Production method of freeze-dried instant milk powder

Abstract

The invention discloses a production process of freeze-dried instant milk powder. The production process comprises the following steps: 1) raw material pretreatment: removing impurities and microorganisms by combining centrifugal separation with double-membrane microfiltration; 2) low-temperature concentration: increasing the solid content by ultrasonic-assisted vacuum evaporation, and preventing layering by a compound stabilizer; 3) composite de-odoring: removing peculiar smell at low temperature by combining activated carbon adsorption with vacuum flash evaporation and keeping natural flavor; 4) gradient freeze-drying: microwave-assisted vacuum freeze-drying, intelligent temperature control to shorten the period and improve the reconstitution property; 5) precise granulation: controlling particle size distribution by an asymmetric crushing technology to ensure balance of instant solubility and oxidation resistance; aluminum foil packaging is matched with two-dimensional code spraying, and a whole-process quality management and control system.According to the technology, physical field cooperative reinforcement and the intelligent control technology are fused, the production efficiency is remarkably improved, meanwhile, the product nutrition retention degree, flavor purity and brewing convenience are guaranteed, and an innovative solution is provided for dairy product processing.

Description

Technical Field

[0001] The present invention relates to the field of milk powder production methods, in particular to a method for producing freeze-dried instant milk powder. Background Art

[0002] As an important product in the high-end dairy field, the core technology of freeze-dried instant milk powder lies in retaining the nutrients and natural flavor of the raw materials through a low-temperature drying process, while achieving the convenient feature of rapid rehydration and dissolution.

[0003] However, traditional production processes generally use thermal spray drying technology, which is limited by the damage of heat-sensitive substances (such as vitamins and active proteins) caused by high-temperature treatment, and the poor rehydration performance caused by the dense particle structure after drying. It is difficult to strike a balance between nutrient retention and quick-dissolving properties.

[0004] In addition, the existing technology system has multiple technical bottlenecks in raw material processing, flavor control, production efficiency and other aspects: During the raw material pretreatment stage, a single filtration process (such as membrane filtration or centrifugal separation) is difficult to achieve both efficient impurity removal and active ingredient retention, resulting in insufficient base material purity or nutrient loss; During the concentration process, conventional high-temperature evaporation technology can easily cause the denaturation of heat-sensitive components. Furthermore, high-solids materials are prone to stratification and agglomeration due to their high viscosity, requiring additional homogenization, which increases process complexity and energy consumption. In terms of flavor control, although high-temperature deodorization processes (such as pasteurization) can remove odors, they will destroy the natural flavor characteristics of the raw materials, resulting in a bland flavor or a "cooked taste" in the product. In terms of drying efficiency and structure control, the traditional freeze-drying process has a long drying cycle due to low heat transfer efficiency and lacks precise control of the sublimation interface temperature, which easily forms a dense crystalline structure and significantly reduces the rehydration speed and dissolution uniformity. In terms of particle morphology and quality traceability, conventional crushing processes make it difficult to achieve precise control of particle size distribution. Excessively fine particles are prone to oxidation and deterioration, while coarse particles affect the brewing performance. At the same time, traditional packaging and traceability systems lack real-time data correlation capabilities, making it difficult to support full-chain quality control and process optimization needs. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the present application provides a method for producing freeze-dried instant milk powder to solve the above technical problems.

[0006] To achieve the above objectives, this application provides the following technical solutions: A method for producing freeze-dried instant milk powder, comprising: S1. Strengthening of raw material pretreatment: The raw materials are centrifuged in a dynamic centrifuge to remove large particles of impurities, and then microfiltered through a 0.22μm Al2O3 ceramic membrane and a 0.1μm PES spiral membrane to remove microorganisms and fine particles. Finally, they are stored in a constant temperature tank for future use. S2. Low temperature concentration and efficiency enhancement: The raw material pretreated in step S1 is concentrated at low temperature through a three-stage vacuum evaporator to increase the solid content in the raw material, and ultrasonic waves are used to assist in reducing the viscosity of the concentrate, and a composite stabilizer is added to improve the stability of the raw material; S3, vacuum deodorization enhancement: The raw material concentrated in step S2 is put into an activated carbon adsorption tower to remove odor components in the raw material using the adsorption properties of the activated carbon, and the deodorization effect is enhanced by a vacuum flash evaporation system; S4. Gradient freeze-drying optimization operation: A vacuum freeze dryer is used to dry the raw materials after the smell of mutton is removed in step S3. A microwave-assisted system is used to accelerate the drying process, and an intelligent control system is used to achieve precise control of the drying process. S5, intelligent post-processing: The raw materials dried in step S4 are intelligently crushed by an asymmetric crushing unit to obtain milk powder particles of a desired particle size, which are then packaged by an aluminum foil bag packaging machine; S6. Full-process quality control: A QR code inkjet printer is used to perform intelligent coding on the outside of the milk powder packaging bag after packaging in step S5, recording the source of raw materials, process parameters and quality inspection results, and achieving full traceability and quality control of the product through an intelligent traceability system.

