Minced Antarctic krill with high astaxanthin retention rate and preparation method of minced Antarctic krill

Abstract

The invention relates to the technical field of marine food preparation, and discloses minced Antarctic krill with a high astaxanthin retention rate and a preparation method thereof.The preparation method comprises the steps that Antarctic krill is pretreated and then soaked in composite antioxidant liquid for composite antioxidant treatment, and then enzyme inhibition liquid is atomized and sprayed for low-temperature enzyme inhibition treatment; grinding at low temperature to obtain minced shrimps; and mixing the minced shrimps with the anti-oxidation emulsion, carrying out secondary anti-oxidation treatment, and then carrying out freezing and shaping. The euphausia superba is subjected to anti-oxidation treatment through the composite anti-oxidation liquid and the anti-oxidation emulsion, and the problem that the retention rate of astaxanthin is low due to the fact that the astaxanthin is sensitive to oxygen and metal ions and prone to oxidation is solved; meanwhile, the low-temperature enzyme inhibition treatment improves the elasticity and the viscosity of the minced shrimps and also reduces the loss of protease-mediated astaxanthin; the low-temperature grinding treatment not only protects the molecular structure integrity of astaxanthin, but also improves the separation rate of crustacean fragments.

Description

Technical Field

[0001] This invention relates to the field of marine food preparation technology, and more specifically, to an Antarctic krill paste with high astaxanthin retention rate and its preparation method. Background Technology

[0002] Antarctic krill is a key biological resource in the Southern Ocean ecosystem, abundant in reserves and rich in astaxanthin, high-quality water-soluble protein, and unsaturated fatty acids (such as EPA and DHA), among other nutrients. Astaxanthin, a potent natural antioxidant, possesses various physiological functions including anti-inflammatory, antioxidant, and immune-boosting effects, making it highly valuable in the food, health product, and cosmetic industries. With the increasing consumer demand for natural and nutritious foods, krill paste products made from Antarctic krill, due to their delicate texture and convenient consumption, are gradually becoming a research hotspot in the aquatic product processing field. Currently, the preparation process of Antarctic krill paste mainly includes steps such as raw material pretreatment, grinding and deshelling, enzyme inactivation, flavoring, and freezing. However, the astaxanthin retention rate of Antarctic krill paste prepared by existing processes is low. The main reason for this is: 1. Antarctic krill contains abundant endogenous proteases. These proteases are easily activated at room temperature or conventional processing temperatures. They not only degrade structural proteins such as myofibrillar protein and actin in krill muscle, resulting in loose texture, reduced viscosity, and excessive water loss, affecting the processing characteristics and edible quality of the product; at the same time, the catalytic action of proteases also accelerates the oxidative decomposition of astaxanthin, causing a large loss of astaxanthin.

[0003] 2. Astaxanthin is a fat-soluble active substance with unstable chemical properties, and it is quite sensitive to temperature, oxygen, light, and metal ions. In existing preparation processes, high-temperature inactivation is often used to inhibit the activity of endogenous proteases. However, high temperatures directly destroy the molecular structure of astaxanthin, leading to its oxidative inactivation. In addition, conventional mechanical grinding processes generate a large amount of frictional heat, raising the temperature of the processing system to 10-15℃, further exacerbating the oxidative decomposition of astaxanthin.

[0004] Therefore, the present invention proposes an Antarctic krill paste with high astaxanthin retention rate and its preparation method, which has important practical significance. Summary of the Invention

[0005] In view of this, the present invention proposes an Antarctic krill paste with high astaxanthin retention rate and its preparation method, aiming to solve the problem of low astaxanthin retention rate in existing Antarctic krill paste.

[0006] This invention proposes a method for preparing Antarctic krill paste with high astaxanthin retention rate, comprising the following preparation steps: Antarctic krill is pretreated and then immersed in a compound antioxidant solution for compound antioxidant treatment to obtain krill raw material; After the enzyme inhibitor solution is atomized and sprayed onto the surface of the krill raw material, it is subjected to low-temperature enzyme inhibition treatment. After the treatment, it is ground at low temperature to obtain shrimp paste. The shrimp paste is mixed with an antioxidant emulsion for a second antioxidant treatment, and the antioxidant-treated shrimp paste is frozen and shaped to obtain the Antarctic krill shrimp paste with high astaxanthin retention rate.

[0007] Furthermore, the preparation method of the composite antioxidant liquid is as follows: Using water as a solvent, add 0.2-0.6 wt% tea polyphenols, 0.1-0.2 wt% vitamin E, 0.1-0.5 wt% sodium citrate, and 1-3 wt% trehalose. Stir at 300 rpm for 10 min at 0-4℃.

[0008] Furthermore, the composite antioxidant treatment specifically includes: The pretreated Antarctic krill was immersed in the composite antioxidant solution at a material-to-liquid ratio of 1:(1-3) (g / mL) and soaked at a constant temperature of 2°C for 20 minutes. After soaking, the krill raw material was obtained.

