Direct immersion type cooling liquid applied to meat preservation and application of direct immersion type cooling liquid

Abstract

The invention belongs to the technical field of cooling liquids, and discloses a direct immersion type cooling liquid applied to meat preservation, and the direct immersion type cooling liquid is prepared from a secondary refrigerant and normal saline; the secondary refrigerant comprises a compound A and a compound B, the compound A is one of choline chloride, betaine and proline; the compound B is one of glucose, trehalose, glycerol, xylitol, malic acid and sorbitol; the molar ratio of the compound A to the compound B is (1-3): (1-2). The direct dipping type cooling liquid applied to meat preservation can be directly applied to meat preservation, has the characteristics of safety and low freezing point, can realize rapid cooling and fresh locking of meat, prolongs the shelf life, and can maintain the quality of slaughtered fresh meat to the maximum extent.

Description

Technical Field

[0001] The invention belongs to the technical field of cooling liquids, and in particular relates to a direct immersion cooling liquid used for meat preservation and application thereof. Background Art

[0002] In the process of slaughtering chickens, in order to reduce the rapid reproduction of microorganisms, they need to be cooled with 4°C water after cleaning to quickly reduce the core temperature of the chicken to below 10°C. However, 4°C water cooling has the problems of slow cooling rate and long time consumption. Studies have found that ultra-fast cooling can significantly improve the quality of fresh meat, and the faster the cooling rate, the better the quality of the meat. Using -35°C liquid cooling has a faster cooling rate than cold storage cooling with air as the medium, and is better for preserving food quality. The -35°C liquid coolants currently used are mainly alcohol compounds, including ethanol, propylene glycol, ethylene glycol, etc. These alcohol compounds are organic solvents. During the cooling process, the food needs to be vacuum-packed first to avoid direct contact with the coolant. At the same time, these alcohol compounds are volatile and flammable, and there are great safety hazards. Summary of the invention

[0003] The object of the present invention is to provide a direct immersion cooling liquid which can be used for rapid cooling and freshness preservation of fresh chicken and has the characteristics of safety and low freezing point.

[0004] The above-mentioned purpose is achieved by the following technical solutions.

[0005] A first aspect of the present invention provides a direct immersion coolant, wherein the direct immersion coolant is prepared by including a coolant and physiological saline;

[0006] Wherein, the coolant includes compound A and compound B; the compound A is one of choline chloride, betaine, and proline; the compound B is one of glucose, trehalose, glycerol, xylitol, malic acid and sorbitol; the molar ratio of the compound A to the compound B is 1-3:1-2.

[0007] In some embodiments, the compound A is choline chloride, and the compound B is one of glucose, trehalose, glycerol, and xylitol.

[0008] In some embodiments, the compound A is proline, and the compound B is one of glycerol and sorbitol.

[0009] In some embodiments, the compound A is betaine, the compound B is one of glycerol, xylitol, and malic acid, and the molar ratio of the compound A to the compound B is 1-2:1-2.

[0010] In some embodiments, the compound A is betaine, and the compound B is glycerol.

[0011] In some embodiments, the molar ratio of the compound A to the compound B is 1:1-2.

[0012] In some embodiments, the mass ratio of the coolant to the physiological saline is 0.1 to 1:1; preferably, the mass ratio of the coolant to the physiological saline is 0.8 to 1:1.

[0013] In some embodiments, the method for preparing the coolant comprises the following steps:

[0014] Compound A and compound B are mixed and then rotary evaporated until a uniform viscous liquid is formed to obtain the cooling agent.

[0015] In some embodiments, the water bath temperature of the rotary evaporation is 75°C to 85°C, and the centrifugal force is 3000×g to 4000×g; preferably, the water bath temperature of the rotary evaporation is 78°C to 82°C, and the centrifugal force is 3800×g to 4200×g.

[0016] A second aspect of the present invention provides a use of the direct immersion cooling liquid as described above in preserving meat.

[0017] In some embodiments, the meat is poultry meat, such as chicken, duck, goose, etc., preferably chicken.

