Production method for prolonging shelf life of hot-slaughtered medium-temperature meat

Abstract

The invention relates to the technical field of food processing and production, in particular to a production method for prolonging the shelf life of hot slaughtered medium-temperature meat, which comprises the following steps: selecting hot slaughtered livestock and poultry meat, treating, soaking a meat blank in a citric acid solution, rinsing after soaking, and draining to obtain a pretreated meat blank; preparing a preservative solution, soaking the pretreated meat blank in the preservative solution, and stirring for multiple times during soaking; after soaking, taking out and draining redundant solution on the surface to obtain a soaked meat blank; adding a pickling material for pickling to obtain a marinated meat blank; cooling the marinated meat blank, keeping the air speed and the relative humidity of a cooling chamber, reducing the central temperature of the meat blank to a target temperature at a certain cooling rate, preparing a semi-finished product, and putting the semi-finished product into a barrier packaging film for sealing treatment to prepare a finished product. The citric acid is used for pretreatment, and the staged temperature control cooling technology is adopted, so that the shelf life is remarkably prolonged, and meanwhile, the safety risk and flavor damage caused by chemical additives are avoided.

Description

Technical Field

[0001] This invention relates to the field of food processing and production technology, and more specifically, to a production method for extending the shelf life of hot-slaughtered, medium-temperature meat. Background Technology

[0002] Hot slaughter refers to the processing of livestock and poultry without subsequent cooling. Meat from hot slaughter is typically cut directly at a high temperature, usually maintained between 20°C and 35°C during the cutting process. Meat within this temperature range is considered medium-temperature hot slaughter meat. Because it hasn't undergone low-temperature treatment, the muscle tissue retains good elasticity, resulting in a tender texture. Furthermore, it offers high processing efficiency and low energy consumption, making it widely used in the meat processing industry.

[0003] However, because it has not undergone low-temperature treatment, hot-slaughtered medium-temperature meat has a significant short shelf life. On the one hand, the temperature environment of 20-35℃ provides suitable conditions for the rapid reproduction of microorganisms such as Escherichia coli, Salmonella, and Staphylococcus aureus, and the number of microorganisms on the surface and inside the meat can easily exceed the standard in a short period of time. On the other hand, the activity of proteases and lipases in meat is high in this medium-temperature environment, which can easily trigger chemical reactions such as protein degradation and fat oxidation, resulting in quality deterioration phenomena such as off-odor, stickiness, and color deterioration.

[0004] Currently, the shelf life of freshly slaughtered meat at medium temperature is typically only 1-2 days, severely limiting its distribution and sales cycle. Existing technologies for extending the shelf life of freshly slaughtered meat at medium temperature mainly involve low-temperature refrigeration or chemical preservative treatment. Low-temperature refrigeration rapidly cools the meat to 0-4°C, which can inhibit microbial and enzyme activity, but the rapid cooling process easily causes muscle fiber contraction, resulting in the loss of a large amount of juice, damaging the texture, and reducing its commercial value. While chemical preservative treatment can inhibit microorganisms in the short term, consumers currently have high concerns about the safety of chemical additives, and they can easily affect the flavor of the meat. Summary of the Invention

[0005] The purpose of this invention is to provide a production method for extending the shelf life of hot-slaughtered meat at medium temperature. This method uses a natural compound preservative and staged temperature-controlled cooling to solve the problems of chemical additives affecting food safety and rapid low-temperature refrigeration reducing the value of commodities in existing related technologies.

[0006] To achieve the above objectives, the present invention provides the following technical solution: A production method for extending the shelf life of hot-slaughtered, medium-temperature meat includes the following steps: S1: Select meat from slaughtered livestock and poultry, remove tendons and fat, cut into meat pieces, soak the meat pieces in citric acid solution, rinse with sterile water after soaking, and drain the water to obtain pre-treated meat pieces. S2: Prepare a preservative solution, immerse the pretreated meat carcass in the preservative solution, and stir it multiple times during the immersion process; the preservative solution contains 0.2-0.5% tea polyphenols, 0.3-0.6% chitosan, and 0.1-0.2% rosemary extract by weight, with the remainder being sterile water. After immersion, remove the meat carcass and drain off excess solution to obtain the soaked meat carcass. S3: Add marinade to the soaked meat blanks to marinate them, and obtain marinated meat blanks; S4: Place the marinated meat blanks into the cooling chamber for cooling. Maintain the airflow and relative humidity in the cooling chamber. Reduce the center temperature of the meat blanks to 4-6℃ at a cooling rate of 3-5℃ / h. After reducing to the target temperature, maintain it for 1.5-2 hours to obtain a semi-finished product. S5: The semi-finished product is placed in a barrier packaging film and sealed to obtain the finished product.

