Processing method of prefabricated conditioned snakehead fillets

Abstract

The invention provides a processing method of prefabricated conditioned snakehead fillets, snakeheads are slaughtered, cleaned, sliced, soaked with high-density carbon dioxide and preserved, and the processing method belongs to the technical field of food processing. The snakehead fillets are treated by high-density carbon dioxide to achieve a certain bacteria reducing effect and enzyme inactivation effect, residual carbon dioxide is volatilized in the form of gas, a microporous structure is formed in the tissue structure of the snakehead fillets, and meanwhile, polysarcosine and carboxyhexyl cucurbit [7] urea are loaded with hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid to prepare the fresh-keeping liquid, so that the fresh-keeping liquid has a good fresh-keeping effect on the snakehead fillets. Hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid rapidly permeates into a microporous structure, a long-chain network formed by polysarcosine and carboxyhexyl cucurbituril [7] urea has a slip ring structure, and the slip ring structure moves back and forth in a cross-linking point of the long-chain network structure, so that hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid is uniformly distributed in a fish tissue structure, and strong anti-oxidation and antibacterial effects are achieved; the freshness and the quality of the prepared snakehead fillet are ensured, and a new thought and a theoretical basis are provided for processing and development of aquatic product prepared food.

Description

Technical Field

[0001] The invention belongs to the technical field of food processing, and in particular relates to a processing method for prefabricated and conditioned black fish fillets. Background Art

[0002] Snakehead, also known as Channa argus, is a common edible fish in China. It has a long and round body, equal head and tail, delicate scales with a dark color and spotted patterns. It has strong adaptability and can survive in a variety of water environments. It is widely distributed. Snakehead has good medicinal value. Its meat has the effects of removing blood stasis, promoting new blood, nourishing and conditioning, promoting muscle growth and blood, and promoting wound healing. It is rich in protein and amino acids, has high nutritional value, and is regarded as a precious tonic. In addition, due to its delicious meat, tender and thick, and rich nutrition, snakehead is often processed into fish segments or fish fillets for cooking, which has high economic value. After the snakehead fish is gutted and cleaned, it is processed to obtain boneless fish fillets, which are rich in high-quality protein, unsaturated fatty acids, vitamins, minerals and other nutrients. Every 100g of snakehead fish contains 18.5g of protein and 1.2g of fat. The protein in snakehead fillets is easily absorbed by the human body and helps muscle growth and repair, while unsaturated fatty acids (such as omega-3 series) are beneficial to cardiovascular health; in addition, minerals such as calcium, phosphorus, iron, and vitamins A and D are important for maintaining bone health and promoting metabolism. Snakehead fillets are favored by consumers for their excellent nutritional value and biological benefits. However, due to their high moisture content, neutral pH conditions, low connective tissue content, endogenous enzymes and autolytic enzymes, etc., the quality of snakehead fillets will deteriorate. High moisture content and neutral pH conditions provide a suitable living and breeding environment for external spoilage bacteria. At the same time, endogenous enzymes and autolytic enzymes in fish fillets further decompose proteins and fats in muscle tissue, providing metabolic substrates for the growth of spoilage bacteria, resulting in the generation of bad flavors and rapid changes in freshness. Most of the existing technologies for improving and maintaining the quality of fish fillets are the combined use of exogenous additives and corresponding technologies, such as vacuum impregnation, microwaves, ultrasound, ozone treatment, irradiation treatment, coating preservation, ultra-high pressure treatment, etc. However, these technologies have certain defects. For example, microwave and ultrasound treatment of fish fillets will produce heat spots inside the fish tissue, causing local overheating and affecting the quality of the fish fillets. Ozone and irradiation will increase the probability of free radical generation and accelerate the oxidation and deterioration of nutrients in fish fillets. Therefore, it is urgent to explore new technologies and materials to ensure the good quality of fish fillets, which can not only promote the rapid development of aquatic prepared foods, but also provide new research ideas for the processing of a variety of fish, which will contribute to the deep processing and high-value utilization of aquatic products. Summary of the invention

