A method for producing milk powder based on the active lock freshness process

Abstract

The application provides a milk powder production method based on an active fresh-keeping process, which comprises the following steps: sterilizing milk, carrying out first pasteurization at 65-75 DEG C for 10-20 s, then carrying out second DSI sterilization at 70-80 DEG C for 5-15 s; after sterilization, concentrating and drying to become milk powder, and finally packaging. The application standardizes a milk powder production method based on an active fresh-keeping process, reduces the denaturation degree of heat-sensitive proteins in the milk powder production process, increases the content of active proteins in the milk powder, and improves the quality of the milk powder.

Description

Technical Field

[0001] This invention belongs to the field of milk powder production and processing technology, and in particular relates to a milk powder production method with an active freshness-locking process. Background Technology

[0002] Milk powder is a powdered product made from qualified milk through processes such as sterilization, concentration, spray drying, powder extraction, and cooling packaging. In dairy processing, milk powder can be used as a raw material in the production of yogurt, cheese, and modified milk powder, or it can be consumed directly as a finished product.

[0003] Milk powder production typically employs high-temperature, short-time sterilization, such as holding at 80℃ for 15 seconds or ultra-high temperature (120-124℃) for 2-4 seconds. The inlet air temperature of the drying tower is above 180℃, which are considered relatively high sterilization and drying temperatures. High sterilization and drying temperatures can lead to the loss of active substances in milk, especially heat-sensitive substances like lactoferrin and immunoglobulins. Therefore, selecting suitable sterilization and spray-drying temperatures is crucial for improving the quality of milk powder.

[0004] Existing technologies have conducted some research on the sterilization temperature and time of milk. For example, patent application number 202111453369.4 provides a milk sterilization method with low protein denaturation rate. This method is a liquid milk processing technology, and additional elastin-like peptides are added to the milk to reduce protein deformability. However, existing research on milk powder processing technologies focuses less on techniques for effectively preserving native active proteins in milk powder. Summary of the Invention

[0005] To increase the content of active proteins in milk powder, this invention provides a milk powder production method based on a native temperature-controlled activity-locking process, particularly for milk powder rich in lactoferrin and immunoglobulins. This invention employs a combined two-stage sterilization process, with pretreatment using a sterilization separation process before the first sterilization, and utilizing a lower spray temperature during the spray drying stage. This ensures that the produced milk powder meets national food safety standards while minimizing the loss of lactoferrin and immunoglobulins during production, thereby improving the quality of the milk powder.

[0006] The specific technical solution of this invention is as follows:

[0007] According to one aspect of the present invention, a method for producing milk powder based on an active freshness-locking process is provided, comprising the following steps:

[0008] (1) Cleans and sterilizes milk;

[0009] (2) Pasteurization;

[0010] (3) DSI sterilization;

[0011] (4) Evaporation and concentration;

[0012] (5) Spray drying;

[0013] (6) Cooled packaging;

[0014] Among them, the pasteurization step (2) is: heating the milk to 65-75℃ and holding it for 10-20 seconds for sterilization;

[0015] The DSI sterilization step (3) is as follows: After pasteurization, the milk is rapidly heated to 70-80℃ and held for 5-15 seconds for a second sterilization.

[0016] Preferably, the spray drying in step (5) involves preheating the concentrated milk to 65-72°C, then pumping it to the top of the drying tower via a high-pressure pump. The liquid droplets are atomized by a spray gun and exchanged with the hot air in the drying tower to evaporate the moisture and form milk powder. During the spray drying process, the inlet air temperature is controlled at 130-170°C and the exhaust air temperature is controlled at 65-85°C.

[0017] According to the milk powder production method, the pasteurization in step (2) involves indirect heat exchange of milk through a plate heat exchanger; preferably, the DSI sterilization in step (3) involves preheating the pasteurized milk and then rapidly heating it through a direct contact sterilizer; preferably, the evaporation and concentration in step (4) involves the DSI-sterilized milk entering a falling film evaporator and being concentrated and having its moisture evaporated under a vacuum of -0.7 to -0.9 bar; more preferably, the cooling and packaging in step (6) involves cooling the dried milk powder with air cooling, controlling the milk powder temperature below 42°C, and then conveying it to packaging equipment by pneumatic or gravity conveying.