[0007] Optionally, the hot-slaughtered livestock and poultry meat selected in S1 is pork or beef with a core temperature of 22-32℃ within 1 hour after hot slaughter, and the weight of a single cut meat piece is 200-500g.

[0008] Optionally, the mass concentration of the citric acid solution in S1 is 0.8-1.2% based on the total mass of the solution, and the soaking time of the meat carcass in the citric acid solution is 5-8 minutes. After soaking, the meat carcass needs to be drained until there are no obvious water stains on the surface of the pretreated meat carcass.

[0009] Optionally, when preparing the preservative solution, tea polyphenols, chitosan, and rosemary extract are added sequentially to sterile water and stirred at a rate of 100-150 r / min for 5-10 min. Then, the pH of the solution is adjusted to 5.5-6.5 with citric acid or sodium carbonate.

[0010] Optionally, the mass ratio of pretreated meat to preservative solution is 1:3-1:5, the soaking temperature is controlled at 30-35℃, the total soaking time is 20-30 minutes, and the meat is stirred once every 5 minutes, with each stirring lasting 30-60 seconds.

[0011] Optionally, the mass ratio of the marinade to the soaked meat carcass is 1:20-1:30, and the marinade contains the following ingredients in parts by weight: 1.5-2.0 parts salt, 0.3-0.5 parts compound phosphate, 0.2-0.3 parts glucose, and 0.05-0.1 parts vitamin C.

[0012] Optionally, the composite phosphate is composed of sodium pyrophosphate, sodium tripolyphosphate, and sodium hexametaphosphate in a weight ratio of 2:1:1.

[0013] Optionally, the marinating process in S3 is carried out in a temperature-controlled marinating chamber at a temperature of 15-20℃ for a total marinating time of 1.5-2.5 hours.

[0014] Optionally, the air velocity in the cooling chamber is 0.8-1.2 m / s, and the relative humidity is 80-85%.

[0015] Optionally, the sealing process requires filling the barrier packaging film with a mixed gas, the volume ratio of which is: oxygen 65-75%, carbon dioxide 15-25%, and nitrogen 5-15%, and the pressure inside the sealed packaging is 0.02-0.05 MPa.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. By using citric acid for pretreatment, combined with the synergistic effect of a natural compound preservative containing tea polyphenols, chitosan and rosemary extract, it can effectively inhibit microbial growth and enzyme activity, delay fat oxidation and protein degradation, significantly extend shelf life, and avoid the safety risks and flavor damage caused by chemical additives. 2. By adopting phased temperature control and cooling technology and specific humidity and wind speed environmental control, efficient cooling is achieved to inhibit microorganisms while reducing muscle fiber contraction and juice loss, thus maximizing the preservation of the tender taste and commercial value of hot-slaughtered meat. 3. The specific proportion of modified atmosphere packaging used in the final step can maintain the bright red color of the oxymyoglobin in the meat to attract consumers. The whole method has moderate equipment requirements, relatively low energy consumption, and is easy to implement and promote in existing meat processing production lines. It is suitable for the large-scale and commercial production of pork and beef hot-slaughtered medium-temperature meat. Attached Figure Description

