A preservative emulsion gel pad for extending the freshness of sashimi and its preparation method

Abstract

This invention discloses a method for preparing a preservative emulsion gel pad to prolong the freshness of sashimi, belonging to the field of aquatic product preservation and processing technology. The method includes: mixing a fish skin gelatin solution with a medium-chain triglyceride containing cinnamaldehyde and subjecting the mixture to high-speed shearing and ultrasonic treatment to prepare a stable emulsion; reacting sodium periodate and sodium alginate in the dark, followed by dialysis and freeze-drying to obtain oxidized sodium alginate powder, which is then redissolved in a carbonate buffer solution; thoroughly stirring the oxidized sodium alginate solution with the emulsion, forming a first network at low temperature, and then immersing it in a CaCl2 solution to form a second network, resulting in a dual-network emulsion gel. This invention constructs a dual-network emulsion gel through the amino competition behavior of the interface and the network, as well as ion diffusion behavior. Its oil droplet distribution and network structure are orderly and uniform, exhibiting strong stability and mechanical properties. It can reduce the generation and release of volatile basic nitrogen and histamine from sashimi, thus prolonging the freshness of sashimi.

Description

Technical Field

[0001] This invention relates to the field of aquatic product preservation and processing technology, and in particular to a preservation emulsion gel pad for extending the freshness of sashimi and its preparation method. Background Technology

[0002] Tuna and other fish are highly nutritious and economically valuable due to their rich content of high-quality protein and polyunsaturated fatty acids, holding an important position in the global seafood market. However, sashimi, a type of fish intended for raw consumption, is highly susceptible to quality deterioration and safety risks during cold chain storage, transportation, and sales. Under the influence of microorganisms, proteins are degraded into volatile basic nitrogen, and histidine is catalyzed by amino acid decarboxylases to produce histamine. This not only reduces quality but also easily triggers poisoning symptoms such as nausea and vomiting in consumers.

[0003] Currently, preservation technologies for sashimi mainly include low-temperature refrigeration, ordinary edible coatings, and chemical preservatives. However, these existing technologies all have significant limitations. For example, while low-temperature refrigeration can slow down microbial growth to some extent, it cannot completely inhibit the activity of histamine-producing bacteria. Histamine and volatile basic nitrogen still accumulate rapidly, making long-term preservation difficult. Some preservation technologies still cannot meet the actual needs of long-term, safe, and high-quality preservation of sashimi. Therefore, developing a novel preservation material that is food-grade, has excellent mechanical properties, stable controlled release of active ingredients, and can effectively inhibit the generation and release of histamine and volatile basic nitrogen has become an urgent technical challenge to be solved in the field of sashimi preservation.

[0004] Emulsion gels, as composite systems possessing the dual properties of emulsions and gels, effectively immobilize oil droplets through their internal three-dimensional gel network, while simultaneously enabling the encapsulation and controlled release of hydrophobic active substances. They represent a highly promising carrier for active ingredients in food preservation. However, there are few reports on solutions to core preservation challenges for sashimi, such as the generation and release of histamine and volatile basic nitrogen during storage. Therefore, developing a novel gel that can be constructed under mild conditions, possesses excellent mechanical properties, and intelligently responds to spoilage signals while simultaneously reducing histamine levels has become crucial for overcoming the preservation bottlenecks of high-value aquatic products.

[0005] CN201811461135.2 discloses a method for preparing tuna preservation film, comprising the following steps: 1.5 g of sodium alginate, 2 g of gelatin, and 100 mL of 2% chitosan are heated in a 90°C water bath for 10 min to prepare a solution, which is then allowed to cool naturally. 0.1-0.2 mL of glycerol and 2 mL of Maillard peptide are added to the cooled solution, and the mixture is magnetically stirred for 30-60 min. The stirred solution is then centrifuged at 4000 rpm for 10-20 min to prepare a film solution. 20 mL of the film solution is poured evenly into an acrylic mold, and the mold is formed in a 35-40°C oven for 12 h. After removal, the mold is allowed to equilibrate at room temperature for 12-24 h before peeling off the film to obtain the product. The processing method has the following defects: (1) The Maillard peptide prepared by this method is mixed with the membrane matrix by physical and mechanical means, without being embedded or immobilized. When it comes into contact with the tuna exudate, the Maillard peptide is released in the membrane, which leads to a reduction in the freshness preservation time; (2) The inhibition of key components such as histamine in the process of tuna quality deterioration has not been achieved, and the effect of preservation is still unknown. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a preservative emulsion gel pad for extending the freshness of sashimi and its preparation method. This invention inhibits the generation and release of histamine and volatile basic nitrogen during the storage of sashimi through the preservative effect of the emulsion gel pad, thereby extending the shelf life of sashimi. Simultaneously, it addresses key challenges related to emulsion stability, intelligent release of active ingredients, and synergistic improvement of gel mechanical properties, thus expanding the application of emulsion gels in the field of food preservation.

