Multi-layer response microcapsule composite fresh-keeping system and application thereof in aquatic product fresh-keeping

Abstract

The invention discloses a multi-layer response microcapsule composite fresh-keeping system and application thereof in aquatic product fresh-keeping. The technical defects that in the prior art, due to one-time release of a traditional preservative, the concentration in the early stage is too high, the flavor is affected, the concentration in the later stage is insufficient, protection is lost, and an existing microcapsule fresh-keeping system is single in response mechanism, and accurate and gradient release is difficult to achieve according to enzyme activity and pH changes in the aquatic product decay process are effectively overcome. Tea polyphenol, erythorbic acid and nisin are embedded in the inner core layer to serve as main antibacterial and antioxidant components; the middle layer is a pH response layer formed by crosslinking modified polysaccharide and high-methoxyl pectin, and the pH is gt in the initial decay stage of the aquatic products; 6.2, the release is triggered; the outer layer is an enzyme response layer formed by compounding modified starch and gelatin, and has protease activity gt in aquatic products; and the release is responded when the volume is 0.15 U / g. The preservative and antioxidant protection is continuously provided for aquatic products in the whole shelf life, the shelf life of the aquatic products is remarkably prolonged, and the flavor quality of the aquatic products is ensured.

Description

Technical Field

[0001] This invention relates to the field of food preservation technology, specifically to a multilayer responsive microcapsule composite preservation system and its application in the preservation of aquatic products. Background Technology

[0002] Aquatic products are rich in nutrients such as protein, unsaturated fatty acids, vitamins, and minerals, making them popular with consumers. However, aquatic products differ from other meat and vegetable products, exhibiting the following inherent drawbacks: First, their high water content (generally exceeding 75%) provides an ideal environment for microbial growth. Second, their high soluble protein content makes them highly susceptible to decomposition by proteases and microorganisms. Third, their fragile muscle tissue, compared to livestock and poultry meat, results in less connective tissue and a more delicate muscle structure, making them easily damaged during harvesting, transportation, storage, and sales. Fourth, the high content of unsaturated fatty acids in fish meat makes it prone to self-oxidation, producing aldehydes and ketones that impart unpleasant flavors. Fifth, aquatic products contain abundant proteases, lipases, and hydrolases, which remain active even under low-temperature conditions, continuing to decompose their own proteins and fats, leading to flavor loss. These factors make aquatic products more prone to spoilage, rendering ordinary preservation methods inadequate. Long-term storage not only reduces the nutritional value and flavor of aquatic products but can also cause food safety issues and significant economic losses.

[0003] The spoilage process of aquatic products can be roughly divided into three stages: rigor mortis, autolysis, and putrefaction. During rigor mortis, the binding of myosin and actin in the muscle causes it to contract and harden. At this stage, the activity of muscle proteases and pH do not change significantly, microbial reproduction is slow, and the quality of the aquatic product remains relatively unchanged; however, this stage is very short-lived. Then comes the autolysis stage, where the number and activity of proteases in the muscle increase, slowly dissolving the muscle. Simultaneously, the small molecules from protein decomposition and water begin to provide nutrients for microorganisms, leading to rapid microbial reproduction. After a large number of microorganisms multiply, they begin to decompose amino acids in the meat into ammonia, sulfides, and other components, causing the muscle pH to rise and spoilage to accelerate. Therefore, it is necessary to control the number and activity of proteases in the early stages of preservation, control pH changes in the middle stages, and release antioxidants in the later stages to enhance the preservation effect, forming a gradient control to extend the shelf life.

[0004] Currently, the main methods for preserving aquatic products include low-temperature preservation, chemical preservatives, and natural preservatives. Among these, chemical preservatives are widely used due to their ease of operation, low cost, and good preservation effect. However, traditional chemical preservatives are mostly released only once. In the early stages of preservation, the concentration of preservatives is too high, which can easily react with proteins, fats, and other components in aquatic products, affecting their flavor. As the preservation time increases, the preservatives are continuously consumed, and the concentration decreases. In the later stages of preservation, they can no longer provide effective anti-corrosion and antioxidant protection for aquatic products, leading to premature spoilage.

