Technology and device for preparing soybean protein powder through ultrasonic-assisted soybean meal crushing

Abstract

The invention relates to the technical field of vegetable protein processing, in particular to a technology and device for preparing soybean protein powder through ultrasonic-assisted soybean meal smashing, and the technology comprises the following steps: (1) raw material pretreatment including low-temperature vacuum drying, magnetic separation and winnowing impurity removal; (2) airflow type superfine grinding: supersonic airflow grinding and online ultrasonic vibration are included; a supersonic jet mill is adopted for supersonic jet milling; an online ultrasonic vibrating screen is adopted for online ultrasonic vibration, and particles with D90 smaller than or equal to 10 microns are obtained through screening; (3) ultrasonic impact grinding: adopting a double-frequency ultrasonic synergistic grinding machine, and configuring a spiral push type grinding cavity; (4) turbine type precision grading: grading by adopting a turbine grading machine to obtain graded protein powder of which D90 is less than or equal to 10 microns and D90gt; 10 [mu] m of coarse powder; and carrying out instantaneous high-temperature sterilization on the graded protein powder to obtain the soybean protein powder. Ultrasonic waves are introduced into production of dry separation of soybean protein, and the separation effect is good.

Description

Technical Field

[0001] The present invention relates to the technical field of plant protein processing, and particularly relates to a process and device for preparing soybean protein powder by ultrasonic-assisted crushing of soybean meal. Background Art

[0002] With the increasingly obvious negative impacts of the livestock industry on the environment and resources, the plant protein market is expanding rapidly. Plant protein has competitive advantages in terms of production cost, energy demand, and sustainability. Soybeans are rich in protein, with a protein content more than twice that of cereal crops such as wheat and rice, usually between 40% and 50%. Soybean protein is a plant-based protein with an amino acid composition similar to that of milk protein. Except for slightly lower methionine, the content of other essential amino acids is relatively rich. It is a complete plant-based protein, equivalent to animal protein in nutritional value, and also the closest to human amino acids in gene structure, making it the most nutritious plant protein.

[0003] Wet separation is the most commonly used method for soybean protein, usually requiring processes such as lye extraction, centrifugal separation, hydrochloric acid flocculation precipitation, lye neutralization, enzymatic hydrolysis, high-temperature sterilization, vacuum drying, spray drying, etc. The resulting protein product has high purity, but consumes a large amount of water and energy, generates waste liquid, resulting in losses of water-soluble protein, protein denaturation, and inactivation. Dry separation is a crushing and separation process that utilizes the physical property differences between proteins and other cell components. It has simple steps, mild conditions, the protein product has a complete composition, and a low degree of denaturation. It is an energy-saving and environmentally friendly protein separation process that can retain the natural functions of proteins and has a wider application range.

[0004] In recent years, ultrasonic technology is a physical modification technology that has widely opened up new fields in food research, covering all aspects of food research and development, such as meat and meat product processing, ultrasonic sterilization and preservation, ultrasonic degradation, ultrasonic crystallization, ultrasonic drying, ultrasonic extraction, ultrasonic ripening of aged wine, ultrasonic demulsification and separation, etc. Chinese Patent CN 105211495A discloses a method for preparing high-calcium and low-viscosity soybean protein. This method adjusts the ionic strength of the solution through a mixed solution of NaOH and Ca(OH)2, uses ultrasonic-assisted alkaline solution to extract soybean protein from soybean meal, and then combines high-pressure microfluidization technology to modify the protein, claiming to improve the solubility of the protein, especially to reduce the viscosity of the protein. However, this is only for the preparation of soybean protein by ultrasonic-assisted wet separation, and the problem of large water and energy consumption itself has not been solved, and there is no disclosure of the solubility data and viscosity data of the soybean protein obtained by this method, so the effect cannot be effectively guaranteed. Summary of the Invention

[0005] In view of the technical problems in the existing wet separation process of soybean protein, such as high water and energy consumption and serious waste liquid pollution; in the dry separation process, large crushing particles often exist in the crushing and separation processes, and it is difficult to separate protein from other components such as fibers, resulting in low protein content. The present invention provides a process and device for preparing soybean protein powder by ultrasonic-assisted crushing of soybean meal, applying ultrasonic waves to the production of dry separation of soybean protein, with good separation effect, high purity and good solubility of the obtained soybean protein powder.

[0006] The technical solution of the present invention is as follows: In the first aspect, the present invention provides a process for preparing soybean protein powder by ultrasonic-assisted crushing of soybean meal, including the following steps: Step 1. Raw material pretreatment: including low-temperature vacuum drying, magnetic separation + air separation for impurity removal; the moisture content of soybean meal is controlled at ≤6% by low-temperature vacuum drying; Step 2. Airflow ultrafine crushing: including supersonic airflow crushing and on-line ultrasonic vibration; supersonic airflow crushing uses a supersonic airflow crusher; on-line ultrasonic vibration uses an on-line ultrasonic vibrating screen, and particles with D 90 ≤10μm are obtained by sieving; Step 3. Ultrasonic impact grinding: a dual-frequency ultrasonic collaborative mill is used, the amplitude of the main vibration source is 50-100μm, the amplitude of the auxiliary vibration source is 10-20μm, a spiral propelling grinding chamber is configured, and the residence time of the material is controlled at 3-5 seconds; Step 4. Turbine precision classification: a turbine classifier is used to classify and obtain classified protein powder with D 90 ≤10μm and coarse powder with D 90 >10μm; The classified protein powder enters the step of instantaneous high-temperature sterilization to obtain soybean protein powder; The coarse powder is recycled through steps 2 to 4 until D 90 ≤10μm.