[0009] Furthermore, the preparation method of the enzyme inhibitor solution is as follows: Using water as a solvent, add 0.06-0.1 wt% soybean protease inhibitor, 0.3-0.8 wt% sodium pyrophosphate, and 2-4 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0010] Furthermore, the amount of the enzyme inhibitor solution sprayed by atomization is 10-14% of the krill mass, the spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm; the temperature of the low-temperature enzyme inhibition treatment is 4 °C, and the treatment time is 25 min.

[0011] Furthermore, the low-temperature grinding specifically involves: The krill raw material after low-temperature enzyme inhibition treatment was ground at 800 rpm for 12 minutes at -10℃ to -5℃. After that, it was centrifuged at 3500 rpm for 6 minutes at 0℃, and the upper layer of shrimp paste was collected.

[0012] Furthermore, the preparation method of the antioxidant emulsion is as follows: The following mixtures were prepared by mixing 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% water at a mass ratio of 0-4°C and 11,000 rpm for 6 minutes.

[0013] Furthermore, the secondary antioxidant treatment specifically includes: Add 8-12% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C, then add 2% by weight of edible salt and 4% by weight of maltodextrin, and continue stirring for 5 minutes.

[0014] Furthermore, the cryopreservation specifically involves: The cooked shrimp paste was pre-frozen at -18℃ for 35 minutes, then frozen at -38℃ for 2.5 hours, and finally refrigerated at -18℃.

[0015] Furthermore, the preprocessing specifically includes: Rinse the Antarctic krill three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no moisture on the surface.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention provides comprehensive antioxidant treatment for Antarctic krill using a compound antioxidant liquid and an antioxidant emulsion. The compound antioxidant liquid is a blend of tea polyphenols (lipid-soluble antioxidants), vitamin E (free radical scavengers), sodium citrate (metal ion chelating agents), and trehalose (active substance structure protectants). It can eliminate free radicals in the krill raw materials in advance, chelate metal ions that accelerate astaxanthin oxidation, and protect the molecular structure of astaxanthin. The antioxidant emulsion is an oil-in-water system constructed with linseed oil, ascorbate palmitate, and Tween 80. It can form a physical protective film on the surface of the krill slurry particles. The dual system works synergistically to achieve oxidation isolation throughout the process, thereby effectively solving the problem of low astaxanthin retention due to its sensitivity to oxygen and metal ions and easy oxidation.

[0017] 2. This invention utilizes low-temperature enzyme inhibition treatment. The soybean protease inhibitor in the enzyme inhibition solution can specifically bind to the active sites of endogenous proteases (cathepsins, trypsins). Sodium pyrophosphate enhances the inhibitory effect by adjusting the pH value of the system. The low-temperature environment promotes the penetration of the inhibitor into muscle tissue and further inhibits enzyme activity, thereby blocking the degradation of myofibril protein and actin by proteases from the source. At the same time, it inhibits the astaxanthin oxidation and decomposition reaction catalyzed by proteases, which greatly improves the elasticity and viscosity of shrimp paste while reducing the loss of astaxanthin mediated by proteases.

[0018] 3. The low-temperature grinding process of the present invention rapidly absorbs the heat generated by mechanical grinding with liquid nitrogen, so that the grinding temperature is always kept below 10°C. At the same time, the low-temperature environment makes the krill shell brittle and easy to break, which not only protects the integrity of the astaxanthin molecular structure to the maximum extent, but also improves the shell fragment separation rate. Detailed Implementation

[0019] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention. It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the present invention.

[0020] Furthermore, regarding the numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included within this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0021] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0022] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0023] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0024] This invention provides a method for preparing Antarctic krill paste with high astaxanthin retention, comprising the following preparation steps: Antarctic krill is pretreated and then immersed in a compound antioxidant solution for compound antioxidant treatment to obtain krill raw material; After the enzyme inhibitor solution is atomized and sprayed onto the surface of the krill raw material, it is subjected to low-temperature enzyme inhibition treatment. After the treatment, it is ground at low temperature to obtain shrimp paste. The shrimp paste is mixed with an antioxidant emulsion for a second antioxidant treatment, and the antioxidant-treated shrimp paste is frozen and shaped to obtain the Antarctic krill shrimp paste with high astaxanthin retention rate.

[0025] Specifically, Understandably, this invention provides comprehensive antioxidant treatment for Antarctic krill using a compound antioxidant liquid and an antioxidant emulsion. The compound antioxidant liquid is a blend of tea polyphenols (lipid-soluble antioxidants), vitamin E (free radical scavengers), sodium citrate (metal ion chelating agents), and trehalose (active substance structure protectants). It can preemptively remove free radicals from krill raw materials, chelate metal ions that accelerate astaxanthin oxidation, and protect the astaxanthin molecular structure. The antioxidant emulsion is an oil-in-water system constructed with linseed oil, ascorbate palmitate, and Tween 80. It can form a physical protective film on the surface of the krill slurry particles. The dual systems work synergistically to achieve full-process oxidation isolation, thereby effectively solving the problem of low astaxanthin retention due to its sensitivity to oxygen and metal ions and easy oxidation.