[0017] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a flowchart of a production method for extending the shelf life of meat produced by hot slaughter at medium temperature, according to the present invention. Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with embodiments. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0019] The present invention will be further explained below with reference to specific embodiments: See Figure 1 A production method for extending the shelf life of hot-slaughtered, medium-temperature meat includes the following steps: S1: Select meat from slaughtered livestock and poultry, remove tendons and fat, cut into meat pieces, soak the meat pieces in citric acid solution, rinse with sterile water after soaking, and drain the water to obtain pre-treated meat pieces. S2: Prepare a preservative solution, immerse the pre-treated meat carcass in the preservative solution, and stir it multiple times during the immersion. The preservative solution contains 0.2-0.5% tea polyphenols, 0.3-0.6% chitosan, and 0.1-0.2% rosemary extract by weight, with the remainder being sterile water. After immersion, remove the meat carcass and drain off the excess solution on the surface to obtain the immersed meat carcass. S3: Add marinade to the soaked meat blanks to marinate them, and obtain marinated meat blanks; S4: Place the marinated meat blanks into the cooling chamber for cooling. Maintain the airflow and relative humidity in the cooling chamber. Reduce the center temperature of the meat blanks to 4-6℃ at a cooling rate of 3-5℃ / h. After reducing to the target temperature, maintain it for 1.5-2 hours to obtain a semi-finished product. S5: The semi-finished product is placed in a barrier packaging film and sealed to obtain the finished product.

[0020] Example 1 In this embodiment, tenderloin from a hot-slaughtered pig is used as the processing target, and the specific steps are as follows: Pretreatment (S1): Select pork tenderloin that has been slaughtered for 45 minutes and has a core temperature of 28°C. Remove the surface fascia and visible fat to ensure the purity of the meat. Pork tenderloin was cut into individual pieces weighing 300g and approximately 3cm thick. A 1.0% citric acid solution was prepared, and the pork pieces were completely submerged in the solution and soaked at room temperature (25℃) for 6 minutes, gently agitating the container twice during this time to promote the removal of surface blood and impurities. After soaking, the pork pieces were rinsed three times with running sterile water, each rinse lasting 1.5 minutes. The rinse solution from the final rinse was used to test for citric acid residue using pH paper. The meat blanks are then placed on a sterile draining rack and allowed to drain naturally for 4 minutes until there are no obvious water stains on the surface of the meat blanks, thus obtaining pre-treated meat blanks.

[0021] Preservative soaking (S2): First, prepare the preservative. Weigh 0.3% tea polyphenols, 0.5% chitosan, and 0.15% rosemary extract by total mass of the solution, and add them to sterile water in sequence. After adding, stir at 120 r / min for 8 min. Then, adjust the solution with 10% citric acid solution and use a pH meter to detect the pH value. Adjust the pH value of the solution to 6.0 to obtain the preservative solution. The pretreated meat carcasses were placed in the preservative solution, and the mass ratio of meat carcasses to solution was controlled at 1:4. The container was placed in a constant temperature water bath and the soaking temperature was maintained at 32℃ for a total soaking time of 25 minutes. During this period, the mixture was stirred with a sterile stirring rod at a speed of 60 r / min for 45 seconds every 5 minutes. After soaking, remove the meat blank with sterile tweezers and place it on sterile filter paper to drain for 3 minutes until no excess solution drips from the surface, thus obtaining the soaked meat blank.

[0022] Pickling (S3): First, prepare the pickling material by weighing the following raw materials by weight: 2.0 parts salt, 0.4 parts compound phosphate (including 0.2 parts sodium pyrophosphate, 0.1 parts sodium tripolyphosphate, and 0.1 parts sodium hexametaphosphate), 0.25 parts glucose, and 0.08 parts vitamin C. Mix them evenly and grind them into a fine powder to obtain the pickling material. Using a marinade-to-meat-after-soaking ratio of 1:25, evenly sprinkle the marinade onto the surface of the meat. Gently rub the meat with sterile gloves for 1 minute to ensure the marinade adheres to the surface and partially penetrates the meat's texture. Then, place the meat in a temperature-controlled marinating chamber, setting the temperature to 18℃ and relative humidity to 72%, for a total marinating time of 2 hours. During this time, turn the meat over every 30 minutes to ensure even marinating. After marinating, you will obtain marinated meat.

