 1% acetic acid solution to obtain a 3% calcium chloride-acetic acid solution, and chitosan is dissolved in the calcium chloride-acetic acid solution to obtain a chitosan solution; S2-3. The primary emulsion in step S2-1 is added dropwise to the chitosan solution in step S2-2, the pH is adjusted to 4-5, and stirring is performed for 20-30 min. After centrifugation, washing, and freeze-drying, the plant essential oil microcapsule is obtained; S3. Modified calcium peroxide preparation: Calcium chloride and PEG1000 are dissolved in deionized water. After complete dissolution, concentrated ammonia water is added to the reaction solution until the pH is 9.

5. After stirring for 3 h, a 30% hydrogen peroxide solution is slowly added, and stirring is performed for 5 h. The pH value is adjusted to 12, and the precipitate is separated by centrifugation. The precipitate is washed with distilled water until the pH value of the filtrate is between 8 and 8.

5. The modified calcium peroxide is obtained by vacuum drying at 50°C. S4. The oxygen scavenger of step S1, calcium chloride, plant essential oil microcapsule of step S2, and modified calcium peroxide of step S3 are vacuum dried at 40°C for 2 h; S5. The above dried raw materials are filled into a polypropylene non-woven fabric separated into two parts by a heat-sealed non-woven fabric. The oxygen scavenger and calcium chloride are filled into the same layer, and the plant essential oil microcapsule and modified calcium peroxide are filled into the other layer. After sealing, the fruit fumigation preservative is obtained.

5. The method of preparing a fruit fumigation preservative according to claim 4, characterized in that, In step S1, the mass concentration of the sodium L-ascorbate aqueous solution is 25%, and the solid-liquid ratio of the activated carbon powder and the sodium L-ascorbate aqueous solution is 1:3 (g:mL).

6. The method of preparing a fruit fumigation preservative according to claim 4, characterized in that, In step S2-1, the volume ratio of thyme essential oil, cinnamon bark essential oil, and sodium alginate aqueous solution is (0.6-1):(0.5-0.9):5, and the amount of Tween 80 added is 0.2-0.5% of the total volume.

7. The method of claim 4, wherein the fruit fumigation preservative is prepared by adding 0.1 to 0.5% of the fumigant to 99.5 to 99.9% of the carrier. In step S2-2, the molecular weight of chitosan is 10-30 kDa, and the degree of deacetylation is not less than 90%. The mass concentration of chitosan in the chitosan solution is 1%.

8. The method of preparing a fruit fumigation preservative according to claim 4, characterized in that, In step S2-3, the mass ratio of the chitosan solution to the primary emulsion is 3:

1.

9. The method of claim 4, wherein the fruit fumigation preservative is prepared by adding 0.1 to 0.5 parts by weight of the compound of formula (I) to 100 parts by weight of the fruit preservative. In step S3, the solid-liquid ratio of calcium chloride: PEG1000: deionized water: concentrated ammonia water: 30% hydrogen peroxide solution was 1:10:50:5:7 (g:g:mL:mL:mL).

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