A cooling and fragrance stabilizing process for rapeseed roasting link

Abstract

The present application relates to the technical field of oil production and preservation, and discloses a cooling and flavor stabilizing process for rapeseed frying, which comprises the following steps: guiding the fried rapeseed material flow into a cooling zone with a vacuum degree of 0.02 MPa to 0.05 MPa, using the sensible heat of the material to induce water flash evaporation, so that the surface of the material is cooled to an intervention window at which the steam pressure release rate decreases; spraying the surface of the material with homogenous rapeseed oil mist with a particle size of 10 μm to 50 μm, using the temperature difference to reduce the oil droplet movement viscosity, and forming a continuous oil film on the surface of the particles, the present application uses the oil film to fill the micropores of the seed coat and dissolve and capture the fat-soluble flavor components, so that the conversion and enrichment of flavor substances from the gas phase to the liquid phase are realized, a physical barrier to block the oxygen permeation is constructed, and the oil oxidation deterioration is inhibited, thereby solving the problems of flavor loss and thermal oxidation quality deterioration in the cooling stage of the fried rapeseed.

Description

Technical Field

[0001] This invention belongs to the field of oil production and preservation technology, and in particular relates to a cooling and aroma stabilization process in the rapeseed roasting process. Background Technology

[0002] In the current rapeseed oil processing, the roasting stage determines the flavor composition of the final product. After roasting, the rapeseed material is at a high temperature of 135℃ to 145℃, where Maillard reactions continue to occur. To stop protein denaturation and prevent oil oxidation and rancidity, methods such as cylindrical cooling or negative pressure air cooling are used to cool the material. Besides hardware improvements such as refining the roasting structure or increasing the contact area, the material cooling temperature control and quality maintenance control logic also face engineering bottlenecks. For example, Chinese invention patent CN223379970U discloses a rapeseed roasting machine with several jets installed above the conveyor belt. After roasting, the rapeseed is cooled by air. In the actual process, during the high-temperature range, the internal moisture of the material comes into contact with negative pressure or strong wind, causing transient flash vaporization. An outward steam flux is formed on the surface of each grain, creating a dynamic steam cushion with physical repulsion. Conventional atomized spraying or simultaneous air cooling blocks the cooling medium from the outward steam pressure and strips it off by the exhaust airflow. The liquid medium cannot reach and adhere to the surface of the grain, limiting the cooling efficiency and lacking mass transfer barrier. This causes fat-soluble flavor components such as pyrazines and sulfur-containing compounds to be lost with the exhaust steam, resulting in a significant reduction in characteristic flavor. The open cooling environment cannot suppress the thermal oxidation reaction in the early stage of cooling of high-temperature materials, and the risk of increased acid value cannot be eliminated.

[0003] Within the high-temperature range, the moisture inside the material undergoes transient flash vaporization upon contact with the negative pressure environment. This phase change process creates an outward steam flux on the surface of individual grains, generating a dynamic steam cushion with a repulsive effect. Existing cooling processes prioritize cooling speed, making it difficult to retain flavor components. When pyrazines or sulfur-containing compounds escape with the hot air, the outward steam cushion blocks the flow, making it difficult for conventional atomized spraying or simultaneous oil film coating methods to establish a liquid sealing film on the grain surface. This mass transfer barrier causes the cooling medium to be lost with the exhaust system, preventing it from contacting the material surface and resulting in a significant reduction in the characteristic flavor of the oil. Simply increasing the atomization volume or increasing the negative pressure intensity cannot penetrate the surface steam resistance; instead, it exacerbates the loss of flavor molecules and increases the deodorization pressure in subsequent refining stages.

[0004] Therefore, how to eliminate the steam cushion resistance on the surface of high-temperature materials and establish a stable and continuous homogeneous flavor capture interface is the technical problem to be solved by this invention. Summary of the Invention

[0005] This invention provides a cooling and aroma-stabilizing process for rapeseed roasting, comprising the following steps: Step 101: The roasted rapeseed material stream is introduced into a closed cooling zone. By adjusting the vacuum rate of the closed cooling zone, the vacuum degree in the closed cooling zone is maintained at 0.02MPa to 0.05MPa. The residual sensible heat carried by the rapeseed material stream is used for depressurization flash evaporation, so that the moisture on the surface of the material vaporizes and the heat is discharged with the exhaust steam flow. The cooling rate of the rapeseed material stream is controlled to be no less than 15℃ / min, and the vapor pressure on the surface of the rapeseed material stream decreases as the surface temperature decreases. Step 102: Monitor the surface temperature of the rapeseed material flow in real time. When the surface temperature of the rapeseed material flow drops to the intervention window of 105°C to 115°C, spray rapeseed oil mist with a temperature of 15°C to 25°C and an average particle size of 10μm to 50μm onto the surface of the rapeseed material flow. Utilize the temperature difference under the intervention window to reduce the kinematic viscosity of the rapeseed oil mist when it reaches the material surface. Through surface wetting and self-leveling, a continuous oil film is formed on the surface of the rapeseed material flow particles. Step 103: The seed coat micropores on the surface of rapeseed material flow particles are filled with a continuous oil film to capture and dissolve the fat-soluble flavor components that seep out from inside the rapeseed material flow, lock the fat-soluble flavor components in the oil phase, and form an oxidative shielding layer on the surface of the rapeseed material flow particles that blocks the penetration of external oxygen.