[0026] Understandably, this invention utilizes low-temperature enzyme inhibition treatment. The soybean protease inhibitor in the enzyme inhibition solution can specifically bind to the active sites of endogenous proteases (cathepsins, trypsins). Sodium pyrophosphate enhances the inhibitory effect by adjusting the pH of the system. The low-temperature environment promotes the penetration of the inhibitor into muscle tissue and further inhibits enzyme activity, thereby blocking the degradation of myofibril protein and actin by proteases from the source. At the same time, it inhibits the astaxanthin oxidation and decomposition reaction catalyzed by proteases, which greatly improves the elasticity and viscosity of shrimp paste while reducing the loss of astaxanthin mediated by proteases.

[0027] It is understood that the low-temperature grinding process of the present invention rapidly absorbs the heat generated by mechanical grinding with liquid nitrogen, so that the grinding temperature is always kept below 10°C. At the same time, the low-temperature environment makes the krill shell brittle and easy to break, which not only protects the integrity of the astaxanthin molecular structure to the maximum extent, but also improves the shell fragment separation rate.

[0028] In this invention, the preprocessing specifically includes: Rinse the Antarctic krill three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no moisture on the surface.

[0029] Specifically, fresh Antarctic krill (caught within 24 hours) are rinsed three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, the krill are drained until there is no moisture on the surface. Then, they are graded according to their size: Antarctic krill of 4-5cm are selected as grade 1, and Antarctic krill of 5-6cm are selected as grade 2. Subsequent processing is carried out in batches according to grade.

[0030] In this invention, the preferred method for preparing the composite antioxidant liquid is as follows: Using water as a solvent, add 0.2-0.6 wt% tea polyphenols, 0.1-0.2 wt% vitamin E, 0.1-0.5 wt% sodium citrate, and 1-3 wt% trehalose. Stir at 300 rpm for 10 min at 0-4℃.

[0031] The preferred composite antioxidant treatment is: The pretreated Antarctic krill was immersed in the composite antioxidant solution at a material-to-liquid ratio of 1:(1-3) (g / mL) and soaked at a constant temperature of 2°C for 20 minutes. After soaking, the krill raw material was obtained.

[0032] Specifically, the water should be turned over every 5 minutes during soaking.

[0033] Understandably, this step involves preparing a compound antioxidant solution containing tea polyphenols (fat-soluble antioxidants), vitamin E (free radical scavengers), sodium citrate (metal ion chelators), and trehalose (active ingredient structure protection). The solution is stirred and dissolved at a low temperature of 0-4℃ to ensure system stability. The krill is then soaked at a constant temperature of 2℃ for 20 minutes, turning it over every 5 minutes to allow the compound antioxidant components to fully penetrate into the krill muscle tissue. At the same time, the solution is drained to control the amount of antioxidant solution residue. This process not only removes free radicals from the raw materials in advance, chelates metal ions that easily accelerate astaxanthin oxidation, and protects the integrity of the astaxanthin molecular structure, but also avoids uneven protection caused by insufficient local antioxidant concentration.

[0034] In this invention, the preferred method for preparing the enzyme inhibitor solution is as follows: Using water as a solvent, add 0.06-0.1 wt% soybean protease inhibitor, 0.3-0.8 wt% sodium pyrophosphate, and 2-4 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0035] The amount of the enzyme inhibitor solution sprayed by atomization is 10-14% of the krill mass, the spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm; the temperature of the low-temperature enzyme inhibition treatment is 4 °C, and the treatment time is 25 min.

[0036] Specifically, an enzyme inhibitor solution is sprayed onto the surface of the drained krill using a spraying method. The preferred spraying amount is 10-14% of the krill mass, the preferred spraying pressure is 0.3 MPa, the preferred nozzle diameter is 0.8 mm, and the preferred spraying distance is 15 cm. After spraying, the krill is placed in a 4°C constant temperature chamber and left to stand for 25 minutes. Understandably, this step achieves efficient inhibition of endogenous protease activity through the synergistic effect of soybean protease inhibitor and sodium pyrophosphate, blocking the degradation of myofibrillar protein and actin by protease and the catalytic oxidation of astaxanthin from the source. This avoids problems such as loose texture and decreased viscosity in subsequent shrimp paste processing. Furthermore, the low-temperature process and the protective effect of sorbitol maintain the stability of enzyme inhibitor activity. At the same time, the spray method ensures uniform coverage of the inhibitor without localized insufficient concentration, providing a guarantee for subsequent low-temperature grinding, high retention of astaxanthin, and stable texture of shrimp paste.

