Liquid preservative for fresh walnut kernel

Abstract

This invention relates to the field of food preservation technology and discloses a liquid preservative for preserving fresh walnut kernels. The preservative comprises a natural preservative, a solubilizing and stabilizing agent, and a solvent. This liquid preservative uses natural phloretin as the preservative component, combined with Tween 80 as a solubilizing and stabilizing agent and ethanol as a solvent. This effectively solves the problems of poor water and oil solubility and inadequate stability of phloretin, allowing it to be stably dispersed in the preservative system and fully exert its antioxidant and antimicrobial effects. Furthermore, the preparation method is simple and easy to implement, and the production process is safe and controllable. It is convenient to use; the preservation of fresh walnut kernels can be achieved through dilution and soaking. The diluted solution can be reused, reducing usage costs. Simultaneously, it can inhibit bacterial growth during the storage of fresh walnut kernels, delay oxidative deterioration, maintain their good appearance and quality, extend shelf life, and meet the market demand for high-quality fresh walnut kernels.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, specifically to a liquid preservative for preserving fresh walnut kernels. Background Technology

[0002] Compared to traditional dried walnuts, fresh walnut kernels are rich in unsaturated fatty acids, lecithin, cephalin, vitamin E, protein, dietary fiber, and various minerals, and have a sweet taste, making them popular with consumers, especially those who value health and a healthy diet. Market demand has been rising steadily in recent years. However, their high water and fat content makes them prone to spoilage after the skin is removed. Given that fresh walnut kernels are easily oxidized and spoiled due to their high fat content, and consumers' increasing demand for high-quality and natural ingredients, there is an urgent need to develop natural and efficient preservation technologies to extend their shelf life and meet the market's continued demand for high-quality fresh walnut kernels. Phloretin, as a preservative, primarily benefits from its natural antioxidant and antimicrobial properties, as well as its regulatory effects on cell metabolism. Phloretin is a natural dihydrochalcone compound found in the peel and root bark of fruits such as apples and pears. It possesses excellent antioxidant capabilities, effectively scavenging free radicals and delaying the oxidative spoilage process of food. Simultaneously, it exhibits antimicrobial activity, inhibiting the growth of harmful microorganisms and thus extending the shelf life of food. More importantly, studies have shown that phloretin has no cytotoxicity to normal cells, ensuring its safety as a food preservative. Although phloretin is a natural functional active ingredient, its application is not widespread at present. The main reasons are: first, phloretin has poor water and oil solubility, making it difficult to apply directly to product formulations; second, phloretin has poor stability, is prone to oxidation and discoloration, and affects the appearance of products. There are no research reports on the application of phloretin as a preservative for the preservation of fresh walnut kernels. Therefore, there is an urgent need to develop a natural and efficient liquid preservative that can solve the above problems and is suitable for fresh walnut kernels. Summary of the Invention

[0003] The purpose of this invention is to provide a liquid preservative for preserving fresh walnut kernels, so as to solve the problem mentioned in the background art that existing fresh walnut kernels are difficult to preserve effectively.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a liquid preservative for preserving fresh walnut kernels, the liquid preservative comprising the following components by weight: 1-3 parts of natural preservative, 2-4 parts of solubilizing and stabilizing agent, and 125-130 parts of solvent. The natural preservative is phloretin powder; The solubilizing stabilizer is Tween 80; The solvent is ethanol.

[0005] The above technical solution facilitates the utilization of phloretin's natural antioxidant and antimicrobial properties. At the same time, the solubilizing and stabilizing effect of Tween 80 improves the defects of phloretin's poor water solubility and easy oxidation and discoloration. Combined with ethanol solvent, it achieves uniform dispersion of each component, forming a stable and effective preservation system, and specifically solves the problems of fresh walnut kernels being high in fat and easily oxidized, and easily spoiled after the kernel skin is removed.

[0006] As a preferred embodiment of the present invention, the phloretin powder has a purity of ≥95% and a particle size of ≤100μm; the Tween 80 has a purity of ≥98%; and the ethanol has a volume fraction of 75% to 95%.

[0007] The above technical solution ensures the activity and stability of each raw material. High-purity phlorizin ensures preservation efficacy, and small particle size facilitates dissolution and dispersion. High-purity Tween 80 avoids interference from impurities and improves solubility. A specific concentration of ethanol can not only efficiently dissolve the raw materials but also help inhibit microorganisms, thus ensuring the overall performance of the preservative.