[0006] Preferably, step 102 further includes: step 1021, adjusting the spray flux of rapeseed oil mist so that the thickness of the continuous oil film on the surface of rapeseed material flow particles is maintained at 5μm to 15μm, and maintaining the fluidity between rapeseed material flow particles by physically sealing the micropores of the seed coat with oil.

[0007] Preferably, step 103 further includes: step 1031, using a continuous oil film as a solvent to capture pyrazine compounds and sulfur-containing compounds in fat-soluble flavor components, and enriching gaseous volatile components in the liquid phase oil film through phase conversion.

[0008] Preferably, in step 101, the rapeseed material flow is made to cross the temperature range of 120°C to 130°C within 3 minutes by adjusting the vacuuming rate.

[0009] Preferably, the rapeseed oil mist is prepared from cold-pressed rapeseed crude oil through a micron-level filtration system. The filtration precision of the cold-pressed rapeseed crude oil is 5μm, and the acid value of the cold-pressed rapeseed crude oil is lower than 2.0mgKOH / g.

[0010] Preferably, while step 103 is being performed, nitrogen gas with a controlled flow rate is introduced into the closed cooling zone to reduce the oxygen volume percentage in the closed cooling zone to less than 2%.

[0011] Preferably, before step 101, the method further includes: step 100, performing cyclone dust removal treatment on the roasted rapeseed material stream to remove char and dust from the surface of the rapeseed material stream and purify the substrate on which the continuous oil film adheres.

[0012] Preferably, in step 102, the temperature distribution vector of the rapeseed material flow in the closed cooling zone is obtained by a distributed temperature sensor array, and the spraying pressure of the spray head at different directions is adjusted according to the spatial difference of the temperature distribution vector so that the thickness distribution deviation of the continuous oil film formed on the surface of the rapeseed material flow is less than 10%.

[0013] Preferably, after step 103 is completed, the rapeseed material flow is fed into a press for pressing, and the fat-soluble flavor components enriched in the continuous oil film are introduced into the finished rapeseed oil obtained by mechanical extrusion.

[0014] Compared with existing technologies, the cooling and aroma-stabilizing process in the rapeseed roasting stage of this invention has the following advantages: 1. In the cooling and aroma stabilization process of rapeseed roasting, a synergistic mechanism of pre-cooling and steam exhaust with temporal decoupling is used to eliminate the transient steam shielding effect on the surface of high-temperature materials, breaking through the physical barrier of gas-solid heat exchange in traditional processes. In a specific high-temperature range after roasting, the internal moisture of the material undergoes intense flash vaporization under a slightly negative pressure environment, generating a strong outward steam flux and forming a dynamic air cushion that hinders the adhesion of cooling medium. This invention sets a specific pure negative pressure flash vaporization heat exhaust period, utilizing the latent heat of phase change of the material's own moisture to carry away a large amount of sensible heat first. While reducing the surface temperature of the material, the outward steam pressure is released and attenuated. This sequential logic of exhausting steam first and then spraying avoids the cooling oil mist being blown away by the steam flux before contacting the material, ensuring that micron-sized droplets can directly reach the surface of the seed coat, achieving a simultaneous improvement in heat exchange efficiency and medium adhesion rate.

[0015] 2. Utilizing the residual sensible heat of the material and the kinematic viscosity change characteristics of homogeneous oil mist, a continuous liquid-sealed film is induced to form, establishing a stable physical interface for flavor retention. When cold-pressed rapeseed oil mist at a temperature of 15℃ to 25℃ is introduced into a material flow at a temperature of 105℃ to 115℃, the droplets experience a sharp decrease in kinematic viscosity due to the temperature difference upon contact, resulting in self-leveling and spreading on the surface of the seed grains. This temperature-triggered physical change causes the discrete oil mist particles to rapidly fuse into a dense and continuous homogeneous oil film, physically covering the micropores of the seed coat. This oil film, acting as an absorption medium for gas-liquid two-phase mass transfer, targets and enriches the fat-soluble characteristic flavor components such as pyrazines and sulfur-containing compounds that slowly overflow from the material, altering the kinetic distribution of flavor substances and transforming them from a volatile gas phase state to a stable liquid phase dissolved state.