[0005] Natural preservatives have advantages such as safety, non-toxicity, and few side effects. For example, tea polyphenols and isoascorbic acid have excellent antioxidant properties, and nisin has good antibacterial activity. However, natural preservatives are easily deactivated by environmental factors (such as temperature, pH, enzymes, etc.) during the preservation of aquatic products, and they also have the problem of difficult-to-control release rate, making it impossible to achieve continuous preservation.

[0006] Microencapsulation technology encapsulates active substances within tiny spherical carriers formed from polymer materials, effectively protecting the stability of these substances and controlling their release rate. Existing microencapsulation preservation systems are mostly single-layer or double-layer structures with limited response mechanisms, making it difficult to achieve precise, gradient release based on environmental changes during the spoilage process of aquatic products. This fails to meet the need for continuous preservation throughout the entire shelf life of aquatic products. Therefore, developing a microencapsulation composite preservation system capable of gradient-response release based on enzyme activity and pH changes during spoilage, and continuously providing preservative and antioxidant protection throughout the entire shelf life, is of significant practical importance. Summary of the Invention

[0007] The purpose of this invention is to overcome the technical defects of existing technologies, such as the one-time release of traditional preservatives leading to excessively high concentrations in the early stage affecting flavor and insufficient concentrations in the later stage resulting in loss of protection, as well as the single response mechanism of existing microcapsule preservation systems, which makes it difficult to achieve precise and gradient release based on enzyme activity and pH changes during the spoilage process of aquatic products. The invention provides a multi-layer responsive microcapsule composite preservation system and its application in the preservation of aquatic products.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A multi-layered responsive microcapsule composite preservation system adopts a three-layer "core-shell-shell" structure and achieves three-stage preservation through gradient release control technology. The specific structure is as follows: 1. Core Layer: Serving as the core carrier of antibacterial and antioxidant active ingredients, this layer encapsulates tea polyphenols, isoascorbic acid, and nisin. Tea polyphenols and isoascorbic acid possess excellent antioxidant properties, effectively inhibiting the oxidation of unsaturated fatty acids in aquatic products. Nisin is a natural antimicrobial peptide with good antibacterial activity and is safe and non-toxic. Experimental screening determined that the optimal mass ratio of tea polyphenols, isoascorbic acid, and nisin is 1:1-2:2-4. This ratio provides the best synergistic antibacterial and antioxidant effect, simultaneously inhibiting microbial growth and oxidation reactions.

[0009] 2. Intermediate Layer: This is a pH-responsive layer, surrounding the inner core layer. It is formed by cross-linking modified polysaccharides (carboxymethyl chitosan or sodium carboxymethyl cellulose) with high-methoxyl pectin to create a pH-sensitive layer. Both the modified polysaccharide and the high-methoxyl pectin contain a large number of carboxyl groups (-COOH). Under low pH conditions, these groups protonate, do not ionize, and hydrophobically shrink to form a water-insoluble gel, effectively protecting the inner core layer. Under high pH conditions, they deprotonate, become negatively charged, and transform into hydrophilic groups, thus swelling and decomposing to release the inner core layer. The intermediate layer, formed by cross-linking the two in a mass ratio of 3-5:1, is structurally stable when the aquatic product is fresh (pH≤6.2), effectively protecting the active ingredients in the inner core layer. When the aquatic product begins to spoil, microorganisms decompose proteins, producing alkaline substances such as ammonia and amines, causing the pH of the aquatic product to rise. When pH>6.2, the intermediate layer swells and ruptures, triggering the release of antibacterial and antioxidant components from the inner core layer, enhancing the preservation effect.