[0003] Technical problem to be solved: In view of the above technical problem, the purpose of the present invention is to provide a processing method for pre-prepared conditioned black fish fillet, wherein the black fish is prepared by slaughtering, washing, slicing, high-density carbon dioxide and immersion preservation, belonging to the field of food processing technology. The black fish fillet can achieve a certain bacteriostatic effect and inactivate enzymes by high-density carbon dioxide treatment, and the residual carbon dioxide evaporates as gas to form a microporous structure in the tissue structure of the black fish fillet. At the same time, polysarcosine and carboxyhexylcucurbitacin [7] urea are loaded with hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid to form a fresh-keeping liquid, which quickly penetrates from the microporous structure. The long-chain network formed by polysarcosine and carboxyhexylcucurbitacin [7] urea has a sliding ring structure, and the sliding ring structure moves back and forth in the cross-linking points of the long-chain network structure, so that hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid is evenly distributed in the fish meat tissue structure, exerting a strong antioxidant and antibacterial effect, ensuring the freshness and quality of the pre-prepared conditioned black fish fillet, and providing a new idea and theoretical basis for the processing and development of aquatic pre-prepared food.

[0004] Technical solution: A method for processing pre-prepared conditioned black fish fillets, comprising the following steps: S1. Select fresh snakehead, slaughter and pre-treat to obtain pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 3-5 mm; S4. The black fish fillet is treated with high-density carbon dioxide, immersed and preserved, and vacuum packed to obtain the pre-prepared conditioned black fish fillet. Furthermore, the method for slaughtering and pre-treatment in step S1 is to remove the scales, head, skin and internal organs of the snakehead fish after slaughtering. Furthermore, the conditions for the high-density carbon dioxide treatment in step S4 are a holding pressure of 10-15 MPa, a holding time of 10-25 min, and a holding temperature of 35-45°C. Furthermore, in step S4, the pressurization time of the high-density carbon dioxide treatment is 5-10 minutes, and the depressurization time of the high-density carbon dioxide treatment is 3-5 minutes. Furthermore, the method of immersion preservation in step S4 is to immerse the black fish fillets treated with high-density carbon dioxide in a fresh-keeping liquid with a solid-liquid ratio of 1:(2-5) for 10-15 minutes. Furthermore, the method for preparing the fresh-keeping liquid comprises the following steps: Step 1. Weigh 0.1-0.5% hydroxytyrosol, 1-3% L-polyguluronic acid, and 0.5-2.0% glycyrrhizic acid, add water to dissolve, and stir at 60-70° C. and 350-550 rpm for 10-20 min to prepare a mixed solution; Step 2. Add water to polysarcosine and carboxyhexylcucurbitacin[7]uril and mix them evenly, treat them at 50-60° C. and 200-300 rpm for 2-4 hours, and obtain a carrier solution by microfiltration; Step 3. The mixed solution and the carrier solution are fully mixed, heated and stirred at 30-40° C. for 30-45 minutes to obtain a fresh-keeping solution. Furthermore, in step 2, the ratio of polysarcosine to carboxyhexylcucurbitacin[7]uril is 1:(3-6). Furthermore, the preparation method of carboxyhexylcucurbitacin[7]uril in step 2 is as follows: hydroxycucurbitacin[7]uril and 6-bromohexyl acetate are heated under nitrogen atmosphere at 55-60°C for 12-14 hours, purified by macroporous adsorption resin, and then mixed with sodium hydroxide and ultrapure water, heated at 55-60°C for 2-3 hours, purified and impurized, and vacuum freeze-dried to obtain carboxyhexylcucurbitacin[7]uril. Furthermore, in step 3, the ratio of the mixed solution to the carrier solution is (2-5):1. The pre-prepared conditioned black fish fillet prepared by any of the methods described above. Beneficial effects: 1. The present invention adopts high-density carbon dioxide technology, and utilizes carbon dioxide as a medium to exert an antibacterial effect in black fish fillets. The high moisture content and high pressure conditions of black fish fillets can promote the dissolution of carbon dioxide in the black fish fillets, so that the pH in the black fish fillets decreases, thereby increasing the energy consumption of the microorganisms in the black fish fillets in order to maintain their own pH biological stability, resulting in a decrease in the ability of the microorganisms to resist environmental changes. The unsuitable pH conditions can passivate or irreversibly inactivate the activity of enzymes related to microbial growth and metabolism, thereby inhibiting the reproduction of microorganisms; at the same time, the high-density carbon dioxide treatment of black fish fillets can also inhibit the activity of endogenous enzymes in the black fish fillets themselves, so that the protein, fat and other substances in the fish meat are not decomposed during the storage and transportation of the black fish fillets, thereby ensuring the freshness and tenderness of the black fish fillets; in addition, the high-density carbon dioxide technology belongs to a new non-thermal processing technology, which not only has good antibacterial and enzyme-passing effects, but also can retain heat-sensitive nutrients, prolong the shelf life of the black fish fillets, and the carbon dioxide remaining in the tissue structure of the black fish fillets after the treatment will volatilize in the form of gas, so that a microporous structure is formed in the tissue structure of the black fish fillets, which is conducive to the infiltration of the preservative solution. 