[0016] 3. By precisely coupling temperature and pressure gradients, rapid cooling is achieved while blocking the biochemical pathways of oil oxidation and deterioration, ensuring the chemical stability of the finished oil. The homogeneous oil film on the surface of the material not only acts as a flavor trap but also forms an antioxidant physical barrier that prevents external oxygen penetration. By maintaining a slightly negative pressure environment in the cooling chamber, heat inside the material is guided to migrate outward and flavor components are driven to accumulate in the oil film layer. At the same time, the encapsulation effect of the oil film inhibits the auto-oxidation reaction of unsaturated fatty acids at high temperatures. This process design shortens the residence time of the material in the oxidation-sensitive temperature range. Without adding chemical antioxidants, the risk of increased acid value and peroxide value of the finished oil is reduced by physical means, extending the oxidation induction period of the oil and achieving the high-standard quality goals of lipid production and preservation. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the technological logic and dynamic control process of cooling and stabilizing the aroma of rapeseed in this invention. Figure 2 This is a diagram of the integrated execution system for cooling and stabilizing fragrance and the overall linkage architecture of the present invention. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0019] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0020] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0021] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0022] A cooling and aroma-stabilizing process for rapeseed roasting includes the following steps: Step 101: The roasted rapeseed material stream is introduced into a closed cooling zone. By adjusting the vacuum rate of the closed cooling zone, the vacuum degree in the closed cooling zone is maintained at 0.02MPa to 0.05MPa. The residual sensible heat carried by the rapeseed material stream is used for depressurization flash evaporation, so that the moisture on the surface of the material vaporizes and the heat is discharged with the exhaust steam flow. The cooling rate of the rapeseed material stream is controlled to be no less than 15℃ / min, and the vapor pressure on the surface of the rapeseed material stream decreases as the surface temperature decreases. Step 102: Monitor the surface temperature of the rapeseed material flow in real time. When the surface temperature of the rapeseed material flow drops to the intervention window of 105°C to 115°C, spray rapeseed oil mist with a temperature of 15°C to 25°C and an average particle size of 10μm to 50μm onto the surface of the rapeseed material flow. Utilize the temperature difference under the intervention window to reduce the kinematic viscosity of the rapeseed oil mist when it reaches the material surface. Through surface wetting and self-leveling, a continuous oil film is formed on the surface of the rapeseed material flow particles. Step 103: The seed coat micropores on the surface of rapeseed material flow particles are filled with a continuous oil film to capture and dissolve the fat-soluble flavor components that seep out from inside the rapeseed material flow, lock the fat-soluble flavor components in the oil phase, and form an oxidative shielding layer on the surface of the rapeseed material flow particles that blocks the penetration of external oxygen.

[0023] Preferably, step 102 further includes: step 1021, adjusting the spray flux of rapeseed oil mist so that the thickness of the continuous oil film on the surface of rapeseed material flow particles is maintained at 5μm to 15μm, and maintaining the fluidity between rapeseed material flow particles by physically sealing the micropores of the seed coat with oil.

[0024] Preferably, step 103 further includes: step 1031, using a continuous oil film as a solvent to capture pyrazine compounds and sulfur-containing compounds in fat-soluble flavor components, and enriching gaseous volatile components in the liquid phase oil film through phase conversion.

[0025] Preferably, in step 101, the rapeseed material flow is made to cross the temperature range of 120°C to 130°C within 3 minutes by adjusting the vacuuming rate.

[0026] Preferably, the rapeseed oil mist is prepared from cold-pressed rapeseed crude oil through a micron-level filtration system. The filtration precision of the cold-pressed rapeseed crude oil is 5μm, and the acid value of the cold-pressed rapeseed crude oil is lower than 2.0mgKOH / g.

[0027] Preferably, in step 102, the spray frequency of the spray head is adjusted in real time through compensation parameters, which follow the following logic: L=k×V / T, where L is the compensation pulse value of the spray frequency; k is the preset flow rate ratio coefficient; V is the instantaneous volumetric flow rate of the rapeseed material flow collected by the flow meter; and T is the real-time surface temperature of the rapeseed material flow collected by the infrared sensor.

[0028] Preferably, while step 103 is being performed, nitrogen gas with a controlled flow rate is introduced into the closed cooling zone to reduce the oxygen volume percentage in the closed cooling zone to less than 2%.

[0029] Preferably, before step 101, the method further includes: step 100, performing cyclone dust removal treatment on the roasted rapeseed material stream to remove char and dust from the surface of the rapeseed material stream and purify the substrate on which the continuous oil film adheres.

[0030] Preferably, in step 102, the temperature distribution vector of the rapeseed material flow in the closed cooling zone is obtained by a distributed temperature sensor array, and the spraying pressure of the spray head at different directions is adjusted according to the spatial difference of the temperature distribution vector so that the thickness distribution deviation of the continuous oil film formed on the surface of the rapeseed material flow is less than 10%.

[0031] Preferably, after step 103 is completed, the rapeseed material flow is fed into a press for pressing, and the fat-soluble flavor components enriched in the continuous oil film are introduced into the finished rapeseed oil obtained by mechanical extrusion.