[0007] The method of this invention can solve the technical problems of existing preservation methods in terms of physical protection and anti-oxidation, significantly extend shelf life, reduce quality loss, and ensure raw material safety and process control, which is of great practical significance for improving the preservation quality of high-value aquatic products.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution: This invention provides a method for preparing a preservative emulsion gel pad to extend the freshness of sashimi, comprising the following steps: 1) Prepare an aqueous phase by dissolving fish skin gelatin in carbonate buffer solution, prepare an oil phase by dissolving cinnamaldehyde in medium-chain triglycerides, and prepare a stable emulsion by mixing the aqueous and oil phases and subjecting them to high-speed shearing and ultrasonic treatment. It should be noted that the carbonate buffer solution in this invention provides an alkaline environment for the system, which is conducive to the Schiff base reaction. After high-speed shearing and ultrasonic treatment, the oil phase is broken into fine oil droplets and dispersed in the aqueous phase, which increases the specific surface area of ​​gelatin molecules and oil droplets in the aqueous phase, reduces interfacial tension, and improves emulsion stability. To prevent the formation of the subsequent emulsion gel network structure from destroying the interfacial stability of the emulsion droplets, cinnamaldehyde is introduced into the oil phase. Based on the principle of condensation reaction between aldehyde groups and primary amines, an interfacial Schiff base emulsion is constructed. The in-situ dynamic covalent cross-linking layer at the interface is used to further improve the emulsion stability.

[0009] 2) Sodium periodate was added to sodium alginate solution, and after reacting in the dark, ethylene glycol was added to terminate the reaction. After dialysis and freeze-drying, sodium alginate oxidized powder was obtained and redissolved in carbonate buffer to obtain sodium alginate oxidized solution. This invention aims to construct a dynamic Schiff base first network structure by oxidizing the vicinal diol structures of β-D-mannuronic acid and α-L-guluronic acid in the sodium alginate molecular chain with sodium periodate to increase the aldehyde content and thus increase the crosslinking sites for subsequent dynamic Schiff bases. Specifically, ethylene glycol containing the vicinal diol structure is used to rapidly react with sodium periodate that has not participated in the sodium alginate oxidation reaction to terminate the oxidation. The degree of oxidation of sodium alginate is controlled by the oxidation time to prevent over-oxidation.

[0010] 3) Thoroughly mix the sodium alginate oxidized solution with the emulsion obtained in step 1) and stir to form a first network gel under low temperature conditions. Remove the gel and immerse it in CaCl2 solution to form a second network gel. After rinsing with deionized water, a double network emulsion gel is obtained.

[0011] Dynamic Schiff bases mainly refer to structural units containing imine or methylimine characteristic groups, which can achieve dynamic and reversible exchange under catalyst-free conditions and have the characteristic of mild reaction conditions. This invention employs a simple stirring method to induce a Schiff base reaction between the aldehyde groups of oxidized sodium alginate and the amino groups of fish skin gelatin, forming cross-linking points in the aqueous phase of the emulsion. This forms a three-dimensional covalent network structure that permeates the system to fix and disperse oil droplets. Furthermore, low temperature further induces the aggregation and entanglement of gelatin molecular chains, synergistically enhancing gel strength. In addition, the dynamic Schiff base emulsion gel is immersed in CaCl2 solution to form a second network. The principle is that sodium alginate carries negatively charged carboxylic acid groups, which react with CaCl2... 2+ After cross-linking, a stable three-dimensional calcium alginate network structure is formed, which in turn forms an interpenetrating network structure with the first network. This dual-network structure significantly enhances the stability of the emulsion gel; the covalent network provides elasticity and dynamic responsiveness, while the ionic network endows the gel with higher rigidity, anti-swelling ability, and water-holding capacity.