2. The fresh-keeping liquid of the present invention contains hydroxytyrosol, polyguluronic acid and glycyrrhizic acid, and polysarcosine and carboxyhexylcucurbitacin [7] uril are used to prepare a network load with a sliding ring structure. The alcoholic hydroxyl group in hydroxytyrosol can interact with the carboxyl group in polyguluronic acid to improve the spicy taste of hydroxytyrosol itself, and glycyrrhizic acid self-assembles to form a gel network structure with hydrogen bonding, which first loads hydroxytyrosol-polyguluronic acid to form an aggregate, and at the same time, the long-chain network structure of polysarcosine and the circular cavity structure of carboxyhexylcucurbitacin [7] uril are nested with each other to form a load body with a sliding ring structure; the aggregate formed by hydroxytyrosol-polyguluronic acid-glycyrrhizic acid interacts with carboxyhexylcucurbitacin [7] uril and is embedded in the sliding ring structure of the load body, thereby ensuring the stable performance of strong antioxidant and antibacterial effects. 3. The high-density carbon dioxide treatment in the present invention gives the black fish fillet a rich microporous structure, the carrier embeds hydroxytyrosol-polyguluronic acid-glycyrrhizic acid, which can quickly enter the tissue structure of the black fish fillet, and polysarcosine interacts with the protein and fat in the fish tissue to accelerate the penetration of the fresh-keeping liquid; at the same time, as the sliding ring moves back and forth between the cross-linking points of the long-chain network structure, the embedded hydroxytyrosol-polyguluronic acid-glycyrrhizic acid is evenly distributed in the black fish fillet, when the hydroxytyrosol-polyguluronic acid-glycyrrhizic acid is released, the hydrophilic group in the sliding ring structure can adsorb and lock water molecules, improve the water retention and freshness of the black fish fillet, and hydroxytyrosol-polyguluronic acid-glycyrrhizic acid can resist the adverse effects of external corrupt microorganisms on the quality of the black fish fillet during storage, prevent deterioration and ensure quality. 4. The present invention utilizes a sliding ring structure to embed a fresh-keeping solution for pre-preparation and conditioning of black fish fillets, which can not only provide a new research direction for the development of pre-prepared fish products, but also promote the rapid development of the aquatic product industry, improve the product quality of pre-prepared black fish fillets during storage and transportation, and has a good market prospect. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is the total number of colonies of Example 6 and Comparative Examples 1-5 during storage; Figure 2 is the juice loss rate of Example 6 and Comparative Examples 1-5 during storage; Figure 3 is the TVB-N value of Example 6 and Comparative Examples 1-5 during storage; Figure 4 is the TBA value of Example 6 and Comparative Examples 1-5 during storage. DETAILED DESCRIPTION The present invention will be further described below in conjunction with embodiments, which are explanations of the present invention and are not limited to the following embodiments: Example 1 A method for preparing a preservative liquid for pre-preparing and conditioning black fish fillets comprises the following steps: Step 1. Weigh 0.5 g of hydroxytyrosol, 2.5 g of L-polyguluronic acid, and 2 g of glycyrrhizic acid, add 95 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution; Step 2. 10 g of polysarcosine and 40 g of carboxyhexylcucurbitacin[7]uril were mixed with water and treated at 50° C. and 300 rpm for 4 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 45 g of the mixed solution and 15 g of the carrier solution thoroughly, heat and stir at 35°C for 40 min to obtain a preservative solution. Example 2 A method for preparing a preservative liquid for pre-preparing and conditioning black fish fillets comprises the following steps: Step 1. Weigh 0.2 g of hydroxytyrosol, 2.0 g of L-polyguluronic acid, and 1.0 g of glycyrrhizic acid, add 96.8 g of water to dissolve, and stir at 65° C. and 450 rpm for 30 min to prepare a mixed solution; Step 2. 10 g of polysarcosine and 40 g of carboxyhexylcucurbitacin[7]uril were mixed with water and treated at 50° C. and 300 rpm for 3 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 45 g of the mixed solution and 15 g of the carrier solution thoroughly, heat and stir at 35°C for 40 min to obtain a preservative solution. Example 3 A method for preparing a preservative liquid for pre-preparing and conditioning black fish fillets comprises the following steps: Step 1. Weigh 0.5 g of hydroxytyrosol, 2.5 g of L-polyguluronic acid, and 2 g of glycyrrhizic acid, add 95 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution; Step 2. 