A method for storing pork at ultra-freezing temperature

Abstract

The invention discloses a method for storing pork at ultra-freezing temperature, which belongs to the cold storage technology of livestock products, and the specific steps are as follows: A. Cut the cold fresh meat into meat pieces of a certain mass and size, and pack the meat pieces with fresh-keeping bags; B. Place the fresh-keeping bags in a magnetoelectric coupling refrigerated and frozen constant temperature incubator, and set the static magnetic field strength of the incubator to 6mT or 8mT, and the temperature to -3°C, so that the central temperature of the meat drops to -3°C and stabilizes within 48 hours; C. The static magnetic field strength of the incubator remains unchanged, and the temperature is adjusted to -4°C, so that the central temperature of the meat drops from -3°C to -4°C; then the meat can maintain an ultra-freezing temperature state for less than 100 hours at a central temperature of -4°C. The invention uses a static magnetic field combined with a staged cooling technology to reduce the ultra-freezing temperature storage temperature of pork to -4°C for the first time, and keeps the pork in a cold but not frozen state for a long time during the storage process at -4°C, thereby maintaining the quality of fresh pork to the maximum extent, which is in line with the development trend of high-end fresh meat.

Description

Technical Field

[0001] The invention belongs to the technical field of refrigeration of livestock products, in particular to a method for storing pork at ultra-freezing temperature. Background Art

[0002] my country is the world's largest producer and consumer of live pigs, accounting for about 50% of the world's total production, and pork consumption has a rigid demand position. In recent years, my country's meat processing industry has undergone a transformation and upgrading from "transporting pigs" to "transporting meat". The meat currently sold on the market includes hot fresh meat, frozen meat and cold fresh meat; hot fresh meat is easily contaminated and spoiled from processing to retail, and has low safety; frozen meat loses a lot of juice during the thawing process due to the formation of ice crystals during the freezing process, resulting in nutritional loss and quality degradation; cold fresh meat is always under cold chain control from processing to retail. Low temperature inhibits enzyme activity and microbial growth, and has advantages in nutrition, safety and taste. It is an inevitable trend in the development of fresh meat. However, the current storage temperature of cold fresh meat is generally 4°C. Because it has sufficient nutrition and water, it is an "ideal culture medium" for various corrupt microorganisms and pathogenic microorganisms. The shelf life is only 3-5 days, which limits the development of cold fresh meat in my country. Therefore, developing new storage and preservation technologies for fresh meat, extending the shelf life of fresh meat, increasing the sales radius of fresh meat, and reducing waste caused by corruption are urgent requirements for accelerating the development of the meat industry and meeting consumers' demand for high-end fresh meat.

[0003] Ultra-freezing temperature technology is a new storage technology that reduces the temperature of food to below the freezing point without phase change (forming ice crystals). The storage temperature range is below the freezing point and above the nucleation point. In this state, the meat is at a lower storage temperature and no ice crystals are produced. It can effectively delay spoilage while maintaining the quality of meat, meet the requirements of high-end meat products, and is of great significance to the development of the meat products industry. Ultra-freezing temperature storage and preservation technology requires that food be in an ultra-freezing temperature state, that is, a supercooled state. This is an extremely unstable metastable state. Different from the equilibrium state performance, in many cases it will produce special properties that are better than the equilibrium state, but the metastable state is extremely unstable and can easily freeze due to sample differences and changes in external factors. Therefore, maintaining the stability of food in a supercooled or ultra-freezing temperature state has become the key to research.

[0004] In the research on stable supercooling state, the supercooling state of food is mainly studied by controlling the cooling temperature and speed, cryoprotectants, electric fields and magnetic fields and other auxiliary freezing technologies to affect the nucleation temperature, supercooling degree and supercooling state stability during the freezing process. In terms of controlling the cooling temperature and speed, a reasonable cooling rate can help food enter and maintain the supercooling state, but the current method of controlling the cooling temperature and rate to achieve supercooling storage has a complex operation process and high requirements for equipment, which increases the difficulty and cost of research. Electric and magnetic fields can have a significant impact on supercooling degree and supercooling state by affecting the ice crystal nucleation process. Under appropriate conditions, supercooling storage can achieve samples that are closer to fresh samples and effectively extend the shelf life of meat products. However, there are currently few research results on the selection of physical parameters for supercooling storage of pork. Therefore, exploring a technical solution that can effectively assist supercooling storage of pork is of great significance to the development of the meat product market and the meat industry. Summary of the invention

[0005] The purpose of the present invention is to provide a method for storing pork at ultra-freezing temperature, which can store pork at -4°C without freezing for more than two days and can keep the freshness of pork, in view of the problems existing in the prior art.

