A humidity and pH dual-responsive aerogel fresh-keeping pad, a preparation method and application thereof

Abstract

This invention discloses a humidity- and pH-responsive aerogel preservation pad, its preparation method, and its application. The preparation method of the aerogel preservation pad includes the following steps: mixing bacterial cellulose and cellulose nanofibers, and then adding a hydrothermal polymer of perillaldehyde-carboxymethyl chitosan to obtain a mixed solution; performing a freeze-freezing treatment according to freezing parameters to form an ice template and then performing an immersion treatment; and finally drying the ice template according to atmospheric pressure drying parameters to obtain the aerogel preservation pad. The aerogel preservation pad prepared by this method releases perillaldehyde as the ambient humidity increases and the pH value decreases, thus being applied to the preservation of fresh fruits and vegetables, extending the shelf life of fruits and vegetables, and solving the problems of poor preservation effect and difficult degradation of preservation pads in existing room temperature preservation technologies.

Description

Technical Field

[0001] This application belongs to the field of functional materials for food technology, specifically relating to a humidity and pH dual-responsive aerogel preservation pad, its preparation method, and its application. Background Technology

[0002] Fresh fruits and vegetables such as strawberries and blueberries are prone to wrinkling, wilting, and rotting during storage and transportation, leading to a sharp decline in quality and causing serious economic losses.

[0003] Pathogen infection causes a series of irreversible quality deterioration processes in fruits and vegetables, including wilting, discoloration, and nutrient loss, significantly shortening shelf life and reducing commercial value. Currently, most commercially available fresh fruits and vegetables are preserved using polystyrene foam or polyolefin-based trays. However, these plastic-based preservation materials are non-renewable and non-degradable, causing "white pollution" and damaging ecosystems. Furthermore, the microplastics they produce can migrate into food, posing immeasurable harm to human health. Most also lack antibacterial activity, failing to meet the needs of fruit and vegetable preservation. Therefore, there is an urgent need to develop new, safe, green, and highly efficient preservation materials with room-temperature antibacterial and preservative activity. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in existing technologies by providing a humidity and pH dual-response aerogel preservation pad, its preparation method, and its application, which can solve problems such as poor preservation effect and difficulty in degradation of existing packaging materials.

[0005] To solve the above-mentioned technical problems, this application is implemented as follows:

[0006] A method for preparing a humidity- and pH-responsive aerogel food preservation pad includes the following steps: Bacterial cellulose was mixed with cellulose nanofibers to obtain a mixed solution; Adjust the pH of the above solution to 6-9 using an alkaline solution; Add perillaldehyde-carboxymethyl chitosan Schiff base to it and mix well; The mixed solution is subjected to freezing and pre-freezing treatment according to the freezing and pre-freezing parameters to form an ice template; According to the freezing and thawing parameters, the ice template was taken out and immersed in an anhydrous ethanol solution containing calcium salt with a mass concentration of 5% to 20%, and then immersed in anhydrous ethanol solution. After drying according to the normal pressure drying parameters, an aerogel pad is obtained.

[0007] Optionally, based on the mass of the mixed solution as 100%, the mass concentration of bacterial cellulose is 1% to 2%; the mass concentration of cellulose nanofibers is 1% to 1.5%; and the mass concentration of perillaldehyde-carboxymethyl chitosan Schiff base is 10% to 15%.

[0008] Optionally, the freezing and pre-freezing parameters include: pre-freezing temperature -75 to -85°C, and pre-freezing time of 15 to 20 hours; The freezing and thawing parameters include: thawing temperature of -20 to -15°C and thawing time of 15 to 20 hours. The atmospheric pressure drying parameters include: drying temperature of 62-65℃ and drying time of 3-5 h.

[0009] Optionally, the perillaldehyde-carboxymethyl chitosan Schiff base is prepared by reacting perillaldehyde and carboxymethyl chitosan. The reaction process is as follows: perillaldehyde essential oil is added to a saturated carboxymethyl chitosan solution, and an equal volume of anhydrous ethanol solution is added. After homogenization, a hydrothermal reaction is carried out. After the resulting liquid is allowed to stand at room temperature, it is washed multiple times with anhydrous ethanol. The resulting gel-like yellow colloid is the biresponsive perillaldehyde-carboxymethyl chitosan Schiff base. The hydrothermal reaction parameters include: a reaction time of 8–10 h and a reaction temperature of 80–90 °C.