[0037] In this invention, the low-temperature grinding specifically refers to: The krill raw material after low-temperature enzyme inhibition treatment was ground at 800 rpm for 12 minutes at -10℃ to -5℃. After that, it was centrifuged at 3500 rpm for 6 minutes at 0℃, and the upper layer of shrimp paste was collected.

[0038] Specifically, the liquid nitrogen-assisted cryogenic grinder is started, and liquid nitrogen is supplied at a rate of 5L / h to precool the grinding chamber to -8℃. The krill raw material after cryogenic enzyme inhibition treatment is added to the grinder, and the grinding speed is set to 800rpm for 12min. During the grinding process, liquid nitrogen is continuously introduced to maintain the temperature of the grinding chamber between -10℃ and -5℃. After the grinding process is completed, the material is transferred to a cryogenic centrifuge (precooled to 0℃) and centrifuged at 3500rpm for 6min. The upper layer of shrimp paste is collected.

[0039] Understandably, this step utilizes liquid nitrogen to rapidly absorb the frictional heat generated during grinding, avoiding the damage to the astaxanthin molecular structure caused by the increased system temperature due to conventional grinding heat generation. At the same time, the low-temperature environment further enhances the inhibitory effect of endogenous proteases, preventing protein degradation and secondary loss of astaxanthin during the grinding process.

[0040] In this invention, the method for preparing the antioxidant emulsion is as follows: The following mixtures were prepared by mixing 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% water at a mass ratio of 0-4°C and 11,000 rpm for 6 minutes.

[0041] The secondary antioxidant treatment specifically includes: Add 8-12% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C, then add 2% by weight of edible salt and 4% by weight of maltodextrin, and continue stirring for 5 minutes.

[0042] Understandably, the physical encapsulation of the antioxidant emulsion and the synergistic effect of the chemical antioxidant properties of ascorbyl palmitate further isolate astaxanthin from contact with oxygen and metal ions, compensating for the oxidation risk caused by the exposure of shrimp paste particles after grinding during the initial antioxidant treatment, thus constructing a secondary antioxidant barrier to consolidate the high retention effect of astaxanthin. Furthermore, the ionic strength regulating effect of edible salt and the thickening and stabilizing effect of maltodextrin significantly improve the viscosity, cohesiveness, and water retention of the shrimp paste. At the same time, the low-temperature process throughout ensures that the activity of antioxidant components and the structure of astaxanthin are not damaged.

[0043] In this invention, the cryopreservation specifically refers to: The shrimp paste, after undergoing a second antioxidant treatment, was pre-frozen at -18℃ for 35 minutes, then frozen at -38℃ for 2.5 hours, and finally refrigerated at -18℃.

[0044] Specifically, the shrimp paste after secondary antioxidant treatment is packed into food-grade polyethylene bags (0.08 mm thick), the air inside the bags is removed (vacuum degree -0.09 MPa), and the bags are sealed. The sealed shrimp paste is first placed in a -18℃ freezer for 35 minutes, then transferred to a -38℃ deep freezer for 2.5 hours, and finally stored in a -18℃ cold storage.

[0045] Understandably, pre-freezing at -18°C allows the shrimp paste to slowly form tiny ice crystals, preventing cell rupture, while freezing at -38°C can quickly lock in astaxanthin and nutrients in the shrimp paste.

[0046] The water used in the preparation method of Antarctic krill paste with high astaxanthin retention rate of the present invention is preferably sterile water.

[0047] Example 1 Reagent preparation Preparation of the compound antioxidant solution: Using sterile water as the solvent, add 0.2wt% tea polyphenols, 0.1wt% vitamin E, 0.1wt% sodium citrate and 1wt% trehalose, and stir at 300rpm for 10min at 0-4℃.

[0048] Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.06 wt% soybean protease inhibitor, 0.3 wt% sodium pyrophosphate and 2 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0049] Preparation of antioxidant emulsion: 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% sterile water were mixed according to the following mass ratio and emulsified at 0-4℃ and 11,000 rpm for 6 minutes.

[0050] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Immerse the pretreated Antarctic krill in the composite antioxidant solution at a material-to-liquid ratio of 1:1 (g / mL) and soak at a constant temperature of 2°C for 20 minutes. Turn the krill over every 5 minutes during the soaking period. After the soaking is completed, drain the krill raw material. S3. Spray enzyme inhibitor solution onto the surface of the drained krill using a spray method. The preferred spray amount is 10% of the krill mass. The spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm. After spraying, place the krill in a 4℃ constant temperature chamber and let it stand for 25 minutes. Start the liquid nitrogen-assisted low temperature grinder and supply liquid nitrogen at a rate of 5 L / h to pre-cool the grinding chamber to -8℃. Add the krill raw material after low temperature enzyme inhibition treatment to the grinder, set the grinding speed to 800 rpm, and the grinding time to 12 minutes. During the grinding time, continuously introduce liquid nitrogen to maintain the grinding chamber temperature between -10 and -5℃. After the grinding is completed, transfer the material to a low temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 minutes. Collect the upper layer of shrimp paste. S4. Add 8% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C, then add 2% by weight of edible salt and 4% by weight of maltodextrin, and continue stirring for 5 minutes. After stirring, pack the mixture into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and pre-freeze the sealed shrimp paste in a -18°C freezer for 35 minutes. Then transfer it to a -38°C deep freezer for 2.5 hours, and finally store it in a -18°C cold storage to obtain Antarctic krill shrimp paste with high astaxanthin retention rate.