[0007] Preferably, in the S1, raw material pretreatment strengthening, the primary membrane is a 0.22μm Al2O3 ceramic membrane with a membrane area of ​​10m² and an operating pressure of 0.8-1.2MPa, and the secondary membrane is a 0.1μm PES spiral membrane with a membrane area of ​​5m² and an operating pressure of 0.8-1.2MPa.

[0008] Preferably, in the S1, raw material pretreatment enhancement, after the dynamic centrifuge has processed the raw materials, the pulse ultraviolet sterilization device is started to inactivate Bacillus spores in the raw materials. The raw materials are stored in a constant temperature tank for ≤12 hours, and the pH value and redox potential are monitored in real time. The pulse ultraviolet sterilization device is equipped with a UV-C module.

[0009] Preferably, in the S2, low-temperature concentration efficiency enhancement, the first-stage evaporator is a falling film evaporator, the second-stage evaporator is a scraped-surface evaporator, and the third-stage evaporator is a thin-film evaporator.

[0010] Preferably, in the S2, low-temperature concentration efficiency enhancement, the three-stage vacuum evaporator further includes an ultrasonic generator and a viscosity sensor, the ultrasonic generator is mounted on the outside of the three-stage vacuum evaporator, and the viscosity sensor is mounted on the inside of the three-stage vacuum evaporator.

[0011] Preferably, in the S3, vacuum deodorization enhancement, the activated carbon adsorption tower is a stainless steel tower body filled with modified activated carbon, the vacuum flash evaporation system is a two-stage Roots vacuum pump group, and the inner cavity of the activated carbon adsorption tower is equipped with an electronic nose detector, which is equipped with twelve groups of metal oxide sensors.

[0012] Preferably, in the S4, gradient freeze-drying optimization operation, the microwave-assisted system is a microwave generator that adopts an intermittent radiation mode. The microwave-assisted system is internally equipped with an infrared thermal imager and an airflow distributor, and the airflow distributor is a spiral guide plate.

[0013] Preferably, in the S4, gradient freeze-drying optimization operation, the raw material is first subjected to a quick-freezing operation at -40°C / 30min→-55°C / 60min, and a VC-PA protective agent is added to the inside of the raw material to inhibit ice crystal growth. The quick-frozen raw material is heated in stages, and the staged heating is respectively -35°C→-25°C for 2h→-25°C→-15°C for 3h. The raw material is sublimated with the assistance of microwaves, and then the raw material is subjected to analytical drying, and the temperature is controlled from 25°C to 35°C by dynamic temperature control, so that the final moisture of the raw material is ≤3%, and the rehydration capacity is ≤5 seconds.

[0014] Preferably, in the S5, intelligent post-processing, the asymmetric crushing units are respectively a planetary ball mill and a jet mill, the raw materials processed by the asymmetric crushing units are put into a microencapsulation reactor for temperature control, and the final raw materials are monitored online by an O2 residual sensor and a water activity meter during packaging.

[0015] Preferably, in the intelligent post-processing S5, it is ensured that the particle size D50 of the raw material after crushing and screening is ≤150 μm, the particle uniformity is ≥95%, and the probiotic microencapsulation embedding rate of the microencapsulation reactor is ≥85%.

[0016] In summary, the present application provides a method for producing freeze-dried instant milk powder, which has the following beneficial effects: This freeze-dried instant milk powder production method achieves a comprehensive improvement in product quality and production efficiency through the coordinated optimization of multiple links. During the raw material pretreatment stage, the combined application of centrifugal separation and multi-stage microfiltration technology effectively removes large particle impurities and microbial contamination from the raw materials, providing a high-purity base material for subsequent processing while avoiding the problem of nutrient loss that may occur with traditional filtration methods. During the concentration stage, the synergistic effect of low-temperature vacuum evaporation and ultrasonic-assisted technology not only ensures the stability of heat-sensitive substances, but also significantly improves the concentration efficiency by reducing viscosity. Combined with the addition of composite stabilizers, it effectively solves the stratification and agglomeration problems that are prone to occur in raw materials with high solids content.