[0032] Example 1: In the industrial application scenario of a continuous strong-aroma rapeseed oil pressing production line, the roasted rapeseed material stream is continuously discharged at an initial temperature of 140°C. At this time, the Maillard reaction inside the material is active, accompanied by the rapid volatilization of fat-soluble flavor components such as sulfur-containing compounds and pyrazines. Traditional cooling methods, when applying strong negative pressure to reduce temperature and inhibit oil oxidation and rancidity, cause the moisture inside the material to directly vaporize in the low-pressure environment. Transient flash evaporation forms an outward steam flux with a repulsive effect on the surface of individual seeds. The outward steam pressure constructs a physical barrier, causing the exhaust airflow to strip away the simultaneously sprayed liquid cooling medium, preventing the liquid cooling medium from adhering to the material surface. The cooling process and the flavor substance locking mechanism conflict in physical space, and a large number of characteristic flavor components are irreversibly lost with the exhaust airflow. The cooling and aroma stabilization process introduces the roasted rapeseed material stream into a closed cooling zone. By adjusting the vacuum rate, the vacuum degree in the zone is maintained at 0.03MPa. In the initial stage of introduction, the spray system is kept closed. The residual sensible heat carried by the rapeseed material stream is used to trigger depressurized flash evaporation, making the material... A large amount of moisture on the surface of the material vaporizes and releases heat with the exhaust steam. The cooling rate is set to be no less than 15℃ / min. The high temperature peak of the repulsive medium is eliminated through the flash evaporation heat removal mechanism, so that the vapor pressure outward from the surface of the rapeseed material decreases as the surface temperature decreases. According to the momentum balance law of gas-solid two phases, when the surface temperature of the rapeseed material is in the range of 105℃ to 115℃, the residual vapor momentum flux emitted from the micropores of the material decreases to below the inertial penetration kinetic energy of 10μm to 50μm oil mist droplets at the preset initial velocity. The physical boundary ensures the liquid medium When the rapeseed reaches the surface of the grain by crossing the gas phase barrier layer, during the pure negative pressure heat dissipation period when the surface temperature of the rapeseed drops from 140℃ to 115℃, the free water inside the material has undergone a violent phase change and has been completely extracted. At this time, the residual water in the range of 105℃ to 115℃ is mainly bound water bound by the capillary force of the surface pores. Its vaporization rate is limited by the diffusion resistance inside the solid phase, exhibiting a slow seepage characteristic with an extremely low flow rate. In this physical process, the surface temperature of the material at 105℃ to 115℃ is higher than 0.02MPa to 0.The boiling point of water vapor at a vacuum of 0.5 MPa is relatively low. However, due to the complete removal of free water from the surface and internal macropores of the material by the initial pure negative pressure flash evaporation, the remaining water inside the material mainly exists in the form of chemically bound water or capillary water in micropores. When this type of water migrates across the solid matrix to the surface, it needs to overcome significant micropore diffusion resistance and physical adsorption energy. Its release rate changes from being dominated by the initial flash phase change to being dominated by confined diffusion in the later stages. In actual engineering operations, the steam flux dynamic pressure data monitored by the infrared sensor array shows that when the surface temperature drops to 115℃, the normal steam repulsion force on the surface of a single seed grain has decreased to 12-18 mPa, a value far lower than the jet impact dynamic pressure of 250-300 mPa imparted to the oil mist droplets by the high-pressure nozzle. Therefore, within this intervention window, cold-pressed rapeseed oil droplets can effectively break through the extremely thin boundary layer formed by residual diffused steam and directly adhere to the rapeseed seed coat surface.

[0033] The system no longer forms a strong repulsive vapor cushion. Simultaneously, when releasing oil mist, the ultrasonic atomizing nozzle utilizes the system's internal micro-positive pressure carrier gas, based on an initial physical jet velocity of 15 m / s to 20 m / s for the droplets. This allows the tiny 10 μm to 50 μm droplets to acquire sufficient initial kinetic energy to overcome the aforementioned weak vapor boundary layer resistance, ensuring direct contact between the droplets and the high-temperature solid surface. Before introducing rapeseed oil mist, the system executes a calibration procedure based on fluid mass conservation parameters to determine the flow rate proportionality coefficient k. A known mass of roasted rapeseed benchmark sample is extracted, and the overall specific surface area of ​​the benchmark sample is obtained. The theoretical required to physically spread a 10 μm thick oil film on the overall specific surface area is calculated. Regarding grease quality, the main control unit sets the ratio of the theoretical grease quality to the product of the reference sample volume and corresponding surface temperature as the flow rate proportionality coefficient k. During continuous operation, the main control unit calculates the output signal based on the compensation parameter logic formula L=k×V×T. In the formula, L refers to the duty cycle of the hydraulic oil supply pump control pulse, V refers to the instantaneous volumetric flow rate, and T refers to the real-time surface temperature. The control pulse duty cycle L constrains the overall grease delivery volume, and is separated from the ultrasonic excitation frequency that determines the surface droplet size in the control logic and physical execution link. To ensure that the control pulse duty cycle calculated by the formula can be accurately converted into the corresponding fluid delivery quality, the oil supply system is equipped with a positive displacement gear pump and... The pressure-stabilizing supply circuit, composed of a constant-pressure relief valve, features a fixed single-cycle displacement of the positive displacement gear pump. After the constant-pressure relief valve filters out the nonlinear interference of pipeline back pressure fluctuations, the grease pumping volume and the pulse duty cycle of the drive motor exhibit a linear positive correlation unaffected by back pressure within the PWM control cycle. Therefore, the system can directly map the product of the volumetric flow rate representing the cooling load demand and the surface temperature into the linear opening of the hydraulic oil pump, achieving seamless coupling between the electronic control logic and the fluid dynamics response. When the surface temperature of the rapeseed material flow drops to the intervention window of 110℃, the distributed ultrasonic atomizing nozzles are activated to spray a solution of grease at a temperature of [missing value] onto the surface of the rapeseed material flow. Rapeseed oil mist at 20℃ with an average particle size of 30μm. The temperature difference drives the decrease in the kinematic viscosity of the liquid cold-pressed rapeseed oil droplets that reach the surface of the material. The highly fluid fine oil droplets wet and spread along the surface of the seed coat, reconstructing the discrete liquid phase medium into a continuous oil film with a uniform thickness of 10μm. When performing control logic compensation for the real-time temperature T of the material, the core control logic of this invention follows the physical principle that heat balance and flavor capture efficiency are positively correlated. Since the rapeseed material flow with higher temperature has a higher residual heat load and stronger flavor dispersion force, in order to achieve the cooling and aroma stabilization effect instantly, the matching oil film heat volume and dissolution medium flux are provided.In its specific calculations, the main control unit treats the instantaneous volumetric flow rate V and the real-time surface temperature T as inversely proportional incremental indicators. The larger the product of the two, the higher the instantaneous heat load and total surface area load the system needs to cover. The control pulse duty cycle L of the hydraulic oil supply pump must be linearly proportional to the temperature T; that is, the pumping opening is determined through a product logic defined by a formula. This design ensures that when production capacity fluctuates or the roasting temperature drifts, the system can enhance the oil film spreading density by increasing the oil supply pressure and duty cycle, thereby locking in characteristic aroma molecules at high temperatures within a very short physical contact time.

