A method for low temperature smoking of bacon and a low temperature smoking chamber

Abstract

The application relates to a method and a special smoking room for low-temperature smoked bacon, and relates to the technical field of meat product deep processing and food machinery engineering. The special part is that a special low-temperature smoking room is used for temperature section smoking: first stage smoking: the smoke temperature is adjusted through a circulating water cooling device, the smoke gas temperature contacted by the bottom layer of bacon blanks in the bacon smoking room is controlled to be 20-25 DEG C, the smoke gas temperature contacted by the top layer of bacon blanks is controlled to be 15-20 DEG C, and smoking is carried out for 2-4 months; second stage smoking: the smoke gas temperature contacted by the bottom layer of bacon blanks in the bacon smoking room is controlled to be 30-35 DEG C, and the smoke gas temperature contacted by the top layer of bacon blanks is controlled to be 25-30 DEG C. Beneficial effects: the oil and fire are separated, and the problem of carcinogens such as benzo[a]pyrene generated by high-temperature cracking of oil is completely eliminated. Meanwhile, the fire risk is greatly reduced, the disadvantages of 'upper maturation and lower growth' or local overheating in the traditional process are eliminated, the controllability of process parameters is high, and a reliable technical path is provided for the standardization and large-scale production of bacon.

Description

Technical Field

[0001] This invention relates to the field of deep processing of meat products and food machinery engineering technology, specifically to a method for low-temperature smoking of cured meat and a low-temperature smoking chamber for implementing this method. The invention aims to effectively inhibit the formation of harmful carcinogens during the smoking process, improve the sensory quality of cured meat, ensure production safety, and achieve an ultra-long-cycle natural fermentation process by improving the physical equipment structure and optimizing process parameters. This addresses industry pain points in traditional smoking processes such as excessive benzo[a]pyrene, meat charring, and the risk of fire. Background Technology

[0002] As a highly representative traditional cured meat product in my country, cured pork belly's unique flavor primarily originates from the smoking process. However, traditional smoking chambers for cured pork belly typically employ a high-temperature direct smoking method, which has several inherent drawbacks. First, regarding food safety, during the traditional smoking process, the dripping oil from the meat undergoes thermal decomposition upon contact with a high-temperature heat source (exceeding 200°C), producing potent carcinogenic polycyclic aromatic hydrocarbons, such as benzo[a]pyrene. These substances easily adhere to and penetrate the surface of the cured pork belly with the smoke, posing a serious safety hazard. Second, in terms of quality control, the high-temperature environment catalyzes severe protein denaturation, causing the surface of the cured pork belly to rapidly char, forming a dense, hard crust that hinders the proper migration of internal moisture, resulting in a dry, hard texture, insufficient aroma, and a lack of the rich flavor derived from deep fermentation. Furthermore, regarding production safety, traditional smoking chambers lack effective temperature control and physical insulation, making the seeping oil highly susceptible to ignition, posing a significant safety risk. Some existing improvement solutions, such as the technology disclosed in CN115812766 A, attempt to avoid oil-fire contact by changing the flue, but their structure is complex, the cost is high, and it is difficult to achieve precise low-temperature control, which cannot meet the comprehensive requirements of stability, safety and high-quality products for large-scale industrial production. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a method for low-temperature smoking of cured meat and a low-temperature smoking chamber. This solution achieves a harmonious balance in the three dimensions of safety, health, and flavor quality in cured meat production by introducing a "fire-blocking and cooling device" with a water-cooling structure, implementing physical protection through "bag filtration," and employing a "low-temperature segmented smoking" process.