[0017] To address the unique flavor optimization needs of dairy products, a combined deodorization process using activated carbon adsorption and vacuum flash evaporation effectively removes odorous components while preserving the natural flavor characteristics of the raw materials. Low-temperature operation in a vacuum environment avoids flavor degradation that can be caused by high-temperature treatment. During the drying stage, a gradient freeze-drying process combined with microwave-assisted technology precisely controls the sublimation interface temperature and heat transfer efficiency. This shortens the drying cycle while maintaining the product's loose and porous structure, significantly improving the product's rehydration properties and substantially enhancing its instant solubility.

[0018] The intelligent post-processing system achieves precise shape control of milk powder particles through asymmetric crushing technology, and the resulting product has a uniform particle size distribution, which not only ensures rapid dispersion during mixing, but also avoids the risk of oxidation caused by overly fine particles. The integrated application of aluminum foil bag packaging and intelligent inkjet coding system has established a full-chain quality control system from raw material traceability to finished product delivery. The QR code information carrier can link production data and quality inspection records in real time, providing reliable data support for product quality traceability and process optimization. The entire process is deeply integrated with physical field collaborative enhancement and intelligent control technology, which not only improves production efficiency but also ensures the product's nutritional retention, flavor purity, and ease of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a production flow chart of the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0021] This application provides a technical solution, please refer to Figure 1 , a method for producing freeze-dried instant milk powder, comprising: S1. Strengthening of raw material pretreatment: The raw materials are centrifuged in a dynamic centrifuge, then passed through two-stage microfiltration membranes of 0.22μm and 0.1μm, and finally stored in a constant temperature tank; ALFALAVAL T6 disc centrifuge with variable frequency speed range of 5000-9000rpm is used to remove fat globules (3-5μm) and somatic cells (10-20μm in diameter) by density gradient separation principle. The fat removal rate is ≥98% and the number of somatic cells is ≤10 4 cells / mL. Variable frequency speed regulation technology can adapt to different raw material viscosities and reduces energy consumption by 25% compared to traditional constant speed centrifuges.

[0022] To further enhance separation efficiency, the inner wall of the centrifuge drum is constructed from titanium alloy with a surface roughness of Ra ≤ 0.4μm, minimizing the buildup of material. Furthermore, the centrifuge is equipped with a Clean-in-Place (CIP) system, which utilizes 80°C hot water for circulating cleaning, ensuring zero cross-contamination between batches.

[0023] The primary membrane is a 0.22μm Al2O3 ceramic membrane with a membrane area of ​​10m² and an operating pressure of 0.8-1.2MPa. It can intercept bacteria, lactoferrin >0.2μm and other macromolecular active substances; the secondary membrane is a 0.1μm PES spiral membrane with a membrane area of ​​5m² and an operating pressure of 0.8-1.2MPa. It can remove nano-scale pollutants such as rotavirus and endotoxin, with a retention rate of ≥99.99%.

[0024] The synergistic effect of two-stage membrane filtration reduces the risk of microbial contamination to below 0.01 CFU / mL and reduces the loss of heat-sensitive proteins by 80% compared to traditional pasteurization.

[0025] To extend the service life of the membrane, the membrane system is equipped with an automatic chemical cleaning unit (CIP), which uses 0.5% NaOH + 1% EDTA solution to circulate and clean at 60°C for 30 minutes to effectively remove organic contamination on the membrane surface.

[0026] After processing in the dynamic centrifuge, a pulsed ultraviolet sterilization device (UV-C module, wavelength 254nm, pulse frequency 30Hz, single energy 5J / cm²) was started to inactivate Bacillus spores in the raw materials, with an inactivation efficiency of 6logCFU / mL.

[0027] The pulsed UV sterilizer uses a quartz sleeve to protect the lamp, ensuring a UV light transmittance of ≥90%. It also features an automatic wiping system to regularly remove dirt from the sleeve surface to maintain sterilization efficiency.

[0028] The raw materials are stored in a constant temperature tank for ≤12 hours. The pH / ORP sensor in the tank is used for real-time monitoring to ensure the pH value is 6.5-6.8 and the redox potential is 200-300mV, thereby inhibiting oxidative browning.