[0018] In the present invention, physiological saline is used as the main coolant component, and a cooling agent is formed by selecting specific compounds, wherein one of choline chloride, betaine and proline from natural sources is used as compound A, and one of glucose, trehalose, sorbitol, xylitol, malic acid and glycerol is used as compound B. Compound A and compound B are mixed to prepare the cooling agent. After the cooling agent is mixed with physiological saline, a direct immersion type rapid cooling liquid directly applied to meat, especially chicken, can be obtained for preserving the freshness. The direct immersion type rapid cooling liquid has the characteristics of safety and low freezing point, can achieve rapid cooling and freshness locking of chicken, extend the shelf life, and can maintain the quality of fresh chicken after slaughter to the maximum extent.

[0019] The present invention also found that the ratio of the refrigerant and physiological saline, as well as the specific composition and ratio of the refrigerant, have a significant effect on the viscosity, density, freezing point and heat transfer performance of the coolant. By optimizing the specific composition and ratio, it has a significant gain effect on obtaining a better cooling and fresh-keeping effect, and can better maintain the quality of fresh chicken after slaughter. DETAILED DESCRIPTION

[0020] In order to facilitate the understanding of the present invention, the present invention will be described more fully below. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the understanding of the disclosure of the present invention more thorough and comprehensive.

[0021] The experimental methods in the following examples without specifying specific conditions are usually carried out under conventional conditions or conditions recommended by the manufacturers. The various commonly used chemical reagents used in the examples are all commercially available products.

[0022] Unless otherwise defined, all technical and scientific terms used in the present invention have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs. The terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in the present invention includes any and all combinations of one or more of the related listed items.

[0023] The technical solution of the present invention is further illustrated by specific embodiments below.

[0024] Example 1

[0025] This embodiment provides a direct immersion coolant, and the preparation method thereof comprises the following steps:

[0026] The coolant and physiological saline were fully stirred and mixed at mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain a direct immersion coolant.

[0027] Among them, the coolant is a choline chloride / glucose (molar ratio 3:2) coolant, and its preparation method is: after mixing choline chloride and glucose, rotary evaporation is performed, and the mixture is placed in an 80°C water bath and rotated at 4000×g until a uniform viscous liquid is formed to obtain the coolant.

[0028] Example 2

[0029] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0030] The cooling agent is choline chloride / trehalose (molar ratio 3:1).

[0031] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0032] Example 3

[0033] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0034] The cooling agent is choline chloride / glycerol (molar ratio 1:2).

[0035] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0036] Example 4

[0037] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0038] The cooling agent is choline chloride / xylitol (molar ratio 1:2).

[0039] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0040] Example 5

[0041] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0042] The cooling agent is betaine / malic acid (molar ratio 1:2).

[0043] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0044] Example 6

[0045] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0046] The cooling agent is betaine / xylitol (molar ratio 2:1) cooling agent.

[0047] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0048] Example 7

[0049] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0050] The cooling agent is betaine / glycerol (molar ratio 1:2).

[0051] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0052] Example 8

[0053] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0054] The cooling agent is proline / glycerol (molar ratio 1:2).

[0055] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0056] Example 9

[0057] This embodiment provides a direct immersion cooling liquid, and its preparation method is consistent with that of embodiment 1, and the difference from embodiment 1 is that:

[0058] The cooling agent is proline / sorbitol (molar ratio 1:1).

[0059] The refrigerant and the physiological saline are fully stirred and mixed in mass ratios of 0.1:1, 0.2:1 and 1:1 to obtain the direct immersion coolant.

[0060] The direct immersion coolant prepared in the above embodiment was tested for performance:

[0061] Viscosity: Use digital viscometer NDJ-8S for measurement. Select a suitable rotor and screw according to the viscosity of the coolant. Pour 25ml of coolant into the drum, and fix the drum on the sleeve. Keep the rotor immersed in the coolant in the drum. Select a suitable speed for measurement until the viscosity value no longer changes. Record the value and repeat the measurement three times to get the average value.