[0034] A distributed temperature sensor array is used to acquire the temperature distribution vector of rapeseed material flow within a closed cooling zone. Based on the principle of local heat exchange and phase change equilibrium, a closed-loop feedback mechanism between the spatial temperature field and the medium supply is established. The control unit extracts the lowest temperature in the temperature distribution vector as a reference baseline and calculates the relative temperature difference ΔT between each spatial sub-region. The control unit calculates the corresponding azimuth pressure compensation increment ΔP according to the linear transformation function ΔP=c×ΔT, where c represents the static pressure conversion constant set based on the pipeline fluid impedance characteristics. The control unit outputs a command signal containing the pressure compensation increment ΔP to drive the proportional valve in the corresponding region to adjust the back pressure of the fluid pipeline. The specific value of the static pressure conversion constant c is determined by the first-order linearized slope of the pressure-flow characteristic curve of the atomizing nozzle in the local pipeline under rated operating conditions after Taylor expansion. Its physical meaning is single The local fluid back pressure difference that needs to be compensated for by the temperature difference is determined in the actual flow control feedback execution flow diagram. After receiving the digital command signal, the electro-hydraulic proportional valve installed in each parallel branch adjusts the valve core displacement through the servo motor to change the throttling cross-sectional area of ​​the local flow channel, thereby fine-tuning the dynamic water head pressure in front of the corresponding nozzle, and thus adjusting the absolute mass of oil mist spraying in the local area until the infrared array detects that the surface temperature of the sub-area has fallen back to the average baseline of the whole field. The control unit synchronously collects the secondary cooling gradient of the rapeseed material flow after the oil film is covered. The spatial consistency of the secondary cooling gradient is used to indirectly characterize the amount of heat carried away per unit area, replacing the surface optical means to confirm the consistency of oil spreading with overall thermodynamic parameters. The spraying pressure of different directional spray nozzles is adjusted according to the temperature distribution vector space difference, so that the thickness distribution deviation of the continuous oil film on the surface of the rapeseed material flow is less than 10%.

[0035] The above-mentioned rapeseed oil mist was prepared by selecting cold-pressed rapeseed crude oil. The continuous oil film filled all the seed coat micropores on the surface of the rapeseed material flow particles, and the oil physically sealed the micropores, maintaining the overall fluidity between the rapeseed material flow particles. At the same time, a gas-liquid two-phase mass transfer interface for targeted adsorption was constructed on the local surface of the particles. The continuous oil film captured and dissolved pyrazine compounds and sulfur-containing compounds that seeped out from the inside of the rapeseed material flow under the drive of residual heat, changing the kinetic distribution state of fat-soluble flavor components and guiding them to accumulate from the gas phase to the liquid phase oil film. The dense liquid oil phase network formed an oxidation shield layer on the surface of the rapeseed material flow particles, blocking the auto-oxidation chain of unsaturated fatty acids under high temperature. Finally, the rapeseed material flow introduced into the press carried the characteristic flavor components locked in the oil phase and the bulk oil in a low initial acid value state.