[0004] One of the technical solutions of the present invention is a method for low-temperature smoking of cured meat, characterized by the use of a special low-temperature smoking chamber, and the process steps including: (1) Pickling steps: Select meat blanks and pickle them with salt as the pickling agent. The pickling temperature is 4-10℃ and the pickling time is 7-12 days. (2) Protective steps: After drying the surface moisture of the marinated meat, put it into a food-grade paper bag with microporous breathability and tie the opening tightly; (3) Fuel selection: Use semi-dry and semi-wet miscellaneous wood as fuel for starting the fire; (4) Fire-starting steps: First, start the fire with dry firewood. After it has burned, add semi-dry and semi-wet mixed firewood to allow the mixed firewood to burn fully and produce open flames and smoke. (5) Segmented smoking process: The first stage of smoking involves regulating the smoke temperature using a circulating water cooling device to maintain the smoke temperature at 20-25℃ at the bottom of the smoking chamber and at 15-20℃ at the top, for a period of 2-4 months. The second stage of smoking involves adjusting the smoke temperature to maintain the smoke temperature at 30-35℃ at the bottom of the smoking chamber and at 25-30℃ at the top, for a period of one month.

[0005] In a preferred embodiment, the paper bag is a food-grade virgin wood pulp paper bag or Xuan paper bag with a thickness of 70-100g / m², used to filter particulate matter in flue gas and delay moisture evaporation.

[0006] In a preferred embodiment, the moisture content of the semi-dry, semi-wet hardwood is 30%-45%.

[0007] In the preferred embodiment, during the first stage of smoking, the smoking time is 2 months when the meat blank thickness is less than 4cm; 3 months when the meat blank thickness is 4-6cm; and 4 months when the meat blank thickness is greater than 6cm.

[0008] The second technical solution of the present invention: a low-temperature smoking chamber for implementing a method of low-temperature smoking of cured meat, comprising a smoking chamber body (4), a combustion chamber (12) provided in the lower part of the smoking chamber body (4), a fire pile (1) provided in the combustion chamber (12), a meat smoking chamber (5) provided in the upper part of the smoking chamber body (4), and a smoke dispersing chamber (7) provided at the top of the smoking chamber body (4). The combustion chamber (12) and the meat smoking chamber (5) are connected by a smoke recirculator (10) controlled by a controller (2). The invention is characterized in that: a fire-blocking and cooling device (3) capable of cooling by water is provided above the fire pile (1) in the combustion chamber (12), and the horizontal projected area of ​​the surface of the fire-blocking and cooling device (3) used to block the flame is at least 1.5 times the horizontal projected area of ​​the fire pile (1); a smoke-blocking and fireproof plate (8) is provided on the bottom surface of the smoke dispersing chamber (7), and lateral smoke exhausters (8-1) are evenly distributed on the smoke-blocking and fireproof plate (8).

[0009] In a preferred embodiment, the lateral exhaust fan (8-1) is an arched baffle (8-1a) with both ends connected to the plate surface, and the arched baffle (8-1a) forms a narrow exhaust port (8-1b) on both sides that communicates with the smoking chamber (5).

[0010] In the preferred embodiment, the fire-blocking and cooling device (3) is a hollow heat exchange structure. Its left side (3-6) is a plane, its top side (3-1) is an inclined surface sloping outward, its bottom side (3-2) is an arc surface, and its front side (3-3) and rear side (3-11) are respectively provided with a water inlet pipe (3-8) and a water outlet pipe (3-9) with valves; the highest point of the outlet of the water outlet pipe (3-9) is higher than the top of the fire-blocking and cooling device (3).

[0011] In a preferred embodiment, the horizontal projected area of ​​the surface of the fire-blocking and cooling device (3) used to block the flame is 2-4 times the horizontal projected area of ​​the fire pile (1). In a preferred embodiment, an oil collection trough (3-5) is provided at the lower edge of the top surface (3-1) of the fire-blocking and cooling device (3), and an oil receiving bucket (3-4) is connected to the outlet of the oil collection trough (3-5) for collecting the oil that falls from the meat carcass.

[0012] In a preferred embodiment, the smoking chamber (5) is equipped with a first temperature sensor (6) and a second temperature sensor (11). The sensors are electrically connected to the controller (2). The controller (2) adjusts the water flow rate of the fire baffle and cooler (3) and the rotation speed of the flue gas circulator (10) according to the temperature data fed back by the sensors.