[0062] Density: Density is measured using a Baume densitometer. Pour the coolant into a measuring cylinder and insert a densitometer with a suitable range into the coolant. After the liquid level stabilizes, record the value and repeat the measurement three times to take the average value.

[0063] Freezing point: Pour the prepared coolant into a beaker, and fix the probe of the thermocouple in the coolant with waterproof tape, and connect the other end to the Picolog TC-08 data logger. Then put it in a refrigerator at -80℃, turn on the data logger, record the cooling curve of the coolant, record the temperature of the coolant every two seconds, and draw a time-temperature curve. During the cooling process of the coolant, there will be a period of time when the cooling rate decreases or the temperature rises slightly. This process is the crystallization process. The average temperature corresponding to the interval on the gentle curve of this section of the cooling curve is taken, which is the freezing point of the coolant.

[0064] Heat transfer performance: The specific heat capacity of the coolant is measured using a DSC 214 Polymer differential scanning calorimeter. First, the instrument is turned on and preheated for 30 minutes, and then the specific heat of the empty crucible, sapphire standard sample and coolant sample is tested to obtain the corresponding DSC curve results. Finally, the test results are input into the analysis software for comparative analysis to obtain the specific heat capacity value of the coolant. 1.3.7 Determination of thermal conductivity and thermal diffusion coefficient of coolant

[0065] The thermal conductivity and thermal diffusivity of the coolant are measured using the LFA467HyperFlash flash method thermal conductivity instrument. First, graphite is evenly sprayed on the upper and lower covers of the low-viscosity liquid sample holder. After the surface is completely dry, the holder is assembled, and then the ternary coolant is injected from the pores, and the gap is sealed and tested on the machine. The laser transmitter will evenly emit a beam of laser to illuminate the center of the lower surface of the thin sheet, and the heat energy will gradually transfer to the upper surface. When the upper surface temperature reaches the set value, the data collector will collect the thermal property values ​​at this temperature three times. Finally, the analysis software is used to calculate the values ​​to obtain the thermal conductivity and thermal diffusivity of the coolant.

[0066] Result comparison 1: Viscosity comparison of direct immersion coolants obtained in Examples 1-9

[0067] Table 1 Viscosity of different coolants

[0068]

[0069] Viscosity is an important indicator for evaluating coolants. The viscosity will affect the heat transfer of coolants. The viscosity of coolants should not be too high. Excessive viscosity will affect the flow of coolants, thereby affecting the heat exchange effect between coolants and food and reducing the cooling rate. As can be seen from Table 1, the greater the proportion of coolant, the greater the viscosity of the coolant. However, excessive use of coolant will also increase the density, resulting in loss of cooling equipment during operation. When the ratio of coolant to saline is constant, the composition of coolants with lower viscosity is: choline chloride / glycerol / saline, choline chloride / glucose / saline, choline chloride / xylitol / saline, betaine / glycerol / saline, choline chloride / trehalose / saline, betaine / malic acid / saline, proline / glycerol / saline, etc.

[0070] Result comparison 2: Coolant density comparison

[0071] Table 2 Density of different coolants

[0072]

[0073] The smaller the density of the refrigerant, the smaller the loss of the cooling equipment during operation. Therefore, the smaller the density of the coolant, the better. From the results in Table 2, it can be seen that with the increase of the refrigerant content in the coolant, the density of the coolant gradually increases. However, if the refrigerant is too little, the freezing point will not be able to meet the requirement of -35°C. The coolants with lower densities are: choline chloride / glycerol / normal saline, choline chloride / xylitol / normal salt, betaine / glycerol / normal saline, proline / glycerol / normal saline, choline chloride / glucose / normal saline.

[0074] Result comparison 3: Comparison of freezing point of coolant

[0075] Table 3 Freezing point of different coolants

[0076]

[0077] Freezing point is a key indicator for evaluating coolants. The lower the freezing point of the coolant, the faster the cooling rate. The greater the proportion of the coolant in the coolant composition, the lower the freezing point of the coolant. According to the standard that the lower the freezing point of the coolant, the better, when the mass ratio of the coolant to saline is selected to be 1:1, the expected goal of a freezing point close to -35°C can be achieved. The coolant compositions with lower freezing points are: choline chloride / glycerol / saline, betaine / glycerol / saline, proline / glycerol / saline and proline / glycerol / saline are better coolants, followed by choline chloride / glucose / saline and proline / sorbitol / saline.