10 g polysarcosine and 50 g carboxyhexylcucurbitacin[7]uril were mixed with water and treated at 50° C. and 300 rpm for 4 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 45 g of the mixed solution and 15 g of the carrier solution thoroughly, heat and stir at 35°C for 40 min to obtain a preservative solution. Example 4 A method for preparing a preservative liquid for pre-preparing and conditioning black fish fillets comprises the following steps: Step 1. Weigh 0.5 g of hydroxytyrosol, 2.5 g of L-polyguluronic acid, and 2 g of glycyrrhizic acid, add 95 g of water to dissolve, and stir at 70° C. and 400 rpm for 30 min to prepare a mixed solution; Step 2. 10 g of polysarcosine and 40 g of carboxyhexylcucurbitacin[7]uril were mixed with water and treated at 50° C. and 300 rpm for 4 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 40 g of the mixed solution and 10 g of the carrier solution thoroughly, heat and stir at 40°C for 40 minutes to obtain a preservative solution. Performance Testing (1) Particle size Take 10 mL of the fresh-keeping solution of Example 1-4, dilute it 100 times with ultrapure water, and measure the average particle size with a laser particle size analyzer at 25° C. and a scattering angle of 90°. (2) Encapsulation efficiency 0.5 mL of preservative solution was added to 1 mL of formic acid solution and ultrasonicated for 2 min, then centrifuged at 12000 rpm for 5 min, and the supernatant was taken and fixed to 5 mL with methanol. The content was determined by high performance liquid chromatography and the encapsulation efficiency was calculated. (3) Antioxidant capacity The antioxidant capacity of Examples 1-4 was determined as follows: ①DPPH·free radical scavenging rate: accurately pipette 2.0mL of fresh-keeping solution into 10mL test tubes, add 2.0mL of prepared DPPH·ethanol (1mgDPPH dissolved in 20mL ethanol) solution, shake well, and place in dark for 30min; adjust the spectrophotometer to zero with anhydrous ethanol, and measure the absorbance value A1 at 517nm; at the same time, accurately pipette 2.0mL of hydroxytyrosol extract and mix with 2.0mL of anhydrous ethanol, and measure the absorbance value A2 at 517nm; accurately pipette 2.0mL The prepared DPPH·-ethanol solution was mixed with 2.0 mL of anhydrous ethanol, and the absorbance value A0 was measured at 517 nm to calculate the scavenging rate of the test solution on DPPH free radicals. The calculation formula is DPPH·free radical scavenging rate (%) = [1-(A1-A2) / A0] × 100%, wherein A0 represents the absorbance of the DPPH·-ethanol solution mixed with anhydrous ethanol, A1 represents the absorbance of the preservative solution mixed with the DPPH·-ethanol solution; A2 represents the absorbance of the preservative solution mixed with anhydrous ethanol; ②ABTS+·Free radical scavenging rate: Accurately transfer 1.0 mL of preservative solution to a 10 mL test tube, add 3.00 mL of ABTS working solution with A734=0.7±0.02, shake well and let stand for 10 min, measure the absorbance A0 at 734 nm, transfer 1.0 mL of anhydrous ethanol to a 10 mL test tube, add A 734 = 0.7 ± 0.02 ABTS working solution 3.00mL, shake well and let stand for 10min, measure the absorbance A at 734nm, calculate the ABTS+·free radical scavenging rate, the formula is ABTS+·free radical scavenging rate (%) = (A0-A) / A0×100%, where A0 represents the absorbance of the ABTS·working solution after mixing with anhydrous ethanol, and represents the absorbance of the preservative solution after mixing with ABTS·working solution. ③ OH radical scavenging rate: 9mmol / LFeS0 was added into 10mL test tubes respectively. 4 Solution 2mL, 9mmol / L salicylic acid-ethanol solution 2mL, fresh-keeping solution 2mL and 8.8mmo1 / LH 2 O 2 2mL, shake well, react in a 37℃ water bath for 30min, measure the absorbance value A3 at 510nm with distilled water as reference, and measure the absorbance A0 of the solution without adding sample solution in the same way. 2 O 2 The absorbance of the solution A4 is used to calculate the scavenging rate of the test solution for ·OH, and the formula is [1-(A3-A4) / A0]×100%, where A0 represents the absorbance of the blank control without adding sample solution, A3 represents the absorbance of the fresh-keeping solution after the mixed solution reacts with ·OH, and A4 represents the absorbance of the fresh-keeping solution without adding color developer. Table 1 Average particle size, encapsulation efficiency and antioxidant activity of Examples 1-4 As can be seen from Table 1, the average particle size of Example 1 is smaller than that of Examples 2-4, while the encapsulation efficiency and antioxidant activity are higher than those of Examples 2-4, indicating that the addition of hydroxytyrosol, L-polyguluronic acid and glycyrrhizic acid deviates from the optimal solution and will affect the antioxidant activity, while the ratio of polysarcosine and carboxyhexylcucurbitacin[7]uril will affect the encapsulation efficiency and the average particle size. Once deviated from the optimal range, insufficient encapsulation will result. Therefore, the preservative solutions in the following examples are all prepared according to the method