[0023] Cooling (S4): Spread the marinated meat blanks in a single layer on a sterile cooling tray and place it in the cooling chamber; set the cooling chamber parameters: wind speed 1.0m / s, relative humidity 82%, and use the programmed cooling mode to reduce the center temperature of the meat blanks from 18℃ to 5℃ at a cooling rate of 4℃ / h; after the temperature drops to the target temperature, maintain it for 1.8h. After cooling is completed, a semi-finished product is obtained.

[0024] Sealing process (S5): Select a high-barrier composite film that meets food safety standards and cut it into a bag shape suitable for meat blanks; The semi-finished product is placed in a packaging film, and a modified atmosphere packaging machine is used to fill it with a mixed gas (volume ratio: 70% oxygen, 20% carbon dioxide, and 10% nitrogen). The packaging machine parameters are adjusted so that the pressure inside the sealed package is 0.04 MPa, the heat sealing temperature is 180℃, and the heat sealing time is 2 seconds. After sealing, the finished product is obtained.

[0025] Example 2 S1: Select beef shank that has been slaughtered for 50 minutes and has a core temperature of 30°C. Remove subcutaneous fat and fascia to avoid fat oxidation affecting shelf life. Cut the meat into individual 400g pieces with a thickness of 4cm; then prepare a 1.2% citric acid solution, completely immerse the meat pieces, and soak at room temperature for 8 minutes, stirring gently every 2 minutes to promote the removal of residual impurities from the fascia; Rinse twice with running sterile water (2 minutes each time). After checking for no citric acid residue, place the meat on a sterile drain rack to drain for 5 minutes until there are no obvious water stains on the surface, and you will get the pre-treated meat carcass.

[0026] S2: Weigh 0.5% tea polyphenols, 0.6% chitosan, and 0.2% rosemary extract by total mass of solution, and add them to sterile water in sequence; stir at 150 r / min for 10 min, adjust the pH to 6.5 with 10% sodium carbonate solution, and observe that there is no flocculent matter to confirm that the chitosan is completely dissolved; Control the mass ratio of pretreated meat carcasses to preservative solution to 1:5, and soak them in a 35℃ constant temperature water bath for 30 minutes; stir with a sterile stirring rod at a rate of 80r / min for 60 seconds every 5 minutes to ensure that the preservative penetrates into the gaps between the beef fibers. After removing the meat, use sterile filter paper to absorb excess solution from the surface and drain for 2 minutes to obtain the soaked meat blank.

[0027] S3: Weigh out the following by weight: 1.8 parts salt, 0.5 parts compound phosphate (0.33 parts sodium pyrophosphate, 0.17 parts sodium tripolyphosphate, 0.17 parts sodium hexametaphosphate), 0.3 parts glucose, and 0.1 parts vitamin C. Mix them together and grind them into a fine powder to avoid coarse particles affecting the taste. Sprinkle the marinade evenly on the surface of the meat blank at a ratio of 1:30 between the marinade and the meat blank, and gently knead for 2 minutes while wearing sterile gloves. Place the meat blank in a temperature-controlled marinating box, set the temperature to 15℃ and the relative humidity to 75%, and marinate for 2.5 hours, turning it over once every 30 minutes during the process to obtain marinated meat blanks.

[0028] S4: Spread the marinated meat blanks in a single layer on a sterile tray, place them in a cooling room, set the wind speed to 1.2m / s and the relative humidity to 85%, and use the programmed cooling mode to reduce the center temperature of the meat blanks from 15℃ to 6℃ at a rate of 5℃ / h; maintain the temperature at the target temperature for 2 hours to obtain a semi-finished product.

[0029] S5: Use a high-barrier composite film that meets food safety standards and cut it into a bag shape suitable for meat blanks; The semi-finished product is placed in a bag and filled with a mixed gas (volume ratio: 75% oxygen, 15% carbon dioxide, and 10% nitrogen). The modified atmosphere packaging machine is adjusted, and after sealing, the pressure inside the package is 0.04 MPa. The package is then heat-sealed for 3 seconds to obtain the finished product.