[0078] Based on the above viscosity, density and freezing point comparison results, although the viscosity and density of the coolant are smaller when the ratio of coolant to saline is 0.2:1 and 0.1:1, the freezing point of the coolant is above -5°C at this ratio, which cannot reach the expected temperature of close to -35°C. Therefore, it is better to choose a 1:1 ratio of coolant to saline.

[0079] Result comparison 4: Comparison of heat transfer performance of coolants

[0080] Table 4 Heat transfer performance of different coolants

[0081]

[0082]

[0083] Based on the physical properties of the above coolant viscosity, density and freezing point, the heat transfer performance of the coolant with a ratio of 1:1 between the coolant and saline was further determined. Specific heat capacity refers to the amount of heat absorbed or released when the temperature of a certain substance per unit mass changes by 1°C. For the coolant, the larger the specific heat capacity, the greater the amount of cold that can be carried by the coolant per unit mass, and the less refrigerant is required; the thermal conductivity reflects the ability of the coolant to transfer heat. The larger the thermal conductivity, the greater the heat transferred, and the better the heat exchange effect with the food; the thermal diffusion coefficient reflects the temperature diffusion rate of the coolant, which is closely related to the thermal conductivity, specific heat and density of the substance. The larger the thermal diffusion coefficient, the better the performance of the coolant. Therefore, based on the selection criteria of the larger specific heat capacity, thermal conductivity and thermal diffusion coefficient, the coolants with better performance are betaine / glycerol / saline, proline / sorbitol / saline, proline / glycerol / saline and choline chloride / trehalose / saline.

[0084] Application Examples

[0085] According to the heat transfer performance and freezing point characteristics, although the cooling liquids choline chloride / trehalose / normal saline, betaine / malic acid / normal saline and betaine / xylitol / normal saline have better heat transfer performance, the freezing point is above -20°C, followed by choline chloride / glucose / normal saline and choline chloride / glycerol / normal saline. The freezing point is below -20°C, but the heat transfer performance is poor. In addition, although the freezing point and heat transfer performance of the cooling liquids proline / glycerol / normal saline and proline / sorbitol / normal saline are both good, the cooling liquid is light yellow after adding proline, so the influence of color needs to be considered during the selection and application process. Therefore, the optimal cooling liquid composition in the embodiment of the present invention is betaine / glycerol / normal saline.

[0086] Based on the properties of the above coolant, the present invention further uses an example to verify the effect of the use of betaine / glycerol / normal saline coolant in the preservation of fresh chicken, and uses choline chloride / trehalose / normal saline, betaine / malic acid / normal saline, proline / glycerol / normal saline and proline / sorbitol / normal saline as comparative examples. The addition ratio of the coolant to the normal saline is 1:1.

[0087] Application Example 1

[0088] The slaughtered and cut chicken breasts were collected, immersed in 4°C cold water, cooled until the core temperature dropped to 10°C, then taken out and stored in a 4°C refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3, and 5 of the storage period.

[0089] Application Example 2

[0090] The slaughtered and cut chicken breasts were collected and immersed in 4°C cooling liquid (betaine / glycerol and saline), cooled until the core temperature dropped to 10°C, then taken out and stored in a 4°C refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3, and 5 during the storage period.

[0091] Application Example 3

[0092] The slaughtered and cut chicken breasts were collected and immersed in -1℃ cooling liquid (betaine / glycerol and saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3 and 5 during the storage period.

[0093] Application Example 4

[0094] The slaughtered and cut chicken breasts were collected and immersed in -5℃ cooling liquid (betaine / glycerol and saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3 and 5 during the storage period.