[0029] The thermostatic tank adopts a double-layer jacket structure, with the inner layer being 316L stainless steel and the outer layer being a carbon steel insulation layer. A constant temperature water bath (temperature fluctuation ±0.5°C) is passed into the jacket to ensure the temperature stability of the raw materials.

[0030] S2. Low temperature concentration and efficiency enhancement: The raw material obtained in step S1 is taken out and subjected to a low-temperature concentration operation using a three-stage vacuum evaporator to concentrate the milk in the raw material to a solid content of 45% to 50%. The viscosity of the concentrated liquid of the raw material is then reduced by ultrasonic assistance, and a composite stabilizer is added to the interior of the raw material; The three-stage vacuum evaporator includes a first-stage falling film evaporator (45°C / 8.5kPa, heat exchange area 50m²) to rapidly remove free moisture and prevent protein denaturation; a second-stage scraper evaporator (52°C / 5.3kPa, heat exchange area 30m²) to process high-viscosity liquids. The scraper-type evaporator forces film formation to reduce residence time, achieving a Maillard reaction inhibition rate of >95%; and a third-stage thin-film evaporator (60°C / 3.2kPa, heat exchange area 20m²) for final concentration to the target solids content. Vapor recompression (MVR) technology reduces energy consumption by 40%.

[0031] To optimize evaporation efficiency, each evaporator is equipped with an online concentration detector (refractive index method) to monitor solids content in real time, ensuring precise control of the concentration endpoint. Furthermore, the evaporator condensate recovery system uses a plate heat exchanger to preheat the raw material, improving thermal energy utilization.

[0032] An ultrasonic generator (40kHz, power density 0.5W / cm²) disrupts intermolecular hydrogen bonds through cavitation, reducing viscosity from 1500mPa·s to 950mPa·s and improving heat transfer by 42%. An online rotational viscometer (measuring range 10-1000mPa·s, accuracy ±1%) provides real-time data feedback, ensuring precise control of the concentration endpoint.

[0033] During the ultrasonic treatment process, the material temperature is maintained at ≤55°C through a heat exchanger to prevent local overheating. At the same time, the ultrasonic horn is made of titanium alloy and sprayed with polytetrafluoroethylene coating to reduce material adhesion.

[0034] The composite stabilizers are trehalose (0.05%) and glutathione (0.03%), which form a synergistic protective network, inhibit the Maillard reaction and improve the resolubility of the freeze-dried powder.

[0035] To further enhance the stabilizer effect, trehalose and glutathione are pre-mixed using a high-speed shearing machine (10,000 rpm) before being mixed with the concentrate. The mixing process uses vacuum suction to prevent air from entering and causing oxidation.

[0036] S3, vacuum deodorization enhancement: The raw materials processed in step S2 are put into an activated carbon adsorption tower for desorption circulation mode; The activated carbon adsorption tower is a stainless steel tower filled with modified activated carbon (with an adsorption capacity of 210 mg / g for nonanal) produced using phosphoric acid activation. It is externally equipped with a two-stage Roots vacuum pump. A Fox 4000 electronic nose (12 metal oxide sensors) is located within the tower to monitor the concentration of odorous substances in real time.

[0037] Before filling the activated carbon, surface dust must be removed by nitrogen purge (flow rate 5m³ / h, time 30 minutes). At the same time, the tower is equipped with a pressure safety valve (set pressure 0.1MPa) to ensure safe operation.

[0038] Adopting a 30s adsorption / 3min desorption cycle mode, the desorption rate is ≥92%, the vacuum flash temperature is 45-50°C, and the desorption cycle is ≤5 minutes. The activated carbon regeneration efficiency is ≥95%, and the service life is extended to more than 5 times.

[0039] To improve desorption efficiency, 95°C hot nitrogen is used as the desorption gas, with the flow rate precisely controlled (±1%FS) by a mass flow meter. The desorption exhaust gas is passed through a condenser (temperature -10°C) to recover the organic solvent, reducing environmental pollution.

[0040] The addition of 0.02% β-CD and 0.01% vanillin worked synergistically to increase the encapsulation rate of residual mutton odor substances to 95%.

[0041] β-CD and vanillin were pre-mixed in a colloid mill (gap 10 μm) and then mixed with the deodorized liquid. A static mixer was used during the mixing process to ensure uniform dispersion of the embedding agent.

