Maize germ oil preparation method based on pressed cake microstructure regulation and control

Abstract

The invention discloses a corn germ oil preparation method based on pressed cake microstructure regulation and control, and relates to the technical field of vegetable oil preparation. Corn germs are regulated to set target water content and softened in a set temperature interval, a three-section variable-pressure pressing process is adopted, cake layer compactness and temperature are detected on line, and the pressed cake microstructure is obtained. And the pressure fluctuation amplitude and frequency of second-stage squeezing are adjusted in real time through a dynamic feedback algorithm, so that the porosity and the pore connectivity rate of a squeezing cake reach the standard. Through press cake microstructure directional regulation and control and three-section variable pressure press dynamic optimization, the porosity and connectivity are remarkably improved, the solvent permeation rate is increased, the leaching time is shortened, and steam consumption, solvent turnover and power consumption are reduced. A low-temperature synchronous refining process is adopted, free fatty acids and pigments are synchronously removed under mild conditions, nutritional ingredients are effectively reserved, the energy consumption of a refining unit is reduced, the production period is shortened, the equipment utilization rate and the productivity are improved, and quality improvement, cost reduction and efficiency improvement in the whole preparation process of the corn germ oil are realized.

Description

Technical Field

[0001] This invention relates to the field of vegetable oil preparation technology, and in particular to a method for preparing corn germ oil based on the microstructure regulation of pressed cake. Background Technology

[0002] Corn germ oil production generally adopts a pre-pressing leaching process. The microstructure of the pre-pressed cake lacks active control, and the porosity, pore size distribution and connectivity fluctuate greatly, resulting in uneven solvent penetration, high mass transfer resistance, long leaching cycle, high solvent consumption and residue, and high energy consumption. This restricts the improvement of production line efficiency and increases safety and environmental risks.

[0003] Traditional refining uses high-temperature segmented processing, with degumming, deacidification, and decolorization carried out independently. High-temperature conditions easily cause a large loss of nutrients such as vitamin E and phytosterols, as well as the loss of natural flavor. At the same time, it increases the risk of trans fatty acid formation. The production process is energy-intensive and has a long processing cycle, making it difficult to meet the market demand for high-end healthy oil products.

[0004] The existing process lacks a coordinated control mechanism for pressing and leaching, and it has not achieved simultaneous deacidification and decolorization under low temperature conditions. There is still considerable room for improvement in overall processing efficiency, product quality, and energy saving. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for preparing corn germ oil based on the microstructure regulation of pressed cake. The technical solution is as follows: A method for preparing corn germ oil based on the microstructure regulation of pressed cake includes the following steps: Step 1: Adjust the corn germ to the set target moisture content and soften it within the set temperature range; Step 2: A three-stage variable pressure pressing process is adopted. The density and temperature of the cake layer are detected online. The pressure fluctuation amplitude and frequency of the second stage pressing are adjusted in real time through a dynamic feedback algorithm to ensure that the porosity and pore connectivity of the pressed cake meet the standards. Step 3: The solvent penetration time, porosity and connectivity of the pressed cake are measured within a set time using the solvent dripping method and slice image analysis method. If the preset threshold is not met, the pressure fluctuation parameters in step 2 are automatically adjusted. Step 4: Based on the connectivity and average pore size measured in Step 3, calculate the Darcy permeability of the solvent in the cake layer, and dynamically set the leaching time and solvent ratio to carry out leaching. Step 5: Under a set low temperature range, add a compound adsorbent to the crude oil to simultaneously remove free fatty acids and pigments under vacuum conditions. Step 6: After short-path distillation to deodorize, cooling, and filtration, the finished oil is obtained.

[0006] Optionally, in step 1: the target moisture content of the corn germ after adjustment is 8%-12%; the set temperature range is 70℃-85℃; and the softening time is 30-60 minutes.