[0095] Application Example 5

[0096] The slaughtered and cut chicken breasts were collected and immersed in -1℃ cooling liquid (choline chloride / trehalose / normal saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3 and 5 during the storage period.

[0097] Application Example 6

[0098] The slaughtered and cut chicken breasts were collected and immersed in -1℃ cooling liquid (betaine / malic acid / normal saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3 and 5 during the storage period.

[0099] Application Example 7

[0100] The slaughtered and cut chicken breasts were collected and immersed in -1℃ cooling liquid (proline / glycerol / normal saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3 and 5 during the storage period.

[0101] Application Example 8

[0102] The slaughtered and cut chicken breasts were collected and immersed in -1℃ cooling liquid (proline / sorbitol / normal saline), cooled in cold water until the core temperature dropped to 0℃, then taken out and stored in a 4℃ refrigerator. Samples were taken and analyzed for volatile basic nitrogen content (TVB-N), water loss (cooking loss and centrifugation loss) and nucleotide content (inosinic acid and hypoxanthine) on days 1, 3, and 5 during the storage period.

[0103] 1. Cooling rate comparison

[0104] The faster the cooling speed, the less the cooling loss, which is of great significance to the improvement of the economic value of the enterprise. The following table 5 shows the cooling rate of each application example.

[0105] Table 5 Cooling rate results of various application examples

[0106]

[0107]

[0108] Referring to Table 5, by comparing the cooling rates of the coolants, it is found that the cooling rate of the betaine / glycerol / saline coolant is much faster than the traditional 4°C water cooling rate and is better than the other application examples. The lower the starting temperature of the coolant, the faster the cooling rate.

[0109] 2. TVB-N Results

[0110] The determination method of volatile basic nitrogen refers to the Chinese Food Safety National Standard Method GB 5009.228-2016 Determination of Total Volatile Basic Nitrogen in Food. Add about 5 g of sample to 20 mL of distilled water, homogenize, soak for 30 min and filter. Add 1 mL of filtrate to the outer chamber of the diffusion dish, and add distilled water to the blank group. Add 1 mL of 20 g / L boric acid and 1 drop (1 g / L toluene red ethanol solution: 5 g / L bromocresol green ethanol solution) to the inner chamber of the diffusion dish. Cover the lid and leave a gap to add 1 mL of saturated potassium carbonate solution. Push the lid flat and incubate in an incubator at 37°C for 2 hours. After the diffusion dish cools, titrate the inner chamber with 0.01M hydrochloric acid, and the color of the titration end point is blue-purple. The calculation formula of TVB-N value is as follows:

[0111] TVB-N(mg / 100g)=(VV 0 )×14×c×100×a / m

[0112] Where V represents the volume of hydrochloric acid consumed by the sample (ml), V 0 represents the volume of hydrochloric acid consumed by the blank group (ml), c is the concentration of hydrochloric acid (M), a is the dilution factor, and m is the sample weight (g).

[0113] According to GB 2707-2016 "National Food Safety Standard for Fresh (Frozen) Livestock and Poultry Products", fresh and frozen poultry must have a volatile basic nitrogen (TVB-N) content of ≤ 15 mg / 100g to be considered fresh meat. The TVB-N content results of each application example are shown in Table 6 below.

[0114] Table 6 TVB-N content results of various application examples

[0115]

[0116]

[0117] As shown in Table 6, after the chicken breasts were stored at 4°C for 5 days, except for the chicken meat in Application Example 4 that was treated with -5°C betaine / glycerol and saline coolant, which was fresh meat, the chicken breasts in the other application examples were not fresh meat. After 4 days of storage, except for the chicken breasts in Application Example 1 that were treated with traditional cooling, which were not fresh meat, the chickens in the other treatment groups were all fresh meat. Therefore, the coolant precooling treatment using Application Examples 2-8 can extend the shelf life of fresh chicken. In addition, after 1 day of storage, the chicken breasts treated with Application Example 4 had the lowest TVB-N content, followed by Application Example 3, Application Example 7, Application Example 8, Application Example 5, Application Example 6, Application Example 2 and Application Example 1, and this order corresponds to the corresponding coolant precooling treatment effect from good to bad.