in Example 1. Example 5 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 10 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 6 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 7 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 15 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 8 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 10 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 9 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 15 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 10 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 35°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Embodiment 11 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 45°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 75 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Example 12 A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. Immerse 100 g of the black fish fillet treated with high-density carbon dioxide in 300 g of the fresh-keeping solution prepared in Example 1, treat for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Comparative Example 1 The difference between this comparative example and Example 6 is that polysarcosine and carboxyhexylcucurbitacin[7]uril are not added. A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. The 75g high-density carbon dioxide treated black fish fillet was immersed in 300g preservative solution, treated for 15min, and vacuum packed to obtain pre-conditioned black fish fillet; The method for preparing the fresh-keeping liquid comprises the following steps: Step 1. Weigh 1.5 g of hydroxytyrosol, 7.5 g of L-polyguluronic acid, and 6 g of glycyrrhizic acid, add 285 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution. Comparative Example 2 The difference between this comparative example and Example 6 is that polysarcosine is not added. A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. The 75g high-density carbon dioxide treated black fish fillet was immersed in 300g preservative solution, treated for 15min, and vacuum packed to obtain pre-conditioned black fish fillet; The method for preparing the fresh-keeping liquid comprises the following steps: Step 1. Weigh 2.5 g of hydroxytyrosol, 12.5 g of L-polyguluronic acid, and 10 g of glycyrrhizic acid, add 475 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution; Step 2. 40 g of carboxyhexylcucurbit[7]uril was mixed with water and uniformly treated at 50° C. and 300 rpm for 4 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 225 g of the mixed solution and 75 g of the carrier solution thoroughly, heat and stir at 35°C for 40 min to obtain a preservative solution. Comparative Example 3 The difference between this comparative example and Example 6 is that carboxyhexylcucurbit[7]uril is not added. A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. The 75g high-density carbon dioxide treated black fish fillet was immersed in 300g preservative solution, treated for 15min, and vacuum packed to obtain pre-conditioned black fish fillet; The method for preparing the fresh-keeping liquid comprises the following steps: Step 1. Weigh 2.5 g of hydroxytyrosol, 12.5 g of L-polyguluronic acid, and 10 g of glycyrrhizic acid, add 475 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution; Step 2. Add 10g of polysarcosine to water and mix evenly, treat at 50°C and 300rpm for 4h, and obtain a carrier solution by microfiltration; Step 3. Thoroughly mix 225g of the mixed solution and 75g of the carrier solution, heat and stir at 35°C for 40min to obtain a preservative solution. Comparative Example 4 The difference between this comparative example and Example 6 is that L-polyguluronic acid and glycyrrhizic acid are not added. A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S4. The black fish fillet was placed in the device, the pressure was increased to 12.5 MPa for 7 minutes, high-density carbon dioxide was treated for 20 minutes at 10 MPa and 40°C, and the pressure was released for 5 minutes to obtain a black fish fillet treated with high-density carbon dioxide; S5. The 75g high-density carbon dioxide treated black fish fillet was immersed in 300g preservative solution, treated for 15min, and vacuum packed to obtain pre-conditioned black fish fillet; The method for preparing the fresh-keeping liquid comprises the following steps: Step 1. Weigh 2.5 g of hydroxytyrosol, add 475 g of water to dissolve, and stir at 65° C. and 400 rpm for 20 min to prepare a mixed solution; Step 2. 