[0051] Example 2 Preparation of the compound antioxidant solution: Using sterile water as the solvent, add 0.4wt% tea polyphenols, 0.15wt% vitamin E, 0.3wt% sodium citrate and 2wt% trehalose, and stir at 300rpm for 10min at 0-4℃.

[0052] Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.08 wt% soybean protease inhibitor, 0.5 wt% sodium pyrophosphate and 3 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0053] Preparation of antioxidant emulsion: 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% sterile water were mixed according to the following mass ratio and emulsified at 0-4℃ and 11,000 rpm for 6 minutes.

[0054] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Immerse the pretreated Antarctic krill in the composite antioxidant solution at a material-to-liquid ratio of 1:2 (g / mL) and soak at a constant temperature of 2°C for 20 minutes. Stir the krill every 5 minutes during the soaking period. After the soaking is completed, drain the krill raw material. S3. Spray enzyme inhibitor solution onto the surface of the drained krill using a spray method. The preferred spray amount is 12% of the krill mass. The spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm. After spraying, place the krill in a 4℃ constant temperature chamber and let it stand for 25 minutes. Start the liquid nitrogen-assisted low temperature grinder and supply liquid nitrogen at a rate of 5 L / h to pre-cool the grinding chamber to -8℃. Add the krill raw material after low temperature enzyme inhibition treatment to the grinder, set the grinding speed to 800 rpm, and the grinding time to 12 minutes. During the grinding time, continuously introduce liquid nitrogen to maintain the grinding chamber temperature between -10 and -5℃. After the grinding is completed, transfer the material to a low temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 minutes. Collect the upper layer of shrimp paste. S4. Add 10% by weight of antioxidant emulsion to the shrimp paste, and stir at 200 rpm for 18 minutes at 0°C. After stirring, add 2% by weight of edible salt and 4% by weight of maltodextrin to the shrimp paste, and continue stirring for 5 minutes. After stirring, pack the mixture into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and pre-freeze the sealed shrimp paste in a -18°C freezer for 35 minutes. Then transfer it to a -38°C deep freezer for 2.5 hours, and finally store it in a -18°C cold storage to obtain Antarctic krill shrimp paste with high astaxanthin retention rate.

[0055] Example 3 Preparation of the compound antioxidant solution: Using sterile water as the solvent, add 0.6wt% tea polyphenols, 0.2wt% vitamin E, 0.5wt% sodium citrate and 3wt% trehalose, and stir at 300rpm for 10min at 0-4℃.

[0056] Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.1 wt% soybean protease inhibitor, 0.8 wt% sodium pyrophosphate and 4 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0057] Preparation of antioxidant emulsion: 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% sterile water were mixed according to the following mass ratio and emulsified at 0-4℃ and 11,000 rpm for 6 minutes.

[0058] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Immerse the pretreated Antarctic krill in the composite antioxidant solution at a material-to-liquid ratio of 1:3 (g / mL) and soak at a constant temperature of 2°C for 20 minutes. Turn the krill over every 5 minutes during the soaking period. After the soaking is completed, drain the krill raw material. S3. Spray enzyme inhibitor solution onto the surface of the drained krill using a spray method. The preferred spray amount is 14% of the krill mass. The spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm. After spraying, place the krill in a 4℃ constant temperature chamber and let it stand for 25 minutes. Start the liquid nitrogen-assisted low temperature grinder and supply liquid nitrogen at a rate of 5 L / h to pre-cool the grinding chamber to -8℃. Add the krill raw material after low temperature enzyme inhibition treatment to the grinder, set the grinding speed to 800 rpm, and the grinding time to 12 minutes. During the grinding time, continuously introduce liquid nitrogen to maintain the grinding chamber temperature between -10 and -5℃. After the grinding is completed, transfer the material to a low temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 minutes. Collect the upper layer of shrimp paste. S4. Add 12% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C, then add 2% by weight of edible salt and 4% by weight of maltodextrin, and continue stirring for 5 minutes. After stirring, pack the mixture into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and pre-freeze the sealed shrimp paste in a -18°C freezer for 35 minutes. Then transfer it to a -38°C deep freezer and freeze for 2.5 hours. Finally, transfer it to a -18°C cold storage to obtain Antarctic krill shrimp paste with high astaxanthin retention rate.