[0036] Example 2: Physical verification of the cooling process in a continuous aromatic rapeseed oil pressing production line was conducted using an industrial-grade continuous roasting and vacuum cooling test platform. This platform integrated a vacuum control system with a range of 0.01 MPa to 0.1 MPa and a control accuracy of 0.005 MPa. An infrared surface temperature scanning array with a temperature measurement accuracy of 0.1℃ and a sampling frequency of 50 Hz was installed inside the platform. The spray module used a piezoelectric ultrasonic atomizing nozzle matrix with continuously adjustable droplet size in the range of 5 μm to 100 μm. The concentration of volatile flavor components was determined using gas chromatography-mass spectrometry (GC-MS), and the initial acid value of the oil was detected using the national standard titration method. The system was then injected with cold... To mitigate the initial moisture content fluctuation noise of rapeseed in the cold-pressed area, a random distribution variable with a fluctuation range of ±2% is superimposed on a preset benchmark to reproduce the discrete humidity conditions of batch raw materials. The surface temperature parameter at the intervention window needs to balance the vapor pressure repulsion effect and the degradation requirements of oil droplet kinematic viscosity. When the surface temperature of the rapeseed material flow remains above 115℃, the latent heat of vaporization of internal moisture is released outward, forming a normal vapor pressure greater than the kinetic energy of the oil mist. This normal vapor pressure constructs an aerodynamic barrier, rebounding and stripping away the deposited liquid medium. When the surface temperature is below 105℃, the residual sensible heat cannot overcome the initial kinematic viscosity of cold-pressed rapeseed oil. After contacting the material, the oil droplets lack the self-leveling spreading force, leading to continuous... To address the oil film disruption, a temperature range of 105℃ to 115℃ was selected as the oil mist intrusion window. This ensured that the attenuated outward vapor pressure was weaker than the oil mist adhesion. Interfacial heat conduction reduced the viscosity of oil mist droplets at 15℃ to 25℃ upon contact, driving capillary penetration and continuous spreading of fine oil droplets along the seed coat micropores. Three experimental groups covering the numerical boundaries and three control groups showing deviations were configured to verify the spatiotemporal coupling law of gas-solid two-phase heat transfer. The initial temperature of the rapeseed material flow in each group was maintained at 140℃. In experimental group 1, the vacuum rate was adjusted to maintain a vacuum of 0.02MPa, and the surface temperature of the intrusion window was set at 105℃. A temperature of 15℃ and an average particle size of 10 mm were used. In test group 2, the vacuum was adjusted to 0.03 MPa, the surface temperature was set to 110°C, and oil mist with an average particle size of 30 μm and a temperature of 20°C was used. In test group 3, the vacuum was adjusted to 0.05 MPa, the surface temperature was set to 115°C, and oil mist with an average particle size of 50 μm and a temperature of 25°C was used. In control group 1, the oil mist spraying step was cut off, and cooling was achieved solely through reduced pressure flash evaporation at 0.03 MPa. In control group 2, an early intervention condition was constructed, and oil mist with an average particle size of 30 μm was sprayed at a surface temperature of 125°C. In control group 3, an over-limit particle size condition was constructed, and oil mist with an average particle size of 80 μm was sprayed at a surface temperature of 110°C.

[0037] After the test platform was started, the infrared array continuously monitored the surface temperature evolution. The cooling rates of test groups 1, 2, and 3 reached 16.2℃ / min, 18.5℃ / min, and 15.8℃ / min, respectively. Under environmental noise interference with an initial moisture content fluctuation of ±2%, the reduced pressure flash evaporation mechanism adaptively matched the vaporization amount based on the physical differences in moisture content, resulting in a drift of only ±4.5s in the time to reach the intervention window. Gas chromatography-mass spectrometry (GC-MS) confirmed that the pyrazine compound rejection amount in test group 2 reached 31.2 mg / kg, with the initial acid value maintained at 0.85 mg / g; the pyrazine compound rejection amount in test group 1 was 29.5 mg / kg, with an initial acid value of 0.88 mg / g; and the pyrazine compound rejection amount in test group 3 was 28.8 mg / kg, with an initial acid value of 0.91 mg / g. All three groups of data met the preset specification limits. Control group 1 lost the continuous oil film seal, allowing moisture vaporization to be released in an open state throughout the process. The residue retention decreased to 12.4 mg / kg. In control group 2, the spraying was triggered at 125℃, encountering undiminished reverse vapor pressure. The exhaust gas flow forcibly entrained the escaping oil mist, reducing the coverage to 38.5%, resulting in a decrease in the residue retention of pyrazine compounds to 16.7 mg / kg. In control group 3, the large-diameter oil droplets could not spread out to form discrete liquid spots under the surface tension at 110℃. Oxygen permeated through the exposed micropores, causing the initial acid value to rise to 1.65 mg / g, exceeding the upper limit of the intervention temperature or the upper limit of the droplet size. The vapor stripping effect and spreading blocking effect cause the reconstruction of the gas-liquid two-phase mass transfer interface to fail. By delaying the process within a vacuum range of 0.02MPa to 0.05MPa until the surface temperature window of 105℃ to 115℃ is reached, oil mist with an average particle size of 10μm to 50μm is sprayed to eliminate the physical obstruction to the outward vapor flux. The spatiotemporal misalignment intervention process within this parameter range maintains the kinetic conversion channel of fat-soluble flavor components from gas phase dissipation to liquid phase dissolution, reducing the probability of oxidative deterioration of the bulk oil.

[0038] Example 3: In a continuous strong-aroma rapeseed oil pressing production line, the initial moisture content of the roasted rapeseed material stream fluctuates randomly. The latent heat of vaporization released by depressurization flash evaporation in the closed cooling zone exhibits non-stationary characteristics. The vacuum system with a fixed pumping rate faces the technical problem of transient overload of vapor pressure inside the cavity. The fixed atomization excitation parameters cannot adapt to the dynamic viscosity and surface tension changes of cold-pressed rapeseed oil in the range of 15°C to 25°C. The above environmental constraints cause the oil mist particle size reaching the surface of the rapeseed material stream to deviate from the preset range of 10μm to 50μm, inducing oil mist aggregation or the formation of discrete liquid spots on the material surface, resulting in the failure of gas-liquid two-phase mass transfer interface reconstruction and causing local loss of fat-soluble flavor components. The closed cooling zone integrates a closed loop consisting of an absolute pressure sensor and a variable frequency vacuum pump. The pressure control network uses an absolute pressure sensor to collect the current vacuum level in the cavity in real time at a sampling frequency of 100Hz. The controller calculates the first-order time derivative of the vacuum level between adjacent sampling periods. When it exceeds the vaporization surge threshold of 0.005MPa / s, the controller generates a feedforward compensation command based on the difference between the current vacuum level and the target vacuum level. This drives the variable frequency vacuum pump to increase its operating frequency to 1.5 times the base frequency. The variable frequency vacuum pump counteracts the transient outward steam flux by increasing the pumping volume rate, maintaining the absolute vacuum level in the closed cooling zone within the operating range of 0.02MPa to 0.05MPa. This operation allows the rapeseed material flow to maintain a cooling rate of no less than 15℃ / min by relying on residual sensible heat, eliminating the repulsive interference of vapor pressure on oil mist spreading.