[0018] More preferably, before step (1), the total bacterial count in the raw milk does not exceed 2 × 10⁻⁶. 6 CFU / ml; and / or filter using a ≤2mm filter, and purify the filtered milk using a milk purifier.

[0019] More preferably, the milk sterilization step in step (1) involves passing the milk through a sterilization device with a rotation speed of 5600-6000 r / min;

[0020] More preferably, after step (2), the pasteurized milk is cooled to below 6°C using a plate heat exchanger.

[0021] More preferably, after step (4), the dry matter content of the concentrated milk is monitored to maintain the dry matter content at 45-55%.

[0022] More preferably, before step (5), the concentrated milk is preheated by a tubular heat exchanger and homogenized by a high-pressure pump.

[0023] More preferably, in step (6), the milk powder is gradually cooled using clean air through a dynamic fluidized bed.

[0024] In step (1), the present invention removes impurities, somatic cells, spores, and large microorganisms that may be present in milk through milk purification and sterilization. In step (2), pasteurization kills most of the easily multiplying microorganisms and pathogens, laying the foundation for a second sterilization process to improve efficiency. At the same time, this gentle sterilization method is more conducive to protecting active substances such as lactoferrin and immunoglobulins in milk.

[0025] Based on pasteurization, step (3) involves DSI sterilization of the milk to further reduce the microorganisms in the milk. DSI sterilization uses a direct steam injection sterilization method, which can instantly heat the milk to the sterilization temperature. This combination of sterilization method and heat preservation time can maximize the retention of these original active substances in the milk while ensuring that the microbial indicators of the product meet the requirements.

[0026] After step (4), before entering spray drying, the concentrated milk is preheated at a temperature of 65-70°C. Optionally, homogenization is performed before spray drying, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 24-35 bar.

[0027] In step (5), a suitable powder spraying temperature should be ensured, with an inlet air temperature of 130-170℃ and an exhaust air temperature of 65-85℃.

[0028] In step (6), in order to ensure the effect of air cooling, the air used for heat exchange needs to be filtered efficiently and dehumidified.

[0029] Compared with conventional technologies, the present invention has the following advantages:

[0030] (1) Before pasteurization, physical centrifugation is used to remove impurities, spores, and large microorganisms from raw milk, laying the foundation for pasteurization.

[0031] (2) The two-stage sterilization process makes the overall sterilization process more gentle, ensuring the sterilization effect while retaining the active protein components such as lactoferrin and immunoglobulins to the greatest extent; the spray drying stage uses a lower temperature treatment method, which can better improve the product quality of milk powder. Detailed Implementation

[0032] The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit the invention.

[0033] General Implementation Examples

[0034] A method for producing milk powder based on an active freshness-locking process, particularly a method for producing milk powder based on a native temperature-controlled active freshness-locking process, includes the following steps:

[0035] 1) Milk Inspection: Inspect the milk to ensure that the total bacterial count does not exceed 2×10⁻⁶. 6 CFU / ml;

[0036] 2) Cooling and temporary storage: After passing the inspection, the milk is cooled to below 6°C and temporarily stored in an insulated storage tank;

[0037] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5600-6000 r / min;

[0038] 4) Pasteurization: The milk is sterilized for the first time by maintaining a temperature of 65-75℃ for 10-20 seconds;

[0039] 5) Cooling and temporary storage: Pasteurized milk is cooled to below 6°C and temporarily stored in insulated storage tanks;

[0040] 6) Preheating: Pasteurized milk is preheated to 65-75℃;

[0041] 7) DSI sterilization: The preheated milk is rapidly heated to 70-80℃ by a direct steam contact sterilizer and held for 5-15 seconds for a second sterilization.

[0042] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.7 to -0.9 bar.

[0043] 9) Tubular preheating: The concentrated milk is preheated through a tubular heat exchanger, with the temperature controlled between 65-70℃.

[0044] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 24-35 bar. Then, deliver the liquid material to the top of the drying tower and atomize it using a spray gun system.

[0045] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 130-170℃ and the exhaust air temperature is controlled at 65-85℃.

