Freezing and fresh-keeping processing technology of low thawing syneresis rate of south American white shrimp meat

Abstract

The application discloses a kind of low thawing water loss rate South American white prawn shelled prawn frozen sleep lock fresh processing technology, it is related to aquatic product processing technical field, including the following steps: raw material pretreatment, low temperature precooling, gradient pressure superhigh pressure shelling, pulse vacuum ultrasonic assisted impregnation true, three-stage temperature control frozen sleep lock fresh freezing and frozen storage.The application is integrated by low temperature precooling, gradient pressure superhigh pressure shelling, pulse vacuum cycle and ultrasonic assisted synergic impregnation true, three-stage temperature control and supercooled state control are combined to frozen sleep lock fresh freezing, each step synergic effect, can effectively reduce shelled prawn thawing water loss rate, inhibit protein denaturation, improve shelling efficiency and shelled prawn integrity.

Description

Technical Field

[0001] This invention relates to the field of aquatic product processing technology, specifically to a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing and water loss rate. Background Technology

[0002] Shellfish (especially shrimp) are important raw materials for aquatic product processing in my country. Shrimp meat is highly favored by consumers for its delicious taste and rich nutrition, and frozen shrimp products occupy an important position in China's frozen aquatic product industry. Taking Litopenaeus vannamei shrimp meat as an example, the following problems still exist in its freezing and storage processes:

[0003] First, during the freezing process, the concentration of solutes and the formation of ice crystals during freezing and storage alter the quality of shrimp meat. As the freezing and storage time increases, shrimp meat proteins undergo freezing denaturation, resulting in reduced water retention, tenderness, gelation, and nutritional value. After thawing, shrimp meat loses more juice, becomes harder and more brittle, has a coarse texture, and a darker appearance.

[0004] Secondly, as the freezing time increases, the formation, growth, and recrystallization of ice crystals in the muscle exacerbate tissue damage, leading to increased loss of muscle juices and deterioration of textural properties after thawing. Especially under the influence of long-distance transportation and storage temperature fluctuations, the water-ice crystals in frozen shrimp muscle undergo repeated freeze-thaw cycles, resulting in severe recrystallization and a continuous decline in the quality of frozen shrimp products.

[0005] Third, in current shrimp processing, shelling mainly relies on manual operation, which is not only inefficient but also prone to causing shrimp meat and tail breakage and mechanical damage. Existing research indicates that ultra-high pressure shelling technology can solve these problems to some extent; however, current ultra-high pressure shelling technology has high equipment requirements and lacks organic integration with subsequent freezing and preservation processes.

[0006] Fourth, existing technologies have reported the use of cryoprotectants to improve the quality of frozen shrimp. For example, using sodium pyrophosphate, sodium tripolyphosphate, trehalose, alginate oligosaccharides, and carrageenan oligosaccharides in combination with vacuum permeation treatment can effectively reduce the thawing loss rate of shrimp. However, compound phosphate water-retaining agents pose certain health risks, and there is still room for improvement in the quality protection effect of single cryoprotectant treatment for long-term frozen storage.

[0007] Fifth, the color of shrimp meat is prone to deterioration during frozen storage, mainly manifested as blackening or reddening of the shrimp meat surface, which affects the appearance quality and commercial value of the product.

[0008] Therefore, a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate is needed to solve the problems existing in the current technology. Summary of the Invention

[0009] The present invention aims to at least partially solve one of the technical problems in the above-mentioned technologies.

[0010] To achieve the above objectives, the first aspect of this invention proposes a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, comprising the following steps:

[0011] S1: Raw material pretreatment—Fresh live whiteleg shrimp are cleaned and placed in crushed ice for shock, with the temperature controlled at 0-4℃, to obtain pretreated shrimp bodies; S2: Low-temperature precooling—The pretreated shrimp bodies are placed in an environment of -5 to 0℃ for precooling for 10-30 minutes, to obtain precooled shrimp bodies; S3: Gradient pressurization ultra-high pressure deshelling—The precooled shrimp bodies are sealed and packaged, and then placed in an ultra-high pressure device. The pressure is increased in stages at a rate of 5-20 MPa / s, first pressurized to 50-80 MPa and held for 1-3 minutes, then pressurized to 150-250 MPa and held for 3-6 minutes. After depressurization, the shrimp meat is removed; S4: Pulsed vacuum ultrasonic-assisted immersion for preservation—The deshelled shrimp meat is placed in a vacuum immersion device and immersed in a preservation agent solution using pulsed vacuum circulation, while ultrasonic assistance is applied. The preservation agent solution is an aqueous solution containing antifreeze protective components. The pulsed vacuum circulation... The process involves: evacuating to 0.06–0.095 MPa and holding for 3–5 minutes, then releasing the pressure to atmospheric pressure and holding for 1–2 minutes, repeating this cycle 2–5 times. The ultrasonic frequency is 20–50 kHz, the power is 100–300 W, the processing time is 5–15 minutes, and the immersion temperature is controlled at 0–10℃. S5: Three-stage temperature-controlled freezing and freshness-locking freezing—The immersed shrimp are subjected to three-stage temperature-controlled freezing treatment: the first stage is the pre-cooling stage, from 0℃ to -5℃ at a cooling rate of 1–3℃ / min. When the core temperature of the shrimp reaches -2–-1℃, this temperature is maintained for 30–120 seconds. The second stage is the phase change stage, from -5℃ to -15℃ at a cooling rate ≥10℃ / min. The third stage is the temperature equalization stage, from -15℃ to -40℃ at a cooling rate of 3–5℃ / min. S6: Freezing—The frozen shrimp are frozen at -18–-25℃.

[0012] In addition, the freezing and preserving process for Litopenaeus vannamei shrimp meat with low thawing water loss rate proposed above according to the present invention may also have the following additional technical features:

[0013] Further, in S4, the fidelity-preserving agent solution is composed of the following components by mass percentage: 5-8% proteolytic peptides from aquatic product by-products, 2-4% β-glucan, 3-5% sodium lactate, 0.05-0.25% konjac glucomannan, with the balance being water.

[0014] Furthermore, in S2, the precooling temperature is -2 to -3°C, and the precooling time is 15 to 20 minutes.

[0015] Furthermore, in S3, the segmented pressurization involves first pressurizing to 50-80 MPa and holding for 1-3 minutes, then pressurizing to 180-220 MPa and holding for 4-5 minutes.

[0016] Furthermore, in S4, the pulsed vacuum cycle is performed by evacuating to 0.08-0.09 MPa and holding for 3-4 minutes, then releasing the gas to atmospheric pressure and holding for 1.5-2 minutes, and repeating the cycle 3-4 times.

[0017] Furthermore, in S4, the ultrasonic frequency is 30-40kHz, the power is 150-250W, and the processing time is 8-12 minutes.

[0018] Furthermore, in S5, in the three-stage temperature-controlled freezing process: the pre-cooling stage has a cooling rate of 2℃ / min, and when the center temperature of the shrimp reaches -1.5 to -1℃, it is maintained for 45 to 90 seconds; the phase change stage has a cooling rate of 10 to 15℃ / min; and the uniform temperature stage has a cooling rate of 3 to 5℃ / min.

[0019] Furthermore, in S6, the freezing temperature is -18 to -20°C.

[0020] This invention discloses a freezing and dormancy preservation process for Litopenaeus vannamei shrimp meat with low thawing water loss rate. It integrates a system of freezing and dormancy preservation freezing, combining low-temperature precooling, gradient pressurization ultra-high pressure deshelling, pulsed vacuum circulation and ultrasonic-assisted synergistic immersion freezing for preservation, and three-stage temperature control with supercooled state control. The synergistic effect of each step effectively reduces the thawing water loss rate of shrimp meat, inhibits protein denaturation, improves deshelling efficiency and shrimp meat integrity. Furthermore, the systematic integration of ultra-high pressure assisted deshelling, vacuum immersion freezing, and a dedicated freezing and dormancy preservation agent reveals the mechanism by which the freezing and dormancy preservation process protects the quality characteristics of shrimp meat, providing a feasible industrial-scale technical solution for shrimp meat preservation. Attached Figure Description

[0021] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0022] Figure 1 This is a flowchart of a freezing and dormancy-locking process for Litopenaeus vannamei shrimp meat with low thawing and water loss rate according to an embodiment of the present invention. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, with examples of the embodiments illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] The following describes a freezing and dormancy-locking process for Litopenaeus vannamei shrimp meat with low thawing and water loss rate according to an embodiment of the present invention, with Litopenaeus vannamei shrimp meat as an example for detailed explanation. However, the scope of protection of the present invention is not limited thereto.