[0118] 3. Water loss results

[0119] Cooking loss: Take the meat sample out of the packaging bag, quickly absorb the excess water on the surface with absorbent paper, and weigh 4×3×3cm 3 The mass of the meat sample is recorded as M 1 , put it in a retort bag and exhaust the air in the bag. Heat it in a 71℃ water bath for 35 min, take it out, cool it with running water for 30 min, wipe off the surface moisture with filter paper and weigh it to record it as M 2 , the calculation formula of cooking loss is as follows:

[0120] Cooking loss (%) = (M 1 -M 2) / M 1 ×100

[0121] Centrifugal loss: Take the meat sample out of the packaging bag, quickly absorb the excess water on the surface with absorbent paper, cut the meat sample (5±0.5 g) at the center, weigh it accurately and record it as M 3 , wrapped with absorbent paper, placed in a 50 mL centrifuge tube, and balanced with absorbent paper. After centrifugation at 4°C, 3819×g for 10 min, take out the meat sample, wipe off the excess water on the surface of the meat sample with filter paper, and weigh it again and record it as M 4 , 3 groups were measured in parallel and the average value was taken. The centrifugal loss was calculated by the following formula:

[0122] Centrifugal loss (%) = (M 3 -M 4 ) / M 3 ×100

[0123] The moisture content of fresh meat during storage is closely related to the taste, flavor and texture of meat after cooking. Moisture loss (cooking loss and centrifugal loss) is the main indicator for measuring the moisture content of meat. The results of cooking loss are shown in Table 7, and the results of centrifugal loss are shown in Table 8.

[0124] Table 7 Cooking loss results of various application examples

[0125]

[0126] Table 8 Centrifugal loss results of various application examples

[0127]

[0128]

[0129] Referring to Tables 7 and 8, after different precooling treatments, the moisture loss of chicken breast meat during storage at 4°C gradually increases with the extension of storage time. After precooling treatment with the coolant of Application Example 2-8, the moisture loss of chicken breast meat during storage is lower than that of chicken breast meat treated with traditional precooling. Moreover, when treated with betaine / glycerol and saline coolant, the difference between -1°C and -5°C is not obvious, and even the -1°C treatment is slightly better than the -5°C treatment.

[0130] 4. Results of nucleotide (inosinic acid and hypoxanthine) content

[0131] The nucleotide content was analyzed by high performance liquid chromatography. Weigh 3 g of sample, place in a 50 mL centrifuge tube, add 15 mL 10% cold perchloric acid to homogenize for 2 min, centrifuge at 4°C and 10610×g for 15 min, aspirate the supernatant, extract the precipitate once with 15 mL 10% cold perchloric acid, and combine the supernatants. The supernatant was adjusted to pH 6.5-6.8 with 0.5 mol / L and 0.05 mol / L NaOH solutions, allowed to stand at 4°C for 30 min to precipitate perchloric acid, and centrifuged at 4°C and 10610×g for 15 min. Take 1 mL of supernatant and filter through a 0.22 μm water filter before injection.

[0132] Detection parameters: chromatographic column is Agilent ZORBAXSB-C18 (250mm×4.6mm, 5μm); column temperature is 30℃; UV detection wavelength is 254nm; flow rate is 1mL / min; injection volume is 20μL; mobile phase A is 0.05mol / L potassium dihydrogen phosphate buffer, mobile phase B is methanol; mobile phase is filtered through 0.45μm filter membrane and ultrasonic before use. The elution procedure is 2% mobile phase B and 98% mobile phase A for 20min. The results are expressed as the content of nucleotides by comparison with the retention time of the standard and the standard curve.

[0133] (1) The reduction in freshness of meat during storage is closely related to the degradation of inosinic acid (IMP). The higher the IMP content, the better the freshness quality of chicken. The inosinic acid content of each application example is shown in Table 9.