[0013] In a preferred embodiment, the right side (3-7) and bottom side (3-2) of the fire-blocking and cooling device (3) are continuous arc-shaped flow guiding structures used to guide the flue gas to flow around.

[0014] The present invention, by adopting the above technical solution, has the following beneficial effects: 1. Intrinsically safe and health-assured: By incorporating a fire-blocking and cooling device with circulating water cooling, "oil and fire separation" is achieved, completely eliminating the chemical prerequisites for the high-temperature decomposition of oils to produce carcinogens such as benzo[a]pyrene. Simultaneously, the combined design of the fire-blocking and cooling device and the smoke-proof fireproof plate effectively blocks sparks, significantly reducing the risk of fire. After applying this invention, the benzo[a]pyrene content in cured meat products can reach undetectable levels (below 0.1 μg / kg), far superior to traditional processes.

[0015] 2. Superior Quality and Rich Flavor: Through segmented low-temperature smoking (20-25℃ for 2-4 months, 30-35℃ for 1 month), the activity of endogenous enzymes is preserved, allowing proteins and fats to be fully degraded and transformed, generating richer flavor precursors. Combined with the physical filtration effect of the paper bag, smoke and carbon black are effectively blocked, giving the product a natural golden or reddish-brown color, a translucent texture, a tender and elastic mouthfeel, and a rich and lingering cured meat aroma. The aroma of cured meat from one household will fill ten households with its fragrance.

[0016] 3. Precise control, suitable for widespread application: Through the linkage of dual temperature sensors and controller, the cooling water flow rate and flue gas circulation rate can be precisely adjusted to ensure a uniform and stable temperature field in the smoking chamber. This eliminates the drawbacks of "top cooking and bottom uncooking" or local overheating in traditional processes. The process parameters are highly controllable, providing a reliable technical path for the standardized and large-scale production of cured meat. Attached Figure Description

[0017] Figure 1 This is a schematic cross-sectional view of the overall structure of the low-temperature fumigation chamber of the present invention.

[0018] Figure 2 This is a schematic diagram of the three-dimensional structure of the fire-blocking and cooling device of the present invention, as well as the internal flow channels and water inlet / outlet logic.

[0019] Figure 3 for Figure 2 The diagram shows the main structural view of the fire-blocking and cooling device.

[0020] Figure 4 This is a schematic diagram of the structure of the smoke-proof and fireproof board of the present invention.

[0021] Figure 5 for Figure 4 Enlarged diagram of the airflow guidance logic of the side exhaust fan.

[0022] In the diagram: 1. Fire pit; 2. Controller; 3. Fire damper and cooler; 3-1. Top surface; 3-2. Bottom surface; 3-3. Front side; 3-4. Oil receiving drum; 3-5. Oil collection trough; 3-6. Left side; 3-7. Right side; 3-8. Water inlet pipe; 3-9. Water outlet pipe; 3-10. Baffle plate; 3-11. Rear side; 4. Smoking chamber body; 5. Smoking chamber; 6. First temperature sensor; 7. Smoke dispersing chamber; 8. Smoke-proof and fireproof board; 8-1. Lateral smoke exhauster; 8-1a. Arched baffle; 8-1b. Smoke outlet; 9. Meat blank; 10. Smoke recirculator; 11. Second temperature sensor; 12. Combustion chamber. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments described are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] Example 1: Engineered Construction of a Low-Temperature Fumigation Chamber like Figure 1As shown, a low-temperature smoking chamber for implementing the method of the present invention includes a smoking chamber body 4, the interior of which is divided into a combustion chamber 12, a smoking chamber 5, and a smoke dispersing chamber 7 from bottom to top. Multiple fire piles 1 (four in this embodiment) are evenly spaced on the floor of the combustion chamber 12. A fire baffle and cooler 3 is installed directly above each fire pile 1, and the fire baffle and cooler is fixed to the wall by a bracket. The fire baffle and cooler 3 is the core heat exchange device of the present invention, and its structure is as follows: Figure 2 , Figure 3 As shown. Its outer shell is made of 304 stainless steel with good thermal conductivity. The interior is a water tank. Its left side 3-6 is flat, while the right side 3-3 and bottom side 3-2 form a continuous arc-shaped flow-guiding structure. This structure not only guides the flue gas flow but also effectively increases the heat exchange area. The top surface 3-1 is an outward-sloping surface (away from the center of the fire). The front side 3-7 and rear side 3-11 of the fire damper 3 are respectively equipped with an inlet pipe 3-8 and an outlet pipe 3-9 with valves. The highest point of the outlet pipe 3-9 is higher than the top of the fire damper 3 to ensure that the internal water tank is always full of cooling water. A guide plate 3-10 is located in the middle of the water tank. Water flows through the inlet pipe 3-8 into the area below the guide plate 3-10, then through the gap between the guide plate 3-10 and the right side 3-7 into the area above the guide plate 3-10, and finally flows out through the outlet pipe 3-9.