[0008] A method for preparing a liquid preservative for preserving fresh walnut kernels includes the following steps: Step 1, Dissolving: The natural preservative and solubilizing stabilizer are placed in a solvent and stirred to dissolve, resulting in a homogeneous mixture; Step 2, Filtration: Filter the mixture to remove impurities and ensure its clarity. Step 3, Sterilization: Place the filtered mixture in a sterile environment and treat it with ultraviolet sterilization to achieve sterilization of the mixture; Step 4: Filling: Under aseptic conditions, quickly fill the sterilized liquid preservative into sealed containers, seal immediately after filling, and store in a dark, room-temperature environment.

[0009] The above technical solution facilitates the stable production of preservatives through standardized processes. The dissolution step ensures that all components are fully integrated, while the filtration and sterilization steps eliminate the risk of impurities and microbial contamination. Aseptic filling and light-proof storage can prevent the preservatives from oxidizing and deteriorating, extend their shelf life, and ensure their safety in use.

[0010] As a preferred embodiment of the present invention, in step two, the mixture is filtered using an organic phase filter membrane with a pore size of 0.22 μm.

[0011] The above technical solution facilitates the effective removal of minute impurities, incompletely dissolved particles, and some microorganisms from the mixture, further improving the clarity and purity of the preservative, preventing impurities from affecting the preservation effect or causing spots on the surface of the walnut kernels, and laying the foundation for subsequent sterilization steps.

[0012] As a preferred technical solution of the present invention, the ultraviolet sterilization treatment time in step three is 20-30 minutes, the ultraviolet lamp power is 30-40W, and the irradiation distance is controlled at 30-50cm.

[0013] The above technical solution facilitates efficient aseptic processing without damaging the effective components of the preservative. This parameter range ensures that ultraviolet light fully acts on the mixture to completely kill residual microorganisms, while avoiding oxidation of phloretin or changes in solvent properties due to excessive irradiation, thus ensuring the stability of the preservative's efficacy.

[0014] A method for using a liquid preservative for preserving fresh walnut kernels includes the following steps: S1. Dilution: Add water to the liquid preservative to dilute it, and stir well to obtain a diluted solution; S2. Soaking: Soak the fresh walnut kernels (after removing the skin) in a diluted solution. S3. Packaging: Take out the soaked fresh walnut kernels, drain the surface moisture, and then package them.

[0015] The above technical solution is easy to operate and implement. The dilution step reduces the concentration of preservatives, avoiding the impact of high concentrations on the taste of walnuts. The soaking method allows the preservatives to adhere evenly to the surface of the walnuts, forming a protective film. Subsequent packaging can reduce secondary contamination and extend the shelf life of the walnuts.

[0016] As a preferred embodiment of the present invention, in step S1, the liquid preservative and water are in a weight ratio of 1:2 to 4.

[0017] The above technical solution facilitates the control of the concentration of effective ingredients in the diluent, ensuring that components such as phloretin can exert their antioxidant and antibacterial effects, while avoiding taste residue or cost waste caused by excessive concentration, thus achieving a balance between preservation effect and eating experience.

[0018] As a preferred embodiment of the present invention, in step S2, the fresh walnut kernels are completely immersed in the diluent for 5 to 10 minutes.

[0019] The above technical solution ensures that the walnut kernels are fully in contact with the diluent, allowing the preservative ingredients to be evenly adsorbed onto their surface and form an effective protective layer. This time range not only meets the requirements for ingredient adhesion but also avoids excessive soaking, which can lead to excessive water absorption and a deterioration in taste, thus balancing preservation effect and product quality.

[0020] As a preferred embodiment of the present invention, the diluent in step S2 can be reused repeatedly until a distinct yellow color is observed.

[0021] The above technical solution facilitates improved resource utilization and reduced usage costs. At the same time, the color change allows for a direct assessment of the diluent's failure point, preventing a decline in preservation effect due to the depletion of effective components in the diluent and ensuring that the diluent achieves the expected preservation effect each time it is used.

[0022] Compared with the prior art, the beneficial effects of the present invention are: the liquid preservative for preserving fresh walnut kernels; Using phloretin powder as the core natural preservative, combined with Tween 80 as a solubilizer and a specific concentration of ethanol as a solvent, it not only successfully solves the inherent defects of phloretin's poor water solubility and easy oxidation and discoloration, achieving uniform dispersion and stable coexistence of each component, but also fully leverages the natural antioxidant and antimicrobial properties of phloretin, specifically addressing the industry pain points of fresh walnut kernels being easily oxidized due to their high fat content and easily spoiled after the skin is removed; Its preparation process involves a standardized procedure of dissolution, organic phase filtration membrane filtration, ultraviolet sterilization, and aseptic light-proof filling, which effectively ensures the purity, sterility, and stability of the preservative and avoids contamination by impurities and the failure of effective ingredients. When using it, simply dilute it and soak the walnut kernels in it. The operation is simple and does not add any extra production steps. At the same time, the diluted solution can be reused until it turns a clear yellow color, which not only improves resource utilization and reduces usage costs, but also allows for a direct judgment of the effectiveness of the product through color changes. It can inhibit bacterial growth and browning during the storage of fresh walnut kernels, significantly reduce malondialdehyde content, effectively delay oxidative deterioration and quality degradation, and significantly extend the shelf life of the product under refrigeration conditions. Moreover, the phloretin is a natural ingredient with no risk of consumption, and both Tween 80 and ethanol meet food-grade standards, ensuring the health and safety of the product. It combines excellent preservation effect, superior eating experience and economic practicality, providing the fresh walnut kernel industry with a natural, efficient, stable, reliable, easy-to-operate and cost-controllable preservation solution, meeting the market's continuous demand for high-quality, natural and safe fresh walnut kernels. Attached Figure Description