[0039] The distributed ultrasonic atomizing nozzle matrix is ​​equipped with a variable frequency drive source with impedance matching function. Temperature probes inside the pipeline extract the delivery temperature of the cold-pressed rapeseed oil in real time. The controller calls upon a built-in physical correlation matrix of kinematic viscosity and surface tension based on the delivery temperature. When the input temperature decreases from 25℃ to 15℃, causing an increase in the oil's surface tension, the variable frequency drive source simultaneously increases the ultrasonic drive frequency applied to the piezoelectric ceramic resonator from 60kHz to 120kHz. In this physical execution architecture, the ultrasonic atomizing nozzle matrix does not rely on forcibly exciting a single piezoelectric ceramic chip across frequency bands. Instead, it integrates dual-band independent resonant physical channels with fundamental frequencies of 60kHz and 120kHz. When the controller outputs a frequency increase command, the system essentially cuts off the power supply to the 60kHz resonant circuit through a solid-state relay array and instantly activates the matching 120kHz inherent resonant circuit. Another set of specific piezoelectric ceramic oscillators with different frequencies. This driving mode based on hardware physical channel switching ensures that the piezoelectric crystal is always fully resonant at its calibrated resonant point, avoiding impedance mismatch and amplitude attenuation problems caused by deviation from the resonant point. The ultrasonic driving source uses high-frequency mechanical excitation force to cut off the oil micro-jets under high surface tension, generating rapeseed oil mist with an average particle size of 10μm to 50μm. When the oil mist droplets with a temperature of 15℃ to 25℃ come into contact with rapeseed particles with a surface temperature of 105℃ to 115℃, the interfacial heat conduction causes the viscosity of the oil droplets to decrease. The low-viscosity fine oil droplets are driven by the capillary force generated along the micropores of the seed coat to self-level and spread, physically fusing to form a continuous oil film of uniform thickness. The continuous oil film constructs an oxide shielding layer that closes the micropores and dissolves pyrazine compounds that seep out from the inside of the particles, outputting a pressed raw material with a low initial acid value and locked characteristic flavor.

[0040] Example 4: In the calibration conditions of a continuous aromatic rapeseed oil pressing production line, the physicochemical properties of a batch of cold-pressed rapeseed crude oil exhibit discrete deviations. The testing equipment collects the surface tension and kinematic viscosity parameters of the crude oil in the temperature range of 15℃ to 25℃ with a test gradient of 1℃. The calculation module receives the collected parameters and calculates the critical mechanical excitation energy required to overcome the corresponding surface tension and induce microjet fracture. Based on the calculated critical mechanical excitation energy, it generates specific ultrasonic frequency values ​​for each temperature node that release droplets with a particle size of 10μm to 50μm. The storage module encapsulates and maps the discrete temperature nodes with the corresponding surface tension parameters, kinematic viscosity parameters, and specific ultrasonic frequency values ​​to construct a physical correlation matrix of kinematic viscosity and surface tension for this batch of oil.

[0041] During production line operation, the pipeline temperature probe extracts the conveying temperature of cold-pressed rapeseed crude oil in real time. The controller extracts this conveying temperature and matches the corresponding target ultrasonic frequency value in the physical correlation matrix of kinematic viscosity and surface tension. The controller converts the target ultrasonic frequency value into a digital control signal. The frequency converter receives the digital control signal and modulates the alternating electric field input to the piezoelectric ceramic oscillator. The piezoelectric ceramic oscillator outputs a mechanical excitation force that matches the target ultrasonic frequency value. The ultrasonic atomizing nozzle releases rapeseed oil mist with a particle size converging in the range of 10μm to 50μm according to the mechanical excitation force. The oil mist droplets with a temperature of 15℃ to 25℃ reach the rapeseed particles with a surface temperature of 105℃ to 115℃. The interfacial heat conduction reduces the kinematic viscosity of the oil mist droplets. The fine oil droplets spread and close under the capillary force generated by the micropores of the seed coat, forming a continuous oil film. The rapeseed material flow carries the pyrazine compounds and sulfur-containing compounds dissolved in the oil film into the next pressing stage.

[0042] Example 5: In the deployment of a continuous aromatic rapeseed oil pressing production line with heterogeneous production capacity, the ratio of the physical cavity volume of the closed cooling zone to the mass flow rate of the rapeseed material changes. The fixed vaporization surge threshold and the static variable frequency vacuum pump feedforward compensation ratio cannot adaptively change the gas-solid two-phase volume relationship. The volume mismatch causes a physical lag in the exhaust steam extraction rate during the depressurization flash evaporation cooling stage, causing the absolute vacuum degree in the closed cooling zone to deviate from the set operating range of 0.02MPa to 0.05MPa, resulting in a cooling rate lower than the preset lower limit and uncontrolled water loss on the material surface. Under the condition of material loading and commissioning, the system starts the air extraction load baseline calibration program. The feeding module delivers a dry rapeseed material reference flow with a constant initial moisture content into the closed cooling zone. The water injection module injects vaporization medium into the dry rapeseed material reference flow in a stepped manner according to the preset mass gradient to reproduce the peak state of moisture release inside the rapeseed after roasting. The absolute pressure sensor collects the pressure step data inside the cavity under different water injection gradients in real time.