[0025] like Figure 1 As shown in the figure, a freezing and dormancy-locking processing method for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to an embodiment of the present invention includes the following steps:

[0026] S1: Raw material pretreatment—After cleaning the fresh whiteleg shrimp, place them in crushed ice to shock them, and control the temperature at 0-4℃ to obtain pretreated shrimp.

[0027] S2: Low-temperature precooling—The pretreated shrimp are placed in an environment of -5 to 0°C for 10 to 30 minutes to obtain precooled shrimp.

[0028] As a preferred embodiment, in S2, the precooling temperature is -2 to -3°C, and the precooling time is 15 to 20 minutes.

[0029] S3: Gradient pressurization and ultra-high pressure shelling—After sealing and packaging the pre-cooled shrimp, place it in an ultra-high pressure device and pressurize it in stages at a pressurization rate of 5-20 MPa / s. First, pressurize it to 50-80 MPa and hold it for 1-3 minutes, then pressurize it to 150-250 MPa and hold it for 3-6 minutes. After depressurization, take out the shrimp meat.

[0030] As a preferred embodiment, in S3, the segmented pressurization involves first pressurizing to 50-80 MPa and holding for 1-3 minutes, then pressurizing to 180-220 MPa and holding for 4-5 minutes.

[0031] S4: Pulsed Vacuum Ultrasonic Assisted Impregnation for Fidelity Preservation—The shelled shrimp are placed in a vacuum impregnation device and impregnated in a fidelity preservation agent solution using a pulsed vacuum cycle, while ultrasonic assistance is applied simultaneously. The fidelity preservation agent solution is an aqueous solution containing antifreeze protective components. The pulsed vacuum cycle involves evacuating to 0.06–0.095 MPa and holding for 3–5 minutes, then releasing the pressure to atmospheric pressure and holding for 1–2 minutes, repeating the cycle 2–5 times. The ultrasonic frequency is 20–50 kHz, the power is 100–300 W, the processing time is 5–15 minutes, and the impregnation temperature is controlled at 0–10℃.

[0032] As a preferred embodiment, in S4, the fidelity-preserving agent solution is composed of the following components by mass percentage: 5-8% proteolytic peptides from aquatic product by-products, 2-4% β-glucan, 3-5% sodium lactate, 0.05-0.25% konjac glucomannan, and the balance being water.

[0033] Specifically, the preparation method of proteolytic peptides from aquatic product by-products includes the following steps: Take aquatic product processing by-products (such as shrimp heads, shrimp shells, fish fillets, fish scales, fish skin, etc.), add 1 to 4 times the mass of water, slurry, heat to 80 to 100℃ and keep warm for 15 to 35 minutes for pretreatment, cool and adjust the pH to 7.0 to 8.5, add 0.05% to 0.2% of protease (at least one of papain, alkaline protease, and trypsin) according to the mass of the slurry, and enzymatically hydrolyze at 50 to 65℃ for 2 to 5 hours. After enzymatic hydrolysis, heat to 95 to 100℃ and keep warm for 5 to 20 minutes to inactivate the enzyme, centrifuge and take the supernatant for ultrafiltration separation, retain the component with a molecular weight cutoff of 1000 to 6000 Da, concentrate and dry to obtain the final product.

[0034] As a specific embodiment of the present invention, the preparation method of aquatic product by-product protease hydrolysate peptides is as follows: Take 100 kg of shrimp heads, add 200 kg of water, mash, heat to 90°C and keep warm for 30 minutes for pretreatment, cool and adjust pH to 8.0, add 0.1 kg of alkaline protease, and enzymatically hydrolyze at 55°C for 4 hours. After enzymatic hydrolysis, heat to 100°C and keep warm for 10 minutes to inactivate the enzyme, centrifuge and take the supernatant for ultrafiltration separation, retain the component with a molecular weight cutoff of 1000-6000 Da, concentrate and dry to obtain the peptides.

[0035] As a preferred embodiment, in S4, the pulsed vacuum cycle is performed by evacuating to 0.08-0.09 MPa and holding for 3-4 minutes, then releasing the gas to atmospheric pressure and holding for 1.5-2 minutes, and repeating the cycle 3-4 times.

[0036] As a preferred embodiment, in S4, the ultrasonic frequency is 30-40kHz, the power is 150-250W, and the processing time is 8-12 minutes.