[0134] Table 9 Results of inosinic acid content in each application example

[0135]

[0136]

[0137] As shown in Table 9, with the extension of storage time, the IMP content of chicken breast meat treated with different precooling treatments showed a downward trend. After storage for 1, 3 and 5 days, the IMP content of chicken breast meat treated with the coolant of Application Examples 2-8 was higher than that of chicken breast meat treated with the traditional precooling treatment group, and the lower the precooling temperature, the higher the IMP content of chicken breast meat, such as Application Example 3 (-1°C) and Application Example 4 (-5°C). After being treated with different coolants, betaine / glycerol and saline, the chicken breast meat showed a higher IMP content than other coolant precooling treatments.

[0138] (2) During the storage of fresh chicken, the decomposition of IMP will produce hypoxanthine (Hx), which will reduce the freshness and quality of chicken. The hypoxanthine content of each application example is shown in Table 10.

[0139] Table 10 Hypoxanthine content of each application example

[0140]

[0141] As shown in Table 10, as the storage time increases, the Hx content in all application examples shows an increasing trend. After storage for 1, 3 and 5 days, the Hx content of chicken breast meat treated with the coolant precooling treatment of application examples 2-8 was lower than that of chicken breast meat treated with the traditional precooling treatment group, and the lower the precooling temperature, the lower the IMP content of chicken breast meat, such as application example 3 (-1°C) and application example 4 (-5°C). Among them, after being treated with betaine / glycerol and saline, the chicken breast meat showed a lower Hx content than other coolant precooling treatments, and the effect was the best.

[0142] In summary, the above application examples verify the effects of betaine / glycerol / saline, 4°C cold water, choline chloride / trehalose / saline, betaine / malic acid / saline, proline / glycerol / saline and proline / sorbitol / saline cooling liquids in the preservation of fresh chicken. It is found that the direct immersion rapid cooling liquid of the present invention can achieve rapid cooling and freshness locking of chicken, extend the shelf life, and can maintain the quality of fresh chicken after slaughter to the maximum extent, among which betaine / glycerol / saline has the best comprehensive effect.

[0143] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0144] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A direct immersion cooling liquid for meat preservation, characterized in that: The direct immersion cooling liquid is prepared from a cooling agent and physiological saline; Wherein, the coolant includes compound A and compound B; the compound A is one of choline chloride, betaine, and proline; the compound B is one of glucose, trehalose, glycerol, xylitol, malic acid and sorbitol; the molar ratio of the compound A to the compound B is 1-3:1-2.

2. The direct immersion coolant according to claim 1, characterized in that The compound A is choline chloride, and the compound B is one of glucose, trehalose, glycerol and xylitol.

3. The direct immersion coolant according to claim 1, characterized in that: The compound A is betaine, the compound B is one of glycerol, xylitol and malic acid, and the molar ratio of the compound A to the compound B is 1-2:1-2.

4. The direct immersion coolant according to claim 3, characterized in that The compound A is betaine, and the compound B is glycerol.

5. The direct immersion coolant according to claim 4, characterized in that The molar ratio of the compound A to the compound B is 1:1-2.

6. The direct immersion coolant according to any one of claims 1 to 5, characterized in that: The mass ratio of the refrigerant to the physiological saline is 0.1 to 1:1; preferably, the mass ratio of the refrigerant to the physiological saline is 0.8 to 1:

1.

7. The direct immersion coolant according to any one of claims 1 to 5, characterized in that: The preparation method of the cooling agent comprises the following steps: Compound A and compound B are mixed and then rotary evaporated until a uniform viscous liquid is formed to obtain the cooling agent.

8. The direct immersion coolant according to claim 7, characterized in that: The water bath temperature of the rotary evaporation is 75°C to 85°C, and the centrifugal force is 3000×g to 4000×g; preferably, the water bath temperature of the rotary evaporation is 78°C to 82°C, and the centrifugal force is 3800×g to 4200×g.

9. Use of the direct immersion cooling liquid according to any one of claims 1 to 7 in preserving meat.

10. The use according to claim 9, characterized in that The meat is poultry meat, preferably chicken.

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