[0012] Preferably, in step 1), the mass fraction of fish skin gelatin in the aqueous phase is 14-18%, the pH of the aqueous phase is 9.5-10.5, the mass fraction of cinnamaldehyde in the oil phase is 10-50%, and during the mixing of the aqueous and oil phases, the volume fraction of the aqueous phase is 60-80% and the volume fraction of the oil phase is 20-40%.

[0013] This invention uses fish skin gelatin as the amino group donor and cinnamaldehyde as the aldehyde group donor. An alkaline environment enhances nucleophilicity by promoting amino deprotonation, inducing a condensation reaction between the amino and aldehyde groups to form a Schiff base structure. Furthermore, the ratio of amino to aldehyde groups is controlled by adjusting the volume fraction of the aqueous and oil phases, thereby regulating the content of interfacial crosslinking sites and the stability of the emulsion. In addition, the phenylpropenal structure in the cinnamaldehyde molecule effectively scavenge free radicals, inhibit microbial proliferation and histamine production, helping to maintain the quality and nutritional value of sashimi.

[0014] Preferably, in step 1), a crude emulsion is prepared by high-speed shearing at 8000-15000 rpm for 2-4 minutes using a homogenizer. The crude emulsion is then ultrasonicated in an ice-water bath for 2-4 minutes at a power of 50-100 W to prepare a stable emulsion. This invention uses high-speed shearing to prepare the crude emulsion, initially breaking the oil phase into micron-sized droplets. The ultrasonic cavitation principle is used to create a high-temperature, high-pressure environment inside the crude emulsion, reducing the droplet size, increasing the specific surface area of ​​the droplets, reducing interfacial tension, and synergistically enhancing emulsion stability with the interfacial Schiff base.

[0015] Preferably, in step 2), the sodium periodate and sodium alginate solution are reacted in the dark for 4-8 hours at a temperature of 20-30°C, followed by the slow addition of ethylene glycol for another 0.5-1.5 hours. The dialysis is performed with a molecular weight cutoff of 3000–4000 Da for 24–72 hours, and the lyophilization time is 48–96 hours.

[0016] In the reaction system of step 2), the mass fraction of sodium alginate is 1-2 wt%, the mass fraction of sodium periodate is 0.5-2 wt%, the mass of ethylene glycol is the same as that of sodium periodate, and the mass fraction of the oxidized sodium alginate solution obtained by reconstitution is 4-8%, with a pH of 9.5-10.5. These conditions not only maintain the original gel properties of sodium alginate, but also allow moderate oxidation to rapidly crosslink with amino groups, forming a dense network structure; the alkaline environment induces the formation of the first network of the subsequent double-network emulsion gel.

[0017] Preferably, in step 3), the emulsion volume fraction is 50-75%, the sodium alginate solution volume fraction is 25-50%, the low temperature condition is 0-4℃, the CaCl2 solution mass fraction is 1-3%, and the soaking time is 1-3 h. This invention constructs an O / W type dual-network emulsion gel system. The emulsion gel constructed under these conditions can effectively stabilize oil droplets, reduce the damage to the interface structure caused by network formation, and achieve environmentally responsive release of cinnamaldehyde to inhibit the generation and release of histamine and volatile basic nitrogen. Furthermore, an appropriate calcium ion concentration can regulate the diffusion rate, forming a relatively uniform and dense ion network structure inside the gel, further enhancing the stability of the first network structure.

[0018] The present invention also provides a food preservation emulsion gel pad prepared by the aforementioned method.

[0019] The preservation emulsion gel pad obtained by the present invention can be used for the preservation of raw fish slices. Preferably, the preservation emulsion gel pad is placed at the bottom of the raw fish slices that need to be preserved, placed in a sealed box, and stored in a refrigerator at 0-4°C.