[0006] The purpose of the present invention is to be solved by the following technical solutions:

[0007] A method for storing pork at ultra-freezing temperature, characterized in that the method comprises the following steps:

[0008] A. Cut the fresh meat into pieces of a certain quality and size, and pack the pieces in fresh-keeping bags;

[0009] B. Place the fresh-keeping bag in a magnetoelectric coupled refrigerated constant temperature incubator. Set the static magnetic field strength of the incubator to 6mT or 8mT and the temperature to -3°C. Allow the core temperature of the meat to drop to -3°C and stabilize for less than 48 hours.

[0010] C. After the core temperature of the meat in step B drops to -3°C and stabilizes for less than 48 hours, the static magnetic field strength of the incubator remains unchanged and the temperature is adjusted to -4°C, so that the core temperature of the meat drops from -3°C to -4°C; thereafter, the meat can be kept in an ultra-freezing state at a core temperature of -4°C for less than 100 hours.

[0011] The chilled fresh meat in step A is fresh pork at 4°C.

[0012] The chilled fresh meat in step A is the longissimus dorsi muscle of pig.

[0013] The mass of the meat block in step A is 100g±5g, and the length*width*height of the meat block is 8±2cm*3±1cm*3±1cm.

[0014] The static magnetic field strength of the incubator in step B is set to 8 mT.

[0015] It takes 3 to 4 hours for the core temperature of the meat in step B to drop to -3°C.

[0016] In step B, the core temperature of the meat product is reduced to -3°C and stabilized for less than 24 hours.

[0017] In step B, the core temperature of the meat product is reduced to -3°C and then stabilized for 4 to 12 hours.

[0018] In the step C, it takes 1 to 2 hours for the core temperature of the meat to drop from -3°C to -4°C.

[0019] The meat in step C can be kept in an ultra-freezing state at a core temperature of -4°C for less than 72 hours; preferably, the ultra-freezing state can be kept for 48 hours.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] The method provided by the present invention utilizes a static magnetic field of a specific intensity in combination with a staged cooling technology to reduce the ultra-freezing storage temperature of pork to -4°C for the first time. The pork can remain in a cold but not frozen state for a long time during the storage at -4°C, and no ice crystals or frost damage occurs on the surface and inside of the meat, thereby inhibiting the freezing of pork at -4°C; the reduction in the texture and nutritional quality of the meat caused by the freezing and thawing of the meat is avoided, and the low temperature further inhibits the growth of psychrophilic bacteria related to meat corruption, and the total colony count of the sample measured after ultra-freezing storage for 48 hours is significantly lower than that of the fresh sample; the pH value is not significantly different from that of the fresh sample, and the quality of the fresh pork is maintained to the greatest extent, which can meet the development trend of high-end fresh meat. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 This is a thermodynamic curve diagram of the freezing point of fresh pork in Example 1 provided by the present invention;

[0023] Attached Figure 2 This is a comparison chart of supercooling rate measurement results of fresh pork stored below freezing point for 48 hours according to Example 2 provided by the present invention;

[0024] Figure 3 This is a comparison chart of the supercooling rate measurement results of the static magnetic field on fresh pork stored at -4°C for 48 hours provided by Example 3 of the present invention;

[0025] Figure 4 This is a comparison chart of the supercooling rate measurement results of pork stored at -4°C for 48 hours using the 8mT static magnetic field of Example 4 provided by the present invention and the 8mT static magnetic field combined with the staged cooling technology. DETAILED DESCRIPTION

[0026] The present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0027] A method for storing pork at an ultra-cold temperature, the method comprising the following steps: A. cutting 4°C cold fresh meat into meat pieces of a certain mass and size, wherein the mass of the meat pieces is 100g±5g, and the length, width and height of the meat pieces are 8±2cm*3±1cm*3±1cm, and the meat pieces are packed in fresh-keeping bags; B. placing the fresh-keeping bags in a magneto-electric coupling refrigerated and frozen constant temperature incubator, wherein the static magnetic field strength of the incubator is set to 6mT or 8mT, and the temperature is set to -3°C, so that the central temperature of the meat product drops to -3°C within 3h to 4h and remains stable for less than 48h; C. after the central temperature of the meat product in step B drops to -3°C and remains stable for less than 48h, the static magnetic field strength of the incubator remains unchanged, and the temperature is adjusted to -4°C, so that the central temperature of the meat product drops from -3°C to -4°C within 1h to 2h; thereafter, the meat product can be kept in an ultra-cold temperature state for less than 100h at a central temperature of -4°C.