[0059] Comparison Example 1 (without antioxidant treatment) Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.08 wt% soybean protease inhibitor, 0.5 wt% sodium pyrophosphate and 3 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0060] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Spray enzyme inhibitor solution onto the surface of the drained krill using a spray method. The preferred spray amount is 12% of the krill mass. The spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm. After spraying, place the krill in a 4℃ constant temperature chamber and let it stand for 25 minutes. Start the liquid nitrogen-assisted low temperature grinder and supply liquid nitrogen at a rate of 5 L / h to pre-cool the grinding chamber to -8℃. Add the krill raw material after low temperature enzyme inhibition treatment to the grinder, set the grinding speed to 800 rpm, and the grinding time to 12 minutes. During the grinding time, continuously introduce liquid nitrogen to maintain the grinding chamber temperature between -10 and -5℃. After the grinding is completed, transfer the material to a low temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 minutes. Collect the upper layer of shrimp paste. S4. Add 2% edible salt and 4% maltodextrin by weight to the shrimp paste, and continue stirring for 5 minutes. After stirring, pack it into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and first place the sealed shrimp paste in a -18℃ freezer for 35 minutes. Then transfer it to a -38℃ deep freezer for 2.5 hours, and finally transfer it to a -18℃ cold storage for preservation to obtain Antarctic krill shrimp paste.

[0061] Control Example 2 (without cryo-enzyme inhibition treatment) Preparation of the compound antioxidant solution: Using sterile water as the solvent, add 0.4wt% tea polyphenols, 0.15wt% vitamin E, 0.3wt% sodium citrate and 2wt% trehalose, and stir at 300rpm for 10min at 0-4℃.

[0062] Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.08 wt% soybean protease inhibitor, 0.5 wt% sodium pyrophosphate and 3 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0063] Preparation of antioxidant emulsion: 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% sterile water were mixed according to the following mass ratio and emulsified at 0-4℃ and 11,000 rpm for 6 minutes.

[0064] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Immerse the pretreated Antarctic krill in the composite antioxidant solution at a material-to-liquid ratio of 1:2 (g / mL) and soak at a constant temperature of 2°C for 20 minutes. Stir the krill every 5 minutes during the soaking period. After the soaking is completed, drain the krill raw material. S3. Add the krill raw material to the grinder, set the grinding speed to 800 rpm and the grinding time to 12 min. During the grinding time, continuously introduce liquid nitrogen to maintain the temperature of the grinding chamber between -10 and -5℃. After the grinding is completed, transfer the material to a low temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 min. Collect the upper layer of shrimp paste. S4. Add 10% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C. After stirring, add 2% by weight of edible salt and 4% by weight of maltodextrin to the shrimp paste, and continue stirring for 5 minutes. After stirring, pack the mixture into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and pre-freeze the sealed shrimp paste in a -18°C freezer for 35 minutes. Then transfer it to a -38°C deep freezer and freeze for 2.5 hours. Finally, transfer it to a -18°C cold storage to obtain Antarctic krill shrimp paste.

[0065] Comparative Example 3 (using conventional grinding treatment) Preparation of the compound antioxidant solution: Using sterile water as the solvent, add 0.4wt% tea polyphenols, 0.15wt% vitamin E, 0.3wt% sodium citrate and 2wt% trehalose, and stir at 300rpm for 10min at 0-4℃.

[0066] Preparation of enzyme inhibitor solution: Using sterile water as solvent, add 0.08 wt% soybean protease inhibitor, 0.5 wt% sodium pyrophosphate and 3 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

[0067] Preparation of antioxidant emulsion: 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% sterile water were mixed according to the following mass ratio and emulsified at 0-4℃ and 11,000 rpm for 6 minutes.

[0068] Preparation method: S1. Rinse fresh Antarctic krill (within 24 hours of capture) three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no water on the surface. Then, grade the krill according to their size: select Antarctic krill of 4-5cm as grade 1 and select Antarctic krill of 5-6cm as grade 2. Process them in batches according to their grades during subsequent processing. S2. Immerse the pretreated Antarctic krill in the composite antioxidant solution at a material-to-liquid ratio of 1:2 (g / mL) and soak at a constant temperature of 2°C for 20 minutes. Stir the krill every 5 minutes during the soaking period. After the soaking is completed, drain the krill raw material. S3. Spray enzyme inhibitor solution onto the surface of the drained krill using a spray method. The preferred spray amount is 12% of the krill mass. The spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm. After spraying, place the krill in a 4℃ constant temperature chamber and let it stand for 25 minutes. Start the grinder, add the krill raw material after low-temperature enzyme inhibition treatment to the grinder, set the grinding speed to 800 rpm, and the grinding time to 12 minutes. After the grinding is completed, transfer the material to a low-temperature centrifuge (pre-cooled to 0℃) and centrifuge at 3500 rpm for 6 minutes. Collect the upper layer of shrimp paste. S4. Add 10% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C. After stirring, add 2% by weight of edible salt and 4% by weight of maltodextrin to the shrimp paste, and continue stirring for 5 minutes. After stirring, pack the mixture into a food-grade polyethylene bag (0.08 mm thick), remove the air from the bag (vacuum degree -0.09 MPa), seal it, and pre-freeze the sealed shrimp paste in a -18°C freezer for 35 minutes. Then transfer it to a -38°C deep freezer and freeze for 2.5 hours. Finally, transfer it to a -18°C cold storage to obtain Antarctic krill shrimp paste.