[0023] Figure 1 The image shows a comparison of the preservation effects of walnut kernels treated in Embodiment 1, Embodiment 2, and Comparative Example 1 after 20 days of cold storage. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0025] The present invention provides a liquid preservative for preserving fresh walnut kernels. The liquid preservative comprises the following components by weight: 1 part natural preservative, 2 parts solubilizing and stabilizing agent, and 125 parts solvent. The natural preservative is phloretin powder with a purity of 95% and a particle size of 100 μm. The solubilizing and stabilizing agent is Tween 80 with a purity of 98%. The solvent is ethanol with a volume fraction of 90%.

[0026] A method for preparing a liquid preservative for preserving fresh walnut kernels includes the following steps: Step 1, Dissolving: The natural preservative and solubilizing stabilizer are placed in a solvent and stirred to dissolve, resulting in a homogeneous mixture; Step 2, Filtration: The mixture is filtered using an organic phase filter membrane with a pore size of 0.22 μm to remove impurities and ensure the clarity of the mixture. Step 3, Sterilization: Place the filtered mixture in a sterile environment and treat it with ultraviolet sterilization for 20 minutes. The ultraviolet lamp power is 40W and the irradiation distance is controlled at 30cm to achieve sterilization of the mixture. Step 4: Filling: Under aseptic conditions, quickly fill the sterilized liquid preservative into sealed containers, seal immediately after filling, and store in a dark, room-temperature environment.

[0027] A method for using a liquid preservative for preserving fresh walnut kernels includes the following steps: S1. Dilution: Add water to the liquid preservative at a weight ratio of 1:2 and stir well to obtain the diluted solution; S2. Soaking: Immerse all the fresh walnut kernels (after removing the skin) in the diluted solution for 5 minutes. S3. Packaging: After soaking, remove the fresh walnut kernels, drain the surface moisture, pack them in a plastic bag, seal the bag, and store in the refrigerator. Example 2

[0028] The present invention provides a liquid preservative for preserving fresh walnut kernels. The liquid preservative comprises the following components by weight: 3 parts of a natural preservative, 4 parts of a solubilizing and stabilizing agent, and 130 parts of a solvent. The natural preservative is phloretin powder with a purity of 97% and a particle size of 100 μm. The solubilizing and stabilizing agent is Tween 80 with a purity of 99%. The solvent is ethanol with a volume fraction of 95%.

[0029] A method for preparing a liquid preservative for preserving fresh walnut kernels includes the following steps: Step 1, Dissolving: The natural preservative and solubilizing stabilizer are placed in a solvent and stirred to dissolve, resulting in a homogeneous mixture; Step 2, Filtration: The mixture is filtered using an organic phase filter membrane with a pore size of 0.22 μm to remove impurities and ensure the clarity of the mixture. Step 3, Sterilization: Place the filtered mixture in a sterile environment and treat it with ultraviolet sterilization for 30 minutes. The ultraviolet lamp power is 30W and the irradiation distance is controlled at 50cm to achieve sterilization of the mixture. Step 4: Filling: Under aseptic conditions, quickly fill the sterilized liquid preservative into sealed containers, seal immediately after filling, and store in a dark, room-temperature environment.

[0030] A method for using a liquid preservative for preserving fresh walnut kernels includes the following steps: S1. Dilution: Add water to the liquid preservative at a weight ratio of 1:4 to dilute it, and stir well to obtain the diluted solution. S2. Soaking: Immerse all the fresh walnut kernels (after removing the skin) in the diluted solution for 10 minutes. S3. Packaging: After soaking, remove the fresh walnut kernels, drain the surface moisture, pack them in a plastic bag, seal the bag, and store in the refrigerator.

[0031] Comparative Example 1 Take fresh walnut kernels with the skin removed, soak them in distilled water for 5 minutes, drain them, seal them in a plastic bag, and store them in the refrigerator.