[0010] A humidity and pH dual-responsive aerogel food preservation mat is prepared by any one of the humidity and pH dual-responsive aerogel food preservation mat preparation methods of the present invention.

[0011] Optionally, the preservation pad has a density of 0.2 g / cm³, possesses excellent water absorption properties, and can release perillaldehyde in response to increases in ambient humidity and decreases in pH value, thereby achieving antibacterial and preservation effects.

[0012] The humidity and pH dual-response aerogel preservation pad described in this invention is used for the preservation of fruits and vegetables.

[0013] Optionally, specific preservation methods include: placing the humidity and pH dual-response aerogel preservation pad at the bottom of the storage container to support and surround the fruits and vegetables to be preserved, thereby achieving storage and preservation.

[0014] Optional, specific preservation methods include: placing a humidity and pH dual-response aerogel preservation pad at the bottom of the storage container, placing the fruits and vegetables to be preserved on it, and then storing them in a sealed container at room temperature.

[0015] Optionally, the storage temperature is 4–23°C.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The preparation method of the aerogel food preservation pad proposed in this application is characterized by green environmental protection and efficient resource utilization. By introducing cellulose nanofibers as reinforcing units into bacterial cellulose, renewable biomass resources are fully utilized, effectively reducing dependence on petrochemical raw materials. The composite of biomass fibers not only reduces material costs but also endows the aerogel with biodegradable properties, which is in line with the concept of sustainable development. At the same time, solvent replacement and atmospheric pressure drying are adopted, which simplifies the traditional preparation process, reduces the requirements for equipment conditions, and effectively avoids the collapse of the pore structure through atmospheric pressure drying technology, providing technical feasibility for large-scale production; (2) The preparation method of the aerogel preservation pad proposed in this application selects perilla aldehyde essential oil, a natural plant extract, as the active ingredient, and generates a pH and humidity responsive aerogel preservation pad by hydrothermal polymerization with carboxymethyl chitosan to encapsulate the plant essential oil. This can solve the problems of low water solubility and easy volatility of plant essential oil, thereby bringing better preservation effect. (3) The aerogel preservation pad prepared in this application is a slow-release preservation pad. Compared with the traditional one that only relies on plant essential oils for preservation, the aerogel preservation pad of this application combines the excellent properties of plant essential oils, fruit storage microenvironment and aerogel. It has good pH and humidity response slow-release performance and can continuously and slowly release essential oil components in high humidity and high acidity environments, and has a long-lasting effect on fresh strawberries, blueberries and other fruits and vegetables. (4) The aerogel preservation pad prepared in this application has good mechanical properties, effectively reducing the risk of mechanical damage from the perspective of physical protection, thereby enhancing the adaptability of fruits and vegetables to the environment during storage and achieving excellent preservation effect. Moreover, the preparation method is simple to operate, green and environmentally friendly, effectively improving the effect of essential oils and significantly improving the quality of fresh strawberries and blueberries. Attached Figure Description

[0017] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings: Figure 1 These are different proportions of aerogel morphology in Example 1; Figure 2 The densities of different proportions of aerogel in Example 1; Figure 3 Infrared spectra of aerogels with different proportions in Example 1; Figure 4 The perillaldehyde-carboxymethyl chitosan Schiff base-cellulose aerogel pad prepared in Example 2; Figure 5 The humidity response of the aerogel pad; Figure 6 pH response of the aerogel pad; Figure 7The antibacterial activity of aerogel pads; Figure 8 For comparative examples and embodiments, the application of aerogel pads in the preservation of strawberries; Figure 9 To compare the preservation effect of treated strawberries in the examples and embodiments; Figure 10 The changes in firmness, weight loss, and titratable acid content of strawberries were compared with those of the comparative and example strawberries. Figure 11 For comparative examples and implementation examples of preservation applications on blueberries; Figure 12 To compare the preservation effect of treated blueberries in the examples and embodiments; Figure 13 The changes in firmness, weight loss, and titratable acid content of blueberries were compared with those of the comparative and example blueberries. Detailed Implementation

[0018] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0019] This invention, through material innovation and process optimization, successfully prepared a multifunctional aerogel that combines the sustained-release properties of essential oils with excellent mechanical properties, breaking through the performance limitations of traditional aerogels and providing a new paradigm for the development of green high-performance materials.