[0037] S5: Three-stage temperature-controlled freezing and freshness-locking freezing—The soaked shrimp are subjected to three-stage temperature-controlled freezing treatment: The first stage is the pre-cooling stage, which drops from 0℃ to -5℃ at a cooling rate of 1 to 3℃ / min. When the core temperature of the shrimp reaches -2 to -1℃, this temperature is maintained for 30 to 120 seconds. The second stage is the phase change stage, which drops from -5℃ to -15℃ at a cooling rate of ≥10℃ / min. The third stage is the temperature equalization stage, which drops from -15℃ to -40℃ at a cooling rate of 3 to 5℃ / min.

[0038] In this invention, the frozen-dormant freezing method, through the synergistic effect of rapidly passing through the maximum ice crystal formation zone and supercooling control, makes the ice crystals in the shrimp tissue uniform and fine, effectively maintaining the integrity of the shrimp cells, thereby delaying protein denaturation, reducing juice loss, improving textural properties and color stability.

[0039] As a preferred embodiment, in S5, the three-stage temperature-controlled freezing process includes: a pre-cooling stage with a cooling rate of 2℃ / min, which is maintained for 45 to 90 seconds when the center temperature of the shrimp reaches -1.5 to -1℃; a phase change stage with a cooling rate of 10 to 15℃ / min; and a uniform temperature stage with a cooling rate of 3 to 5℃ / min.

[0040] In this invention, the supercooled state refers to the state where the temperature of the shrimp core is below its freezing point but ice crystal nucleation has not yet occurred. By controlling the temperature of the shrimp core at -2 to -1℃ and maintaining it for 30 to 120 seconds, the temperature of the shrimp can be evenly distributed. At this time, the free water inside the shrimp tissue is in a metastable state, and ice crystal nucleation is temporarily inhibited. After the temperature of the shrimp is uniform, it is then passed through the phase transition section at a rate of ≥10℃ / min, which allows ice crystals to nucleate simultaneously and uniformly, forming a fine and dense ice crystal structure.

[0041] S6: Frozen storage—Freeze the frozen shrimp at -18 to -25°C.

[0042] As a preferred embodiment, in S6, the freezing temperature is -18 to -20°C.

[0043] In this invention, the range of process parameters for each step is determined based on the material characteristics of shellfish such as shrimp and the principle of freezing processing. The following explanation uses whiteleg shrimp meat as an example, and is not a simple conventional choice.

[0044] It should be noted that the ultra-high pressure shelling parameters (150-250 MPa, 3-6 minutes) are as follows: if the pressure is below 150 MPa, the shrimp shell and shrimp meat will not separate completely, and the shelling effect will be poor. If the pressure is above 250 MPa, the shrimp meat tissue will be subjected to excessive pressure, which will lead to protein structure damage and texture deterioration. If the holding time is less than 3 minutes, the high pressure effect will be insufficient, and if it exceeds 6 minutes, it will have an adverse effect on the quality of the shrimp meat.

[0045] It should be noted that the pre-cooling parameters (-5 to 0℃, 10 to 30 minutes) are as follows: if the pre-cooling temperature is below -5℃, the surface of the shrimp will freeze prematurely, affecting the subsequent ultra-high pressure peeling effect. If it is above 0℃, the pre-cooling effect will be insufficient and it will not be able to effectively reduce the temperature of the shrimp. If the pre-cooling time is less than 10 minutes, the temperature of the shrimp will not drop evenly. If it exceeds 30 minutes, the processing efficiency will be reduced and the freshness of the shrimp meat will be affected.

[0046] It should be noted that the pulse vacuum parameters (0.06~0.095MPa, 3~5 minutes / cycle, 2~5 cycles) are as follows: when the vacuum degree is below 0.06MPa, the exhaust effect is insufficient; when it is above 0.095MPa, the equipment requirements are too high and it will cause excessive stretching of the shrimp tissue; when the pressure holding time is less than 3 minutes, the gas is not fully discharged; when it exceeds 5 minutes, the efficiency decreases; when the number of cycles is less than 2, the penetration effect is limited; when it exceeds 5, the processing time is increased and the effect is not significantly improved.

[0047] It should be noted that the ultrasonic parameters (20-50kHz, 100-300W, 5-15 minutes) are as follows: when the frequency is below 20kHz, the ultrasonic cavitation effect is insufficient; when it is above 50kHz, it will damage the shrimp tissue; when the power is below 100W, the enhanced penetration effect is limited; when it is above 300W, too much heat will be generated, affecting the control of the soaking temperature; when the treatment time is less than 5 minutes, the penetration is insufficient; and when it exceeds 15 minutes, it will affect the texture of the shrimp.