[0010] 3. Outer Layer: This is an enzyme-responsive layer, surrounding the middle layer. It is formed by combining modified starch (obtained by esterification of pregelatinized starch or maltodextrin with sodium pyrophosphate or sodium tripolyphosphate at a temperature of 70-80℃ for 1-2 hours) and gelatin. During the modification process, the hydrogen bonds of the pregelatinized starch or maltodextrin break, reducing its molecular weight and creating a porous, loose structure with enhanced water absorption and retention capacity. Because its structure is open, it is more easily acted upon by proteases during rehydration, resulting in strong enzyme sensitivity and rapid response to changes in protease concentration. Phosphate esterification further enhances its stability, while gelatin possesses excellent film-forming properties and air permeability. The outer layer is formed by combining these two materials at a mass ratio of 2-3:1. In the early stages of aquatic product preservation, the protease activity is low (≤0.15U / g), the outer layer structure is stable, and a small amount of antibacterial and antioxidant components (20%) are slowly released, providing basic protection for the aquatic products and avoiding excessively high initial concentrations that could affect the flavor. As the preservation time is extended, microorganisms in the aquatic products multiply in large quantities, and the protease activity gradually increases. When the protease activity is >0.15U / g, the outer layer is degraded by the protease, triggering the release of antibacterial and antioxidant components in the middle and core layers.

[0011] This preservation system achieves a three-stage gradient release through the synergistic effect of the outer layer's enzyme response and the middle layer's pH response: In the initial stage (0-3 days), the aquatic products are in a fresh state, with protease activity ≤0.15U / g and pH ≤6.2. The outer layer slowly releases 20% of antibacterial and antioxidant components, providing basic anti-corrosion and antioxidant protection for the aquatic products, and the low concentration release avoids affecting the flavor of the aquatic products; in the middle stage (3-7 days), the aquatic products begin to show slight spoilage, with protease activity >0.15U / g, the outer layer is degraded by protease, and at the same time, the pH of the aquatic products rises to >6.2. The middle layer triggers the release of 50% of antibacterial and antioxidant components, significantly enhancing the preservation effect; in the later stage (7-10 days), the degree of spoilage of the aquatic products intensifies, the middle layer completely ruptures, and the core layer releases the remaining 30% of antibacterial and antioxidant components, ensuring continuous protection for the aquatic products and extending their shelf life.

[0012] In some preferred embodiments, the present invention also provides a method for preparing the above-mentioned multilayer responsive microcapsule composite preservation system, comprising three steps: core layer preparation, intermediate layer encapsulation, and outer layer encapsulation. 1. Core layer preparation: Mix tea polyphenols, isoascorbic acid, and nisin in a mass ratio of 1:1:2, add a 1%-3% (w / w) gum arabic solution (gum arabic acts as an emulsifier to improve the dispersibility of active ingredients), and ultrasonically disperse for 15-25 min to form a homogeneous aqueous phase; mix 5%-8% (w / w) soybean oil with 0.5%-1.5% (w / w) Tween 80 (Tween 80 acts as a surfactant to reduce the interfacial tension between oil and water, forming a stable oil phase; add the aqueous phase to the oil phase at a volume ratio of 1:3-1:5, and stir at high speed for 30-40 min at a speed of 2000-3000 r / min to form a stable O / W type emulsion, which is the core layer.

[0013] 2. Intermediate layer encapsulation: Modified polysaccharide (carboxymethyl chitosan or sodium carboxymethyl cellulose) and high-methoxyl pectin are mixed at a mass ratio of 3:1, and deionized water is added to prepare a mixed solution with a mass concentration of 2%-4%. The pH is adjusted to 5.0-6.0. Under this pH condition, carboxymethyl chitosan and high-methoxyl pectin can be fully cross-linked. The core layer is added to the mixed solution at a mass ratio of 1:8-1:12. The mixture is stirred for 1-2 hours, and the temperature is controlled at 30-40℃ to promote the cross-linking reaction. After the reaction is completed, the mixture is centrifuged (3000-4000 r / min, 10-15 min), and the precipitate is collected. This is the semi-finished product of microcapsules encapsulating the intermediate layer.