[0028] The above-mentioned cold fresh meat is preferably the longissimus dorsi of the pig. After the core temperature of the meat drops to -3°C, it is preferably stable for less than 24 hours, and more preferably stable for 4 hours to 12 hours; the meat can be kept in an ultra-freezing state at a core temperature of -4°C for less than 72 hours; more preferably, it can be kept in an ultra-freezing state for 48 hours.

[0029] The following will illustrate the technical solution provided by the present invention from verification examples in multiple dimensions, and describe the technical solution of the present invention clearly and completely. Obviously, the verification examples described are part of the present invention, but not all of it.

[0030] Example 1: Test for determining the freezing point of pork

[0031] The purpose of the freezing point test is to accurately determine the freezing point temperature of fresh pork by DSC method.

[0032] Step 1: Take 5.0-7.0 mg of sample into an aluminum crucible, accurate to 0.1 mg, and seal it with an aluminum lid; use an empty crucible as a reference sample, and use nitrogen (analytical grade) as the carrier gas at a flow rate of 20 mL / min.

[0033] Step 2: Cool the sample from room temperature to -15°C, equilibrate at -15°C for 10 min, and then heat to 10°C at a heating rate of 2°C / min. Repeat the test 5 times.

[0034] The Pyris analysis software was used to analyze the thermodynamic image to obtain the onset (initial freezing point). The thermodynamic curve of the freezing point of fresh pork is shown in the figure below. Figure 1 The initial freezing point of the fresh pork is shown to be -2.05°C, so the freezing point temperature of the fresh pork is determined to be -1.94°C±0.15°C.

[0035] Example 2 Experiment on determining the temperature range of pork ultra-freezing storage

[0036] Step 1: Cut the longissimus dorsi muscle of the pig into 100g±5g pieces, pack the pieces in a fresh-keeping bag, and place them in a refrigerator at 4℃ for later use;

[0037] Step 2: Place the meat pieces packed in the fresh-keeping bag obtained in step 1 in a magnetic-electric coupling refrigerated and frozen constant temperature incubator, and set the incubator temperatures to -2°C, -3°C, -4°C and -5°C respectively; 12 samples are tested in each batch, and the core temperature of each sample is measured;

[0038] Step 3: The freezing state of the meat is identified by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the sensory perception of the meat being soft and deformable are used as the basis for determining whether the sample is in an over-freezing temperature state. The supercooling rate of the sample is calculated accordingly.

[0039] Table 1 Determination results of supercooling rate of fresh pork stored below freezing point for 4h to 48h

[0040] Below freezing temperature 4h 8h 12h 24h 48h -2℃ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ -3℃ 100.00％ 100.00％ 100.00％ 100.00％ 100.00％ -4℃ 0 0 0 0 0 -5℃ 0 0 0 0 0

[0041] Depend on Figure 2 As shown in Table 1, after being stored at -2 and -3°C for 48 hours, the supercooling rate of pork is still 100%, that is, all samples are in an ultra-freezing state; but after being stored at -4°C and -5°C for 4 hours, the supercooling rate of pork is 0%, that is, all samples are frozen. Therefore, the temperature range suitable for ultra-freezing storage of pork is from freezing point to -3°C.

[0042] Example 3 Static magnetic field assisted optimization of ultra-freezing temperature storage conditions for pork

[0043] Step 1: Cut the longissimus dorsi muscle of the pig into 100g±5g pieces, pack the pieces in a fresh-keeping bag, and place them in a 4℃ refrigerator for later use;

[0044] Step 2: placing the meat pieces packed in the fresh-keeping bag obtained in step 1 in a magnetoelectric coupled refrigerated constant temperature incubator, the incubator temperature is -4°C, and the static magnetic field strength is set to 0mT, 4mT, 5mT, 6mT, 7mT, 8mT, 9mT, and 10mT respectively; 12 samples are tested in each batch of experiments, and the central temperature of the meat is measured for each sample, with the 0mT group as the control group;

[0045] Step 3: The freezing state of the meat is identified by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the sensory perception of the meat being soft and deformable are used as the basis for determining whether the sample is in an over-freezing temperature state. The supercooling rate of the sample is calculated accordingly.