[0007] Further, in step 1, during low-temperature vacuum drying, the vacuum degree is 0.08MPa, the temperature of the circulating air for drying soybean meal is 40-50°C, the wind speed is 5-8m / s, the drying time of the circulating air is maintained for 2-3 hours, and the discharge temperature is ≤55°C after completion.

[0008] When the vacuum pump maintains a vacuum degree of 0.08MPa and the temperature of the circulating air is 40-50°C, the moisture diffusion coefficient of soybean meal is increased by 3-5 times, and at the same time, the Maillard reaction is avoided (when the temperature exceeds 60°C, the reducing sugar and protein in soybean meal are prone to browning).

[0009] Further, in Step 1, during magnetic separation + pneumatic separation for impurity removal, a permanent magnetic drum is used for magnetic separation to remove ferromagnetic impurities, with a magnetic field intensity of 0.6 - 1.2 T. For pneumatic separation, a Venturi pneumatic separator is adopted, with an air velocity of 15 - 20 m / s, and a vibrating conveyor is configured at the discharge port.

[0010] Configuring a vibrating conveyor at the discharge port of the Venturi pneumatic separator can prevent material blockage.

[0011] Further, in Step 2, the supersonic airflow mill adopts a Laval nozzle design, with a nozzle pressure of 0.8 - 1.2 MPa, a classifier wheel rotational speed of 3000 - 5000 rpm, a compressed air dew point ≤ -40 °C, and the discharge particle size is monitored online through an integrated laser particle size analyzer; the amplitude of the online ultrasonic vibrating screen is 0.5 - 1.0 mm, and the screen aperture is configured as 1.2 times the target value. 90 1.2 times the target value.

[0012] Further, in Step 3, the main vibration source of the dual-frequency ultrasonic co-mill is 20 kHz, and a sandwich-type ultrasonic transducer array is adopted; the auxiliary vibration source is 40 kHz, and a sandwich-type transducer is adopted; the cavity of the screw propelling milling chamber adopts an Archimedes spiral structure, with a pitch of 20 - 30 mm and a rotational speed of 100 - 200 rpm.

[0013] Further, in Step 4, the classifier wheel rotational speed of the turbo classifier is 8000 - 10000 rpm, the airflow velocity is 5 - 15 m / s, and a plate heat exchanger is used to maintain the temperature of the classification airflow at 15 - 25 °C; the number of times the coarse powder is recycled through Steps 2 to 4 is 2 - 3 times.

[0014] Further, for instant high-temperature sterilization, the classified protein powder obtained in Step 4 contacts superheated steam in the mixing chamber of the sterilizer for 0.5 - 1.5 seconds, and then the protein particles with a particle size ≥ 5 μm are separated and collected; the temperature of the superheated steam is 140 - 150 °C, the degree of superheat is 30 - 50 °C, and the pressure is 0.3 - 0.5 MPa.

[0015] Further, product packaging and storage are also carried out after instant high-temperature sterilization; the entire process is monitored by a data acquisition and monitoring control system.

[0016] In a second aspect, the present invention provides a device for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal, which includes a closed-loop vacuum dryer. The discharge port of the closed-loop vacuum dryer is connected to the feed port of a magnetic separator. The discharge port of the magnetic separator is connected to the feed port of a Venturi air classifier. The discharge port of the Venturi air classifier is connected to the feed port of a supersonic airflow crusher. The discharge port of the supersonic airflow crusher is connected to the feed port of an on-line ultrasonic vibrating screen. The discharge port of the on-line ultrasonic vibrating screen is connected to the feed port of a dual-frequency ultrasonic collaborative mill. The discharge port of the dual-frequency ultrasonic collaborative mill is connected to the feed port of a turbo classifier. One discharge port of the turbo classifier is connected to the feed port of the supersonic airflow crusher, and the other discharge port of the turbo classifier is connected to the feed port of a sterilizer. The discharge port of the sterilizer is connected to the feed port of a long-cone cyclone separator. The discharge port of the long-cone cyclone separator is connected to the feed port of a full-automatic vacuum packaging machine.

[0017] Furthermore, the discharge port of the closed-loop vacuum dryer is connected to the feed port of the magnetic separator through a first screw conveyor; the discharge port of the Venturi air classifier is connected to the feed port of the supersonic airflow crusher through a first elevator; the discharge port of the supersonic airflow crusher is connected to the feed port of the on-line ultrasonic vibrating screen through a second screw conveyor; the discharge port of the dual-frequency ultrasonic collaborative mill is connected to the feed port of the turbo classifier through a second elevator; the turbo classifier is also connected to a plate heat exchanger; the discharge port of the long-cone cyclone separator is connected to the feed port of the full-automatic vacuum packaging machine through a third elevator.

[0018] The beneficial effects of the present invention are as follows: The present invention provides a process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal. Through raw material pretreatment of low-temperature vacuum drying and impurity removal by magnetic separation + air separation, the quality of the raw materials is ensured, and the moisture content is controlled ≤ 6%, providing the best brittle conditions for subsequent crushing. In the stage of airflow ultrafine crushing, a supersonic airflow crusher is combined with on-line ultrasonic vibration to preliminarily refine the particle size of the material to D 90 ≤ 10 μm. In the key ultrasonic impact milling link, a dual-frequency ultrasonic collaborative mill is used. The amplitude of the main vibration source is 50 - 100 μm, and the amplitude of the auxiliary vibration source is 10 - 20 μm. A spiral propelling type milling chamber is configured to accurately control the residence time of the material for 3 - 5 seconds, improving the crushing effect. Without damaging the natural functions of proteins, the particles are further refined, laying a good foundation for subsequent processes. Subsequently, through turbine precision classification, a classified protein powder with a particle size D 90 ≤ 10 μm is obtained. It is worth mentioning that for the coarse powder with a particle size D 90 > 10 μm generated during the classification process, it will be recycled through steps two to four until its D 90≤10 μm. This cyclic mechanism improves the utilization rate of raw materials, avoids material waste, increases the fiber utilization rate in the overall process to 95%, and realizes the efficient utilization of soybean meal raw materials. The entire process not only achieves energy conservation and environmental protection, significantly reduces energy consumption compared with traditional wet separation, and avoids a large amount of water consumption and waste liquid generation, but also the purity (dry basis) of the prepared soy protein powder is ≥90%, and the NSI (protein solubility index) is ≥85%. The product has excellent quality and wide applicability.