[0069] Test case 1. Grouping of test samples Experimental group: Antarctic krill paste with high astaxanthin retention rate prepared in Example 2 of this invention; Control group A: Antarctic krill paste prepared in control example 1; Control group B: Antarctic krill paste prepared in control example 2; Control group C: Antarctic krill paste prepared in control example 3; Each group was set up with 3 replicates, and the mean ± standard deviation was taken as the final data.

[0070] 2. Testing Methods The astaxanthin retention rate of each group of samples was determined by high performance liquid chromatography. S1. Extraction in the dark: Take 1.0g of shrimp paste from each group, add 10mL of methanol-methyl tert-butyl ether mixture, vortex and then extract in a 37℃ water bath in the dark for 60 minutes.

[0071] S2. Centrifugation and filtration: After removal, cool rapidly, centrifuge at 8000 rpm for 10 minutes, and take the supernatant and filter it through a 0.22 μm organic phase filter membrane.

[0072] S3. Chromatographic analysis: Inject the filtrate into the HPLC system for chromatographic analysis, wherein the chromatographic conditions are as follows: Chromatographic column: YMC C30 column (250mm×4.6mm, 5μm); Column temperature: 30℃; Mobile phase: methanol (A) / methyl tert-butyl ether (B), gradient elution; Flow rate: 1.0 mL / min; Detection wavelength: 472nm; Injection volume: 10 μL.

[0073] S4. Quantitative calculation: A standard curve was prepared using all-trans astaxanthin as a standard, and the astaxanthin retention rate (%) was calculated using the external standard method. The astaxanthin retention rate was calculated as follows: (Astaxanthin content in the finished shrimp paste / Astaxanthin content in the fresh raw shrimp) × 100%.

[0074] The elasticity of shrimp paste in each group of samples was tested using a texture analyzer puncture method. S1. Sample preparation: Fill the shrimp paste into a specific mold (such as a cylindrical container with a diameter of 30 mm) and then thaw to form a gel block; S2. Instrument Testing: Place the gel sample on the texture analyzer's sample stage, aligning the probe with the sample center. Start the program; the probe will press down at the set speed until it pierces the sample. The equipment parameters are as follows: Probe: Cylindrical probe with a diameter of 5mm or 12.7mm (P / 5); Test mode: Compression to breakage; Test speed: 1.0 mm / s; Trigger force: 5g; Puncture depth: 70% of the sample height.

[0075] S3. Data Analysis: Read the peak force at the first break from the force-distance curve. Elasticity (gel strength) is directly expressed as breaking force (N).

[0076] The viscosity of shrimp paste in each group of samples was determined using a rotational rheometer steady-state flow test (using a parallel plate fixture, in steady-state shear mode, the shear stress and viscosity of the shrimp paste at different shear rates were measured. The apparent viscosity value at a specific shear rate can directly characterize the viscosity): S1. Sample loading: Take freshly prepared shrimp paste from each group and use a scraper to evenly fill the center of the lower parallel plate.

[0077] S2. Gap setting: Lower the upper parallel plate to the measurement gap (1.0mm) and scrape off the excess sample.

[0078] S3. Program Execution: Execute the steady-state flow scanning program; the instrument automatically acquires data; select a shear rate of 50 s. -1 The apparent viscosity value (mPa·s) at a given time is used as an indicator for viscosity comparison. The test parameters are as follows: Instrument: Rotational rheometer (MCR302 model) Fixture: Parallel plate (25mm in diameter) Test mode: Steady-state flow Shear rate range: 0.1s -1 up to 100s -1 Temperature: 4℃.

[0079] The separation rate of shell fragments in each group of samples was tested using the wet sieve weighing method (utilizing the difference in permeability between shrimp paste and shell fragments on a sieve with specific mesh size, physical separation was achieved with the aid of water washing, and the separation rate was calculated by weighing): S1. Wet sieve separation: Weigh 50g of each group of ground wet shrimp paste samples (i.e., the upper layer of shrimp paste after centrifugation) (denoted as M total) and place them on a pre-weighed standard sieve (90 mesh, 180μm aperture). Gently stir and rinse with the aid of a gentle water flow (or soaking in ice water) to allow the shrimp paste to pass through the sieve while leaving the shell fragments on the sieve.

[0080] S2. Collection and drying: Transfer all residue (shell fragments) on the sieve to a pre-weighed petri dish and dry in an oven at 105°C until constant weight (usually about 4 hours).

