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CN-121970800-A - Low-temperature low-loss pig slaughtering precooling process

CN121970800ACN 121970800 ACN121970800 ACN 121970800ACN-121970800-A

Abstract

The invention discloses a low-temperature low-loss pig slaughtering precooling process, and relates to the technical field of meat product processing. The process comprises spraying the surface of the carcass to form a liquid water-containing film, feeding the carcass into a precooling room for gradient precooling, controlling the temperature to be reduced from-5 ℃ to-8 ℃ at a rate of 0.1 ℃ to 0.2 ℃ per minute to-15 ℃ to-18 ℃ in a starting stage, maintaining the relative humidity to 92% to 98%, gradually freezing the water-containing film to release the latent heat of phase change, monitoring the freezing area proportion in real time, switching to a quick cooling stage when the freezing area proportion reaches 70% to 85%, and controlling the temperature to be-20 ℃ to-23 ℃ in the quick cooling stage, wherein the air flow speed is 2.2m/s to 3.0m/s until the central temperature of the carcass is reduced to 4 ℃ to 7 ℃. The invention slows down the cold impact through the phase change buffer mechanism, and is beneficial to reducing the precooling loss and improving the meat quality.

Inventors

  • LIU HUAQIANG
  • LIU XIAOMIN

Assignees

  • 河南润蕴食品有限公司

Dates

Publication Date
20260505
Application Date
20260321

Claims (10)

  1. 1. The low-temperature low-loss pig slaughtering precooling process is characterized by comprising the following steps of: s1, carrying out surface spray treatment on slaughtered live pig carcasses to form a liquid water-containing film on the surfaces of the carcasses; S2, conveying the carcasses into a precooling room for gradient precooling, wherein the gradient precooling comprises a starting stage, the initial temperature of the precooling room is controlled to be gradually reduced to-15 ℃ to-18 ℃ from-5 ℃ to-8 ℃ at a cooling rate of 0.1 ℃ to 0.2 ℃ per minute in the starting stage, the relative humidity of the precooling room is controlled to be kept at 92% to 98%, the air flow speed of the precooling room is controlled to be 0.8m/S to 1.2m/S, and the liquid water-containing film on the surfaces of the carcasses is gradually frozen in the cooling process through the synergistic effect of the cooling rate and the humidity; s3, monitoring the icing degree of the surface of the carcass in real time in the starting stage, and ending the starting stage and switching to the quick cooling stage when the icing area proportion of the surface of the carcass is monitored to be 70-85%; And S4, in the rapid cooling stage, controlling the temperature between precooling to be maintained at-20 ℃ to-23 ℃, naturally falling the relative humidity to 82% to 88%, increasing the air flow speed to 2.2m/S to 3.0m/S, and continuously cooling until the central temperature of the thickest part of the carcass is reduced to 4 ℃ to 7 ℃.
  2. 2. The low temperature low loss pig slaughtering precooling process according to claim 1, wherein the start-up stage in S2 comprises a film forming sub-stage in which the temperature between precooling is controlled to be maintained at-5 ℃ to-8 ℃, the relative humidity is maintained above 98%, the air flow speed is lower than 1.0m/S, and the air flow speed is maintained for 8min to 12min, so that a liquid water-containing film with uniform thickness is formed on the carcass surface.
  3. 3. The low temperature low loss pig slaughter pre-cooling process according to claim 2, wherein the start-up stage in S2 further comprises a phase change buffer sub-stage after the film forming sub-stage, in which the pre-cooling inter-stage temperature is controlled to gradually decrease from-5 ℃ to-8 ℃ to-15 ℃ to-18 ℃ at a rate of 0.1 ℃ to 0.2 ℃ per minute, while the relative humidity is controlled to be maintained at 92% to 95%, so that the liquid water-containing film on the carcass surface gradually freezes and the latent heat of phase change is continuously released.
  4. 4. The low-temperature low-loss pig slaughtering precooling process according to claim 3, wherein in the phase change buffer sub-stage, the phase change buffer process is judged by monitoring the residence time of the carcass surface temperature near 0 ℃, and when the residence time of the surface temperature in the range of-1 ℃ to +1 ℃ reaches 15min to 25min, the latent heat of phase change is released in the icing process of the liquid water-containing film on the carcass surface is confirmed.
  5. 5. The low-temperature low-loss pig slaughtering precooling process according to claim 1, wherein in S3, the real-time monitoring of the icing degree of the carcass surface is performed by an infrared thermal imaging method, and the ratio of the area of the region with the temperature ranging from-1 ℃ to +1 ℃ to the total area of the carcass surface is identified and calculated as the icing area ratio of the carcass surface by analyzing the carcass surface temperature distribution image.
  6. 6. The low temperature low loss pig slaughter pre-cooling process according to claim 5, wherein the carcass surface icing area ratio is determined to be 70% to 85% when the area of the region monitored by infrared thermal imaging at a temperature in the range of-1 ℃ to +1 ℃ reaches a maximum.
  7. 7. The low temperature low loss pig slaughtering precooling process according to any one of claims 1 to 6, wherein the temperature, humidity and air flow speed between precooling are controlled in a partitioning manner in S2 and S4, specifically comprising increasing the air flow speed of the corresponding region of the rear leg of the carcass by 20% to 30% compared with other regions of the carcass, maintaining the relative humidity of the corresponding region of the abdomen of the carcass by 3% to 5% compared with other regions of the carcass, and applying infrared radiation to the corresponding region of the back of the carcass to slow down the cooling rate thereof.
  8. 8. The low temperature low loss pig slaughter pre-cooling process according to claim 7, wherein the power density of the infrared radiation applied to the corresponding area of the carcass back is 0.1W/cm 2 to 0.3W/cm 2 and is dynamically adjusted according to the carcass back surface temperature feedback.
  9. 9. The low temperature low loss pig slaughter pre-cooling process according to any one of claims 1 to 6, wherein the surface spraying treatment in S1 is a solution containing a food grade additive, the food grade additive being at least one of glycerol or sorbitol, with a total mass concentration of 2% to 6%, a spraying time of 18S to 25S and a spraying pressure of 0.22MPa to 0.28MPa.
  10. 10. The low-temperature low-loss pig slaughtering precooling process according to any one of claims 1 to 6, wherein after the central temperature of the thickest part of the carcass in S4 is reduced to 4 ℃ to 7 ℃, the carcass is transferred out of the precooling room and is sent into a maturation room of 0 ℃ to 4 ℃ for acid removal and maturation for 16 to 24 hours.