[0019] The device for preparing soy protein powder by ultrasonic-assisted soybean meal crushing involved in the present invention has the equipment closely connected to form an efficient and smooth production line. The closed-loop vacuum dryer ensures that the soybean meal is dried in a low-temperature vacuum environment, minimizing the loss of heat-sensitive components to the greatest extent. Moreover, the closed-loop design effectively reduces energy consumption and thermal pollution to the environment. The magnetic separator and the Venturi air separator cooperate in sequence to accurately remove magnetic impurities and light debris in the raw materials, ensuring the purity of the soybean meal entering the subsequent crushing process and providing guarantee for the preparation of high-quality products. The combination of the supersonic airflow crusher and the on-line ultrasonic vibrating screen realizes the preliminary efficient ultrafine crushing of materials, and the transfer of materials between equipment is smooth and efficient, reducing material residue and loss. The connection of the dual-frequency ultrasonic co-grinder and the turbo classifier further optimizes the crushing and classification effects. The turbo classifier sends the coarse powder that does not meet the particle size requirements back to the supersonic airflow crusher for cyclic treatment. This closed-loop design greatly improves the utilization rate of raw materials. The orderly connection of the sterilizer, the long-cone cyclone separator, and the fully automatic vacuum packaging machine realizes full-automatic operation from product sterilization, collection to packaging. It not only improves production efficiency but also reduces the pollution risk that may be brought by manual intervention, ensuring the quality stability and hygienic safety of the soy protein powder product, and comprehensively enhancing the economic benefits and market competitiveness of the entire production process. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without creative efforts.

[0021] Figure 1 It is the process flow diagram of preparing soy protein powder by ultrasonic-assisted soybean meal crushing of the present invention.

[0022] Figure 2 It is the schematic diagram of the device for preparing soy protein powder by ultrasonic-assisted soybean meal crushing of the present invention.

[0023] In the figure, 1 - closed - loop vacuum dryer, 2 - first screw conveyor, 3 - magnetic separator, 4 - Venturi pneumatic separator, 5 - first elevator, 6 - supersonic airflow mill, 7 - second screw conveyor, 8 - on - line ultrasonic vibrating screen, 9 - dual - frequency ultrasonic collaborative mill, 10 - second elevator, 11 - turbine classifier, 12 - plate heat exchanger, 13 - sterilizer, 14 - long - cone cyclone separator, 15 - third elevator, 16 - full - automatic vacuum packaging machine. Detailed implementation mode

[0024] In order to enable those skilled in the art of this technology to better understand the technical solutions in the present invention, the following will, in conjunction with the accompanying drawings in the embodiments of the present invention, clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0025] Embodiment 1 A process for preparing soy protein powder by ultrasonic - assisted crushing of soybean meal (see the process flow chart in Figure 1 ), which includes the following steps: Step 1. Raw material pretreatment, and the raw material pretreatment includes low - temperature vacuum drying and magnetic separation + pneumatic separation for impurity removal; Low - temperature vacuum drying: Put soybean meal (with a moisture content of 8%) into a closed - loop vacuum dryer for low - temperature vacuum drying to obtain dried soybean meal. Start the vacuum pump until the vacuum degree reaches 0.08 MPa, then introduce circulating air for drying. The temperature of the circulating air is 50 °C, the wind speed of the circulating air is 5 m / s, and the drying time of the circulating air is maintained for 2 hours. The moisture content of the soybean meal is monitored in real - time through an on - line moisture meter (connected and controlled by a data acquisition and monitoring control system). When the moisture content ≤ 6%, the drying end point is reached, and the material can be discharged. The discharge temperature ≤ 55 °C to avoid protein denaturation; During the low - temperature vacuum drying process, keep the material in a uniformly tumbling state, record the vacuum degree, temperature, and moisture content data every hour, and automatically alarm when the deviation exceeds ± 5%; When the vacuum pump maintains a vacuum degree of 0.08 MPa and the vacuum pump maintains the temperature of the circulating air at 40 - 50 °C, the moisture diffusion coefficient of the soybean meal increases by 3 - 5 times, and at the same time, the Maillard reaction is avoided (when the temperature exceeds 60 °C, the reducing sugar and protein in the soybean meal are prone to browning). For every 1% increase in the moisture content, the crushing energy consumption increases by 8% - 12%. A moisture content ≤ 6% provides the best brittle condition for subsequent crushing.

[0026] Magnetic separation + air separation for impurity removal: The soybean meal after low-temperature vacuum drying is sent out from the discharge port of the closed-loop vacuum dryer, and then enters the magnetic separator through the first screw conveyor. Ferromagnetic impurities are removed by the permanent magnet drum to obtain the de-magnetized soybean meal. The impurity removal efficiency of the magnetic separator is ≥99.8%; the de-magnetized soybean meal enters the Venturi air separator. The air speed of the Venturi air separator is 20 m / s, and light and small impurities (such as soybean skin fragments) are separated using the density difference to obtain the impurity-removed soybean meal; the magnetic field intensity of the magnetic separator is calibrated regularly (once a month) to ensure that the magnetic field intensity is 0.6 T; a vibrating conveyor is configured at the discharge port of the Venturi air separator to prevent material blockage; The combined impurity removal efficiency of magnetic separation + air separation can reach 99.8%, ensuring no risk of blockage for subsequent equipment.