[0020] The gel size can be flexibly selected according to the size requirements of the fish fillets to be preserved, such as 3×3×2 cm, and this invention does not impose any limitations. Placing the double-network emulsion gel of this invention at the bottom of the tuna sashimi fillet and placing it in a sealed box can prevent the loss of cinnamaldehyde after its release and volatilization, thereby inhibiting the generation and release of histamine and volatile basic nitrogen; in addition, low temperature will further inhibit microbial activity and enzyme activity.

[0021] Typical, but not limited, sashimi can be tuna sashimi, and the tuna can be either yellowfin tuna or bluefin tuna.

[0022] Compared with the prior art, the beneficial effects of the present invention include: (1) The preservation emulsion gel pad for extending the freshness of fish fillets provided by the present invention maintains the quality of tuna sashimi to the maximum extent, realizes the synergistic effect of stable encapsulation of active ingredients, high-strength physical barrier and intelligent response release, inhibits the generation and release of histamine and volatile basic nitrogen, and provides a new multifunctional preservation strategy for aquatic products such as tuna.

[0023] (2) In the preparation method of the present invention, natural cinnamaldehyde is used as both a functional factor and a cross-linking site to achieve simultaneous completion of oil droplet stabilization and active loading. The process is green and simple, and can obtain an emulsion with stable cross-sectional structure.

[0024] (3) In the preparation method of the present invention, a first network is constructed by dynamic Schiff base to realize intelligent response release; a second network is constructed by ionic bonds to increase the stability and mechanical properties of the emulsion gel and synergistically improve the functional characteristics of the emulsion gel. Attached Figure Description

[0025] Figure 1 Rheological properties of the emulsion gels obtained in all embodiments and comparative examples; Figure 2 Cryo-electron microscopy images of the emulsion gels obtained in all examples and comparative examples. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described below through specific examples. It should be understood that the one or more method steps mentioned in this invention do not preclude the existence of other method steps before or after the combined steps, or the insertion of other method steps between these explicitly mentioned steps; it should also be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of this invention.

[0027] To better understand the above technical solutions, exemplary embodiments of the present invention are described in more detail below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0029] All raw materials used in the examples and comparative examples are commercially available.

[0030] Example 1 (Best Example): This embodiment provides a method for preparing a preservative emulsion gel pad to extend the freshness of sashimi, comprising the following steps: Fish skin gelatin (Sigma-Aldrich (Shanghai) Trading Co., Ltd., sourced from cold-water fish skin, CAS: 9000-70-8, molecular weight: 60kDa) was dissolved in 0.05 M, pH 9.5 carbonate buffer and stirred at 40℃ to prepare a 16% (w / w) fish skin gelatin solution as the aqueous phase. Cinnamaldehyde was dissolved in medium-chain triglycerides (Shanghai Yuanye Biotechnology Co., Ltd., fatty acid composition: 58.9% C8 triglycerides, 40.8% C10 triglycerides, 0.1% C12 triglycerides) as the oil phase, with a w / w ratio of 50%. The aqueous phase (80% by volume) and the oil phase (20% by volume) were mixed and homogenized at 12,000 rpm for 3 min to prepare a crude emulsion. The crude emulsion was then sonicated in an ice-water bath for 2-4 min at a power of 50-100 W to obtain a stable emulsion.

[0031] 5 g of sodium alginate was dissolved in 500 mL of deionized water. 5 g of sodium periodate was added in the dark, and the mixture was stirred for 6 h at 25 °C. Then, 5 mL of ethylene glycol was added dropwise, and the reaction continued for another 2 h. After the reaction was complete, the solution was dialyzed and lyophilized. The dialysis molecular weight was 3500 Da, the dialysis time was 48 h, and the lyophilization time was 72 h, yielding oxidized sodium alginate.

[0032] Sodium alginate was dissolved in 0.05 M, pH 9.5 carbonate buffer to prepare an 8% sodium alginate solution. A 67% emulsion and a 33% sodium alginate solution were rapidly mixed, poured into a mold, and placed at 4℃ to induce gelation. After removal, the mixture was immersed in a 2% CaCl2 solution for 1 h. The surface was then rinsed with deionized water to obtain a double-network emulsion gel. Place the double-network emulsion gel pad at the bottom of the tuna sashimi, put it in a sealed box, and store it in a refrigerator at 4°C.