[0014] 3. Outer Coating: Modified starch (obtained by esterification of gelatinized starch or maltodextrin with sodium pyrophosphate or sodium tripolyphosphate) and gelatin are mixed at a mass ratio of 2:1. Deionized water is added to prepare a composite solution with a mass concentration of 3%-5%. The solution is heated to 50-60℃ to completely dissolve the composite solution. The semi-finished microcapsule coating for the middle layer is added to the composite solution at a mass ratio of 1:10-1:15. The mixture is stirred for 30-50 minutes to ensure that the composite solution uniformly coats the surface of the semi-finished microcapsule. The temperature is lowered to 20-25℃, and 1%-2% transglutaminase is added. Transglutaminase acts as a cross-linking agent to enhance the stability of the outer layer structure. The cross-linking and curing process is carried out for 30-40 minutes. The mixture is then filtered and vacuum dried (at 40-50℃ for 6-8 hours) to obtain a multilayer responsive microcapsule composite preservation system.

[0015] This invention also protects the application of the above-mentioned multilayer responsive microcapsule composite preservation system in the preservation of aquatic products. The application method is simple and easy to implement: mix the multilayer responsive microcapsule composite preservation system with deionized water to prepare a preservation solution with a mass concentration of 0.5%-2%; adjust the concentration of the preservation solution according to the type and freshness of the aquatic products. For easily perishable aquatic products (such as shrimp and shellfish), the concentration of the preservation solution can be appropriately increased to 1.3%-2%, and for perishable aquatic products (such as frozen fish), the concentration of the preservation solution can be reduced to 0.5%-1%; immerse the aquatic products in the preservation solution for 10-20 minutes at a temperature of 4-10℃. Low-temperature immersion can reduce the loss of nutrients in aquatic products; after immersion, remove the aquatic products, drain the surface water, and store them in the refrigerator (0-4℃) or freeze (-18℃ to -20℃).

[0016] The present invention has the following beneficial effects: (1) Compared with the traditional preservation system, which has a short preservation time and a single response mechanism of single-layer microcapsules, this preservation system adopts a three-layer structure design of "core-shell-shell" and achieves three-stage preservation through gradient release control technology. It effectively solves and overcomes the technical defects of existing technologies, such as the one-time release of traditional preservatives leading to excessively high concentration in the early stage affecting the flavor and insufficient concentration in the later stage losing protection, and the difficulty of existing microcapsule preservation systems to achieve precise and gradient release based on enzyme activity and pH changes during the spoilage process of aquatic products.

[0017] (2) In this invention, modified starch (obtained by esterification of gelatinized starch or maltodextrin with sodium pyrophosphate or sodium tripolyphosphate) is preferably combined with gelatin to form an enzyme-sensitive layer. This layer rapidly senses changes in protease concentration, taking advantage of the increased protease activity in the early stages of aquatic product spoilage. During the modification process, hydrogen bonds in the pregelatinized starch or maltodextrin break, reducing its molecular weight and creating a porous, loose structure with enhanced water absorption. Because its structure is open, it is more easily acted upon by protease during rehydration, resulting in strong enzyme sensitivity. When the protease concentration increases, the modified starch is decomposed by the protease, the outer layer collapses, and the middle layer is released, achieving the first step of preservation.

[0018] (3) The present invention creatively crosslinks the modified polysaccharide with high-methoxyl pectin to form a pH-sensitive layer, which can quickly and effectively monitor the pH changes of aquatic products, taking into account the characteristic of pH increase in the later stage of spoilage. Both the modified polysaccharide and the high-methoxyl pectin contain a large number of carboxyl groups (-COOH), which are protonated in a low pH environment, do not ionize, and hydrophobically shrink to form a water-insoluble gel, which can effectively protect the core layer; while in a high pH environment, they are deprotonated, carry a negative charge, become hydrophilic groups, and thus swell and decompose, releasing the core layer and forming a continuous preservation effect.

