Preparation method of a new fruit fresh-keeping material

Abstract

The application provides a preparation method of a novel fruit fresh-keeping material, and belongs to the technical field of fruit and vegetable fresh-keeping materials; the method is used for preparing a core-shell structure fruit and vegetable fresh-keeping material ZnM@EA; the ZnM@EA takes EA as an inner core and a zinc-based compound as a shell; the zinc-based compound shell can selectively permeate ethylene olefin gas and block the invasion of external gas and water vapor, and protects the inner core EA, so that the inner core EA maintains ethylene adsorption performance; the preparation method sequentially comprises an EA inner core synthesis step and a ZnM coating step. The core-shell structure ZnM@EA fruit and vegetable fresh-keeping material prepared by the method can selectively permeate ethylene olefin gas, block the invasion of external gas and water vapor, and protect the inner core EA, so that the inner core EA maintains ethylene adsorption performance for a long time; when the material is applied to a food fresh-keeping bag, the ethylene concentration in the bag can be reduced, and the fruit fresh-keeping period can be effectively prolonged.

Description

Technical Field

[0001] This invention provides a method for preparing a novel fruit preservation material, belonging to the technical field of fruit and vegetable preservation materials. Background Technology

[0002] Even after harvesting, fruits continue to respire and metabolize, continuously releasing ethylene gas. Ethylene, as a ripening hormone, accelerates fruit ripening, aging, and spoilage, significantly shortening shelf life and storage period. Current fruit preservation methods include low-temperature refrigeration, controlled atmosphere storage, and preservative treatment. Low-temperature and controlled atmosphere storage have high requirements for equipment and storage conditions, limiting their application scenarios; chemical preservatives pose a risk of pesticide residues, which is detrimental to food safety.

[0003] Existing ethylene adsorption and preservation materials have significant drawbacks: some are susceptible to environmental moisture and external impurities, leading to the easy destruction of their adsorption active components, rapid decline in ethylene adsorption capacity, and short service life; others lack selective gas permeability, making them vulnerable to moisture erosion while adsorbing ethylene, hindering their long-term stable preservation effect and limiting their practical application in food packaging products such as food preservation bags. Therefore, developing a fruit preservation material that can stably maintain ethylene adsorption performance and is resistant to moisture interference has practical application value. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing ethylene adsorption and preservation materials, which are easily corroded by moisture and external gases and have rapid degradation of adsorption performance, and to provide a novel method for preparing fruit preservation materials. This method prepares a core-shell structured ZnM@EA fruit and vegetable preservation material. The zinc-based compound in the outer shell selectively allows ethylene-based olefin gases to permeate while simultaneously blocking the intrusion of external gases and moisture, protecting the core EA and enabling the core EA to maintain its ethylene adsorption performance for a long time. Applying this material to food preservation bags can reduce the ethylene concentration inside the bag and effectively extend the fruit's shelf life.

[0005] To address the aforementioned problems, the present invention proposes the following technical solution: a method for preparing a novel fruit preservation material, wherein the method is used to prepare a core-shell structured fruit and vegetable preservation material ZnM@EA; the ZnM@EA has EA as its core and a zinc-based compound as its outer shell; the zinc-based compound outer shell selectively allows ethylene-based olefin gases to permeate while blocking external gases and moisture from entering, protecting the core EA and maintaining its ethylene adsorption properties; the preparation method sequentially includes an EA core synthesis step and a ZnM coating step; The EA core synthesis steps are as follows: 1.46 g of cyclodextrin and 0.673 g of alkali are dissolved in 20 mL of water. Methanol is slowly added dropwise to the resulting aqueous solution while stirring at room temperature, and a white precipitate is formed in the system. Stirring is continued for 24 h for aging. After filtration, the filter cake is washed three times with methanol to obtain white EA solid. The obtained white EA solid is dispersed in methanol solvent to prepare EA methanol dispersion. The ZnM coating steps are as follows: zinc salt is added to the EA methanol dispersion to prepare solution A; oxalate and nitrogen-containing heterocyclic compound are dissolved in methanol to prepare solution B; solution B is added dropwise to solution A under stirring at room temperature; after the addition is complete, the mixture is stirred and matured for 120 min; after the reaction is complete, the mixture is filtered, the filter cake is washed with methanol, and dried at 60℃~80℃ to obtain ZnM@EA fruit preservation material.

[0006] Furthermore, the cyclodextrin is selected from any one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

[0007] Furthermore, the alkali is sodium hydroxide or potassium hydroxide.