[0048] It should be noted that the supercooling control parameters (-2 to -1℃, 30 to 120 seconds) are as follows: when the temperature is below -2℃, ice crystals begin to nucleate, and supercooling control cannot be achieved. When the temperature is above -1℃, the supercooling state has not been reached, and the shrimp has not yet entered the freezing point. When the supercooling state is maintained for less than 30 seconds, the internal temperature of the shrimp is not uniform. When the temperature drops rapidly, the nucleation of ice crystals is inconsistent. When the temperature exceeds 120 seconds, spontaneous nucleation of ice crystals is inevitable.

[0049] It should be noted that the cooling rate in the phase transition section (≥10℃ / min): when the cooling rate is lower than 10℃ / min, it is impossible to quickly pass through the maximum ice crystal formation zone (-1℃~-5℃), and the formation of large ice crystals will cause cell damage. Passing through this temperature range at a rate of ≥10℃ / min can make the water inside and outside the cells form small and uniform ice crystals almost simultaneously.

[0050] Example 1

[0051] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0052] First, select fresh, live whiteleg shrimp, wash them with clean water, and then place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Next, pre-cool the pre-treated shrimp in a -3℃ environment for 20 minutes to obtain pre-cooled shrimp. Then, place the pre-cooled shrimp into food-grade plastic bags, add water to submerge the shrimp, vent and seal, and place them in an ultra-high pressure device. Pressurize to 60MPa at a rate of 10MPa / s, hold for 2 minutes, then pressurize to 200MPa and hold for 5 minutes. After depressurization, remove the shrimp; the shell and shrimp meat will automatically separate, allowing you to remove the whole shrimp meat. Next, prepare a preservation agent solution (components by weight percentage: 6% protease hydrolysate from aquatic product byproducts, 3% β-glucan, 4% sodium lactate, 0.1% konjac glucomannan, with the remainder being water). Then, use the deshelled shrimp... The shrimp were then placed in a vacuum impregnation device and impregnated in a fidelity agent solution using a pulsed vacuum cycle: vacuum was applied to 0.08 MPa and held for 4 minutes, then released to atmospheric pressure and held for 1.5 minutes, and this cycle was repeated 3 times. Simultaneously, 40 kHz ultrasound with a power of 200 W was applied for 10 minutes, with the impregnation temperature controlled at 4℃. After that, the impregnated shrimp underwent a three-stage temperature-controlled freezing process: the pre-cooling stage reduced the temperature from 0℃ to -5℃ at a rate of 2℃ / min, and when the core temperature of the shrimp reached -1.5℃, this temperature was maintained for 60 seconds; the phase change stage reduced the temperature from -5℃ to -15℃ at a rate of 12℃ / min; and the temperature equalization stage reduced the temperature from -15℃ to -40℃ at a rate of 4℃ / min. Finally, the frozen shrimp were packaged and transferred to a -20℃ cold storage for freezing.

[0053] Example 2

[0054] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0055] First, select live whiteleg shrimp, wash them with clean water, and then place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Second, place the pre-treated whiteleg shrimp in a -2℃ environment for 15 minutes to obtain pre-cooled shrimp. Then, seal the pre-cooled shrimp in packaging and place them in an ultra-high pressure device, pressurizing them to 50MPa at a pressurization rate of 8MPa / s, holding the pressure for 3 minutes, then pressurizing them to 180MPa, holding the pressure for 4 minutes, and then releasing the pressure to remove the shrimp meat. Next, prepare a fidelity preservation solution (composition by mass percentage: 6% protease hydrolysate peptides from aquatic product by-products, 3% β-glucan, 4% sodium lactate, 0.1% konjac glucomannan, with the remainder being water). The shelled shrimp were placed in a vacuum immersion device and subjected to pulsed vacuum circulation: vacuum was applied to 0.09 MPa and held for 3 minutes, then released to atmospheric pressure and held for 2 minutes, and the cycle was repeated 4 times. At the same time, 30 kHz ultrasound with a power of 150 W was applied for 12 minutes, and the immersion temperature was controlled at 6℃. Then, the immersion shrimp were subjected to a three-stage temperature-controlled freezing process: the pre-cooling stage reduced the temperature from 0℃ to -5℃ at a rate of 2℃ / min, and when the core temperature of the shrimp reached -1℃, it was maintained at this temperature for 90 seconds; the phase change stage reduced the temperature at a rate of 10℃ / min; and the uniform temperature stage reduced the temperature at a rate of 3℃ / min. Finally, the frozen shrimp were stored at -20℃.