[0019] (4) The multilayer responsive microcapsule composite preservation system prepared by the present invention addresses the spoilage and deterioration of aquatic products during storage, and solves the problem that natural preservatives are easily deactivated by environmental factors (such as temperature, pH, enzymes, etc.) during the preservation of aquatic products. It continuously provides anti-corrosion and antioxidant protection, significantly extends the shelf life of aquatic products and ensures their flavor quality (from the traditional 5-7 days to 10-12 days). Detailed Implementation

[0020] Example 1: Preparation of a multilayer responsive microcapsule composite preservation system 1.1. Core layer preparation: Weigh 1g of tea polyphenols, 1g of isoascorbic acid and 2g of nisin, mix them evenly, add 100mL of 2% gum arabic solution, and sonicate for 20min to form an aqueous phase; weigh 50g of soybean oil and 0.5g of Tween 80, mix them evenly to form an oil phase; add the aqueous phase to the oil phase at a volume ratio of 1:4, stir at high speed for 35min at a speed of 2500r / min to form an emulsion, which is the core layer.

[0021] 1.2. Intermediate layer encapsulation: Weigh 3g of carboxymethyl chitosan and 1g of high-methoxyl pectin, mix them evenly, add 100g of deionized water, stir to dissolve, and prepare a mixed solution with a mass concentration of 3%. Adjust the pH to 5.5 with citric acid. Add 10g of the core layer to the mixed solution, stir and react at 35℃ for 1.5h. After the reaction is completed, centrifuge at 3500r / min for 12min, collect the precipitate, and obtain the microcapsule semi-finished product with the intermediate layer encapsulated.

[0022] 1.3. Outer Coating: Weigh 2g of modified starch (gelatinized starch and sodium pyrophosphate mixed at a mass ratio of 1:0.2, esterified at 70-80℃ for 1h with water as solvent, and dried for 6h) and 1g of gelatin, mix evenly, add 100g of deionized water, heat to 55℃ and stir to dissolve, and prepare a composite solution with a mass concentration of 4%; add 8g of the microcapsule semi-finished product with the middle layer to the composite solution, stir for 40min, cool to 22℃, add 5g of 1.5% transglutaminase solution, crosslink and solidify for 35min, filter, and vacuum dry at 45℃ for 7h to obtain a multilayer responsive microcapsule composite preservation system.

[0023] Example 2: Application of a multilayer responsive microcapsule composite preservation system in the preservation of fresh sea bass 2.1 Preparation of preservation solution: Weigh 1 g of multilayer responsive microcapsule composite preservation system, add 100 g of deionized water, stir at 250 r / min for 18 min to prepare a preservation solution with a mass concentration of 1%, and adjust the pH to 6.0.

[0024] 2.2 Soaking Treatment: Select fresh sea bass with a body length of 30-35cm and a weight of 500-600g. Process the sea bass within 2 hours of catching by removing scales, gills, and internal organs, rinsing three times with water, and draining the surface moisture (surface water content ≤5%). Soak the pre-treated sea bass completely in the preservation solution at a temperature of 6℃ for 18 minutes. Two control groups were set up. Control group ① was the semi-finished product of microcapsules with the middle layer obtained in step 1.2 of Example 1; control group ② was the microcapsule composite preservation system prepared by replacing the outer layer described in step 1.3 of Example 1 with the same method using gelatinized starch and gelatin in a 2:1 mass ratio.