50 g of polysarcosine and 200 g of carboxyhexylcucurbitacin[7]uril were mixed with water and treated at 50° C. and 300 rpm for 4 h, and then microfiltered to obtain a carrier solution; Step 3. Mix 225 g of the mixed solution and 75 g of the carrier solution thoroughly, heat and stir at 35°C for 40 min to obtain a preservative solution. Comparative Example 5 The difference between this comparative example and Example 6 is that high-density carbon dioxide treatment is not used. A method for processing pre-prepared conditioned black fish fillet comprises the following steps: S1. Select fresh snakehead, remove the scales, head, skin and viscera after slaughtering, and prepare pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 5 mm; S5. Immerse 75 g of black fish fillet in 300 g of the fresh-keeping solution prepared in Example 1 for 15 min, and vacuum pack to obtain pre-prepared conditioned black fish fillet. Performance Testing (1) Sensory evaluation The prepared black fish fillets were put into a boiling water pot at 100℃ and boiled for 30s, and then the prepared black fish fillets were taken out for sensory evaluation. The sensory evaluation was conducted by 10 pre-trained tasters (5 males and 5 females) aged 22-25 years old. The sensory evaluation criteria are shown in Table 2. Table 2 Sensory evaluation table of pre-prepared conditioned black fish fillet (2) Chroma The chromaticity of Examples 5-12 and Comparative Examples 1-5 was measured using a colorimeter, and L*, a*, and b* were recorded. The calculation formula for whiteness is as follows: Wherein: W represents whiteness, L* represents lightness value, a* represents red-green value, and b* represents yellow-blue value. (3) Water holding capacity Before placing the black fish fillet into the centrifuge tube, weigh the weight of the black fish fillet m1, centrifuge at 4°C and 4000r / min for 15min, then take the black fish fillet out of the centrifuge tube and weigh the weight of the black fish fillet m2 again; the water holding rate (%) of the black fish fillet is calculated as follows: Wherein: m1 represents the weight of black fish fillet, m2 represents the weight of black fish fillet after centrifugation, and w represents the water content of black fish fillet (77.32%). (4) Cooking loss rate Weigh the black fish fillet before putting it into the cooking bag, record it as m1, steam it at 100℃ for 3 minutes, cool it at room temperature, gently wipe the surface moisture of the black fish fillet with filter paper and weigh it, record it as m2. The cooking loss rate of black fish fillet is calculated as follows: Where m1 represents the mass of black fish fillet, and m2 represents the mass of cooked black fish fillet. Table 3 Sensory evaluation, whiteness, water holding rate and cooking loss rate of Examples 5-12 and Comparative Examples 1-5 As shown in Table 3, the black fish fillets prepared in Examples 5-12 are superior to those in Comparative Examples 1-5 in terms of sensory evaluation, whiteness, water retention rate and cooking loss rate, with Example 6 being the best. This indicates that high-density carbon dioxide treatment is conducive to the penetration of the fresh-keeping solution, and the L-polyguluronic acid and glycyrrhizic acid in the fresh-keeping solution can improve the unpleasant flavor of hydroxytyrosol and enrich the sensory quality of the black fish fillets; at the same time, the chain-like network with a sliding ring structure formed by polysarcosine and carboxyhexylcucurbitacin [7] uril can absorb water molecules in the black fish fillets, and the hydrophilic groups in the sliding ring structure further lock the water molecules, thereby ensuring the freshness and water retention of the black fish fillets, thereby reducing the quality loss of the black fish fillets during processing. (5) Storage test The black fish fillets prepared in Example 6 and Comparative Examples 1-5 were stored at 4° C. for 20 days. The total bacterial count, juice loss rate, volatile basic nitrogen (TVB-N), and thiobarbituric acid value (TBA) were measured every 5 days, as follows: ①Total number of colonies The total colony count of Example 6 and Comparative Examples 1-5 was determined according to GB 4789.2-2022 “National Food Safety Standard - Determination of Total Colony Count for Food Microbiological Examination”. ② Juice loss rate The weight of black fish fillet is measured with an electronic balance before packaging and refrigeration, recorded as m0. After storage for a certain period of time, the sample is taken out and the moisture on the surface of the sample is absorbed with filter paper or kitchen paper. The mass of the sample after storage for a certain period of time is measured and recorded as m1. The formula for calculating the juice loss rate is as follows: Where m0 represents the mass of black fish fillet before storage, and m1 represents the mass of black fish fillet after storage for a certain period of time. ③ Volatile basic nitrogen (TVB-N) The volatile basic nitrogen (TVB-N) of Example 6 and Comparative Examples 1-5 was determined according to GB 5009.228-2016 “National Food Safety Standard Determination of Volatile Basic Nitrogen in Foods”. ④Thiobarbituric acid value (TBA) Crush the black fish fillet with batter, weigh 10g (accurate to 0.001) in a 250mL conical flask, add 50mL 7.5% trichloroacetic acid (containing 0.1% EDTA), oscillate for 30min, centrifuge for 10min (4000r / min), filter after centrifugation; take 5mL of supernatant and add 5mL 0.02mol / L TBA solution, water bath at 95℃ for 40min, centrifuge for 5min (5000r / min), take 5mL of supernatant, add an equal volume of chloroform, oscillate and mix, centrifuge for 3min (1600r / min), and measure its absorbance at 532nm and 600nm respectively. TBA value is calculated as follows: Where A 532 is the absorbance value of black fish fillet at 532nm wavelength, A 600 is the absorbance value of black fish fillet at a wavelength of 600 nm, m is the mass of black fish fillet, 72.06 is the molar mass of malondialdehyde, and 155 is the