[0042] S4. Gradient freeze-drying optimization operation: The raw material obtained in step S3 is dried by a vacuum freeze dryer and a microwave-assisted system is used for drying; The vacuum freeze dryer has a cold trap temperature of -80°C, a vacuum level of <1 Pa, and a shelf area of ​​2 m². The microwave-assisted system uses a 2450 MHz, 300 W microwave generator operating in intermittent radiation mode (10 minutes of radiation followed by a 5-minute pause). It is equipped with a FLIRA655sc infrared thermal imager (temperature measurement range -40-150°C, accuracy ±2°C) and a spiral airflow distributor.

[0043] To optimize freeze-drying efficiency, the shelf surfaces are anodized to improve thermal conductivity. Meanwhile, the ice traps are coated with PTFE to reduce ice crystal adhesion and facilitate de-icing.

[0044] Pre-freezing stage: quick freezing at -40℃ / 30min→-55℃ / 60min, adding 1.5% VC-PA protective agent to inhibit ice crystal growth, cell survival rate>98%; sublimation stage: step-by-step heating from -35℃→-25℃ (2h)→-25℃→-15℃ (3h), combined with intermittent microwave radiation, the sublimation rate reaches 2.8g / cm²·h; decomposition stage: dynamic temperature control from 25℃→35℃, combined with a dew point sensor to control the final moisture content to ≤3%, and rehydration capacity to ≤5 seconds.

[0045] To precisely control the pre-freezing rate, the quick-freezing process uses a programmed cooling device with an adjustable cooling rate (1-5°C / min). Simultaneously, the microwave radiation power is adjusted in real time via a PID controller to ensure tray temperature uniformity of ≤±2°C.

[0046] S5, intelligent post-processing: The raw materials obtained in step S4 are intelligently crushed by an asymmetric crushing unit, and finally the processed raw materials are packaged by an aluminum foil bag packaging machine; The asymmetric crushing unit includes a planetary ball mill (rotation speed 1500rpm, zirconium oxide grinding media) and a jet mill (pressure 2.5MPa, classification wheel rotation speed 2500rpm), achieving a particle size D50 ≤ 150μm and a uniformity ≥ 95%, reducing energy consumption by 30% compared with traditional crushing.

[0047] To optimize the pulverization effect, the planetary ball mill uses a wet pulverization process with a material-liquid ratio of 1:1. The grinding time is precisely controlled by a timer (±1s). The airflow mill is equipped with a cyclone separator, achieving a classification accuracy of D97 ≤ 10μm.

[0048] After crushing, the raw materials are put into the microencapsulation reactor and the sodium alginate-chitosan composite embedding technology is used. The embedding rate is ≥85%, the probiotic survival rate is 82%, and it is stored at 4°C for 3 months.

[0049] The microencapsulation reactor is equipped with an online pH meter and temperature sensor to monitor the reaction conditions in real time (pH 6.5-7.0, temperature 25°C). The encapsulation process uses a spray drying method with an inlet air temperature of 180°C and an outlet air temperature of 80°C to ensure the integrity of the microencapsulated particles.

[0050] During packaging, online monitoring is performed through an O2 residual sensor and a water activity meter to ensure that the O2 content in the aluminum foil bag is less than 3% and the water activity is less than 0.2.

[0051] The aluminum foil bags utilize a three-layer composite structure (PET / AL / PE) with a heat seal strength of ≥30N / 15mm. The packaging process is carried out in a Class A cleanroom, with an ambient temperature of 25°C and humidity ≤30%RH, to ensure that the product meets microbiological standards.

[0052] S6. Full-process quality control: The outside of the packaging bag of the raw material packaged in step S5 is subjected to a coding process by a two-dimensional code inkjet printer device to record the source of the raw material, process parameters and quality inspection results.

[0053] A complete cryogenic protection chain is formed through cryogenic concentration, gradient freeze-drying, and nitrogen-filled packaging, achieving a lactoferrin retention rate of ≥92% and immunoglobulin IgA ≥65mg / 100g. Dynamic centrifugation, vacuum degassing, and embedding and masking achieve multi-dimensional taint removal, with residual nonanal ≤0.05μg / 100g.

[0054] To enhance quality traceability, the QR code contains the raw material batch number, production date, operator ID, and key process parameters (such as centrifuge speed and evaporation temperature). Furthermore, a blockchain-based evidence storage system ensures that data cannot be tampered with.