[0046] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed to control the temperature of the milk powder below 42°C, and then transported to the packaging equipment by pneumatic or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0047] Example 1

[0048] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0049] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 1.0 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0050] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 3.6℃ and temporarily stored in an insulated storage tank;

[0051] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5858 r / min;

[0052] 4) Pasteurization: The milk is first pasteurized by holding it at 72.1℃ for 15 seconds;

[0053] 5) Cooling and temporary storage: Pasteurized milk is cooled to 3.5°C and temporarily stored in an insulated storage tank;

[0054] 6) Preheating: Pasteurized milk is preheated to 70.3℃;

[0055] 7) DSI sterilization: The preheated milk is rapidly heated to 75.5℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0056] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0057] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 68.6℃;

[0058] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 29.3 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0059] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 164.2℃ and the exhaust air temperature is controlled at 83.3℃.

[0060] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, and the temperature of the milk powder is controlled at 30.5℃. It is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0061] Example 2

[0062] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0063] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 2.8 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0064] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 3.7℃ and temporarily stored in an insulated storage tank;

[0065] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5858 r / min;

[0066] 4) Pasteurization: The milk is first pasteurized by holding it at 72.5℃ for 15 seconds;

[0067] 5) Cooling and temporary storage: Pasteurized milk is cooled to 3.7°C and temporarily stored in an insulated storage tank;

[0068] 6) Preheating: Pasteurized milk is preheated to 70.0℃;

[0069] 7) DSI sterilization: The preheated milk is rapidly heated to 75.0℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0070] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0071] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 68.5℃;

[0072] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 29.5 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0073] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 163.9℃ and the exhaust air temperature is controlled at 80.6℃.

[0074] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, the temperature of the milk powder is controlled at 30.0℃, and it is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0075] Example 3

[0076] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0077] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 1.3 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0078] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 3.8℃ and temporarily stored in an insulated storage tank;

[0079] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5859 r / min;

[0080] 4) Pasteurization: The milk is first pasteurized by holding it at 72.3℃ for 15 seconds;

[0081] 5) Cooling and temporary storage: Pasteurized milk is cooled to 2.9°C and temporarily stored in an insulated storage tank;

[0082] 6) Preheating: Pasteurized milk is preheated to 70.0℃;

[0083] 7) DSI sterilization: The preheated milk is rapidly heated to 75.1℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0084] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0085] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 68.0℃;

[0086] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 32.4 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0087] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 162.7℃ and the exhaust air temperature is controlled at 80.4℃.

[0088] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, the temperature of the milk powder is controlled at 30.0℃, and it is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0089] Example 4

[0090] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0091] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 1.9 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0092] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 3.3℃ and temporarily stored in an insulated storage tank;

[0093] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5860 r / min;

[0094] 4) Pasteurization: The milk is first pasteurized by holding it at 71.9℃ for 15 seconds;

[0095] 5) Cooling and temporary storage: Pasteurized milk is cooled to 3.4°C and temporarily stored in an insulated storage tank;

[0096] 6) Preheating: Pasteurized milk is preheated to 70.2℃;

[0097] 7) DSI sterilization: The preheated milk is rapidly heated to 75.4℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0098] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0099] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 67.2℃;

[0100] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 31 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0101] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 158.1℃ and the exhaust air temperature is controlled at 83.7℃.

[0102] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, the temperature of the milk powder is controlled at 30.0℃, and it is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0103] Example 5

[0104] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0105] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 0.9 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0106] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 3.4℃ and temporarily stored in an insulated storage tank;

[0107] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5857 r / min;

[0108] 4) Pasteurization: The milk is first pasteurized by holding it at 72.5℃ for 15 seconds;

[0109] 5) Cooling and temporary storage: Pasteurized milk is cooled to 3.3°C and temporarily stored in an insulated storage tank;

[0110] 6) Preheating: Pasteurized milk is preheated to 69.8℃;

[0111] 7) DSI sterilization: The preheated milk is rapidly heated to 75.1℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0112] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0113] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 66.8℃;

[0114] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 31.1 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0115] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 154.5℃ and the exhaust air temperature is controlled at 78.1℃.