[0008] Furthermore, the zinc salt is selected from any one of zinc citrate, zinc formate, zinc propionate, zinc gluconate, and zinc acetate.

[0009] Furthermore, the oxalate is sodium oxalate or potassium oxalate.

[0010] Furthermore, the nitrogen-containing heterocyclic compound is selected from any one of 3-amino-1,2,4-triazole, 1,2,3-triazole, 1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-methyl-1,2,4-triazole, imidazole, pyrazole, and tetrazolium.

[0011] Furthermore, in the EA core synthesis step, the volume of methanol added is 40mL-60mL.

[0012] Furthermore, the prepared ZnM@EA fruit preservation material was used to make food preservation bags. By reducing the ethylene concentration inside the preservation bag, fruit preservation and the fruit preservation period were extended.

[0013] Due to the adoption of the above technical solution, the beneficial effects of the preparation method of the novel fruit preservation material of the present invention are as follows: 1. The present invention prepares a core-shell structured ZnM@EA preservation material, in which the core EA serves as the main body for ethylene adsorption, and the outer shell is a zinc-based compound layer; the outer shell can selectively permeate ethylene-based olefin gases, and the ethylene released by the fruit can pass through the shell layer and be adsorbed by the core EA. At the same time, the outer shell blocks the intrusion of external water vapor and other gases, preventing the core EA from being destroyed by the environmental medium, and ensuring that the material can maintain its ethylene adsorption capacity for a long time.

[0014] 2. All reaction operations of this invention are completed at room temperature, the process conditions are mild, no high temperature and high pressure equipment is required, the preparation process is simple and controllable, and the post-processing only requires filtration, washing and low temperature drying. The production energy consumption is low and it is easy to scale up production.

[0015] 3. The ZnM@EA material prepared by this invention can be directly compounded to prepare food preservation bags, which can reduce the ethylene concentration inside the packaging bag, inhibit the ripening process of fruit, and extend the preservation and storage time of fruit; the material components are safe and suitable for food contact preservation packaging application scenarios. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0017] This embodiment provides a method for preparing a novel fruit preservation material, using α-cyclodextrin, sodium hydroxide, zinc citrate, sodium oxalate, and 3-amino-1,2,4-triazole as raw materials.

[0018] Synthesis of EA kernel: Take 1.46 g of α-cyclodextrin and 0.673 g of sodium hydroxide, add them to 20 mL of water, and stir until completely dissolved; under continuous stirring at room temperature, slowly add 50 mL of methanol, and a white precipitate gradually precipitates in the system; keep stirring at room temperature for 24 h for aging; after aging, filter and wash the filter cake three times with methanol to obtain white EA solid; disperse the white EA solid in methanol solvent to prepare EA methanol dispersion.

[0019] ZnM coating: Zinc citrate was added to the above EA methanol dispersion and stirred until homogeneous to obtain solution A; sodium oxalate and 3-amino-1,2,4-triazole were dissolved in methanol to prepare solution B; solution B was added dropwise to solution A under stirring at room temperature; after the addition was complete, stirring was continued for 120 min; after the reaction was completed, the mixture was filtered, the filter cake was washed with methanol, and dried at 70℃ to obtain core-shell structured ZnM@EA fruit preservation material.

[0020] The obtained ZnM@EA material was used to prepare food preservation bags: the material was added to the preservation bag substrate to make the bag, which was then filled with fruit to be preserved and sealed for storage. Ethylene released by the fruit inside the bag can pass through the zinc-based compound shell and be adsorbed by the EA core. The shell also blocks external moisture and other gases from entering, thereby reducing the ethylene concentration inside the bag, slowing down the fruit ripening process, and helping to extend the fruit's shelf life. Example

[0021] This embodiment provides a method for preparing a novel fruit preservation material, using β-cyclodextrin, potassium hydroxide, zinc formate, potassium oxalate, and imidazole as raw materials.

[0022] Synthesis of EA kernel: Take 1.46 g of β-cyclodextrin and 0.673 g of potassium hydroxide, add them to 20 mL of water, and stir until completely dissolved; under continuous stirring at room temperature, slowly add 40 mL of methanol, and a white precipitate gradually precipitates in the system; keep stirring at room temperature for 24 h for aging; after aging, filter and wash the filter cake three times with methanol to obtain white EA solid; disperse the white EA solid in methanol solvent to prepare EA methanol dispersion.