[0027] Step 2: Airflow ultrafine grinding, which includes supersonic airflow grinding and on-line ultrasonic vibration; Supersonic airflow grinding: The impurity-removed soybean meal is sent out from the discharge port of the Venturi air separator, and enters the grinding chamber of the supersonic airflow mill through the first elevator from the feed port of the supersonic airflow mill for supersonic airflow grinding to obtain the ground soybean meal; Start the air compressor of the supersonic airflow mill, adjust the nozzle pressure to 0.8 MPa. The supersonic airflow mill adopts a Laval nozzle design. Compressed air is accelerated to supersonic speed (Mach number 1.5 - 2.0) through adiabatic expansion. The material obtains an impact speed of 500 m / s at the nozzle intersection; the rotational speed of the classification wheel is adjusted by the frequency converter. The rotational speed of the classification wheel is 3000 rpm (3000 rpm corresponds to D90≈15 μm), and the discharge particle size is monitored on-line through an integrated laser particle size analyzer (sampling frequency 10 Hz, connected and controlled by the data acquisition and monitoring control system), and D 90 is 10 - 15 μm; the dew point of the compressed air ≤ -40 °C (to avoid moisture absorption and agglomeration of the material); check the nozzle wear every two hours, and replace it in time when the wear exceeds 1 mm; On-line ultrasonic vibration: The ground soybean meal is sent out from the discharge port of the started supersonic airflow mill, and enters the feed port of the on-line ultrasonic vibrating screen through the second screw conveyor. The screen aperture of the on-line ultrasonic vibrating screen is 12 μm (the screen aperture is configured as 1.2 times the D90 target value) to obtain the screened soybean meal, and the discharge particle size D 90 ≤10 μm; the screening efficiency ≥92%. A high-frequency vibrator (20 - 40 kHz) is attached to the screen surface. The amplitude of the ultrasonic vibrating screen is controlled at 0.5 - 1.0 mm. The screen hole blockage is reduced through the acoustic standing wave effect, and the ultrasonic power is monitored in real time (connected and controlled by the data acquisition and monitoring control system), and automatically adjusted when the fluctuation exceeds ±10%; the screen of the ultrasonic vibrating screen is cleaned daily, and back blown with compressed air (pressure is 0.4 MPa).

[0028] Step 3: Ultrasonic impact milling. Feed the sieved soybean meal into the feed inlet of a dual-frequency ultrasonic assisted mill to obtain ground soybean meal. The dual-frequency ultrasonic assisted mill uses a screw propelled milling chamber with an Archimedes spiral structure. The pitch is 25 mm and the rotation speed is 150 rpm. Start the main vibration source at 20 kHz (power 1500 W) and the auxiliary vibration source at 40 kHz (power 800 W). The residence time of the material is 5 seconds (precisely controlled by a frequency converter). The inner wall of the chamber is inlaid with tungsten carbide wear-resistant lining (hardness HRC70) with a service life of over 8000 hours. Among them, the main vibration source (20 kHz, amplitude 50 - 100 μm) uses a sandwich ultrasonic transducer array with an energy density of 10 - 20 W / cm 2 , and the amplitude is increased to 50 - 100 μm through an amplitude amplification rod, generating local high temperature (5000 K) and high pressure (100 MPa) when the cavitation bubbles collapse, destroying the cell wall structure. The auxiliary vibration source (40 kHz, amplitude 10 - 20 μm) uses a sandwich transducer to achieve nano-scale dispersion through the acoustic streaming effect, reducing the probability of agglomeration. Moreover, maintain the temperature at 15 - 20 °C through a cooling water jacket. Record the ultrasonic amplitude (the maximum distance that the mass point deviates from the equilibrium position during ultrasonic vibration) every hour. The normal range is 50 - 100 μm for the main vibration source and 10 - 20 μm for the auxiliary vibration source. Check the tungsten carbide lining every 2000 hours of operation and replace it in time when the wear depth exceeds 2 mm. Conduct a dynamic balance test on the spiral blades every quarter, with the vibration value ≤ 5 m / s 2 .

[0029] Step 4: Turbine precision classification. The ground soybean meal is sent out from the discharge outlet of the dual-frequency ultrasonic assisted mill and then enters a turbine classifier for classification to obtain classified protein powder (D 90 ≤ 10 μm). Adjust the rotation speed of the classification wheel to 8000 - 10000 rpm and the air flow speed to 5 - 15 m / s. The classified protein powder (D 90 ≤ 10 μm) enters the next step of instant high-temperature sterilization, while the coarse powder (D 90 > 10 μm) is returned to the supersonic airflow mill for recycling (considering maximizing the utilization of materials and energy conservation, steps 2 to 4 are cycled three times). The air bearing temperature of the turbine classifier ≤ 60 °C, and it is monitored in real time through an infrared thermal imager (connected and controlled by a data acquisition and monitoring control system). ≤ ±5% Turbine precision classification uses air flow temperature control. The classification air flow exchanges heat through a plate heat exchanger to maintain the classification air flow temperature at 15 - 25 °C to avoid protein thermal denaturation. The plate heat exchanger uses stainless steel corrugated plates with a heat exchange area of 50 m 2, the refrigerant of the plate heat exchanger is ethylene glycol solution at -10°C, and the ethylene glycol flow rate is 5 - 10 m 3 / h, and it is feedback-regulated through a thermocouple (accuracy ±1°C); the classification wheel is supported by an air bearing (rotation speed can reach 10000 rpm), and precise cutting of particles with a particle size of 1 - 10 μm is achieved by adjusting the impeller angle (0° - 30°) and the air flow velocity (5 - 15 m / s).