[0032] The fresh walnut kernels treated in Example 1, Example 2, and Comparative Example 1 were tested after being stored in a refrigerator for 20 days. Visual inspection: Specifically as follows Figure 1 As shown, after 20 days of cold storage, the fresh walnut kernels in Comparative Example 1 showed obvious yellowing on the surface and many black spots, indicating a serious deterioration in appearance quality. However, the samples in Examples 1 and 2 treated with the liquid preservative of this invention maintained the unique white color of fresh walnut kernels, without yellowing, black spots, or other deterioration. Their overall appearance was significantly better than that of Comparative Example 1, fully demonstrating the good effect of the preservative on maintaining the appearance quality of walnut kernels. Total bacterial count and malondialdehyde (MDA) content determination: details are shown in the table below.

[0033] From the test data in the table above, we can see that: Regarding the total bacterial count, the total bacterial count of Comparative Example 1 reached 330 CFU / g after 20 days of storage, while the total bacterial counts of Examples 1 and 2 after the same storage period were only 40 CFU / g and 20 CFU / g, respectively, which were 87.9% and 93.9% lower than that of Comparative Example 1. This indicates that the liquid preservative of the present invention can effectively inhibit the bacterial proliferation during the storage of fresh walnut kernels and significantly reduce the risk of microbial contamination. Regarding the malondialdehyde (MDA) content, after 20 days of storage, the MDA content in Comparative Example 1 increased to 4.89 μmol / g, a significant increase from the initial value. After 20 days of storage, the MDA contents in Examples 1 and 2 were 0.87 μmol / g and 0.55 μmol / g, respectively, which were only 17.8% and 11.2% of those in Comparative Example 1, and close to the initial values. This indicates that the preservative of the present invention can effectively block the lipid oxidation chain reaction, significantly delay the oxidative deterioration process of fresh walnut kernels, and ensure their intrinsic quality stability.

[0034] The contents not described in detail in this specification are existing technologies known to those skilled in the art.

[0035] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A liquid preservative for preserving fresh walnut kernels, characterized in that, The liquid preservative comprises the following components by weight: 1-3 parts of natural preservative, 2-4 parts of solubilizing and stabilizing agent, and 125-130 parts of solvent. The natural preservative is phloretin powder; The solubilizing stabilizer is Tween 80; The solvent is ethanol.

2. The liquid preservative for preserving fresh walnut kernels according to claim 1, characterized in that, The phloretin powder has a purity of ≥95% and a particle size of ≤100μm; the Tween 80 has a purity of ≥98%; and the ethanol has a volume fraction of 90%–95%.

3. A method for preparing a liquid preservative for preserving fresh walnut kernels, characterized in that, Includes the following steps: Step 1, Dissolving: The natural preservative and solubilizing stabilizer are placed in a solvent and stirred to dissolve, resulting in a homogeneous mixture; Step 2, Filtration: Filter the mixture to remove impurities and ensure its clarity. Step 3, Sterilization: Place the filtered mixture in a sterile environment and treat it with ultraviolet sterilization to achieve sterilization of the mixture; Step 4: Filling: Under aseptic conditions, quickly fill the sterilized liquid preservative into sealed containers, seal immediately after filling, and store in a dark, room-temperature environment.

4. A method for preparing a liquid preservative for preserving fresh walnut kernels according to claim 3, characterized in that, In step two, the mixture is filtered using an organic phase filter membrane with a pore size of 0.22 μm.

5. A method for preparing a liquid preservative for preserving fresh walnut kernels according to claim 3, characterized in that, In step three, the ultraviolet sterilization treatment time is 20-30 minutes, the ultraviolet lamp power is 30-40W, and the irradiation distance is controlled at 30-50cm.

6. A method for using a liquid preservative for preserving fresh walnut kernels, characterized in that, Includes the following steps: S1. Dilution: Add water to the liquid preservative to dilute it, and stir well to obtain a diluted solution; S2. Soaking: Soak the fresh walnut kernels (after removing the skin) in a diluted solution. S3. Packaging: Take out the soaked fresh walnut kernels, drain the surface moisture, and then package them.

7. The method of using a liquid preservative for preserving fresh walnut kernels according to claim 6, characterized in that, In step S1, the liquid preservative and water are mixed in a weight ratio of 1:2 to 4.

8. The method of using a liquid preservative for preserving fresh walnut kernels according to claim 6, characterized in that, In step S2, the fresh walnut kernels are completely immersed in the diluted solution for 5-10 minutes.

9. The method of using a liquid preservative for preserving fresh walnut kernels according to claim 6, characterized in that, The diluent in step S2 can be reused until a distinct yellow color is observed.

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