[0046] Table 2 Results of supercooling rate measurement of fresh pork stored at -4℃ for 4h to 48h by static magnetic field

[0047] Magnetic field strength / mT 4h 8h 12h 24h 48h 0 0 0 0 0 0 4 0 0 0 0 0 5 0 0 0 0 0 6 33.33％ 25.00％ 25.00％ 25.00％ 25.00％ 7 0 0 0 0 0 8 66.67％ 66.67％ 66.67％ 58.33％ 58.33％ 9 0 0 0 0 0 10 0 0 0 0 0

[0048] Depend on Figure 3 As shown in Table 2, freezing of pork at -4℃ mostly occurred in the first 4h of storage. After 4h of storage at -4℃, the supercooling rate of fresh pork in the 0mT, 4mT, 5mT, 7mT, 9mT, and 10mT treatment groups was 0%, that is, all samples were frozen, the supercooling rate of the 6mT treatment group was 33.33%, and the supercooling rate of the 8mT treatment group was 66.67%, the highest among all groups, and the supercooling rate was still 58.33% after 48h of storage; this indicates that the 8mT treatment effectively increased the supercooling rate of pork at -4℃ compared with other treatment groups, and determined that the 8mT static magnetic field intensity was the optimal static magnetic field parameter for assisting the ultra-freezing temperature storage of pork, and the 6mT static magnetic field intensity was the suboptimal static magnetic field parameter for assisting the ultra-freezing temperature storage of pork.

[0049] Example 4 8mT static magnetic field combined with staged cooling technology to assist in optimizing pork ultra-freezing temperature storage conditions

[0050] Step 1: Cut the longissimus dorsi muscle of the pig into 100g±5g pieces, pack the pieces in a fresh-keeping bag, and place them in a 4℃ refrigerator for later use;

[0051] 1) Control group: The meat pieces packaged in the fresh-keeping bag obtained in step 1 were placed in a magneto-electric coupled refrigerated constant temperature incubator. The incubator temperature was -4°C and the static magnetic field strength was set to 8 mT. Twelve samples were placed on the test bench each time. The center temperature of each sample was measured and stored for 48 hours.

[0052] 2) Magnetic field combined with staged cooling group: The meat pieces packaged in the fresh-keeping bag obtained in step 1 were placed in a magneto-electric coupled refrigerated constant temperature incubator, the incubator temperature was -3°C, and the static magnetic field strength was set to 8mT; 12 samples were placed on each test bench, and the central temperature of the meat was measured for each sample. After the central temperature dropped to -3°C and stabilized for 12 hours, the ambient temperature of the box was adjusted to -4°C, and the meat was stored for 48 hours after the central temperature dropped to -4°C;

[0053] Step 2: The freezing state of the meat is identified by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the soft and deformable meat feeling when touched are used as the basis for determining whether the sample is in an over-freezing temperature state, and the supercooling rate is calculated based on this.

[0054] Table 3 The results of supercooling rate measurement of pork stored at -4℃ for 4h to 48h by 8mT static magnetic field and 8mT static magnetic field combined with staged cooling technology

[0055] Group 4h 8h 12h 24h 48h 8mT 66.67％ 66.67％ 66.67％ 58.33％ 58.33％ 8mT combined with staged cooling 91.67％ 91.67％ 91.67％ 83.33％ 83.33％

[0056] Depend on Figure 4As shown in Table 3, after storage at -4℃ for 4h, the supercooling rate of the 8mT combined with staged cooling treatment group was 91.67%, which was 25% higher than that of the 8mT group, and the supercooling rate after storage for 48h was still about 25% higher than that of the 8mT group; therefore, the optimal condition for ultra-freezing storage of pork at -4℃ was the 8mT static magnetic field combined with staged cooling treatment.

[0057] Example 5 8mT static magnetic field combined with staged cooling technology to assist pork ultra-freezing temperature storage verification test

[0058] Step 1: Cut the longissimus dorsi muscle of the pig into 100g±5g pieces, pack the pieces in a fresh-keeping bag, and place them in a 4℃ refrigerator for later use;

[0059] Step 2: Place the meat pieces packed in the fresh-keeping bag obtained in step 1 in a magnetoelectric coupled refrigerated constant temperature incubator, the incubator temperature is -3°C, and the static magnetic field strength is set to 8mT; 12 samples are placed on each test bench, and the central temperature of the meat is measured for each sample. After the central temperature drops to -3°C and stabilizes for 12 hours, the ambient temperature of the box is adjusted to -4°C, and the meat is stored for 48 hours after the central temperature drops to -4°C;