[0030] Step Five: Instantaneous high-temperature sterilization. The classified protein powder enters the sterilizer and contacts superheated steam (the steam is accelerated to 300 - 400 m / s by a Venturi nozzle) in the Venturi mixing chamber of the sterilizer for 0.5 seconds, and then enters a long-cone cyclone separator with a cone angle of 20° to separate the steam and protein particles. The protein particles are the soybean protein powder; the tail gas generated during separation is filtered through a PTFE bag filter; the temperature of the superheated steam is 140°C, the superheat degree is 50°C, and the pressure is 0.5 MPa; The superheat degree of the superheated steam is monitored in real time through a pressure-temperature sensor (connected and controlled by a data acquisition and monitoring control system), and the deviation ≤ ±2°C; the microbial killing rate of the superheated steam treatment ≥ 5 log (such as Salmonella), and the total number of colonies is detected daily (the detection standard refers to GB 4789.2 - 2022); the cyclone separator separates protein particles with a particle size ≥ 5 μm, and the separation efficiency ≥ 98%; the PTFE bag filter is equipped with a PTFE membrane filter bag, the filtration accuracy is 0.1 μm, and the emission concentration of the PTFE bag filter ≤ 10 mg / m 3 .

[0031] Step Six: Product packaging and storage. Cool the soybean protein powder to ≤ 40°C, enter a fully automatic vacuum packaging machine (nitrogen filling protection) through the third elevator for packaging, and transport it to the warehouse for storage; packaging specification: 25 kg / bag (aluminum foil composite film), the nitrogen filling pressure is 0.05 MPa, and the oxygen content ≤ 2%; storage conditions: the warehouse temperature ≤ 25°C, the humidity ≤ 60%, keep away from light, and the stack spacing ≥ 0.5 m to prevent packaging extrusion and damage.

[0032] This process is monitored through a data acquisition and monitoring control system (SCADA system). When problems occur, it will automatically trigger a shutdown and send a text message to notify the operator.

[0033] Using the method provided by GB / T22493 - 2008, the technical indicators of the prepared soybean protein powder are measured: the protein powder purity (dry basis) is 90.1%, D90 ≤ 10 μm, and NSI (protein solubility index) is 85.3%.

[0034] Cost calculation: The annual processing volume is 10,000 tons of soybean meal. Using this method, 3,500 tons of protein soybean powder are produced, and the fiber utilization rate is increased to 95% (the by-product dietary fiber is sold at 2,000 yuan / ton). Compared with the traditional process, the energy consumption is reduced by 30%, about 0.8 kWh / kg.

[0035] Example 2 A process for preparing soybean protein powder by ultrasonic-assisted soybean meal crushing, comprising the following steps: Step 1: Raw material pretreatment, which includes low-temperature vacuum drying and magnetic separation + air separation for impurity removal; Low-temperature vacuum drying: Put soybean meal (with a moisture content of 10%) into a closed-circuit vacuum dryer for low-temperature vacuum drying to obtain dried soybean meal. Start the vacuum pump until the vacuum degree reaches 0.08 MPa, then introduce circulating air for drying. The temperature of the circulating air is 40°C, the wind speed of the circulating air is 8 m / s, and the drying time of the circulating air is maintained for 3 hours. The moisture content of the soybean meal is monitored in real time by an on-line moisture meter (connected and controlled by a data acquisition and monitoring control system). When the moisture content ≤ 6%, the drying end point is reached and the material can be discharged, and the discharge temperature ≤ 55°C to avoid protein denaturation; During the low-temperature vacuum drying process, keep the material in a uniformly tumbling state, record the vacuum degree, temperature, and moisture content data every hour, and automatically alarm when the deviation exceeds ±5%; When the vacuum pump maintains a vacuum degree of 0.08 MPa and the vacuum pump maintains the temperature of the circulating air at 40 - 50°C, the moisture diffusion coefficient of the soybean meal is increased by 3 - 5 times, and at the same time, the Maillard reaction is avoided (when the temperature exceeds 60°C, the reducing sugar and protein in the soybean meal are prone to browning). For every 1% increase in moisture content, the crushing energy consumption increases by 8% - 12%. When the moisture content ≤ 6%, it provides the best brittle condition for subsequent crushing.

[0036] Magnetic separation + air separation for impurity removal: The soybean meal after low-temperature vacuum drying is sent out from the discharge port of the closed-circuit vacuum dryer, and then enters the magnetic separator through the first screw conveyor. Remove ferromagnetic impurities through a permanent magnet drum to obtain de-magnetized soybean meal. The impurity removal efficiency of the magnetic separator ≥ 99.8%; The de-magnetized soybean meal enters the Venturi air separator. The wind speed of the Venturi air separator is 15 m / s, and light and small impurities (such as soybean skin fragments) are separated using the density difference to obtain impurity-removed soybean meal; The magnetic field intensity of the magnetic separator is calibrated regularly (once a month) to ensure that the magnetic field intensity is 1.2 T; A vibrating conveyor is configured at the discharge port of the Venturi air separator to prevent material blockage; The combined impurity removal efficiency of magnetic separation + air separation can reach 99.8%, ensuring no risk of blockage for subsequent equipment.