[0081] S3. Cooling and Weighing: Transfer the petri dishes to a desiccator to cool to room temperature, weigh them, and calculate the separation rate (%) as follows: [1 - (W_shell / M_total)] × 100% Where W_shell = (weight of dried petri dish + weight of shell fragments) - (weight of petri dish).

[0082] 3. Test results (as shown in Table 1) Table 1 Test Results Table for Test Cases

[0083] As shown in Table 1, the astaxanthin retention rate of control group A (68.2%) was much lower than that of the experimental group (92.5%), a decrease of about 26%. This shows that the whole-process antioxidant system of the present invention, from "pretreatment" to "emulsion encapsulation", effectively solves the problem of easy oxidation of astaxanthin. The elasticity and viscosity data of control group B were the lowest among all groups, decreasing by approximately 10% and 29% respectively compared to the experimental group. This directly demonstrates that in the absence of targeted enzyme inhibition, the degradation effect of endogenous proteases leads to severe deterioration of the texture of shrimp surimi. Control group C showed the worst performance in both astaxanthin retention and shell separation rate. This indicates that even with antioxidant treatment, the heat and mechanical shear generated by conventional grinding still significantly damage astaxanthin; at the same time, the changes in material brittleness caused by low temperature can greatly improve the purity of shell separation.

[0084] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing Antarctic krill paste with high astaxanthin retention rate, characterized in that, The preparation steps include the following: Antarctic krill is pretreated and then immersed in a compound antioxidant solution for compound antioxidant treatment to obtain krill raw material; After the enzyme inhibitor solution is atomized and sprayed onto the surface of the krill raw material, it is subjected to low-temperature enzyme inhibition treatment. After the treatment, it is ground at low temperature to obtain shrimp paste. The shrimp paste is mixed with an antioxidant emulsion for a second antioxidant treatment, and the antioxidant-treated shrimp paste is frozen and shaped to obtain the Antarctic krill shrimp paste with high astaxanthin retention rate.

2. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 1, characterized in that, The preparation method of the composite antioxidant liquid is as follows: Using water as a solvent, add 0.2-0.6 wt% tea polyphenols, 0.1-0.2 wt% vitamin E, 0.1-0.5 wt% sodium citrate, and 1-3 wt% trehalose. Stir at 300 rpm for 10 min at 0-4℃.

3. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 2, characterized in that, The specific details of the composite antioxidant treatment are as follows: The pretreated Antarctic krill was immersed in the composite antioxidant solution at a material-to-liquid ratio of 1:(1-3) (g / mL) and soaked at a constant temperature of 2°C for 20 minutes. After soaking, the krill raw material was obtained.

4. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 3, characterized in that, The method for preparing the enzyme inhibitor solution is as follows: Using water as a solvent, add 0.06-0.1 wt% soybean protease inhibitor, 0.3-0.8 wt% sodium pyrophosphate, and 2-4 wt% sorbitol, and stir at 250 rpm for 8 min at 0-4℃.

5. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 4, characterized in that, The amount of the enzyme inhibitor solution sprayed by atomization is 10-14% of the krill mass, the spray pressure is 0.3 MPa, the nozzle diameter is 0.8 mm, and the spray distance is 15 cm; the temperature of the low-temperature enzyme inhibition treatment is 4 °C, and the treatment time is 25 min.

6. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 5, characterized in that, The low-temperature grinding specifically refers to: The krill raw material after low-temperature enzyme inhibition treatment was ground at 800 rpm for 12 minutes at -10℃ to -5℃. After that, it was centrifuged at 3500 rpm for 6 minutes at 0℃, and the upper layer of shrimp paste was collected.

7. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 6, characterized in that, The preparation method of the antioxidant emulsion is as follows: The following mixtures were prepared by mixing 6 wt% flaxseed oil, 0.25 wt% ascorbate palmitate, 1.5 wt% Tween 80, and 92.25 wt% water at a mass ratio of 0-4°C and 11,000 rpm for 6 minutes.

8. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 7, characterized in that, The secondary antioxidant treatment specifically includes: Add 8-12% by weight of antioxidant emulsion to the shrimp paste, stir at 200 rpm for 18 minutes at 0°C, then add 2% by weight of edible salt and 4% by weight of maltodextrin, and continue stirring for 5 minutes.

9. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 8, characterized in that, The cryopreservation process specifically involves: The cooked shrimp paste was pre-frozen at -18℃ for 35 minutes, then frozen at -38℃ for 2.5 hours, and finally refrigerated at -18℃.

10. The method for preparing Antarctic krill surimi with high astaxanthin retention rate according to claim 9, characterized in that, The preprocessing specifically includes: Rinse the Antarctic krill three times with sterile water at 0-4℃ for 30 seconds each time, with a water flow rate of 0.5m / s. After rinsing, drain until there is no moisture on the surface.

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