[0025] The horizontal projected area of ​​the fire-blocking and cooling device 3 used to block the flame is designed to be 2-4 times the horizontal projected area of ​​the corresponding fire pile 1 (3 times in this embodiment) to ensure that the direct heat radiation of the fire pile is completely blocked and the smoke is forced to flow around its edge and rise, increasing the contact heat exchange time with the cooling surface.

[0026] An oil collection trough 3-5 is provided at the lower edge of the top surface 3-1 of the fire-blocking and cooling device 3. The end of the oil collection trough 3-5 is connected to an oil receiving tank 3-4 located outside the smoking room through a pipeline to collect the oil dripping from the meat blank 9 above, thereby achieving physical isolation between oil and fire.

[0027] The smoking chamber 5 is 4-5 meters high and contains multiple layers of 304 stainless steel racks for hanging meat blanks 9. A second temperature sensor 11 is installed at the height of the bottom layer of meat blanks (e.g., 1.5 meters above the ground), and a first temperature sensor 6 is installed above the top layer of meat blanks (e.g., 4 meters above the ground). The top of the smoking chamber 5 is connected to the smoke distribution chamber 7, and the bottom plate of the smoke distribution chamber 7 is the smoke-proof and fireproof board 8. Figure 4 , Figure 5 As shown, lateral smoke exhausters 8-1 are distributed on the smoke-proof and fireproof plate 8. The lateral smoke exhausters 8-1 consist of arched baffles 8-1a connected to the plate surface at both ends. The sides of the arched baffles 8-1a form narrow, elongated smoke exhaust ports 8-1b that communicate with the smoking chamber 5. This structure allows the smoke to diffuse evenly and creates a slight positive pressure at the top of the smoking chamber, prolonging the smoking time. Simultaneously, it can suppress any fire that may occur in the smoking chamber, preventing the fire from spreading. The combustion chamber 12 and the smoking chamber 5 are connected by a flue gas circulator 10 (such as an explosion-proof axial flow fan), which is controlled by the controller 2. The first temperature sensor 6 and the second temperature sensor 11 are electrically connected to the controller 2, feeding back real-time temperature data to the controller 2. The controller 2 automatically adjusts the opening of the solenoid valve of the fire baffle cooling device 3's water inlet pipe to control the cooling water flow rate and adjusts the rotation speed of the flue gas circulator 10 according to the preset temperature thresholds (bottom layer 20-25℃, top layer 15-20℃ or bottom layer 30-35℃, top layer 25℃-30℃), thereby achieving precise and uniform temperature control in the smoking chamber.

[0028] Example 2: Standardized Process of Low-Temperature Smoking of Cured Meat Based on the low-temperature fumigation chamber constructed in Example 1, a fumigation task was carried out for a period of 5 months.