[0033] In this embodiment, the obtained dual-network emulsion gel sample and fish fillet sample are named "Sample-1" and "Fish Fillet-1" respectively, and this naming rule also applies below.

[0034] Example 2: This embodiment provides a method for preparing a preservative emulsion gel pad to prolong the freshness of raw fish slices. The difference from Embodiment 1 is that in step (1), cinnamaldehyde is 10% of the mass fraction of medium-chain triglycerides.

[0035] The remaining operations are the same as in Example 1. The resulting double-network emulsion gel sample and fish fillet sample are named “Sample-2” and “Fish Fillet-2”, respectively.

[0036] Example 3: This embodiment provides a method for preparing a fresh-preserving emulsion gel pad to extend the freshness of raw fish slices. The difference from Embodiment 1 is that the mass fraction of the fish skin gelatin solution in step (1) is 14%.

[0037] The remaining operations are the same as in Example 1. The resulting double-network emulsion gel sample and fish fillet sample are named “Sample-3” and “Fish Fillet-3”, respectively.

[0038] Example 4: This embodiment provides a method for preparing a fresh-preserving emulsion gel pad to extend the freshness of raw fish slices. The difference from Embodiment 1 is that the mass fraction of the fish skin gelatin solution in step (1) is 18%.

[0039] The remaining operations are the same as in Example 1. The final double-network emulsion gel sample and fish fillet sample are named "Sample-4" and "Fish Fillet-4".

[0040] Example 5: This embodiment provides a method for preparing a fresh-preserving emulsion gel pad to extend the freshness of raw fish slices. The difference from Embodiment 1 is that in step (3), the emulsion liquid fraction is 50% and the volume fraction of sodium alginate oxidized solution is 50%.

[0041] The remaining operations are the same as in Example 1. The final double-network emulsion gel sample and fish fillet sample are named "Sample-5" and "Fish Fillet-5".

[0042] Example 6: This embodiment provides a method for preparing a fresh-preserving emulsion gel pad to extend the freshness of raw fish slices. The difference from Embodiment 1 is that in step (3), the emulsion liquid volume fraction is 75% and the sodium alginate solution volume fraction is 25%.

[0043] The remaining operations are the same as in Example 1. The resulting double-network emulsion gel sample and fish fillet sample are named “Sample-6” and “Fish Fillet-6”, respectively.

[0044] Comparative Example 1: This comparative example provides a method for preparing a preservative emulsion gel pad to extend the freshness of sashimi. The difference from Example 1 is that in step (3), the dynamic Schiff base emulsion gel is not soaked in CaCl2 solution, i.e., a single-network emulsion gel.

[0045] In this comparative example, the obtained single-network emulsion gel sample and fish fillet sample are named "Sample Comparison-1" and "Fish Fillet Comparison-1".

[0046] Comparative Example 2: This comparative example provides a method for preparing a preservative emulsion gel pad to prolong the freshness of sashimi. The difference from Example 1 is that cinnamaldehyde is not introduced in step (1), and no interfacial Schiff base emulsion is formed.

[0047] In this comparative example, the obtained double-network emulsion gel sample and fish fillet sample are named "Sample Comparison-2" and "Fish Fillet Comparison-2".

[0048] Table 1 shows the effects of cinnamaldehyde content, fish skin gelatin content, and emulsion volume on volatile basic nitrogen, histamine, and malondialdehyde in tuna sashimi after 7 days of storage in various embodiments of the present invention.

[0049] Table 1. Results of determination of volatile basic nitrogen, histamine and malondialdehyde in tuna sashimi

[0050] As shown in Table 1, the volatile basic nitrogen, histamine, and malondialdehyde levels in the tuna meat preserved using the gel obtained in Example 1 were the lowest in all examples. This indicates that the dual-network emulsion gel of the present invention can effectively inhibit the production of volatile basic nitrogen, reduce the formation of biogenic amines and delay lipid oxidation, thus maximizing the freshness of the fish meat and delaying spoilage.

[0051] Figure 1 The rheological property test results of the gels in the examples and comparative examples are shown, where A is the frequency scan, B is the strain scan, C is the time scan, and D is the alternating strain scan. Figure 1 It is evident that Example 2 exhibits the highest energy storage modulus, indicating its extremely strong three-dimensional network structure and excellent resistance to deformation. In the time-scan test, the energy storage modulus of Example 1 remained stable over a long period, demonstrating excellent stability.