[0023] ZnM coating: Zinc formate was added to the above EA methanol dispersion and stirred until homogeneous to obtain solution A; potassium oxalate and imidazole were dissolved in methanol to prepare solution B; solution B was added dropwise to solution A under stirring at room temperature; after the addition was complete, stirring and aging continued for 120 min; after the reaction was completed, the mixture was filtered, the filter cake was washed with methanol, and dried at 60℃ to obtain core-shell structured ZnM@EA fruit preservation material.

[0024] The obtained ZnM@EA material was used to prepare food preservation bags, and its usage was the same as in Example 1. By reducing the ethylene concentration inside the bag, the ripening process of the fruit can be slowed down, which is beneficial to extending the fruit preservation period. Example

[0025] This embodiment provides a method for preparing a novel fruit preservation material, using γ-cyclodextrin, sodium hydroxide, zinc gluconate, sodium oxalate, and pyrazole as raw materials.

[0026] Synthesis of EA kernel: Take 1.46 g of γ-cyclodextrin and 0.673 g of sodium hydroxide, add them to 20 mL of water, and stir until completely dissolved; under continuous stirring at room temperature, slowly add 60 mL of methanol, and a white precipitate gradually precipitates in the system; keep stirring at room temperature for 24 h for aging; after aging, filter and wash the filter cake three times with methanol to obtain white EA solid; disperse the white EA solid in methanol solvent to prepare EA methanol dispersion.

[0027] ZnM coating: Zinc gluconate was added to the above EA methanol dispersion and stirred until homogeneous to obtain solution A; sodium oxalate and pyrazole were dissolved in methanol to prepare solution B; solution B was added dropwise to solution A under stirring at room temperature; after the addition was complete, stirring was continued for 120 min; after the reaction was completed, the mixture was filtered, the filter cake was washed with methanol, and dried at 80℃ to obtain core-shell structured ZnM@EA fruit preservation material.

[0028] The obtained ZnM@EA material was used to prepare food preservation bags, and its usage was the same as in Example 1. By reducing the ethylene concentration inside the bag, the ripening process of the fruit can be slowed down, which is beneficial to extending the fruit preservation period.

[0029] The present invention and its embodiments have been described above. This description is not restrictive. In short, if a person skilled in the art is inspired by this description and designs a similar structure and embodiment without departing from the spirit of the present invention, such design should fall within the protection scope of the present invention.

Claims

1. A method for preparing a novel fruit preservation material, characterized in that, The method is used to prepare a core-shell structured fruit and vegetable preservation material ZnM@EA; the ZnM@EA has EA as the core and a zinc-based compound as the shell; the zinc-based compound shell can selectively permeate ethylene-based olefin gases and block the intrusion of external gases and water vapor, protecting the core EA and enabling the core EA to maintain its ethylene adsorption performance; the preparation method includes, in sequence, an EA core synthesis step and a ZnM coating step. The EA core synthesis steps are as follows: 1.46 g of cyclodextrin and 0.673 g of alkali are dissolved in 20 mL of water. Methanol is slowly added dropwise to the resulting aqueous solution while stirring at room temperature, and a white precipitate is formed in the system. Stirring is continued for 24 h for aging. After filtration, the filter cake is washed three times with methanol to obtain white EA solid. The obtained white EA solid is dispersed in methanol solvent to prepare EA methanol dispersion. The ZnM coating steps are as follows: zinc salt is added to the EA methanol dispersion to prepare solution A; oxalate and nitrogen-containing heterocyclic compound are dissolved in methanol to prepare solution B; solution B is added dropwise to solution A under stirring at room temperature; after the addition is complete, the mixture is stirred and matured for 120 min; after the reaction is complete, the mixture is filtered, the filter cake is washed with methanol, and dried at 60℃~80℃ to obtain ZnM@EA fruit preservation material.

2. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, The cyclodextrin is selected from any one of α-cyclodextrin, β-cyclodextrin, and γ-cyclodextrin.

3. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, The alkali is sodium hydroxide or potassium hydroxide.

4. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, The zinc salt is selected from any one of zinc citrate, zinc formate, zinc propionate, zinc gluconate, and zinc acetate.

5. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, The oxalate is sodium oxalate or potassium oxalate.

6. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, The nitrogen-containing heterocyclic compound is selected from any one of 3-amino-1,2,4-triazole, 1,2,3-triazole, 1,2,4-triazole, 3,5-diamino-1,2,4-triazole, 3-methyl-1,2,4-triazole, imidazole, pyrazole, and tetrazolium.

7. The method for preparing a novel fruit preservation material according to claim 1, characterized in that, In the EA core synthesis step, the volume of methanol added is 40mL-60mL.