[0060] Step 3: Identify the frozen state of the meat by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the soft and deformable meat block when touched are used as the basis for determining the super-frozen temperature state samples, and divide them into frozen samples and super-frozen temperature samples;

[0061] Step 4: All samples were sampled at 0h, and after being stored at -4℃ for 48h, samples in the super-freezing state were taken to determine the ice crystal content; the ice crystal content was measured by impedance method. The impedance measurement used a homemade needle electrode. The electrode material was copper, the electrode length was 1.5cm, the electrode spacing was 1.5cm, the measurement temperature was 4℃, and the measurement frequency was 50kHz. The needle probe of the impedance meter was quickly inserted into the stored meat sample, and the impedance amplitude at this time was recorded. The ice crystal content was calculated according to the method in Ding Daming's paper (Ding Daming. Effect of micro-frozen storage on the shelf life and quality of pork [D]. Nanjing Agricultural University, 2020. DOI: 10.27244 / d.cnki.gnjnu.2020.000143.).

[0062] Table 4 Results of the verification test on ultra-freezing storage of pork assisted by 8mT static magnetic field combined with staged cooling technology

[0063] Fresh samples Super-freezing temperature samples Impedance(Ω) <![CDATA[107.72±10.57 A ]]> <![CDATA[107.95±9.58 A ]]> Ice crystal content 0％ 0％

[0064] As shown in Table 4, there is no significant difference in impedance amplitude between the super-freezing temperature samples and the fresh samples, and the ice crystal content is 0, which indicates that no ice crystals are generated in the super-freezing temperature samples, further verifying the super-freezing temperature state of the samples.

[0065] Example 6 8mT static magnetic field combined with staged cooling technology to assist pork ultra-freezing temperature storage bacterial count test

[0066] Step 1: Cut the longissimus dorsi muscle of the pig into 100g±5g pieces, pack the pieces in a fresh-keeping bag, and place them in a 4℃ refrigerator for later use;

[0067] Step 2: Place the meat pieces packed in the fresh-keeping bag obtained in step 1 in a magnetoelectric coupled refrigerated constant temperature incubator, the incubator temperature is -3°C, and the static magnetic field strength is set to 8mT; 12 samples are placed on each test bench, and the central temperature of the meat is measured for each sample. After the central temperature drops to -3°C and stabilizes for 12 hours, the ambient temperature of the box is adjusted to -4°C, and the meat is stored for 48 hours after the central temperature drops to -4°C;

[0068] Step 3: Identify the frozen state of the meat by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the soft and deformable meat block when touched are used as the basis for determining the super-frozen temperature state samples, and divide them into frozen samples and super-frozen temperature samples;

[0069] Step 4: All samples were sampled at 0h, and after being stored at -4℃ for 48h, samples in the super-freezing state were taken to determine the bacterial count. The specific steps are as follows:

[0070] Accurately weigh 25.0 g of meat sample, place it in a homogenizing bag containing 225 mL of sterile physiological saline, and homogenize it in a slapping homogenizer for 2 minutes; after ten-fold gradient dilution, select 1 mL of sample solution with appropriate dilution gradient and put it in a sterile plate, pour the cooled plate counting agar medium into the plate, and use 1 mL of blank dilution as a blank control; after the agar solidifies, turn the plate over, incubate at 37℃ for 48 hours, and then count with an automatic image analyzer.

[0071] Table 5 Results of the bacterial count test of pork stored at ultra-freezing temperature assisted by 8mT static magnetic field combined with staged cooling technology

[0072] Fresh samples Super-freezing temperature samples <![CDATA[Total number of colonies (Log(CFU·g -1 ))]]> <![CDATA[5.16±0.14 A ]]> <![CDATA[4.51±0.34 B ]]>

[0073] As shown in Table 5, the total number of colonies in the super-freezing temperature samples decreased significantly compared with the fresh samples, indicating that the static magnetic field of 8mT combined with the staged cooling treatment can inhibit the growth and reproduction of microorganisms.

[0074] Example 7: pH test of pork storage at ultra-freezing temperature assisted by 8mT static magnetic field combined with staged cooling technology

[0075] Step 1: Cut the longissimus dorsi muscle of the pig into pieces of 100g±5g, wrap the pieces in a fresh-keeping bag, and place them in a 4℃ refrigerator for later use.