[0020] In this invention, bacterial cellulose (BC) is a type of cellulose produced by microbial fermentation, with a solid content of about 1.5%, and is an aqueous dispersion that is flocculent and semi-transparent.

[0021] Cellulose nanofibers (CNF) are a type of nanocellulose prepared by the TEMPO oxidation method. They have a solid content of 1-1.2%, contain hydroxyl and carboxyl groups on their surface, are semi-transparent, and have excellent dispersibility.

[0022] This invention provides a method for preparing an aerogel food preservation pad, comprising the following steps: mixing bacterial cellulose (BC) with cellulose nanofibers (CNF) to obtain a mixed solution; adjusting the pH of the above solution with a 0.1 mol / L sodium hydroxide solution; adding 3% to 20% of perillaldehyde-carboxymethyl chitosan Schiff base and homogenizing with a homogenizer, and placing it in a 4°C refrigerator for crosslinking overnight; performing a freeze-pre-freezing treatment on the mixed solution according to freeze-pre-freezing parameters to form an ice template; removing the ice template according to freeze-thaw parameters and immersing it in a 10% anhydrous ethanol solution of calcium salts (including calcium nitrate, calcium chloride, etc.), and then immersing it in an equal volume of anhydrous ethanol solution; drying according to atmospheric pressure drying parameters to obtain the aerogel pad.

[0023] In this invention, the mass concentration of bacterial cellulose is 1% to 2% based on the mass of the mixed solution being 100%; and the mass concentration of the cellulose nanofibers is 1% to 1.5%.

[0024] In this invention, the mass concentration of perillaldehyde-carboxymethyl chitosan Schiff base is 10%–15% based on the mass of the mixed solution as 100%. Perillaldehyde-carboxymethyl chitosan Schiff base is prepared by reacting perillaldehyde and carboxymethyl chitosan. The reaction process is as follows: perillaldehyde essential oil is added to a saturated carboxymethyl chitosan solution, and an equal volume of anhydrous ethanol solution is added. The mixture is then homogenized using a high-speed dispersant homogenizer for 3 min. The resulting solution is placed in an 80 ℃ constant temperature oil bath and stirred at 1000 rpm / min for 10 hours. After the reaction, the resulting liquid is allowed to stand at room temperature and then washed repeatedly with anhydrous ethanol to thoroughly remove the perillaldehyde essential oil adhering to the exterior of the carboxymethyl chitosan. The resulting gel-like yellow colloid is the biresponsive perillaldehyde-carboxymethyl chitosan Schiff base, named PC. In this invention, bacterial cellulose and cellulose nanofibers are mixed in volume ratios of 1:9, 3:7, 1:1, 7:3 and 9:1, respectively.

[0025] In this invention, the concentration of the sodium hydroxide solution is 0.1~1 mol / L.

[0026] In this invention, the reaction conditions for perillaldehyde-carboxymethyl chitosan Schiff base are a reaction time of 8-10 h, a reaction temperature of 80-90 °C, and a stirring rate of 1500 r / min.

[0027] In this invention, the freezing and pre-freezing parameters include: a pre-freezing temperature of -75 to -85°C and a pre-freezing time of 15 to 20 h; the freezing and thawing parameters include: a thawing temperature of -20 to -15°C and a thawing time of 15 to 20 h; and the atmospheric pressure drying parameters include: a drying temperature of 62 to 65°C and a drying time of 3 to 5 h.

[0028] This invention provides an aerogel food preservation mat, which is prepared by the above-described aerogel food preservation mat preparation method.

[0029] This invention provides an application of aerogel preservation mats for preserving fresh fruits and vegetables such as strawberries and blueberries, comprising the following steps: Fresh strawberries and blueberries are pre-treated to obtain pre-treated fresh strawberries and blueberries; Place an aerogel food storage mat at the bottom of the storage container, put fresh strawberries and blueberries on top, and then store them.