[0037] Step 2: Pneumatic ultrafine crushing, which includes supersonic airflow crushing and on-line ultrasonic vibration; Supersonic airflow pulverization: The defatted soybean meal after impurity removal is sent out from the discharge port of the Venturi air separator, and enters the pulverization chamber of the supersonic airflow pulverizer through the first elevator from the feed port of the supersonic airflow pulverizer for supersonic airflow pulverization to obtain pulverized defatted soybean meal; Start the air compressor of the supersonic airflow pulverizer, adjust the nozzle pressure to 1.2 MPa. The supersonic airflow pulverizer adopts a Laval nozzle design, and the compressed air is accelerated to supersonic speed (Mach number 1.5 - 2.0) through adiabatic expansion. The material obtains an impact speed of 800 m / s at the nozzle intersection; The rotational speed of the classification wheel is adjusted by a frequency converter, the rotational speed of the classification wheel is 5000 rpm, and the particle size of the discharged material is monitored online through an integrated laser particle size analyzer (sampling frequency 10 Hz, connected and controlled by a data acquisition and monitoring control system), D 90 is 10 - 15 μm; The dew point of the compressed air ≤ -40 °C (to avoid moisture absorption and agglomeration of the material); Check the wear condition of the nozzle every two hours, and replace it in time when the wear amount exceeds 1 mm; Online ultrasonic vibration: The pulverized defatted soybean meal is sent out from the discharge port of the started supersonic airflow pulverizer, and enters the feed port of the online ultrasonic vibrating screen through the second screw conveyor. The screen aperture of the online ultrasonic vibrating screen is 12 μm (the screen aperture is configured as 1.2 times the D90 target value) to obtain sieved defatted soybean meal, and the discharged particle size D 90 ≤ 10 μm; The screening efficiency ≥ 92%. The surface of the screen is attached with a high-frequency vibrator (20 - 40 kHz), and the amplitude of the ultrasonic vibrating screen is controlled at 0.5 - 1.0 mm. The clogging of the screen holes is reduced through the acoustic standing wave effect, and the ultrasonic power is monitored in real time (connected and controlled by a data acquisition and monitoring control system), and automatically adjusted when the fluctuation exceeds ±10%; The screen of the ultrasonic vibrating screen is cleaned daily, and backblown with compressed air (pressure is 0.4 MPa).

[0038] Step 3: Ultrasonic impact grinding. Feed the sieved defatted soybean meal into the feed port of the dual-frequency ultrasonic assisted grinding mill to obtain ground defatted soybean meal; The dual-frequency ultrasonic assisted grinding mill adopts a spiral propulsion grinding chamber. The chamber adopts an Archimedes spiral structure, with a pitch of 20 mm and a rotational speed of 100 rpm; Start the main vibration source of 20 kHz (power is 1500 W) and the auxiliary vibration source of 40 kHz (power is 800 W), and the residence time of the material is 3 seconds (precisely controlled by a frequency converter); The inner wall of the chamber is inlaid with tungsten carbide wear-resistant liners (hardness is HRC70), and the service life reaches more than 8000 hours; Among them, the main vibration source (20 kHz, amplitude is 50 - 100 μm) adopts a sandwich-type ultrasonic transducer array, and the energy density reaches 10 - 20 W / cm 2, the amplitude is increased to 50 - 100 μm by the amplitude amplification rod, generating local high temperature (5000 K) and high pressure (100 MPa) when the cavitation bubbles collapse, which destroys the cell wall structure; the auxiliary vibration source (40 kHz, amplitude of 10 - 20 μm) uses a sandwich transducer to achieve nano-scale dispersion through the acoustic streaming effect and reduce the agglomeration probability; Moreover, the temperature is maintained at 15 - 20 °C through the cooling water jacket; the ultrasonic amplitude (the maximum distance that the particles deviate from the equilibrium position during ultrasonic vibration) is recorded every hour. The main vibration source being 50 - 100 μm and the auxiliary vibration source being 10 - 20 μm are within the normal range; the tungsten carbide lining is inspected every 2000 hours of operation, and is replaced in time when the wear depth exceeds 2 mm; the spiral blade undergoes a dynamic balance test every quarter, and the vibration value ≤ 5 m / s 2 。

[0039] Step Four: Turbine-type precision classification. The ground soybean meal is sent out from the discharge port of the dual-frequency ultrasonic assisted mill and then enters the turbine classifier for classification to obtain classified protein powder (D 90 ≤ 10 μm); the rotational speed of the classification wheel is adjusted to 8000 - 10000 rpm, and the air flow rate is 5 - 15 m / s; the classified protein powder (D 90 ≤ 10 μm) enters the next step of instantaneous high-temperature sterilization, while the coarse powder (D 90 > 10 μm) returns to the supersonic airflow pulverizer for cyclic processing (for the sake of maximizing the utilization of materials and energy conservation, steps two to four are cycled twice); the air bearing temperature of the turbine classifier ≤ 60 °C, and is monitored in real time through an infrared thermal imager (connected and controlled by the data acquisition and monitoring control system); ≤ ±5% Turbine-type precision classification adopts air flow temperature control. The classification air flow exchanges heat through a plate heat exchanger to maintain the classification air flow temperature at 15 - 25 °C to avoid protein thermal denaturation; the plate heat exchanger uses a stainless steel corrugated plate, and the heat exchange area is 20 m 2 , the refrigerant of the plate heat exchanger is ethylene glycol solution at -10 °C, and the ethylene glycol flow rate is 5 - 10 m 3 / h, and is feedback-regulated through a thermocouple (accuracy ±1 °C); the classification wheel is supported by an air bearing (the rotational speed can reach 10000 rpm), and precise cutting of particles with a diameter of 1 - 10 μm is achieved by adjusting the impeller angle (0° - 30°) and the air flow rate (5 - 15 m / s).