[0030] Example 3 This embodiment is basically the same as Embodiment 1, except that some process parameters have been adjusted, and the processing object is pork shoulder from hot-slaughtered pigs. The following focuses on explaining the modified process parameters, and the specific steps are as follows: S1: Select pork shoulder meat that has been slaughtered for 35 minutes and has a core temperature of 26℃. Remove excess fat and fascia, and cut into individual pieces weighing 350g and approximately 3.5cm thick. Place the meat pieces in a 0.9% citric acid solution and soak at 24℃ for 6 minutes. Then rinse twice with sterile water and drain thoroughly to obtain pre-treated meat pieces.

[0031] S2: Prepare a preservative solution containing 0.25% tea polyphenols, 0.4% chitosan, and 0.12% rosemary extract, with the pH adjusted to 5.8. The mass ratio of pretreated meat to preservative solution is 1:3.5. Soak at a constant temperature of 31℃ for 22 minutes, stirring for 40 seconds every 5 minutes.

[0032] S3: The ratio of marinade to soaked meat carcass is 1:22. The marinade consists of: 1.7 parts salt, 0.35 parts compound phosphate (0.175 parts sodium pyrophosphate, 0.0875 parts sodium tripolyphosphate, 0.0875 parts sodium hexametaphosphate), 0.22 parts glucose, and 0.07 parts vitamin C. The meat carcass is marinated at 19℃ for 2 hours to obtain the marinated meat carcass.

[0033] S4: Place the marinated meat blanks into the cooling chamber, set the air velocity to 0.9 m / s and the relative humidity to 81%. Reduce the center temperature of the meat blanks from 19℃ to 4.5℃ at a cooling rate of 3.5℃ / h and maintain this temperature for 1.7h to obtain a semi-finished product.

[0034] S5: The semi-finished product is packaged with a barrier packaging film using modified atmosphere packaging. The mixed gas ratio is 68% oxygen, 22% carbon dioxide, and 10% nitrogen. After sealing, the pressure inside the packaging is 0.03 MPa, and the finished product is obtained.

[0035] Example 4 This embodiment is basically the same as Embodiment 2, except that it uses beef brisket and the parameters are adjusted. The following focuses on explaining the modified process parameters, and the specific steps are as follows: S1: Select beef brisket that has been slaughtered for 55 minutes and has a core temperature of 31°C. After trimming, cut it into individual pieces weighing 450g and approximately 4.5cm thick. Place the meat pieces in a 1.1% citric acid solution and soak at 26°C for 7.5 minutes. Rinse thoroughly and drain to obtain pre-treated meat pieces.

[0036] S2: Prepare a preservative solution containing 0.45% tea polyphenols, 0.58% chitosan, and 0.19% rosemary extract, with the pH adjusted to 6.3. The mass ratio of pretreated meat to preservative solution is 1:4.5. Soak at a constant temperature of 34℃ for 28 minutes, stirring for 55 seconds every 5 minutes.

[0037] S3: The ratio of marinade to soaked meat carcass is 1:28. The marinade consists of: 1.9 parts salt, 0.45 parts compound phosphate (0.225 parts sodium pyrophosphate, 0.1125 parts sodium tripolyphosphate, 0.1125 parts sodium hexametaphosphate), 0.28 parts glucose, and 0.09 parts vitamin C. The meat carcass is marinated at 16℃ for 2.4 hours to obtain the marinated meat carcass.

[0038] S4: Place the marinated meat blanks into the cooling chamber, set the air velocity to 1.1 m / s and the relative humidity to 84%. Reduce the center temperature of the meat blanks from 16℃ to 5.5℃ at a cooling rate of 4.5℃ / h and maintain this temperature for 1.9h to obtain a semi-finished product.

[0039] S5: The semi-finished product is packaged with a barrier packaging film using modified atmosphere packaging. The mixed gas ratio is 73% oxygen, 17% carbon dioxide, and 10% nitrogen. After sealing, the pressure inside the packaging is 0.04 MPa, and the finished product is obtained.

[0040] Example 5 This embodiment is basically the same as Embodiment 1, except that: In step S2, when preparing the preservative solution, the concentration of tea polyphenols is adjusted to 0.2%, the concentration of chitosan is adjusted to 0.6%, the concentration of rosemary extract is kept at 0.15%, and the pH value is adjusted to 6.0; the mass ratio of pretreated meat to solution is adjusted to 1:5; the soaking temperature is 35℃, the total soaking time is 20 minutes, and the stirring frequency remains unchanged.