[0025] 2.3. Storage and Testing: After soaking, the sea bass was removed and drained at room temperature for 5 minutes. It was then placed in a sealed container and stored in a refrigerator at 0-4℃. Samples were taken periodically for testing. Samples were taken at 0, 7, and 12 days to test the sensory quality, total bacterial count, and TVB-N (volatile basic nitrogen) content of the fish. The results are as follows:

[0026] Example 3: Application of a multi-layer responsive microcapsule composite preservation system for Litopenaeus vannamei. 3.1. Preparation of preservation solution: Weigh 1.6g of the multilayer responsive microcapsule composite preservation system prepared in Example 1, add 100g of deionized water, stir to dissolve, and prepare a preservation solution with a mass concentration of 1.6%.

[0027] 3.2. Soaking Treatment: Select fresh whiteleg shrimp (12-15cm in length, vigorous, and undamaged), clean them thoroughly, and drain the surface water. Soak the shrimp in a preservative solution at 6℃ for 15 minutes. After soaking, remove the shrimp and drain the surface water. A control group consisting of untreated fresh shrimp and a traditional preservation group soaked in a 0.1% tea polyphenol solution were also set up.

[0028] 3.3. Storage and Quality Testing: The processed shrimp were stored at 0-4℃. Samples were taken at 0, 5, and 10 days to test the sensory quality, protease activity, and TBARS (thiobarbituric acid reactant) content. The results are as follows:

[0029] 3.4. Response Mechanism Verification After 3 days of storage, the pH of the shrimp surface rose to 6.4, and the middle layer began to respond and release. The protease activity reached 0.15 U / g after 5 days, and the outer layer degraded rapidly. At this time, the cumulative release of active ingredients was 69.8%, and complete release was achieved after 10 days, which is in line with the three-stage release design.

[0030] Example 4: Application of a multi-layer responsive microcapsule composite preservation system for scallops 4.1 Preparation of preservation solution: Weigh 1.3g of the compound preservation system (product of Example 1), add 100g of water, stir at 250r / min for 17min to prepare a 1.3% concentration preservation solution.

[0031] 4.2. Soaking Treatment: Select fresh scallops with shell lengths of 5-6 cm, ensuring the shells are intact and undamaged. After sand removal treatment (using clean water with a little salt, let stand for 24 hours), rinse thoroughly with water and drain. Soak the scallops at 7℃ for 16 minutes. A control group of untreated scallops was set up, while the traditional preservation group was soaked in a 0.12% compound phosphate solution (the compound phosphate was prepared according to the method described in CN108502863A, wherein sodium tripolyphosphate, sodium pyrophosphate, and sodium hexametaphosphate were prepared in a mass ratio of 9:1:1).

[0032] 4.3. Storage and Testing: After draining, spread the scallops evenly on trays, cover with plastic wrap, and store at 0-4℃. Samples were taken at 0, 6, and 10 days to test the lipoxygenase activity, sensory evaluation, and spoilage rate of the scallops. The results are as follows:

[0033] Example 5: Application of a multi-layer responsive microcapsule composite preservation system for mixed aquatic products 5.1 Preparation of preservation solution: Weigh 1.4g of the compound preservation system (product of Example 1), add 100g of deionized water, stir at 240r / min for 19min to prepare a 1.4% concentration preservation solution.

[0034] 5.2 Soaking treatment: Sea bass pieces (2cm×2cm, taken from sea bass in Example 2), shrimp meat (taken from whiteleg shrimp in Example 3, shelled), and clams (treated to remove sand, the same as scallops in Example 4) were mixed at a mass ratio of 1:1:1 and soaked at 6°C for 17 minutes. At the same time, a control group was set up with untreated mixed aquatic products, and the traditional preservation group was soaked in a mixed solution of 0.1% potassium sorbate + 0.1% tea polyphenols.