[0043] The computing unit analyzes the pressure step data and extracts the first-order time derivative of the vacuum degree corresponding to the maximum water injection gradient. This first-order time derivative of the vacuum degree is established as the threshold for the targeted vaporization surge. Based on the ideal gas law, the target pumping volumetric rate required to vent the corresponding stepped vaporization medium is calculated. The ratio of the target pumping volumetric rate to the basic operating frequency of the variable frequency vacuum pump is calculated, and the computing unit outputs this ratio and solidifies it as a volume mapping coefficient. ,in, This is a constant representing the ratio of the frequency compensation increment to the current pressure change rate. After the production line enters normal operation, the controller compares the first-order time derivative of the real-time vacuum degree returned by the absolute pressure sensor with the target vaporization surge threshold in real time. When the first-order time derivative of the real-time vacuum degree is greater than the target vaporization surge threshold, the controller reads the volume mapping coefficient. The controller will map the volume coefficients. The frequency compensation increment of the variable frequency vacuum pump is calculated by multiplying the current pressure difference that exceeds the threshold. The controller outputs a digital control signal containing the frequency compensation increment to drive the variable frequency vacuum pump to speed up operation. Under heterogeneous production conditions, the closed cooling zone maintains the absolute vacuum degree within the operating range of 0.02MPa to 0.05MPa and undertakes the subsequent oil mist spraying process.

[0044] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A cooling and aroma-stabilizing process for rapeseed roasting, characterized in that, Includes the following steps: Step 101: The roasted rapeseed material stream is introduced into a closed cooling zone. By adjusting the vacuum rate of the closed cooling zone, the vacuum degree in the closed cooling zone is maintained at 0.02MPa to 0.05MPa. The residual sensible heat carried by the rapeseed material stream is used for depressurization flash evaporation, so that the surface moisture of the material vaporizes and the heat is discharged with the exhaust steam flow. The cooling rate of the rapeseed material stream is controlled to be no less than 15℃ / min, and the vapor pressure on the surface of the rapeseed material stream decreases as the surface temperature decreases. Step 102: Monitor the surface temperature of the rapeseed material flow in real time. When the surface temperature of the rapeseed material flow drops to the intervention window of 105℃ to 115℃, spray a solution with a temperature of 15℃ onto the surface of the rapeseed material flow. Up to 25 Furthermore, the rapeseed oil mist with an average particle size of 10μm to 50μm utilizes the temperature difference under the intervention window to reduce the kinematic viscosity of the rapeseed oil mist when it reaches the surface of the material, and forms a continuous oil film on the surface of the rapeseed material flow particles through surface wetting and self-leveling. Step 103: Use a continuous oil film to fill the seed coat micropores on the surface of rapeseed material flow particles, capture and dissolve the fat-soluble flavor components that seep out from inside the rapeseed material flow, lock the fat-soluble flavor components in the oil phase, and form an oxidative shielding layer on the surface of rapeseed material flow particles that blocks the penetration of external oxygen. Step 102 further includes: Step 1021, adjusting the spray flux of rapeseed oil mist so that the thickness of the continuous oil film on the surface of rapeseed material flow particles is maintained at 5μm to 15μm, and maintaining the fluidity between rapeseed material flow particles by physically sealing the micropores of the seed coat with oil. In step 102, the temperature distribution vector of the rapeseed material flow in the closed cooling zone is obtained by a distributed temperature sensor array. The spraying pressure of the spray head at different directions is adjusted according to the spatial difference of the temperature distribution vector so that the thickness distribution deviation of the continuous oil film formed on the surface of the rapeseed material flow is less than 10%.

2. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, Step 103 further includes: Step 1031, using a continuous oil film as a solvent to capture pyrazine compounds and sulfur-containing compounds in fat-soluble flavor components, and enriching gaseous volatile components in the liquid phase oil film through phase transformation.

3. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, In step 101, the rapeseed material flow is made to cross the temperature range of 120°C to 130°C within 3 minutes by adjusting the vacuuming rate.

4. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, Rapeseed oil mist is prepared from cold-pressed rapeseed crude oil through a micron-level filtration system. The filtration precision of the cold-pressed rapeseed crude oil is 5μm, and the acid value of the cold-pressed rapeseed crude oil is less than 2.0mgKOH / g.

5. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, While step 103 is being performed, nitrogen gas with a controlled flow is introduced into the closed cooling zone to reduce the oxygen volume percentage in the closed cooling zone to less than 2%.

6. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, Before step 101, the process also includes step 100, which involves performing cyclone dust removal on the roasted rapeseed material stream to remove char and dust from the surface of the rapeseed material stream and purify the substrate on which the continuous oil film adheres.

7. The cooling and aroma-stabilizing process for rapeseed roasting according to claim 1, characterized in that, After step 103 is completed, the rapeseed material flow is fed into the press for pressing. Through mechanical extrusion, the fat-soluble flavor components enriched in the continuous oil film are introduced into the finished rapeseed oil obtained by pressing.

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