[0076] Step 2: Place the meat pieces packed in the fresh-keeping bag obtained in step 1 in a magnetoelectric coupled refrigerated constant temperature incubator, the incubator temperature is -3°C, and the static magnetic field strength is set to 8mT; 12 samples are placed on each test bench, and the central temperature of the meat is measured for each sample. After the central temperature drops to -3°C and stabilizes for 12 hours, the ambient temperature of the box is adjusted to -4°C, and the meat is stored for 48 hours after the central temperature drops to -4°C;

[0077] Step 3: Identify the frozen state of the meat by the temperature curve at the center of the meat. The absence of ice crystal nucleation and phase change in the temperature curve and the soft and deformable meat block when touched are used as the basis for determining the super-frozen temperature state samples, and divide them into frozen samples and super-frozen temperature samples;

[0078] Step 4: All samples were sampled at 0h, and after being stored at -4℃ for 48h, samples in the super-freezing state were taken to measure the pH value; specifically refer to the portable handheld pH meter method in A2 of NY / T 2793-2015 "Objective Evaluation Method for Edible Quality of Meat": Before the measurement, the pH was calibrated at two points (pH 4.00 and pH 7.01) using a standard solution, and the calibrated pH meter was directly inserted into the meat block (thickness not less than 2cm, diameter not less than 3cm), and the pH value of the sample was read after the pH meter reading stabilized.

[0079] Table 6 Effects of 8mT static magnetic field combined with staged cooling technology on pH value of pork ultra-freezing storage

[0080] Fresh samples Super-freezing temperature samples pH <![CDATA[5.47±0.03 A ]]> <![CDATA[5.49±0.03 A ]]>

[0081] As shown in Table 6, there is no significant difference in pH value between the ultra-freezing temperature samples and the fresh samples, which means that the ultra-freezing temperature samples are closer to the fresh sample state and can better maintain the quality of fresh meat.

[0082] The method provided by the present invention utilizes a static magnetic field of a specific intensity in combination with a staged cooling technology to reduce the ultra-freezing storage temperature of pork to -4°C for the first time. The pork can remain in a cold but not frozen state for a long time during the storage at -4°C, and no ice crystals or frost damage occurs on the surface and inside of the meat, thereby inhibiting the freezing of pork at -4°C; the reduction in the texture and nutritional quality of the meat caused by the freezing and thawing of the meat is avoided, and the low temperature further inhibits the growth of psychrophilic bacteria related to meat corruption, and the total colony count of the sample measured after ultra-freezing storage for 48 hours is significantly lower than that of the fresh sample; the pH value is not significantly different from that of the fresh sample, and the quality of the fresh pork is maintained to the greatest extent, which can meet the development trend of high-end fresh meat.

[0083] The above embodiments are only for illustrating the technical idea of ​​the present invention, and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the present invention; any technology not involved in the present invention can be realized by existing technologies.

Claims

1. A method for storing pork at ultra-freezing temperature, characterized in that: The steps of this method are as follows: A. Cut the fresh meat into pieces of a certain quality and size, and pack the pieces in fresh-keeping bags; B. Place the fresh-keeping bag in a magnetoelectric coupled refrigerated constant temperature incubator. Based on the actual supercooling rate of meat storage, the static magnetic field strength of the incubator is set to 8mT and the temperature is set to -3°C. The center temperature of the meat is reduced to -3°C and stabilized for 4h to 12h. C. After the central temperature of the meat in step B drops to -3°C and stabilizes for 4h to 12h, the static magnetic field strength of the incubator remains unchanged and the temperature is adjusted to -4°C, so that the central temperature of the meat drops from -3°C to -4°C; thereafter, the meat can be kept in an ultra-freezing temperature state for less than 100h at a central temperature of -4°C; The chilled fresh meat in step A is fresh pork at 4°C; The mass of the meat block in step A is 100 g ± 5 g, and the length * width * height of the meat block is 8 ± 2 cm * 3 ± 1 cm * 3 ± 1 cm; It takes 3 to 4 hours for the core temperature of the meat in step B to drop to -3°C; In the step C, it takes 1 to 2 hours for the core temperature of the meat to drop from -3°C to -4°C.

2. The method for storing pork at ultra-low temperature according to claim 1, characterized in that: The chilled fresh meat in step A is the longissimus dorsi muscle of pig.

3. The method for storing pork at ultra-low temperature according to claim 1, characterized in that: The meat in step C can be kept in an ultra-freezing temperature state at a core temperature of -4°C for less than 72 hours.

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