[0029] Phase 1: Raw Material Selection and Pre-treatment. High-quality local pork is selected as the source meat, and trimmed into strips (9). During curing, only table salt is used; 3-3.5 kg of sea salt is used per 100 kg of meat strips. The meat is cured in a 4-6℃ cold storage for 10 days, turning it 2-3 times during this period to ensure even salt penetration. After curing, the meat strips are removed, washed, and dried. Then, each piece (9) is placed in a food-grade, unbleached paper bag or rice paper bag with a thickness of 80g / m², and the bag opening is tied tightly at the hook.

[0030] Second stage: Low-temperature smoking. A fire is first started with dry firewood. After it burns, semi-dry mixed wood (in this embodiment, oak and camellia wood are used, with a moisture content controlled at around 35%) is added to allow the mixed wood to burn fully, producing open flames and smoke. Controller 2 is activated, opening the cooling water circulation of the fire baffle and cooler 3, with an initial flow rate set to 5 L / min. As the smoke rises, it is forcibly cooled by the fire baffle and cooler 3 and flows around its curved bottom surface 3-2 and right side surface 3-3 into the smoking chamber 5. The paper-bag-packaged meat blanks 9 begin the smoking process in this low-temperature smoke environment.

[0031] The entire smoking process is divided into two stages: Phase 1 (Flavor Formation Period): The smoking time depends on the thickness of the meat blanks. In this embodiment, the selected meat blanks are all thicker than 6cm, so the smoking time for this phase is 4 months. The bottom layer temperature is set to 23±2℃ and the top layer temperature is set to 18±2℃ by the controller 2. This temperature range is maintained by adjusting the cooling water flow rate and the rotation speed of the flue gas recirculator 10. The low-temperature environment allows sufficient time for phenolic substances in the smoke to slowly permeate through the paper bag, undergoing complex biochemical reactions with amino acids and fatty acids produced by fat oxidation and protein degradation in the meat blanks, generating rich flavor compounds.

[0032] The second stage (appearance coloring period): the smoking time is 1 month. The bottom temperature is set to maintain 32±2℃ and the top temperature to maintain 28±2℃ by controller 2. This temperature range is maintained by adjusting the cooling water flow and the rotation speed of the flue gas circulator 10. The focus of this stage is to make the cured meat turn reddish-yellow and the meat translucent.

[0033] Phase Three: Quality Assessment and Output. After smoking, the meat is allowed to cool naturally, removed from the paper bag, and then cured. The resulting cured meat has a natural golden-yellow sheen, firm texture, and when cut open, the lean meat is rose-red while the fat is translucent. Laboratory testing showed that its benzopyrene content was below 0.1 μg / kg (not detected), and peroxide value and other indicators were far below the national standard limits. After cooking, it has a rich and lingering cured aroma, a tender and chewy texture, and no burnt or greasy taste.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art can make various improvements and modifications without departing from the spirit and principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for low-temperature smoking of cured meat, characterized in that, The process utilizes a specialized low-temperature fumigation chamber and includes the following steps: (1) Pickling steps: Select meat blanks and pickle them with salt as the pickling agent. The pickling temperature is 4-10℃ and the pickling time is 7-12 days. (2) Protective steps: After drying the surface moisture of the marinated meat, put it into a food-grade paper bag with microporous breathability and tie the opening tightly; (3) Fuel selection: Use semi-dry and semi-wet miscellaneous wood as fuel for starting the fire; (4) Fire-starting steps: First, start the fire with dry firewood. After it has burned, add semi-dry and semi-wet mixed firewood to allow the mixed firewood to burn fully and produce open flames and smoke. (5) Segmented smoking process: The first stage of smoking: The smoke temperature is regulated by a circulating water cooling device to maintain the smoke temperature at 20-25℃ at the bottom of the smoking chamber and at 15-20℃ at the top, and the smoking time is 2-4 months. The second stage of smoking involves adjusting the smoke temperature to maintain the smoke temperature at 30-35℃ at the bottom of the smoking chamber and at 25-30℃ at the top, for a period of one month.