absorption coefficient. Depend on Figure 1 It can be seen that the total number of colonies in Example 6 and Comparative Examples 1-5 increases with the extension of storage time, and the total number of colonies in Example 6 is the smallest. When stored for 20 days, it does not exceed the maximum acceptable limit of microorganisms in fish meat (61g CFU / g), while Comparative Examples 1-5 all exceed the limit, indicating that the quality of black fish fillets will gradually deteriorate during storage and breed spoilage microorganisms. These microorganisms can use the nutrients in the black fish fillets to reproduce and metabolize to produce harmful substances and bad odors. In this patent, high-density carbon dioxide is first used to treat black fish fillets. Carbon dioxide dissolves in the black fish fillets to reduce the pH, deviating from the appropriate pH range for the survival of initial microorganisms, achieving a certain bacteriostatic effect, and passivating the activity of enzymes required for microbial growth; in addition, the hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid embedded in the sliding ring structure formed by polysarcosine and carboxyhexylcucurbituril [7] uril has a good antibacterial effect, which can inhibit the invasion of external microorganisms on black fish fillets in the early stage of storage, destroy the structure and function of microbial cell membranes, achieve a good antibacterial effect, and extend the storage time of black fish fillets. Depend on Figure 2 It can be seen that the juice loss rate of Example 6 is significantly lower than that of Comparative Examples 1-5, indicating that in the method for preparing black fish fillet, the high-density carbon dioxide treatment first makes the surface of the black fish fillet have a structure, which is conducive to the penetration of the fresh-keeping liquid. The network structure formed by polysarcosine-carboxyhexylcucurbitacin [7] uril interacts with the protein in the black fish fillet and is embedded therein. When hydroxytyrosol-L-polyguluronide-glycyrrhizic acid is released, the cavity structure in the sliding ring structure can absorb water molecules in the black fish fillet, thereby locking in moisture and improving the water retention of the black fish fillet. The sliding ring structure can maintain a certain stability, so that the moisture of the black fish fillet is still tightly locked as the external conditions fluctuate during storage, and effectively inhibits the destruction of the muscle tissue structure in the black fish fillet, thereby reducing the juice loss rate. Depend on Figure 3It can be seen that with the extension of storage time, the TVB-N of the black fish fillets prepared in Example 6 and Comparative Examples 1-5 both show an increasing trend, wherein the TVB-N of Example 6 is greater than that of Comparative Examples 1-5, indicating that the freshness of Example 6 is better than that of Comparative Examples 1-5, indicating that the high-density carbon dioxide treatment can reduce bacteria and inactivate enzymes to a certain extent, inhibiting the degradation of substances such as proteins in the black fish fillets, while polysarcosine-carboxyhexylcucurbitacin [7] uril combines with proteins in the black fish fillets, and the antibacterial effect of hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid effectively reduces microbial growth, reduces protease secretion, reduces protein decomposition, and inhibits its decomposition into alkaline compounds such as ammonia and amines, thereby ensuring the quality of the black fish fillets. Depend on Figure 4 It can be seen that the TBA value reflects the degree of fat oxidation in the black fish fillet, and the lower the value, the higher the freshness of the black fish fillet. The TBA of the black fish fillet prepared in Example 6 during storage is lower than that of Comparative Examples 1-5, indicating that high-density carbon dioxide treatment and composite fresh-keeping liquid immersion synergistically inhibit fat oxidation during storage of black fish fillets, and the hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid in the composite fresh-keeping liquid has a highly efficient antioxidant property, which can inhibit the oxidative decomposition of fat in the black fish fillet during storage, and the embedded sliding ring structure can move back and forth with the cross-linking points in the long-chain network of polysarcosine, so that hydroxytyrosol-L-polyguluronic acid-glycyrrhizic acid can be evenly distributed in the tissue structure of the black fish fillet to play an antioxidant role, inhibit the generation of malondialdehyde, and reduce the TBA value. The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the art can make many possible changes and modifications to the technical solution of the present invention by using the above disclosed methods and technical contents without departing from the spirit and technical solution of the present invention, or modify it into an equivalent embodiment of equivalent changes. Therefore, any simple modification, equivalent replacement, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still falls within the scope of protection of the technical solution of the present invention.