[0041] Example 6 This embodiment is basically the same as Embodiment 1, except that: In step S4, the cooling rate is adjusted from 5℃ / h to 3℃ / h.

[0042] Example 7 This embodiment is basically the same as Embodiment 1, except that: In S1, the concentration of citric acid solution is 0.8%, and the soaking time is set to 5 min; in S2, the preservative solution contains 0.2% tea polyphenols, 0.3% chitosan, and 0.1% rosemary extract, and the mass ratio of meat to solution is 1:3, with a total soaking time of 20 min; in S4, the cooling rate is 3℃ / h, and the target temperature is maintained at 4℃ for 1.5 h.

[0043] Example 8 This embodiment is basically the same as Embodiment 1, except that: When preparing the preservative solution in S2, use a 1% sodium carbonate solution and adjust the pH of the solution to 6.5.

[0044] Comparative Example 1 The only difference between this comparative example and Example 1 is that: In S1, pork tenderloin with a core temperature of 28°C and 45 minutes post-slaughter was selected. After removing the fascia and fat, the tenderloin was cut into 300g pieces and rinsed three times with running sterile water (1.5 minutes each time). The pieces were then drained until there were no obvious water stains on the surface, resulting in meat pieces without citric acid pretreatment. This comparative example omits the citric acid soaking step in S1 of Example 1.

[0045] Comparative Example 2 The only difference between this comparative example and Example 1 is that: Prepare a 0.1% potassium sorbate solution (food grade) in S2, and soak the pre-treated meat pieces in the solution at a mass ratio of 1:4. Maintain a constant temperature of 32℃ for 25 minutes, stirring for 45 seconds every 5 minutes, and drain until no liquid drips from the surface. This comparative example only replaces the natural compound preservative in S2 with a traditional chemical preservative.

[0046] Comparative Example 3 The only difference between this comparative example and Example 1 is that: In step S4, the marinated meat blanks are placed in a cooling chamber with a set air velocity of 1.0 m / s and a relative humidity of 82%. The core temperature of the meat blanks is reduced from 18°C ​​to 5°C at a rapid cooling rate of 10°C / h. Once the target temperature is reached, the meat blanks are removed directly to obtain a semi-finished product. This comparative example only modifies the cooling parameters in step S4, employing rapid low-temperature cooling.

[0047] Comparative Example 4 The only difference between this comparative example and Example 1 is that: In S5, the same barrier packaging film as in Example 1 is used, but the semi-finished product is placed inside and then directly vacuumed to a vacuum level of -0.085 MPa, without filling with mixed gas. This comparative example only replaces the modified atmosphere packaging in S5 with ordinary vacuum packaging.

[0048] Testing and Experiment Finished products were prepared using the methods described in Examples 1-8 and Comparative Examples 1-4, respectively. All finished products were tested within 1 hour of preparation, with sampling taken from the center and surface of the meat carcass. All testing items followed industry-standard methods. The main tests included microbial indicators (total bacterial count, E. coli) and shelf life. Physicochemical indicators and sensory evaluation were also conducted. Physicochemical indicators included juice loss rate, fat oxidation value, and pH value. The juice loss rate was determined by weighing the finished product, refrigerating it at 4°C for 3 days, and then weighing it again to calculate the weight difference percentage. The fat oxidation value (TBARS) was obtained by TCA extraction and TBA color development, with absorbance measured using a spectrophotometer. The pH value was measured directly using a pH meter after homogenizing the sample. Sensory evaluation was conducted by 10 people. All prepared products were cooked using the same method, primarily evaluating appearance, aroma, and taste. Each of these three indicators was scored separately, with equal weighting for each. A 9-point scale was used, and the final result was the average score. For shelf life determination, the product was refrigerated at 4°C (75%-80% humidity). Testing was performed and recorded after 3 days of refrigeration, and then daily thereafter until the total bacterial count was >10. 6 CFU / g or the presence of browning or off-odors was detected, and the number of days was recorded. Detailed test results are shown in Table 1.