[0040] Step 5: Instant high-temperature sterilization. The classified protein powder enters the sterilizer and contacts superheated steam (the steam is accelerated to 300 - 400 m / s by a Venturi nozzle) in the Venturi mixing chamber of the sterilizer for 1.5 seconds, and then enters a long-cone cyclone separator with a cone angle of 20° to separate the steam and protein particles. The protein particles are the soy protein powder; the tail gas generated during separation is filtered through a PTFE bag filter; the temperature of the superheated steam is 150 °C, the degree of superheat is 30 °C, and the pressure is 0.3 MPa; The degree of superheat of the superheated steam is monitored in real time by a pressure-temperature sensor (connected and controlled by a data acquisition and monitoring control system), and the deviation ≤ ±2 °C; the microbial killing rate of the superheated steam treatment ≥ 5 log (such as Salmonella), and the total number of colonies is detected daily (the detection standard refers to GB 4789.2 - 2022); the cyclone separator separates protein particles with a particle size ≥ 5 μm, and the separation efficiency ≥ 98%; the PTFE bag filter is equipped with a PTFE membrane filter bag with a filtration accuracy of 0.1 μm, and the emission concentration of the PTFE bag filter ≤ 10 mg / m 3 .

[0041] Step 6: Product packaging and storage. Cool the soy protein powder to ≤ 40 °C, enter a fully automatic vacuum packaging machine (nitrogen-filled protection) through a third elevator for packaging, and transport it to the warehouse for storage; packaging specification: 25 kg / bag (aluminum foil composite film), nitrogen-filling pressure is 0.05 MPa, and oxygen content ≤ 2%; storage conditions: warehouse temperature ≤ 25 °C, humidity ≤ 60%, stored in the dark, stack spacing ≥ 0.5 m to prevent packaging from being squeezed and damaged.

[0042] This process is monitored by a data acquisition and monitoring control system (SCADA system). In case of problems, it automatically triggers a shutdown and sends a text message to notify the operator.

[0043] Using the method provided by GB / T22493 - 2008, the technical indicators of the prepared soy protein powder are measured: the purity of the protein powder (dry basis) is 90%, D90 ≤ 10 μm, and NSI (protein solubility index) is 85%.

[0044] Example 3 As Figure 2An apparatus for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal is shown, which includes a closed-circuit vacuum dryer 1. The discharge port of the closed-circuit vacuum dryer 1 is connected to the feed port of a magnetic separator 3 through a first screw conveyor 2. The discharge port of the magnetic separator 3 is connected to the feed port of a Venturi air classifier 4. The discharge port of the Venturi air classifier 4 is connected to the feed port of a supersonic airflow crusher 6 through a first elevator 5. The discharge port of the supersonic airflow crusher 6 is connected to the feed port of an on-line ultrasonic vibrating screen 8 through a second screw conveyor 7. The discharge port of the on-line ultrasonic vibrating screen 8 is connected to the feed port of a dual-frequency ultrasonic collaborative mill 9. The discharge port of the dual-frequency ultrasonic collaborative mill 9 is connected to the feed port of a turbine classifier 11 through a second elevator 10. The turbine classifier 11 is also connected to a plate heat exchanger 12. One discharge port of the turbine classifier 11 is connected to the feed port of the supersonic airflow crusher 6, and the other discharge port of the turbine classifier 11 is connected to the feed port of a sterilizer 13. The discharge port of the sterilizer 13 is connected to the feed port of a long-cone cyclone separator 14. The discharge port of the long-cone cyclone separator 14 is connected to the feed port of a full-automatic vacuum packaging machine 16 through a third elevator 15; the data acquisition and monitoring control system is respectively connected to the closed-circuit vacuum dryer 1, the supersonic airflow crusher 6, the on-line ultrasonic vibrating screen 8, the turbine classifier 11, and the sterilizer 13.

[0045] Soybean meal with a moisture content of 8%-10% first enters the closed-circuit vacuum dryer 1, and the moisture content is controlled at ≤6% in a low-temperature vacuum environment. The dried soybean meal is transported to the magnetic separator 3 through the first screw conveyor 2 to remove magnetic impurities, and then enters the Venturi air classifier 4 to separate light impurities; then it enters the supersonic airflow crusher 6 through the first elevator 5 and is preliminarily crushed to D 90 a particle size of 10-15 μm, and then enters the on-line ultrasonic vibrating screen 8 through the second screw conveyor 7 and is refined to D 90 a particle size of ≤10 μm, and then enters the dual-frequency ultrasonic collaborative mill 9, where it stays for 3-5 seconds for deep refinement under the action of a main vibration source of 20 kHz, an amplitude of 50-100 μm, an auxiliary vibration source of 40 kHz, an amplitude of 10-20 μm, and a spiral propelling grinding chamber; then it enters the turbine classifier 11 through the second elevator 10 and is classified under the conditions of a classifier wheel speed of 8000-10000 rpm and an air flow rate of 5-15 m / s, D 90 The coarse powder with a particle size >10 μm is sent back to the cycle for processing through the channel connecting the turbine classifier 11 and the supersonic airflow crusher 6, D 90 The classified protein powder with a particle size ≤10 μm enters the sterilizer 13 for instantaneous high-temperature sterilization, then enters the long-cone cyclone separator 14 for centrifugal collection, and finally is transported to the full-automatic vacuum packaging machine 16 through the third elevator 15 and is packaged under nitrogen protection.

[0046] Although the present invention has been described in detail by referring to the accompanying drawings and in conjunction with the preferred embodiments, the present invention is not limited thereto. Without departing from the spirit and essence of the present invention, those of ordinary skill in the art can make various equivalent modifications or substitutions to the embodiments of the present invention, and these modifications or substitutions should all be within the scope of the present invention. / Any person skilled in the art within the technical scope disclosed by the present invention can easily conceive of changes or substitutions, which should all be covered by the protection scope of the present invention.