[0030] In this invention, the pretreatment includes selection; the step of placing an aerogel preservation pad at the bottom of a storage container, placing fresh strawberries and blueberries on it, and then storing them specifically includes: placing an aerogel preservation pad at the bottom of a storage container to surround the pretreated fresh strawberries and blueberries, and then storing them in a sealed container at room temperature.

[0031] In this invention, the storage temperature is 4 to 23°C, and the preferred room temperature storage temperature is 23°C.

[0032] To better understand the essence of the invention, the following embodiments are used to illustrate the technical content of the invention in detail, but the invention is not limited to these embodiments.

[0033] Example 1: Preparation of Aerogel Pads Previous studies investigated cellulose aerogel carriers prepared by different ratios of bacterial cellulose and cellulose nanofibers (1:9, 3:7, 1:1, 7:3, 9:1), such as... Figure 1 As shown. The densities of aerogels with different proportions are as follows. Figure 2 As shown. Infrared spectra of aerogels with different proportions are shown in the figure. Figure 3 As shown. Figure 1 Experimental results show that neither pure BC nor pure CNF can maintain a good shape after being dried under normal pressure, and both materials collapse to varying degrees. However, when BC and CNF are mixed, CNF can effectively fill the large pores in the three-dimensional network of BC. The combination of the two reduces the internal voids of the material, making the structure more compact. Furthermore, the huge specific surface area of ​​CNF greatly increases the hydrogen bonding points between fibers, forming a denser hydrogen bond network, thereby significantly improving the structural strength and mechanical properties of the material. By adjusting the ratio of BC to CNF, the pore size and distribution of the final material can be controlled, thus meeting specific requirements. Figure 2 This indicates that a higher BC ratio can form a higher density structure, while the appropriate introduction of CNF can play a certain role in regulating and optimizing the material density. The aerogel prepared by the 1:1 ratio has excellent density and appearance, with a density of 23 mg / cm³. 3 . Figure 3 Infrared spectroscopy revealed that the introduction of BC into the CNF system may partially disrupt the existing dense hydrogen bond network, leading to more hydroxyl groups forming single-type or more uniformly strong hydrogen bonds with BC molecules. Considering the practical applications of fruit and vegetable preservation, we selected a 1:1 volume ratio of BC to CNF as the final preparation condition.

[0034] Bacterial cellulose and cellulose nanofibers were mixed uniformly at a volume ratio of 1:1. The pH was adjusted to approximately 7 using a 0.1 mol / L sodium hydroxide solution. The mixture was then ultrasonically cleaned for 30 min, followed by the addition of 5% perillaldehyde-carboxymethyl chitosan Schiff base. After thorough mixing, the mixture was placed in a mold for shaping and left overnight at 4°C to allow for full cross-linking. The next day, it was frozen at -80°C for 36 h to form an ice template. The ice template was then immersed in a 20% calcium nitrate alcohol solution and placed at -20°C for solvent exchange. After a certain time, it was immersed again in anhydrous ethanol. After soaking for a certain period, the ice template was removed from the anhydrous ethanol and dried in a 60-65°C oven for 3 hours. It was then stored in a dry place for later use. The prepared aerogel pad is shown below. Figure 4 As shown. This aerogel mat was used as the experimental material for subsequent humidity and pH response experiments, antibacterial activity experiments, and fruit preservation experiments.

[0035] Example 2: Humidity and pH response of aerogels The responsive release of aerogel materials can not only reduce the volatilization loss of perillaldehyde but also enable its controlled utilization. An aerogel material with a BC / CNF ratio of 1:1 and a Schiff base loading of 5% was used as the experimental subject. Figure 5 and 6 The prepared aerogel pad exhibits dual pH and humidity responsiveness. To verify the controllable release of perillaldehyde from the aerogel material under different humidity levels, release curves were plotted under different humidity conditions (35%, 80%), as shown below. Figure 5 As shown, under high humidity (80%), perillaldehyde was rapidly and significantly released, reaching approximately 81% of its final release within 7 days. However, under low humidity (35%), the release process quickly plateaued after 2-3 days, with the final release limited to around 38%. This indicates the material's significant potential as a humidity-responsive release system.