[0052] Figure 2 These are cryo-electron microscopy images of the gels from the examples and comparative examples. AF corresponds sequentially to Examples 1 to 6, and G and H correspond to Comparative Example 1 and Comparative Example 2, respectively. Figure 2 It can be clearly observed that Example 1 exhibits a highly uniform and dense porous network structure, which is conducive to forming an effective physical barrier, giving it optimal barrier performance and mechanical stability.

[0053] In summary, although Example 2 is superior to Example 1 in terms of mechanical strength, Example 1 demonstrates the best performance in terms of stability, long-term preservation ability, and actual freshness retention. Therefore, based on a comprehensive consideration of the preservation purpose, Example 1 is determined to be the optimal example.

[0054] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing a preservative emulsion gel pad for extending the freshness of sashimi, characterized in that, Includes the following steps: 1) Prepare an aqueous phase by dissolving fish skin gelatin in carbonate buffer solution, prepare an oil phase by dissolving cinnamaldehyde in medium-chain triglycerides, and prepare a stable emulsion by mixing the aqueous and oil phases and subjecting them to high-speed shearing and ultrasonic treatment. 2) Sodium periodate was added to sodium alginate solution, and after reacting in the dark, ethylene glycol was added to terminate the reaction. After dialysis and freeze-drying, sodium alginate oxidized powder was obtained and redissolved in carbonate buffer to obtain sodium alginate oxidized solution. 3) Thoroughly mix the sodium alginate oxidized solution with the emulsion obtained in step 1) and stir to form a first network gel under low temperature conditions. Remove the gel and immerse it in CaCl2 solution to form a second network gel. After rinsing with deionized water, a double network emulsion gel is obtained.

2. The preparation method according to claim 1, characterized in that, In step 1), the mass fraction of fish skin gelatin in the aqueous phase is 14-18%, and the pH of the aqueous phase is 9.5-10.5; the mass fraction of cinnamaldehyde in the oil phase is 10-50%. During the mixing of the aqueous and oil phases, the volume fraction of the aqueous phase is 60-80%, and the volume fraction of the oil phase is 20-40%.

3. The preparation method according to claim 1, characterized in that: In step 1), the high-speed shearing and ultrasonic treatment includes: using a homogenizer to shear at a speed of 8000-15000 rpm for 2-10 min to prepare a crude emulsion, and placing the crude emulsion in an ice-water bath for ultrasonication for 2-10 min at an ultrasonic power of 50-100 W.

4. The preparation method according to claim 1, characterized in that: Step 2) The sodium periodate and sodium alginate solution react in the dark for 4-8 hours at a temperature of 20-30°C.

5. The preparation method according to claim 1, characterized in that, The molecular weight cutoff for dialysis was 3000–4000 Da, the dialysis time was 24–72 h, and the lyophilization time was 48–96 h.

6. The preparation method according to claim 1, characterized in that: In the reaction system of step 2), the mass fraction of sodium alginate is 1-2 wt%, the mass fraction of sodium periodate is 0.5-2 wt%, the amount of ethylene glycol added to terminate the reaction is the same as the mass of sodium periodate, and the mass fraction of the oxidized sodium alginate solution obtained by reconstitution is 4-8%, and the pH is 9.5-10.

5.

7. The preparation method according to claim 1, characterized in that: In step 3), the emulsion volume fraction is 50-75%, the sodium alginate solution volume fraction is 25-50%, the low temperature condition is 0-4℃, the CaCl2 solution mass fraction is 1-3%, and the soaking time is 1-3 h.

8. A food preservation emulsion gel pad prepared by the method according to any one of claims 1-7.

9. The application of the preservation-type emulsion gel pad according to claim 8 in the preservation of sashimi, characterized in that, Place the preservative emulsion gel pad at the bottom of the raw fish slices to be preserved, put them in a sealed container, and store at 0-4℃.

10. The application according to claim 9, characterized in that, The sashimi is either yellowfin tuna sashimi or bluefin tuna sashimi.

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