[0056] Example 3

[0057] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0058] First, select live whiteleg shrimp, wash them with clean water, and then place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Second, place the pre-treated whiteleg shrimp in a -5℃ environment for 10 minutes to obtain pre-cooled shrimp. Then, seal the pre-cooled shrimp in packaging and place them in an ultra-high pressure device, pressurizing them to 50MPa at a pressurization rate of 5MPa / s, holding the pressure for 3 minutes, then pressurizing them to 150MPa, holding the pressure for 6 minutes, and then releasing the pressure to remove the shrimp meat. Next, prepare a fidelity preservation solution (composition by mass percentage: 6% protease hydrolysate peptides from aquatic product by-products, 3% β-glucan, 4% sodium lactate, 0.1% konjac glucomannan, with the remainder being water). The shelled shrimp were placed in a vacuum immersion device and subjected to pulsed vacuum circulation: vacuum was applied to 0.06 MPa and held for 5 minutes, then released to atmospheric pressure and held for 2 minutes, and the cycle was repeated twice. At the same time, 20 kHz ultrasound with a power of 100 W was applied for 15 minutes, and the immersion temperature was controlled at 0℃. Then, the immersed shrimp were subjected to a three-stage temperature-controlled freezing process: the pre-cooling stage reduced the temperature from 0℃ to -5℃ at a rate of 1℃ / min, and when the core temperature of the shrimp reached -2℃, it was maintained at this temperature for 30 seconds; the phase change stage reduced the temperature at a rate of 10℃ / min; and the uniform temperature stage reduced the temperature at a rate of 3℃ / min. Finally, the frozen shrimp were stored at -18℃.

[0059] Example 4

[0060] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0061] First, select live whiteleg shrimp, wash them with clean water, and place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Second, place the pre-treated whiteleg shrimp in a 0℃ environment for 30 minutes to obtain pre-cooled shrimp. Then, seal the pre-cooled shrimp and put them into an ultra-high pressure device, pressurize them to 80MPa at a pressurization rate of 20MPa / s, hold the pressure for 1 minute, then pressurize them to 250MPa and hold the pressure for 3 minutes. After depressurization, remove the shrimp meat. Next, prepare a fidelity preservation solution (components by mass percentage: 6% protease hydrolysate peptides from aquatic product by-products, 3% β-glucan, 4% sodium lactate, 0.1% konjac glucomannan, and the remainder is water). The shelled shrimp were placed in a vacuum impregnation device and subjected to pulsed vacuum circulation: vacuum was applied to 0.095 MPa and held for 3 minutes, then released to atmospheric pressure and held for 1 minute, and the cycle was repeated 5 times. At the same time, 50 kHz ultrasound with a power of 300 W was applied for 5 minutes, and the impregnation temperature was controlled at 10℃. Then, the impregnated shrimp were subjected to a three-stage temperature-controlled freezing process: the pre-cooling stage was from 0℃ to -5℃ at a cooling rate of 3℃ / min. When the core temperature of the shrimp reached -1℃, this temperature was maintained for 120 seconds. The phase change stage had a cooling rate of 15℃ / min, and the uniform temperature stage had a cooling rate of 5℃ / min. Finally, the frozen shrimp were stored at -25℃.

[0062] Example 5

[0063] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0064] First, select fresh, live whiteleg shrimp, wash them with clean water, and then place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Next, pre-cool the pre-treated shrimp in a -3℃ environment for 20 minutes to obtain pre-cooled shrimp. Then, place the pre-cooled shrimp into food-grade plastic bags, add water to submerge the shrimp, vent and seal, and place them in an ultra-high pressure device. Pressurize to 60MPa at a rate of 10MPa / s, hold for 2 minutes, then pressurize to 200MPa and hold for 5 minutes. After depressurization, remove the shrimp; the shell and shrimp meat will automatically separate, allowing you to extract the whole shrimp meat. Next, prepare a fidelity-preserving agent solution (components by weight percentage: 5% protease hydrolysate from aquatic product byproducts, 4% β-glucan, 5% sodium lactate, 0.05% konjac glucomannan, with the remainder being water). Then, remove the shelled shrimp... The shrimp were then placed in a vacuum impregnation device and impregnated in a fidelity agent solution using a pulsed vacuum cycle: vacuum was applied to 0.08 MPa and held for 4 minutes, then released to atmospheric pressure and held for 1.5 minutes, and this cycle was repeated 3 times. Simultaneously, 40 kHz ultrasound with a power of 200 W was applied for 10 minutes, with the impregnation temperature controlled at 4℃. After that, the impregnated shrimp underwent a three-stage temperature-controlled freezing process: the pre-cooling stage reduced the temperature from 0℃ to -5℃ at a rate of 2℃ / min, and when the core temperature of the shrimp reached -1.5℃, this temperature was maintained for 60 seconds; the phase change stage reduced the temperature from -5℃ to -15℃ at a rate of 12℃ / min; and the temperature equalization stage reduced the temperature from -15℃ to -40℃ at a rate of 4℃ / min. Finally, the frozen shrimp were packaged and transferred to a -20℃ cold storage for freezing.