[0036] To investigate the responsiveness of aerogels to acidic environments, pH response experiments were designed using PBS solutions with different pH values ​​for testing. Figure 6 The release rate of perillaldehyde from the aerogel material over time was shown in liquid environments at different pH values ​​(3, 5, and 7). In an acidic environment (pH 3), the material exhibited rapid and almost complete release (>95%), while in a neutral environment (pH 7), release was significantly inhibited (approximately 43%). The release behavior at pH 5 was intermediate between the two. This strong pH dependence indicates the material's great potential as a pH-responsive release system.

[0037] Example 3 Antibacterial activity To investigate the antibacterial effect of aerogel materials against *Botrytis cinerea*, we conducted in-vessel antibacterial experiments. In-vessel antibacterial experiments were performed on materials with different PC contents. Under the fumigation effect of the materials, the antibacterial rate first increased and then decreased with increasing dosage, revealing a dynamic balance between "release of active ingredients" and "blockage of release channels." B1C1S5 exhibited superior antibacterial performance, where the aerogel maximized the release of volatile antibacterial molecules without blocking itself. Aerogels loaded with Schiff bases released the antibacterial substance perillaldehyde, which diffused through the gas phase into the entire petri dish space, acting on *Botrytis cinerea*. With a Schiff base loading of 3%, the antibacterial rate was 34% after five days, while B1C1S5 reached 44%. The subsequent antibacterial rates for B1C1S7 and B1C1S10 were 28% and 24%, respectively. This means that loading more Schiff bases produces a higher concentration of volatile antibacterial molecules accumulating in the sealed space of the petri dish, but the antibacterial rate decreased with increasing Schiff base content. At excessively high doses, aerogel particles are more prone to agglomeration, which significantly reduces the effective total release surface area and increases the difficulty of internal molecular diffusion, thereby reducing the overall release efficiency. The results indicate that this material has an "optimal loading rate"; beyond 5%, the physical adsorption properties of the aerogel carrier shift from an advantage to a disadvantage, beginning to inhibit its function. Experimental results are as follows: Figure 7 As shown.

[0038] Example 4: Preserving Strawberries Fresh, uniformly sized, appropriately ripe, and free from pests, diseases, and mechanical damage were selected from the market and placed indoors for 12 hours. An aerogel material with a BC / CNF ratio of 1:1 and a Schiff base loading of 5% was used as the experimental material. The prepared preservation pad was placed at the bottom of the fruit, and fresh strawberries were placed in the middle of the preservation box. The fresh strawberries were then stored in a sealed container at room temperature (20-23°C) to preserve them. Compared to the examples, the comparative example only used a commercially available bottom fruit tray, indicating that the preservation effect of the commercially available bottom fruit tray is not as good as that of the essential oil slow-release aerogel preservation pad of this application. The placement method is as follows... Figure 8 As shown.

[0039] The fruit appearance of the comparative and example samples was observed and measured at 0, 3, 5, and 7 days, and relevant indicators were determined. Based on the results... Figure 9 The results showed that the decay rate of the fruit in the example group was significantly reduced. The comparative example showed signs of decay by the 3rd day of storage, and the decay rate reached 99% by the 7th day, while the fruit in the example group showed no obvious decay. The experiment demonstrates that the aerogel material successfully extended the shelf life of strawberries at room temperature from 3 days to 7 days. Figure 10 As shown, the embodiment is superior to the comparative example in terms of hardness, weight loss rate, and titratable acidity during storage.

[0040] Example 5: Preserving Blueberries Fresh, uniformly sized, appropriately ripe, and free from pests, diseases, and mechanical damage were selected from the market and placed indoors for 12 hours. An aerogel material with a BC / CNF ratio of 1:1 and a Schiff base loading of 5% was used as the experimental material. The prepared preservation pad was placed at the bottom of the fruit, and fresh blueberries were placed in the middle of the preservation box. The fresh blueberries were then stored in a sealed container at room temperature (20-23°C) to preserve them. Compared to the examples, the comparative example only used a commonly available bottom fruit tray, indicating that the preservation effect of the commonly available bottom fruit tray is not as good as that of the essential oil slow-release aerogel preservation pad of this application. The placement method is as follows... Figure 11 As shown.