[0055] The PLC fuzzy PID algorithm adjusts temperature, pressure and material flow in real time. Combined with online sensor data feedback, the process parameter deviation is <1%.

[0056] The PLC system adopts a redundant design with hot backup of master and slave controllers to ensure control continuity. Furthermore, historical data storage period of ≥3 years supports process optimization and problem tracing.

[0057] Through the three-dimensional synergy of physical separation, chemical modification, and intelligent control, this product addresses the pain points of traditional freeze-dried milk powder, such as significant loss of active ingredients, high residual taint, and high energy consumption. The introduction of microwave-assisted sublimation, β-CD / vanillin dual encapsulation, and blockchain traceability technologies significantly improves product nutritional indicators, energy efficiency, and quality stability.

[0058] Raw material pretreatment enhancement technology: Dynamic centrifugation utilizes the centrifugal force difference of the disc centrifuge to achieve graded separation of fat globules and somatic cells through variable frequency speed regulation, combined with temperature control to inhibit fat oxidation. Cross-flow microfiltration is coupled, using a 0.22μm ceramic membrane and a 0.1μm polyethersulfone membrane in series to achieve Log6 level microbial retention through turbulent enhanced mass transfer. Pulsed UV sterilization uses 254nm UV light in a pulse mode of 2ms / time and 30 times / min to inactivate thermophilic Bacillus stearothermophilus spores, and an online buffer tank is used to maintain the activity of the raw materials.

[0059] Low temperature concentration and synergistic process: Three-stage vacuum gradient evaporation: first-stage evaporation, falling film evaporation quickly removes free moisture; second-stage evaporation, scraper evaporation enhances heat transfer efficiency; third-stage evaporation, thin film evaporation ensures that the solid content is concentrated to 45% to 50%, and then reduces the viscosity of the concentrate by 35% through the 40kHz ultrasonic cavitation effect, increases the heat transfer coefficient by 42%, and avoids lactoferrin denaturation caused by high temperature.

[0060] Vacuum deodorization strengthening unit: Activated carbon adsorption: Activated carbon modified by phosphoric acid activation selectively adsorbs odorous substances such as nonanal through a 30s adsorption / 3min desorption cycle. Vacuum flash desorption: A two-stage Roots vacuum pump group desorbs the activated carbon adsorption sites at 45-50°C, with a regeneration efficiency of ≥95%. Flavor modification: β-cyclodextrin encapsulates nonanal, supplemented by vanillin flavor compensation, combined with online monitoring of the electronic nose to achieve precise odor control.

[0061] Gradient freeze-drying process: Pre-freezing stage: The quick freezing process forms uniform ice crystals, and VC-PA (1.5%) is added to stabilize the cell membrane structure and inhibit the growth of ice crystals.

[0062] Sublimation drying stage: A staged temperature increase (-35°C → -25°C → -15°C) combined with intermittent microwave radiation (2450MHz / 300W) achieves a sublimation rate of 2.8g / cm²·h; infrared thermal imaging controls the vacuum level in real time (50→30→15Pa) to prevent damage to heat-sensitive components.

[0063] Analytical drying stage: Dynamic temperature control combined with spiral air flow distributor, the final moisture content is ≤3%.

[0064] Intelligent post-processing and packaging system: Asymmetric crushing: A planetary ball mill and a jet mill are combined to achieve precise control of particle size; active encapsulation: Sodium alginate-chitosan microencapsulation technology encapsulates probiotics, with an encapsulation rate ≥85% and a survival rate of 82% at 4°C; smart packaging: Aluminum foil bags, combined with blockchain to store full process parameters.

[0065] Thermosensitive protection chain: low temperature concentration <60℃ → gradient freeze-drying, sublimation temperature -35℃ → -15℃ → nitrogen-filled packaging, O2 <3%, forming a full low temperature protection chain to avoid denaturation of active ingredients.

[0066] Odor control chain: dynamic centrifugation, interception of large molecular odor carriers → vacuum degassing, removal of volatile components → encapsulation and masking, β-cyclodextrin inclusion, to achieve multi-dimensional odor removal.

[0067] Intelligent control chain: PLC fuzzy PID algorithm adjusts temperature, pressure and material flow in real time.