Claims

1. A process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal, characterized in that, It includes the following steps: Step 1, raw material pretreatment: including low-temperature vacuum drying, magnetic separation + air separation for impurity removal; the moisture content of soybean meal is controlled at ≤6% by low-temperature vacuum drying; Step 2: Airflow ultrafine grinding: including supersonic airflow grinding and on-line ultrasonic vibration; supersonic airflow grinding uses a supersonic airflow mill; on-line ultrasonic vibration uses an on-line ultrasonic vibrating screen, and particles with D 90 ≤ 10 μm are obtained by sieving; Step 3, ultrasonic impact milling: a dual-frequency ultrasonic collaborative mill is used, the amplitude of the main vibration source is 50 - 100μm, the amplitude of the auxiliary vibration source is 10 - 20μm, a spiral propelling milling chamber is configured, and the residence time of the material is controlled at 3 - 5 seconds; Step 4. Turbine precision classification: Use a turbine classifier to classify and obtain classified protein powder with D 90 ≤ 10 μm and coarse powder with D 90 > 10 μm; The classified protein powder enters the step of instant high-temperature sterilization to obtain soybean protein powder; The coarse powder is recycled to perform Step 2 to Step 4 until D 90 ≤ 10 μm.

2. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, wherein In Step 1, during low-temperature vacuum drying, the vacuum degree is 0.08MPa, the temperature of the circulating air used for drying soybean meal is 40 - 50°C, the wind speed is 5 - 8m / s, the drying time of the circulating air is maintained for 2 - 3 hours, and the discharge temperature is ≤55°C after completion.

3. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, wherein, In Step 1, during magnetic separation + air separation for impurity removal, a permanent magnet drum is used for magnetic separation to remove ferromagnetic impurities, the magnetic field intensity is 0.6 - 1.2T, a Venturi air separator is used for air separation, the wind speed is 15 - 20m / s, and a vibrating conveyor is configured at the discharge port.

4. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, wherein, In Step 2, the supersonic airflow mill adopts a Laval nozzle design, the nozzle pressure is 0.8 - 1.2 MPa, the rotational speed of the classification wheel is 3000 - 5000 rpm, the dew point of the compressed air is ≤ -40 °C, and the particle size of the discharged material is monitored online by an integrated laser particle size analyzer; the amplitude of the online ultrasonic vibrating screen is 0.5 - 1.0 mm, and the screen aperture is configured as 1.2 times the target value. 90 1.2 times the target value.

5. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, characterized in that, In Step 3, the main vibration source of the dual-frequency ultrasonic collaborative mill is 20kHz, and a sandwich-type ultrasonic transducer array is used; the auxiliary vibration source is 40kHz, and a sandwich-type transducer is used; the cavity of the spiral propelling milling chamber adopts an Archimedes spiral structure, the pitch is 20 - 30mm, and the rotation speed is 100 - 200rpm.

6. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, characterized in that, In Step 4, the rotation speed of the classification wheel of the turbo classifier is 8000 - 10000rpm, the air flow speed is 5 - 15m / s, and a plate heat exchanger is used to maintain the classification air flow temperature at 15 - 25°C; the number of times the coarse powder is recycled through Steps 2 to 4 is 2 - 3 times.

7. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, characterized in that, Instant high-temperature sterilization is that the classified protein powder obtained in Step 4 contacts superheated steam in the mixing chamber of the sterilizer for 0.5 - 1.5 seconds, and then the protein particles with a particle size ≥5μm are separated and collected; the temperature of the superheated steam is 140 - 150°C, the degree of superheat is 30 - 50°C, and the pressure is 0.3 - 0.5MPa.

8. The process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal according to claim 1, characterized in that, Product packaging and storage are also carried out after instant high-temperature sterilization; the entire process of the process is monitored by a data acquisition and monitoring control system.

9. An apparatus for preparing soybean protein powder by ultrasonic-assisted crushing of soybean meal, characterized in that, It is possible to prepare soy protein powder by using the process for preparing soy protein powder by ultrasonic-assisted crushing of soybean meal as described in any one of claims 1-7; it includes a closed-loop vacuum dryer (1), the discharge port of the closed-loop vacuum dryer (1) is connected to the feed port of a magnetic separator (3), the discharge port of the magnetic separator (3) is connected to the feed port of a Venturi air classifier (4), the discharge port of the Venturi air classifier (4) is connected to the feed port of a supersonic airflow crusher (6), the discharge port of the supersonic airflow crusher (6) is connected to the feed port of an on-line ultrasonic vibrating screen (8), the discharge port of the on-line ultrasonic vibrating screen (8) is connected to the feed port of a dual-frequency ultrasonic collaborative mill (9), the discharge port of the dual-frequency ultrasonic collaborative mill (9) is connected to the feed port of a turbine classifier (11), one discharge port of the turbine classifier (11) is connected to the feed port of the supersonic airflow crusher (6), the other discharge port of the turbine classifier (11) is connected to the feed port of a sterilizer (13), the discharge port of the sterilizer (13) is connected to the feed port of a long-cone cyclone separator (14), and the discharge port of the long-cone cyclone separator (14) is connected to the feed port of a fully automatic vacuum packaging machine (16).

10. The device for preparing soybean protein powder by ultrasonic-assisted crushing of soybean meal according to claim 9, characterized in that, The discharge port of the closed-loop vacuum dryer (1) is connected to the feed port of the magnetic separator (3) through a first screw conveyor (2); the discharge port of the Venturi air classifier (4) is connected to the feed port of the supersonic airflow crusher (6) through a first elevator (5); the discharge port of the supersonic airflow crusher (6) is connected to the feed port of the on-line ultrasonic vibrating screen (8) through a second screw conveyor (7); the discharge port of the dual-frequency ultrasonic collaborative mill (9) is connected to the feed port of the turbine classifier (11) through a second elevator (10); the turbine classifier (11) is also connected to a plate heat exchanger (12); the discharge port of the long-cone cyclone separator (14) is connected to the feed port of the fully automatic vacuum packaging machine (16) through a third elevator (15).

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