[0041] The fruit appearance of the comparative example and the embodiment were observed and measured at 0, 3, 5, 7, and 10 days, and the relevant indicators were determined. Based on the results... Figure 12 The results showed that the rot rate of the fruits in the example group was significantly reduced. The comparative example showed signs of rot on the 3rd day of storage, reaching 50% rot rate on the 7th day, and almost completely rotten by the 10th day. In contrast, the fruits in the example group did not rot until the 10th day. The experiment demonstrates that the aerogel material successfully extended the shelf life of blueberries at room temperature from 3 days to 10 days. Figure 13 As shown, the embodiment outperforms the comparative example in terms of rot rate, hardness, weight loss rate, and titratable acidity during storage.

[0042] The embodiments of this application have been described above with reference to the accompanying drawings. However, this application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of this application.

Claims

1. A method for preparing a humidity and pH dual-responsive aerogel fresh-keeping pad, characterized in that, Includes the following steps: Bacterial cellulose was mixed with cellulose nanofibers to obtain a mixed solution; Adjust the pH of the above solution to 6-9 using an alkaline solution; Add perillaldehyde-carboxymethyl chitosan Schiff base to it and mix well; The mixed solution is subjected to freezing and pre-freezing treatment according to the freezing and pre-freezing parameters to form an ice template; According to the freezing and thawing parameters, the ice template was taken out and immersed in an anhydrous ethanol solution containing calcium salt with a mass concentration of 5% to 20%, and then immersed in anhydrous ethanol solution. After drying according to the normal pressure drying parameters, an aerogel pad is obtained.

2. The method for preparing the humidity and pH dual-response aerogel food preservation pad according to claim 1, characterized in that, Based on the mass of the mixed solution as 100%, the mass concentration of bacterial cellulose is 1% to 2%; the mass concentration of cellulose nanofibers is 1% to 1.5%; and the mass concentration of perillaldehyde-carboxymethyl chitosan Schiff base is 10% to 15%.

3. The method of claim 1 or 2, wherein the method is characterized by, The freezing and pre-freezing parameters include: pre-freezing temperature -75 to -85℃, and pre-freezing time 15 to 20 hours; The freezing and thawing parameters include: thawing temperature of -20 to -15°C and thawing time of 15 to 20 hours. The atmospheric pressure drying parameters include: drying temperature of 62-65℃ and drying time of 3-5 h.

4. The method of claim 1 or 2, wherein the method is characterized by, The perillaldehyde-carboxymethyl chitosan Schiff base is prepared by reacting perillaldehyde and carboxymethyl chitosan. The reaction process is as follows: perillaldehyde essential oil is added to a saturated carboxymethyl chitosan solution, and an equal volume of anhydrous ethanol solution is added. After homogenization, a hydrothermal reaction is carried out. After the resulting liquid is allowed to stand at room temperature, it is washed multiple times with anhydrous ethanol. The resulting gel-like yellow colloid is the biresponsive perillaldehyde-carboxymethyl chitosan Schiff base. The hydrothermal reaction parameters include: a reaction time of 8–10 h and a reaction temperature of 80–90 °C.

5. A humidity and pH dual-responsive aerogel fresh-keeping pad, characterized in that, It is prepared by the method of any one of claims 1 to 4 for preparing a humidity and pH dual-responsive aerogel food preservation pad.

6. The humidity and pH dual-responsive aerogel fresh-keeping pad according to claim 5, characterized in that, The preservation pad has a density of 0.2 g / cm³, excellent water absorption, and can release perillaldehyde in response to increases in ambient humidity and decreases in pH, thereby achieving antibacterial and preservation effects.

7. The application of the humidity and pH dual-response aerogel preservation mat according to claim 5 or 6 for the preservation of fruits and vegetables.

8. Use according to claim 7, characterized in that, Specific preservation methods include: placing the humidity and pH dual-response aerogel preservation pad at the bottom of the storage container to support and surround the fruits and vegetables to be preserved, thereby achieving storage and preservation.

9. Use according to claim 7, characterized in that, Specific preservation methods include: placing a humidity and pH dual-response aerogel preservation pad at the bottom of the storage container, placing the fruits and vegetables to be preserved on it, and then storing them in a sealed container at room temperature.

10. Use according to claim 8 or 9, characterized in that, The storage temperature is 4–23°C.

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