[0068] The entire freeze-dried instant milk powder production process of this solution consists of six modules: raw material pretreatment enhancement, low-temperature concentration efficiency enhancement, vacuum deodorization enhancement, gradient freeze-drying optimization, intelligent post-processing and full-process quality control. The raw materials first enter the dynamic centrifuge, and the ALFALAVAL T6 disc centrifuge with variable frequency speed regulation realizes density gradient separation of fat globules and somatic cells. The speed range is adjustable from 5000 to 9000 rpm. With the titanium alloy drum inner wall and online CIP cleaning system, after removing ≥98% fat and ≤10 4cells / mL somatic cells, while reducing the material from sticking to the wall and preventing cross contamination. The raw materials after centrifugation are sequentially microfiltered through a 0.22μm Al2O3 ceramic membrane and a 0.1μm PES spiral membrane. The former intercepts bacteria and macromolecular active substances, while the latter removes nano-scale pollutants, and cooperates with the automatic CIP cleaning unit to maintain membrane performance. The pulsed UV sterilizer is then started to inactivate Bacillus spores in the raw materials at a wavelength of 254nm and a pulse frequency of 30Hz. The quartz sleeve and automatic wiping system ensure that the UV transmittance is ≥90%. The treated raw materials enter the constant temperature tank, and the double-layer jacket structure is used to maintain the pH value at 6.5-6.8 and the redox potential at 200-300mV. The storage time does not exceed 12 hours.

[0069] The cryogenic concentration stage utilizes a three-stage vacuum evaporator, with the feedstock sequentially passing through a 45°C / 8.5kPa falling-film evaporator, a 52°C / 5.3kPa scraped-film evaporator, and a 60°C / 3.2kPa thin-film evaporator. MVR vapor recompression technology reduces energy consumption by 40%. During the concentration process, a 40kHz ultrasonic generator uses cavitation to reduce the viscosity of the feed from 1500mPa·s to 950mPa·s. Simultaneously, a composite stabilizer consisting of trehalose and glutathione is added, and mixing with a high-speed shearing machine enhances the resolubility of the lyophilized powder. The concentrate then enters an activated carbon adsorption tower, where modified activated carbon undergoes a 30s adsorption / 3min desorption cycle. Combined with 95°C hot nitrogen desorption and β-CD / vanillin encapsulation technology, the residual nonanal content is controlled to ≤0.05μg / 100g.

[0070] The gradient freeze-drying process is carried out in a vacuum freeze dryer. Under the conditions of a cold trap temperature of -80°C and a vacuum degree of <1Pa, the raw materials are quickly frozen from -40°C to -55°C and a VC-PA protective agent is added. Subsequently, during the sublimation stage, a 2450MHz / 300W microwave generator is used for segmented heating and intermittent irradiation. In combination with an infrared thermal imager, a temperature uniformity of ≤±2°C is achieved. Dynamic temperature control and a spiral airflow distributor are used in the analysis stage to ultimately control the moisture content to ≤3%. The freeze-dried milk powder enters an asymmetric crushing unit and is processed in a combination of a planetary ball mill and an airflow mill to achieve a particle size D50 ≤150μm. It is then microencapsulated using a sodium alginate-chitosan composite embedding technology. After spray drying, it is packaged in aluminum foil bags to ensure O2 <3% and a water activity <0.2.

[0071] Throughout the entire quality control process, QR code printers record raw material sources and process parameters, and a blockchain-based evidence storage system ensures data immutability. A PLC fuzzy PID algorithm adjusts temperature, pressure, and material flow in real time, and in conjunction with online sensors, achieves process parameter deviations of less than 1%. This process utilizes a three-dimensional synergy of physical separation, chemical modification, and intelligent control. Through the combined efforts of a low-temperature protection chain, an odor control chain, and an intelligent regulation chain, it ensures a lactoferrin retention rate of ≥92% and an immunoglobulin A level of ≥65mg / 100g, while simultaneously achieving improved energy efficiency and consistent quality.

[0072] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus.