2. The method for low-temperature smoking of cured meat according to claim 1, characterized in that, The paper bag is a food-grade virgin wood pulp paper bag or Xuan paper bag with a thickness of 70-100g / m², used to filter particulate matter in flue gas and delay moisture evaporation.

3. The method for low-temperature smoking of cured meat according to claim 1, characterized in that, The moisture content of the semi-dry, semi-wet miscellaneous wood is 30%-45%.

4. The method for low-temperature smoking of cured meat according to claim 1, characterized in that, In the first stage of smoking, the smoking time is 2 months when the meat blank thickness is less than 4cm; 3 months when the meat blank thickness is 4-6cm; and 4 months when the meat blank thickness is greater than 6cm.

5. A low-temperature smoking chamber for implementing the method according to any one of claims 1-4, comprising a smoking chamber body (4), a combustion chamber (12) provided in the lower part of the smoking chamber body (4), a fire pit (1) provided in the combustion chamber (12), a meat-smoking chamber (5) provided in the upper part of the smoking chamber body (4), and a smoke-dispersing chamber (7) provided at the top of the smoking chamber body (4), wherein the combustion chamber (12) and the meat-smoking chamber (5) are connected by a smoke recirculator (10) controlled by a controller (2); characterized in that: A fire-blocking and cooling device (3) capable of cooling by water is provided above the fire pile (1) in the combustion chamber (12). The horizontal projected area of ​​the surface of the fire-blocking and cooling device (3) used to block the flame is at least 1.5 times the horizontal projected area of ​​the fire pile (1). A smoke-blocking and fireproof plate (8) is provided on the bottom surface of the smoke-dispersing chamber (7). Lateral smoke exhausters (8-1) are evenly distributed on the smoke-blocking and fireproof plate (8). The lateral smoke exhausters (8-1) are arched baffles (8-1a) with both ends connected to the plate surface. The arched baffles (8-1a) form narrow and long smoke exhaust ports (8-1b) on both sides that communicate with the smoking chamber (5).

6. A low-temperature fumigation chamber according to claim 5, characterized in that: The fire-blocking and cooling device (3) is a hollow heat exchange structure. Its left side (3-6) is a plane, its top side (3-1) is an inclined surface that slopes outward, its bottom side (3-2) is an arc surface, and its front side (3-3) and rear side (3-11) are respectively equipped with a water inlet pipe (3-8) and a water outlet pipe (3-9) with valves. The highest point of the outlet of the water outlet pipe (3-9) is higher than the top of the fire-blocking and cooling device (3).

7. A low-temperature fumigation chamber according to claim 5 or 6, characterized in that: The horizontal projected area of ​​the fire-blocking and cooling device (3) used to block the flame is 2-4 times the horizontal projected area of ​​the fire pile (1).

8. A low-temperature fumigation chamber according to claim 5 or 6, characterized in that: The top surface (3-1) of the fire-blocking and cooling device (3) is provided with an oil collection trough (3-5) at the lower edge. The outlet of the oil collection trough (3-5) is connected to an oil receiving bucket (3-4) for collecting the oil that falls from the meat.

9. A low-temperature fumigation chamber according to claim 5, characterized in that: The smoking chamber (5) is equipped with a first temperature sensor (6) and a second temperature sensor (11). The sensors are electrically connected to the controller (2). The controller (2) adjusts the water flow rate of the fire baffle and cooler (3) and the rotation speed of the flue gas circulator (10) according to the temperature data fed back by the sensors.

10. A low-temperature fumigation chamber according to claim 5 or 6, characterized in that: The right side (3-7) and bottom side (3-2) of the fire-blocking and cooling device (3) are continuous arc-shaped flow guiding structures used to guide the flue gas to flow around.

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