[0116] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, the temperature of the milk powder is controlled at 29.5℃, and it is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0117] Example 6

[0118] A method for producing milk powder based on a native temperature-controlled active freshness-locking process includes the following steps:

[0119] 1) Milk Inspection: The milk is inspected, and the total bacterial count is 0.8 × 10⁻⁶. 4 CFU / ml, sensory and physicochemical indicators are qualified, meeting the national standards for raw milk;

[0120] 2) Cooling and temporary storage: After passing inspection, the milk is cooled to 4.1℃ and temporarily stored in an insulated storage tank;

[0121] 3) Milk purification and sterilization: Sterilization is performed using the principle of centrifugation, with the sterilization equipment rotating at 5855 r / min;

[0122] 4) Pasteurization: The milk is first pasteurized by holding it at 72.2℃ for 15 seconds;

[0123] 5) Cooling and temporary storage: Pasteurized milk is cooled to 3.1°C and temporarily stored in an insulated storage tank;

[0124] 6) Preheating: Pasteurized milk is preheated to 69.4℃;

[0125] 7) DSI sterilization: The preheated milk is rapidly heated to 74.5℃ by a direct steam contact sterilizer and held for 15 seconds for a second sterilization.

[0126] 8) Evaporation and Concentration: After DSI sterilization, the milk enters a vacuum falling film evaporator, where water is evaporated under a vacuum of -0.8 bar.

[0127] 9) Tubular preheating: The concentrated milk is preheated in a tubular heat exchanger at a temperature of 66.7℃.

[0128] 10) High-pressure delivery: Homogenize the material using a high-pressure pump, maintaining a primary homogenization pressure of 70 bar and a secondary homogenization pressure of 24.9 bar. Then, deliver the liquid to the top of the drying tower and atomize it using a spray gun system.

[0129] 11) Spray drying: The liquid droplets are atomized in the drying tower through the spray gun system, and the water is evaporated by exchanging heat with the hot air entering the tower to form milk powder. During the spray drying process, the inlet air temperature is controlled at 154.8℃ and the exhaust air temperature is controlled at 78.3℃.

[0130] 12) Cooling and Packaging: The powder is cooled by a dynamic fluidized bed, the temperature of the milk powder is controlled at 30.0℃, and it is then transported to the packaging equipment by pneumatic conveying or gravity conveying to obtain milk powder containing lactoferrin and immunoglobulins.

[0131] Comparative Example 1

[0132] The raw milk standards and process steps used in this comparative example are the same as those in Example 1. The only difference from Example 1 is in the following steps:

[0133] In step 4), the pasteurization temperature is 80.2℃.

[0134] In step 7), the DSI sterilization temperature is 90.3℃.

[0135] In step 9), the preheating temperature of the concentrated milk is 72.1℃.

[0136] Comparative Example 2

[0137] The raw milk standards and process steps used in this comparative example are the same as those in Example 2. The only difference from Example 2 is in the following steps:

[0138] In step 4), the pasteurization temperature is 80.6℃.

[0139] In step 7), the DSI sterilization temperature is 90.4℃.

[0140] In step 9), the preheating temperature of the concentrated milk is 72.5℃.

[0141] Comparative Example 3

[0142] The raw milk standards and process steps used in this comparative example are the same as those in Example 4. The only difference from Example 4 is in the following steps:

[0143] In step 4), the pasteurization temperature is 80.4℃.

[0144] In step 7), the DSI sterilization temperature is 90.4℃.

[0145] In step 9), the preheating temperature of the concentrated milk is 72.1℃.

[0146] Test case

[0147] In Examples 1-6 and Comparative Examples 1-3, the contents of various milk proteins (β-lactoglobulin, immunoglobulins, and lactoferrin) and alkaline phosphatase in milk, pasteurized milk, concentrated milk, and milk powder were measured. Each group was tested twice, and the average value was taken. The test results are shown in Tables 1, 2, and 3.

[0148] Table 1 Lactoferrin

[0149]

[0150] Lactoferrin in milk and milk powder was detected using liquid chromatography. Table 1 shows that the lactoferrin content in the milk used in Examples 1-6 and Comparative Examples 1-3 ranged from 64.3 to 90.0 mg / 100g. Compared to Comparative Examples 1-3, lactoferrin was detected in the milk powder of Examples 1-6, with contents ranging from 26.3 to 34.9 mg / 100g, which is 30% to 53.1% of the lactoferrin content in milk. Comparative Examples 1-3 show that lactoferrin was undetectable in the concentrated milk after evaporation and concentration.