[0065] Example 6

[0066] This embodiment provides a freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, including the following steps:

[0067] First, select fresh, live whiteleg shrimp, wash them with clean water, and then place them in crushed ice to shock them, controlling the temperature at 0-4℃ to obtain pre-treated shrimp. Next, pre-cool the pre-treated shrimp in a -3℃ environment for 20 minutes to obtain pre-cooled shrimp. Then, place the pre-cooled shrimp into food-grade plastic bags, add water to submerge the shrimp, vent and seal, and place them in an ultra-high pressure device. Pressurize to 60MPa at a rate of 10MPa / s, hold for 2 minutes, then pressurize to 200MPa and hold for 5 minutes. After depressurization, remove the shrimp; the shell and shrimp meat will automatically separate, allowing you to extract the whole shrimp meat. Next, prepare a preservation agent solution (components by weight percentage: 8% protease hydrolysate from aquatic product byproducts, 2% β-glucan, 3% sodium lactate, 0.25% konjac glucomannan, and the remainder being water). Then, remove the shelled shrimp... The shrimp were then placed in a vacuum impregnation device and impregnated in a fidelity agent solution using a pulsed vacuum cycle: vacuum was applied to 0.08 MPa and held for 4 minutes, then released to atmospheric pressure and held for 1.5 minutes, and this cycle was repeated 3 times. Simultaneously, 40 kHz ultrasound with a power of 200 W was applied for 10 minutes, with the impregnation temperature controlled at 4℃. After that, the impregnated shrimp underwent a three-stage temperature-controlled freezing process: the pre-cooling stage reduced the temperature from 0℃ to -5℃ at a rate of 2℃ / min, and when the core temperature of the shrimp reached -1.5℃, this temperature was maintained for 60 seconds; the phase change stage reduced the temperature from -5℃ to -15℃ at a rate of 12℃ / min; and the temperature equalization stage reduced the temperature from -15℃ to -40℃ at a rate of 4℃ / min. Finally, the frozen shrimp were packaged and transferred to a -20℃ cold storage for freezing.

[0068] Comparative Example

[0069] Comparative Example 1: Fresh whiteleg shrimp were cleaned and the shrimp meat was removed manually. Without vacuum impregnation for preservation, the shrimp meat was placed directly in a -18℃ cold storage for slow freezing (cooling rate of about 0.5℃ / min) and then frozen.

[0070] Comparative Example 2: Ultra-high pressure deshelling was performed using a one-time pressurization method (200MPa, 5 minutes). Without vacuum impregnation for fidelity preservation, the product was directly placed in a -18℃ cold storage for slow freezing (cooling rate of about 0.5℃ / min) and then frozen.

[0071] Comparative Example 3: Shrimp meat was removed by manual shelling, immersed in sodium pyrophosphate solution under constant vacuum (0.08MPa) for 20 minutes, and then placed directly in a -18℃ cold storage for slow freezing (cooling rate of about 0.5℃ / min) without ultrasonic treatment and frozen storage.

[0072] Shrimp treated in Examples 1 to 6 and Comparative Examples 1 to 3 were placed at room temperature to thaw naturally, and the morphology, texture and juice seepage of each group of shrimp were observed after thawing.

[0073] The results showed that after thawing, the shrimp in Examples 1 to 6 were intact, firm, and dry. After thawing, the shrimp in Comparative Example 1 were loose, with visible cracks and obvious juice seepage. After thawing, the shrimp in Comparative Example 2 were relatively intact but the meat was soft and there was juice seepage. After thawing, the shrimp in Comparative Example 3 were basically intact but the meat was less elastic and there was slight juice seepage.

[0074] It should be noted that the method of the present invention is also applicable to the freezing and preserving of freshness of other shellfish such as shrimp.