Description

Low-temperature low-loss pig slaughtering precooling process Technical Field The invention relates to the technical field of meat product processing, in particular to a low-temperature low-loss pig slaughtering and precooling process. Background Chilled meat is a major form of pork consumption with its good eating quality and long shelf life. The carcass temperature is higher after pig slaughtering, and the carcass temperature needs to be quickly reduced through precooling treatment so as to inhibit microorganism growth and prolong the shelf life. The weight loss caused by the evaporation of water on the carcass surface in the precooling process is one of the main problems facing slaughter enterprises, and the precooling loss directly affects the economic benefit of the enterprises. Meanwhile, the precooling mode has important influence on the color, water retention, tenderness and other edible qualities of pork. The existing precooling process mainly comprises a one-stage cooling method and a two-stage cooling method. The hot carcass is directly sent into a refrigeration house with the temperature of 0 ℃ to 4 ℃ to be cooled for 16h to 24h by a one-stage cooling method, and the precooling loss is high. The two-stage cooling method firstly cools the carcass for about 90min between rapid cooling at-20 ℃ to-30 ℃ and then shifts to the equilibrium temperature between precooling at 0 ℃ to 4 ℃, which is helpful for reducing precooling loss, but still has the problem of muscle contraction and water loss caused by cold impact. Chinese patent CN104273200a discloses a method for processing live pigs, pre-cooling white pork strips at-30 ℃ for 1h, dividing, pre-cooling again at-20 ℃ for 6h, and cooling by two-stage pre-cooling at different temperatures. Although the method achieves the precooling effect, the two sections of precooling adopt constant low temperature, the strong cooling at the temperature of-30 ℃ in the first section easily causes quick freezing of the surface of the carcass, ice shells are formed to prevent internal heat from radiating, and the muscle cold contraction is obvious. Chinese patent CN103815000a discloses a method for reducing pre-cooling loss of live pig carcass, by prolonging on-orbit time of carcass and adding multiple spraying, the temperature of cavity before carcass entering quick cooling chamber is reduced to 28-30 ℃, then quick cooling and acid discharging maturation are carried out. The method reduces the temperature difference between the carcass and the refrigeration house through spray cooling, is beneficial to reducing the precooling loss, but the repeated spray increases the production procedures and time, has higher requirements on the layout of the production line, and does not solve the problem of cold impact in the quick cooling start stage. Disclosure of Invention In order to overcome the defects in the prior art, the embodiment of the invention provides a low-temperature low-loss pig slaughtering precooling process, which aims to solve the problems of higher precooling loss, obvious muscle cold contraction and meat quality to be improved in the prior art. In order to achieve the aim, the invention provides the following technical scheme that the low-temperature low-loss pig slaughtering and precooling process comprises the following steps: S1, surface spraying treatment. And (3) carrying out surface spraying treatment on the slaughtered live pig carcasses to form a liquid water-containing film on the surfaces of the carcasses, wherein the liquid water-containing film is used as a medium in a subsequent phase-change buffering process. S2, gradient precooling in a starting stage. The carcass is sent to a precooling room for gradient precooling, and the gradient precooling comprises a starting stage. In the start-up phase, the initial temperature of the pre-cooling chamber temperature from-5 ℃ to-8 ℃ is controlled to be gradually reduced to-15 ℃ to-18 ℃ at the cooling rate of 0.1 ℃ to 0.2 ℃ per minute, the relative humidity of the pre-cooling chamber is controlled to be maintained at 92% to 98%, and the air flow speed of the pre-cooling chamber is controlled to be 0.8m/s to 1.2m/s. Through the synergistic effect of the cooling rate and the humidity, the liquid water-containing film on the surface of the carcass is gradually frozen in the cooling process, and the thermal shock of cold air to the carcass is buffered by utilizing the phase change latent heat released by water freezing. S3, monitoring the icing degree and switching the stages. And monitoring the icing degree of the surface of the carcass in real time in the starting stage, and ending the starting stage and switching to the quick cooling stage when the icing area proportion of the surface of the carcass is monitored to be 70-85%. S4, a rapid cooling stage. In the rapid cooling stage, the temperature between precooling is controlled to be maintained at-20 ℃ to-23 ℃, the relative humidity naturally drops back to 82