[0151] Table 2 Immunoglobulins

[0152]

[0153]

[0154] The immunoglobulin content in milk and milk powder was determined by liquid chromatography. Table 2 shows that the immunoglobulin content in the milk used in Examples 1-6 and Comparative Examples 1-3 ranged from 391.5 to 468 mg / 100g. The immunoglobulin content gradually decreased in the pasteurized milk, concentrated milk, and milk powder, indicating that the milk powder production process leads to immunoglobulin loss. In Examples 1-6, the immunoglobulin content in the milk powder was 152.9-168.3 mg / 100g, approximately 35-40% of the content in the milk. In Comparative Examples 1-3, the immunoglobulin content in the milk powder was approximately 50 mg / 100g, approximately 10% of the content in the milk. This demonstrates that milk powder produced using the native temperature-controlled active freshness-locking process can effectively retain the immunoglobulins in milk.

[0155] Table 3 Alkaline phosphatase

[0156]

[0157]

[0158] Alkaline phosphatase activity is a crucial indicator in the dairy processing industry, signifying the success of pasteurization. According to the requirements for high-quality pasteurized milk in my country's "Research on Core Indicators of High-Quality Dairy Engineering Technology System," the negative alkaline phosphatase level is ≤350 mU / L. A kit method was used to detect the alkaline phosphatase content in milk and milk powder. The results show that, in both Examples 1-6 and Comparative Examples 1-3, the produced milk powder effectively reduced alkaline phosphatase levels to acceptable levels.

[0159] Unless otherwise specified, the raw materials and equipment used in this invention are all commonly used in the field; unless otherwise specified, the methods used in this invention are all conventional methods in the field.

[0160] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A method for producing milk powder based on an active freshness-locking process, characterized in that, Includes the following steps: (1) Cleans and sterilizes milk; (2) Pasteurization; (3) DSI sterilization; (4) Evaporation and concentration; (5) Spray drying; (6) Cooled packaging; Among them, the pasteurization step (2) is: heating the milk to 65-75℃ and holding it for 10-20 seconds for sterilization; The DSI sterilization step (3) is as follows: After pasteurization, the milk is rapidly heated to 70-80℃ and held for 5-15 seconds for a second sterilization.

2. The milk powder production method as described in claim 1, characterized in that: The spray drying in step (5) involves preheating the concentrated milk to 65-72°C, then pumping it to the top of the drying tower via a high-pressure pump. The liquid droplets are atomized by a spray gun and exchanged with the hot air in the drying tower to evaporate the moisture and form milk powder. During the spray drying process, the inlet air temperature is controlled at 130-170°C and the exhaust air temperature is controlled at 65-85°C.

3. The milk powder production method as described in claim 1 or 2, characterized in that: The pasteurization in step (2) involves indirect heat exchange of the milk through a plate heat exchanger; and / or The DSI sterilization step in step (3) involves preheating the pasteurized milk and then rapidly heating it using a direct contact sterilizer; and / or The evaporation and concentration step (4) involves the DSI-sterilized milk entering a falling film evaporator and being concentrated and the water evaporated under a vacuum of -0.7 to -0.9 bar; and / or The cooling packaging in step (6) involves cooling the dried milk powder with air cooling to control the temperature of the milk powder below 42°C, and then conveying it to the packaging equipment by pneumatic conveying or gravity conveying for packaging.

4. The milk powder production method as described in claim 1 or 2, characterized in that... Before step (1), the total bacterial count in the raw milk should not exceed 2 × 10⁻⁶. 6 CFU / ml; and / or filter using a ≤2mm filter, and purify the filtered milk using a milk purifier.

5. The milk powder production method as described in claim 1 or 2, characterized in that... After step (2), the pasteurized milk is cooled to below 6°C using a plate heat exchanger.

6. The milk powder production method according to claim 1 or 2, characterized in that... After step (4), the dry matter content of the concentrated milk is monitored to maintain it at 45-55%.

7. The milk powder production method as described in claim 1 or 2, characterized in that... Before step (5), the concentrated milk is preheated by a tubular heat exchanger and homogenized by a high-pressure pump.

8. The milk powder production method as described in claim 1 or 2, characterized in that... In step (6), the milk powder is gradually cooled by using clean air through a dynamic fluidized bed.

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