[0075] In summary, the low thawing water loss rate processing technology for Litopenaeus vannamei shrimp meat according to an embodiment of the present invention achieves superior results compared to other comparative studies in terms of morphological integrity, meat firmness, and juice retention. This is achieved through multiple synergistic effects, including gradient pressure peeling to obtain whole shrimp meat, pulsed vacuum circulation and ultrasonic-assisted synergistic immersion to enhance the penetration of the preservative agent, and three-stage temperature-controlled freezing and thawing to quickly pass through the maximum ice crystal formation zone.

[0076] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Those skilled in the art can make various improvements and modifications to the present invention without departing from its principles, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0077] In the description of this specification, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0078] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0079] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate, characterized in that, Includes the following steps: S1: Raw material pretreatment - After cleaning the fresh whiteleg shrimp, place them in crushed ice to shock them, and control the temperature at 0-4℃ to obtain pretreated shrimp bodies; S2: Low-temperature precooling—The pretreated shrimp are placed in an environment of -5 to 0°C for 10 to 30 minutes to obtain precooled shrimp; S3: Gradient pressurization ultra-high pressure shelling—After sealing and packaging the pre-cooled shrimp, place it in an ultra-high pressure device and pressurize in stages at a pressurization rate of 5-20 MPa / s. First, pressurize to 50-80 MPa and hold for 1-3 minutes, then pressurize to 150-250 MPa and hold for 3-6 minutes. After depressurization, remove the shrimp meat. S4: Pulsed Vacuum Ultrasonic Assisted Impregnation for Fidelity Preservation—The shelled shrimp are placed in a vacuum impregnation device and impregnated in a fidelity preservation agent solution using a pulsed vacuum cycle, while ultrasonic assistance is applied simultaneously. The fidelity preservation agent solution is an aqueous solution containing antifreeze protective components. The pulsed vacuum cycle involves evacuating to 0.06–0.095 MPa and holding for 3–5 minutes, then releasing the pressure to atmospheric pressure and holding for 1–2 minutes, repeating the cycle 2–5 times. The ultrasonic frequency is 20–50 kHz, the power is 100–300 W, the processing time is 5–15 minutes, and the impregnation temperature is controlled at 0–10℃. S5: Three-stage temperature-controlled freezing and freshness-locking freezing—The soaked shrimp are subjected to three-stage temperature-controlled freezing treatment: The first stage is the pre-cooling stage, which drops from 0℃ to -5℃ at a cooling rate of 1 to 3℃ / min. When the core temperature of the shrimp reaches -2 to -1℃, this temperature is maintained for 30 to 120 seconds. The second stage is the phase change stage, which drops from -5℃ to -15℃ at a cooling rate of ≥10℃ / min. The third stage is the temperature equalization stage, which drops from -15℃ to -40℃ at a cooling rate of 3 to 5℃ / min. S6: Frozen storage—Freeze the frozen shrimp at -18 to -25°C.

2. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S4, the fidelity-preserving agent solution is composed of the following components by mass percentage: 5-8% proteolytic peptides from aquatic product by-products, 2-4% β-glucan, 3-5% sodium lactate, 0.05-0.25% konjac glucomannan, and the balance being water.

3. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S2, the pre-cooling temperature is -2 to -3°C, and the pre-cooling time is 15 to 20 minutes.

4. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S3, the segmented pressurization involves first pressurizing to 50-80 MPa and holding for 1-3 minutes, then pressurizing to 180-220 MPa and holding for 4-5 minutes.

5. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S4, the pulsed vacuum cycle is performed by evacuating to 0.08-0.09 MPa and holding for 3-4 minutes, then releasing the gas to atmospheric pressure and holding for 1.5-2 minutes, and repeating the cycle 3-4 times.

6. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S4, the ultrasonic frequency is 30-40kHz, the power is 150-250W, and the processing time is 8-12 minutes.

7. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S5, during the three-stage temperature-controlled freezing process: the pre-cooling stage has a cooling rate of 2℃ / min, and when the center temperature of the shrimp reaches -1.5 to -1℃, it is maintained for 45 to 90 seconds; the phase change stage has a cooling rate of 10 to 15℃ / min; and the uniform temperature stage has a cooling rate of 3 to 5℃ / min.

8. The freezing and dormancy-locking processing technology for Litopenaeus vannamei shrimp meat with low thawing water loss rate according to claim 1, characterized in that, In S6, the freezing temperature is -18 to -20°C.

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