[0073] Although the embodiments of the present application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations may be made to these embodiments without departing from the principles and spirit of the present application, and the scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A method for producing freeze-dried instant milk powder, characterized in that: include: S1. Strengthening of raw material pretreatment: The raw materials are centrifuged in a dynamic centrifuge to remove large particles of impurities, and then microfiltered through a 0.22μm Al2O3 ceramic membrane and a 0.1μm PES spiral membrane to remove microorganisms and fine particles. Finally, they are stored in a constant temperature tank for future use. S2. Low temperature concentration and efficiency enhancement: The raw material pretreated in step S1 is concentrated at low temperature through a three-stage vacuum evaporator to increase the solid content in the raw material, and ultrasonic waves are used to assist in reducing the viscosity of the concentrate, and a composite stabilizer is added to improve the stability of the raw material; S3, vacuum deodorization enhancement: The raw material concentrated in step S2 is put into an activated carbon adsorption tower to remove odor components in the raw material using the adsorption properties of the activated carbon, and the deodorization effect is enhanced by a vacuum flash evaporation system; S4. Gradient freeze-drying optimization operation: A vacuum freeze dryer is used to dry the raw materials after the smell of mutton is removed in step S3. A microwave-assisted system is used to accelerate the drying process, and an intelligent control system is used to achieve precise control of the drying process. S5, intelligent post-processing: The raw materials dried in step S4 are intelligently crushed by an asymmetric crushing unit to obtain milk powder particles of a desired particle size, which are then packaged by an aluminum foil bag packaging machine; S6. Full-process quality control: A QR code inkjet printer is used to perform intelligent coding on the outside of the milk powder packaging bag after packaging in step S5, recording the source of raw materials, process parameters and quality inspection results, and achieving full traceability and quality control of the product through an intelligent traceability system.

2. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S1, raw material pretreatment enhancement, the primary membrane is a 0.22μm Al2O3 ceramic membrane with a membrane area of ​​10m² and an operating pressure of 0.8-1.2MPa, and the secondary membrane is a 0.1μm PES spiral membrane with a membrane area of ​​5m² and an operating pressure of 0.8-1.2MPa.

3. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the aforementioned S1, intensified raw material pretreatment, after the dynamic centrifuge has processed the raw materials, the pulsed ultraviolet sterilization device is started to inactivate Bacillus spores in the raw materials. The raw materials are stored in a constant temperature tank for ≤12 hours, and the pH value and redox potential are monitored in real time. The pulsed ultraviolet sterilization device is equipped with a UV-C module.

4. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S2, low-temperature concentration efficiency enhancement, the first-stage evaporator is a falling film evaporator, the second-stage evaporator is a scraper evaporator, and the third-stage evaporator is a thin film evaporator.

5. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S2, low-temperature concentration efficiency enhancement, the three-stage vacuum evaporator further includes an ultrasonic generator and a viscosity sensor. The ultrasonic generator is assembled on the outside of the three-stage vacuum evaporator, and the viscosity sensor is assembled on the inside of the three-stage vacuum evaporator.

6. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S3, vacuum deodorization enhancement, the activated carbon adsorption tower is a stainless steel tower filled with modified activated carbon, the vacuum flash evaporation system is a two-stage Roots vacuum pump group, and the inner cavity of the activated carbon adsorption tower is equipped with an electronic nose detector equipped with twelve groups of metal oxide sensors.

7. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S4, gradient freeze-drying optimization operation, the microwave-assisted system is a microwave generator that adopts an intermittent radiation mode. The microwave-assisted system is internally equipped with an infrared thermal imager and an airflow distributor, and the airflow distributor is a spiral guide plate.

8. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S4, gradient freeze-drying optimization operation, the raw material is first quick-frozen at -40°C / 30min→-55°C / 60min, and VC-PA protective agent is added inside the raw material to inhibit ice crystal growth. The quick-frozen raw material is heated in stages, and the staged heating steps are: -35°C→-25°C for 2h→-25°C→-15°C for 3h. The raw material is then sublimated with the assistance of microwaves, and then the raw material is subjected to analytical drying, and the temperature is controlled dynamically from 25°C to 35°C, so that the final moisture of the raw material is ≤3%, and the rehydration capacity is ≤5 seconds.

9. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S5, intelligent post-processing, the asymmetric crushing units are respectively a planetary ball mill and a jet mill. The raw materials processed by the asymmetric crushing units are put into a microencapsulation reactor for temperature control. The final raw materials are monitored online by an O2 residual sensor and a water activity meter during packaging.

10. The method for producing freeze-dried instant milk powder according to claim 1, wherein: In the S5, intelligent post-processing, it is ensured that the particle size D50 of the raw materials after crushing and screening is ≤150 μm, the particle uniformity is ≥95%, and the probiotic microencapsulation embedding rate of the microencapsulation reactor is ≥85%.

Images