[0035] 5.3 Storage and Testing: After draining, pack into vacuum-sealed plastic bags and store at 0-4℃. Samples were taken at 0, 6, and 11 days to test the average TVB-N value, average total bacterial count, and moisture loss rate. The results are as follows:

[0036] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A multilayer responsive microcapsule composite preservation system, characterized in that, It adopts a three-layer structure of "core-shell-shell", including: The core layer contains antibacterial and antioxidant components; The middle layer, which wraps around the outer side of the core layer, is formed by cross-linking modified polysaccharides and high-methoxyl pectin, and is a pH-responsive layer; The outer layer, which wraps around the middle layer, is formed by a composite of modified starch and gelatin and serves as an enzyme-responsive layer. The outer layer triggers release when the protease activity in aquatic products is >0.15 U / g, and the middle layer triggers release when the pH is >6.2, achieving a three-stage gradient release.

2. The multilayer responsive microcapsule composite preservation system according to claim 1, characterized in that, The antibacterial and antioxidant components include tea polyphenols, isoascorbic acid, and nisin, with a mass ratio of 1:1-2:2-4.

3. The multilayer responsive microcapsule composite preservation system according to claim 1, characterized in that, The mass ratio of the modified polysaccharide to high-methoxyl pectin is 3-5:1; the modified polysaccharide is carboxymethyl chitosan or sodium carboxymethyl cellulose; the high-methoxyl pectin has an esterification degree >60%; The mass ratio of modified starch to gelatin is 2-3:

1. The modified starch is obtained by esterification of gelatinized starch or maltodextrin with sodium pyrophosphate or sodium tripolyphosphate. The esterification reaction temperature is 70-80℃ and the reaction time is 1-2h.

4. The multilayer responsive microcapsule composite preservation system according to claim 1, characterized in that, The three-stage gradient release ratios are as follows: 20% release in the initial stage (0-3 days), 50% release in the middle stage (3-7 days), and 30% release in the later stage (7-10 days).

5. A method for preparing the multilayer responsive microcapsule composite preservation system according to any one of claims 1-4, characterized in that, Includes the following steps: (1) Preparation of the core layer: Disperse the antibacterial and antioxidant components in the emulsifier solution, add them to the oil phase and emulsify at high speed to form a core emulsion; (2) Encapsulation of the middle layer: The modified polysaccharide and high methoxyl pectin were mixed into a solution, added to the core layer, and separated after cross-linking reaction to obtain the microcapsule semi-finished product; (3) Coating the outer layer: Prepare a composite solution by mixing modified starch and gelatin, add microcapsule semi-finished product, cross-link and solidify, and then dry to obtain the preservation system.

6. The application of the multilayer responsive microcapsule composite preservation system according to any one of claims 1-4 in the preservation of aquatic products.

7. The application according to claim 6, characterized in that, The preservation system is prepared as a preservation solution with a mass concentration of 0.5%-2%. Aquatic products are immersed in the preservation solution at a temperature of 4-10°C for 10-20 minutes. After immersion, they are drained and stored in the refrigerator or freezer at a temperature of 0-4°C, which extends the shelf life to 10-12 days. The freezing temperature is -18°C to -20°C, which extends the shelf life to 3-6 months. The aquatic products include at least one of fish, shrimp, and shellfish.

8. A preservative solution for preserving aquatic products, characterized in that, The multilayer responsive microcapsule composite preservation system according to any one of claims 1-4 has a mass concentration of 0.5%-2% in water.

9. A method for preserving aquatic products, characterized in that, Includes the following steps: (1) Preparation of preservation solution: Mix the preservation system described in any one of claims 1-4 with deionized water to prepare a preservation solution with a mass concentration of 0.5%-2%; (2) Soaking treatment: Soak the aquatic products in the preservation solution at a temperature of 4-10℃ for 10-20 minutes; (3) Drain and store: Take out the aquatic products, drain the surface moisture, and store them in the refrigerator or freezer.

10. Application of a multilayer responsive microcapsule composite preservation system in inhibiting spoilage microorganisms and delaying oxidation reactions in aquatic products.

Images