[0049] Table 1 Performance Test Table As can be seen from Example 1 and Table 1, the process parameters in Example 1 adopted the intermediate parameters recommended by this invention. The test results show that the microbial control is good, the juice loss rate is low, the water retention effect is excellent, the antioxidant effect is strong, the finished product has a pure meat aroma and tender taste, and also has a long shelf life.

[0050] In Example 2, the meat was replaced with beef shank, which is a common processed product of beef. Some process parameters were also adjusted. Although the final test results showed that the microbial content was slightly higher than that of pork, it still met the safety standards. This shows that the present invention is well adapted to beef products. Although the indicators of meat characteristics fluctuate slightly, it still maintains a high quality level.

[0051] Example 3 is based on Example 1, but the process parameters were adjusted for pork shoulder. The final total bacterial count was the lowest in the group, the juice loss rate was the lowest, and the sensory score and shelf life were the highest. It can be seen that through parameter optimization, the antibacterial, water-retaining and flavor-preserving effects of the present invention can be optimized.

[0052] In Example 4, the beef cut from Example 2 was replaced with beef brisket. Beef brisket has a slightly higher fat content, and the process parameters were adjusted compared to Example 2. As shown in Table 1, the other test items were normal. Due to the coarser fibers of beef brisket, the juice loss rate was slightly higher, but still within the normal range. This demonstrates that the present invention is applicable to different cuts of beef, and even with coarser-fiber beef brisket, it can still control juice loss and microorganisms, ensuring quality.

[0053] Example 5 only modified the S2 preservative parameter, and the rest was the same as in Example 1; Example 6 only modified the S4 cooling rate, and the rest was the same as in Example 1; As shown in Table 1, within the preferred ratio range of the method of the present invention, even if the concentration of tea polyphenols is reduced and the soaking time is shortened, the natural compound preservative can still maintain a stable effect, and when the cooling rate is adjusted within the preferred range of 3-5℃ / h, it does not affect the final quality and shelf life. The same applies to Example 7.

[0054] Example 8 only modifies the pH adjustment method in S2, and the rest is the same as in Example 1. As shown in Table 1, the pH adjustment in S2 can use citric acid or sodium carbonate without affecting the final effect, which proves the flexibility of the process of the present invention in terms of acid-base adjustment method.

[0055] Comparative Example 1 is based on Example 1, but citric acid pretreatment is omitted. As shown in Table 1, the total number of colonies in the final product is 2.9 times that of Example 1, the lipid oxidation value is 31% higher than that of Example 1, and the shelf life is only 6 days. It can be seen that citric acid pretreatment can effectively inhibit the initial microbial growth and delay lipid oxidation. It is a basic step of the method of the present invention and cannot be omitted.

[0056] Comparative Example 2, based on Example 1, replaced the natural compound preservative in the method of this invention with 0.1% potassium sorbate. Other aspects remained the same as in Example 1. As shown in Table 1, the lipid oxidation value was 38% higher than in Example 1. Due to the astringent taste caused by potassium sorbate residue, the final sensory score was lower. Furthermore, potassium sorbate residue was detected, which, although compliant with national standards, raises safety concerns. It is evident that the natural compound preservative in the method of this invention is significantly superior to chemical preservatives in terms of antioxidant properties, flavor retention, and safety.

[0057] Comparative Example 3, based on Example 1, uses rapid low-temperature cooling instead of the temperature-controlled cooling method of the present invention. As shown in Table 1, the juice loss rate is 2.7 times that of Example 1, and the total sensory score is lower. It can be seen that staged temperature-controlled cooling can indeed avoid muscle fiber contraction and reduce juice loss. It is also the key to maintaining the tender taste of hot-cooked meat in the method of the present invention. Although the existing rapid cooling technology can preserve the shelf life, it will destroy the commodity value.