Claims

1. A method for processing pre-prepared conditioned black fish fillet, characterized in that: The following steps are involved: S1. Select fresh snakehead, slaughter and pre-treat to obtain pre-treated snakehead; S2. The pre-treated snakehead fish is removed from the back of the spine to obtain snakehead fish meat; S3. Wash the black fish meat with clean water at room temperature and drain the water, and cut into black fish slices with a thickness of 3-5 mm; S4. The black fish fillet is treated with high-density carbon dioxide, immersed and preserved, and vacuum packed to obtain the pre-prepared conditioned black fish fillet.

2. The method for processing pre-cooked black fish fillet according to claim 1, characterized in that: The method for slaughtering and pre-treatment in step S1 is to remove the scales, head, skin and internal organs of the snakehead fish after slaughtering.

3. The method for processing pre-cooked black fish fillet according to claim 1, characterized in that: The conditions for the high-density carbon dioxide treatment in step S4 are a holding pressure of 10-15 MPa, a holding time of 10-25 min, and a holding temperature of 35-45° C.

4. The method for processing pre-cooked black fish fillet according to claim 1, characterized in that: The pressurization time of the high-density carbon dioxide treatment in step S4 is 5-10 minutes, and the depressurization time of the high-density carbon dioxide treatment is 3-5 minutes.

5. The method for processing pre-cooked black fish fillet according to claim 1, characterized in that: The method of immersion preservation in step S4 is to immerse the black fish fillets treated with high-density carbon dioxide in a fresh-keeping liquid with a material-liquid ratio of 1:(2-5) for 10-15 minutes.

6. The method for processing pre-cooked black fish fillet according to claim 1, characterized in that: The preparation method of the fresh-keeping liquid comprises the following steps: Step 1. Weigh 0.1-0.5% hydroxytyrosol, 1-3% L-polyguluronic acid, and 0.5-2.0% glycyrrhizic acid, add water to dissolve, and stir at 60-70° C. and 350-550 rpm for 10-20 min to prepare a mixed solution; Step 2. Add water to polysarcosine and carboxyhexylcucurbitacin[7]uril and mix them evenly, treat them at 50-60° C. and 200-300 rpm for 2-4 hours, and obtain a carrier solution by microfiltration; Step 3. The mixed solution and the carrier solution are fully mixed, heated and stirred at 30-40° C. for 30-45 minutes to obtain a preservative solution.

7. The method for processing pre-cooked black fish fillet according to claim 6, characterized in that: In the step 2, the ratio of polysarcosine to carboxyhexylcucurbitacin[7]uril is 1:(3-6).

8. The method for processing pre-cooked black fish fillet according to claim 6, characterized in that: The ratio of the mixed solution to the carrier solution in step 3 is (2-5):

1.

9. Pre-prepared conditioned black fish fillet prepared according to the method described in any one of claims 1 to 8.

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