[0058] Comparative Example 4 is based on Example 1, but uses ordinary vacuum packaging instead of modified atmosphere packaging. As shown in Table 1, the total bacterial count is 5.3 times that of Example 1, the lipid oxidation value is 48% higher than that of Example 1, the total sensory score is lower, and the shelf life is only 4 days. It is evident that the modified atmosphere packaging method of this invention can inhibit excessive microbial levels and maintain the bright red color of the meat. This is also an important guarantee for extending the shelf life and maintaining sensory quality, which ordinary vacuum packaging cannot meet. This is because carbon dioxide can inhibit aerobic bacteria, and oxygen can inhibit anaerobic bacteria, keeping the total bacterial count at a low level. At the same time, high oxygen levels can maintain the bright red color of myoglobin, resulting in a better sensory appearance and less susceptibility to browning. Combined with the previous processing steps, this leads to a longer shelf life.

[0059] In summary, this invention demonstrates good applicability to various types of meat. The processed pork and beef exhibit low total bacterial counts and juice loss rates, along with high sensory scores and shelf life, which are superior to existing technologies.

[0060] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of this application, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat, characterized in that, Includes the following steps: S1: Select meat from slaughtered livestock and poultry, remove tendons and fat, cut into meat pieces, soak the meat pieces in citric acid solution, rinse with sterile water after soaking, and drain the water to obtain pre-treated meat pieces. S2: Prepare a preservative solution, immerse the pretreated meat carcass in the preservative solution, and stir it multiple times during the immersion process; the preservative solution contains 0.2-0.5% tea polyphenols, 0.3-0.6% chitosan, and 0.1-0.2% rosemary extract by weight, with the remainder being sterile water. After immersion, remove the meat carcass and drain off excess solution to obtain the soaked meat carcass. S3: Add marinade to the soaked meat blanks to marinate them, and obtain marinated meat blanks; S4: Place the marinated meat blanks into the cooling chamber for cooling. Maintain the airflow and relative humidity in the cooling chamber. Reduce the center temperature of the meat blanks to 4-6℃ at a cooling rate of 3-5℃ / h. After reducing to the target temperature, maintain it for 1.5-2 hours to obtain a semi-finished product. S5: The semi-finished product is placed in a barrier packaging film and sealed to obtain the finished product.

2. The production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: The hot-slaughtered livestock and poultry meat selected in S1 is pork or beef with a core temperature of 22-32℃ within 1 hour after hot slaughter, and the weight of a single cut piece of meat is 200-500g.

3. The production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: Based on the total mass of the solution, the mass concentration of the citric acid solution in S1 is 0.8-1.2%, the soaking time of the meat carcass in the citric acid solution is 5-8 minutes, and after soaking, it needs to be drained until there are no obvious water stains on the surface of the pretreated meat carcass.

4. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: When preparing the preservative solution, tea polyphenols, chitosan, and rosemary extract are added sequentially to sterile water and stirred at a rate of 100-150 r / min for 5-10 min. Then, the pH of the solution is adjusted to 5.5-6.5 with citric acid or sodium carbonate.

5. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 4, characterized in that: The mass ratio of pretreated meat to preservative solution is 1:3-1:

5. The soaking temperature is controlled at 30-35℃. The total soaking time is 20-30 minutes. Stir once every 5 minutes, and each stirring lasts for 30-60 seconds.

6. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: The mass ratio of the marinade to the soaked meat carcass is 1:20-1:

30. The marinade contains the following ingredients in parts by weight: 1.5-2.0 parts salt, 0.3-0.5 parts compound phosphate, 0.2-0.3 parts glucose, and 0.05-0.1 parts vitamin C.

7. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 6, characterized in that: The complex phosphate is composed of sodium pyrophosphate, sodium tripolyphosphate, and sodium hexametaphosphate in a weight ratio of 2:1:

1.

8. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 7, characterized in that: The pickling process in S3 is carried out in a temperature-controlled pickling chamber at a temperature of 15-20℃ for a total pickling time of 1.5-2.5 hours.

9. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: The cooling chamber has an air velocity of 0.8-1.2 m / s and a relative humidity of 80-85%.

10. A production method for extending the shelf life of hot-slaughtered, medium-temperature meat according to claim 1, characterized in that: The sealing process requires filling the barrier packaging film with a mixed gas, the volume ratio of which is: oxygen 65-75%, carbon dioxide 15-25%, and nitrogen 5-15%. After sealing, the pressure inside the packaging is 0.02-0.05 MPa.

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