[0007] Optionally, the three-stage variable pressure pressing process in step 2 is as follows: First stage: Pressure 5MPa-10MPa, heating rate 2℃ / min; Second segment: Pressure 15MPa-25MPa, superimposed with pressure fluctuations of frequency 0.1Hz-0.2Hz and amplitude ±2MPa-5MPa; Third stage: Pressure 30MPa-40MPa.

[0008] Optionally, the dynamic feedback algorithm in step 2 includes: The real-time estimated porosity is equal to 1 minus the ratio of the online detected cake layer density to the germ skeleton density, where the online detected cake layer density is the value obtained from real-time detection, and the germ skeleton density is pre-determined using the gas replacement specific gravity bottle method. When the real-time estimated porosity is lower than the set target porosity, the pressure fluctuation amplitude of the second stage is increased by an increment value. The increment value is equal to the product of the pressure coefficient and the difference between the set target porosity and the real-time estimated porosity. The pressure coefficient ranges from 0.5 MPa / % to 1 MPa / %. When the temperature inside the cake layer detected online is greater than the set maximum temperature threshold, the heating rate is reduced to 1℃ / min.

[0009] Optionally, the solvent dripping method judgment criterion in step 3 is as follows: 100 μL of n-hexane is added to the surface of the pressed cake, and the complete penetration time of the droplet is recorded. ;like Then it is judged as qualified, if This will trigger the automatic adjustment of the pressure fluctuation parameters in step 2.

[0010] Optionally, the slice image analysis method in step 3 includes: freezing and slicing the pressed cake, acquiring images under a 200x microscope, and calculating the image porosity using the OTSU threshold segmentation method. The porosity was calculated using a pixel adjacency-based disjoint-set data structure algorithm. The preset threshold is and Otherwise, automatic adjustment will be triggered.

[0011] Optionally, the formula for calculating Darcy permeability in step 4 is: ; Where K is Darcy penetration rate. The median aperture obtained from image analysis, This is the shape factor, with a value ranging from 0.7 to 0.9.

[0012] Optionally, the leaching time can be dynamically set in step 4. The formula is: ; in L is the solvent viscosity, and L is the cake layer thickness. For the leaching tank pressure differential, The initial oil content, To achieve the target oil content, When calculated When the solvent ratio is 1.2:1, reduce it by 10%-15%; otherwise, maintain the standard solvent ratio.

[0013] Optionally, in step 5: the low temperature range is set to 40℃-60℃; the compound adsorbent is composed of activated clay, activated carbon and diatomaceous earth in a mass ratio of 70:15:15, and the amount added is 1.5%-3.0% of the oil weight; the vacuum conditions are an absolute pressure of 0.08MPa-0.095MPa, and the reaction time is 30-45 minutes.

[0014] Optionally, the conditions for short-path distillation deodorization in step 6 are: temperature 100℃-110℃, absolute pressure 200Pa-300Pa, and time 30-60 minutes; in the resulting finished oil, the steam consumption of the leaching process is reduced by 15-20%, the solvent turnover is reduced by more than 10%, and the unit energy consumption of the refining process is reduced by 10%-15%.

[0015] In summary, the present invention has at least one of the following beneficial technical effects: This invention provides a method for preparing corn germ oil based on the microstructure regulation of the pressed cake. Through directional regulation of the pressed cake's microstructure and dynamic optimization using three-stage variable pressure pressing, it significantly improves porosity and connectivity, accelerates solvent penetration, shortens extraction time, and reduces steam consumption, solvent turnover, and electricity consumption. Employing a low-temperature simultaneous refining process, it simultaneously removes free fatty acids and pigments under mild conditions, effectively preserving nutrients, reducing energy consumption in the refining unit, shortening the production cycle, and improving equipment utilization and capacity. This achieves quality improvement, cost reduction, and efficiency enhancement throughout the entire corn germ oil preparation process. Attached Figure Description

[0016] Figure 1 This is a schematic flowchart of the corn germ oil preparation method based on the microstructure regulation of pressed cake according to the present invention. Detailed Implementation

[0017] The present invention will be further described in detail below with reference to the accompanying drawings.

[0018] This invention discloses a method for preparing corn germ oil based on the microstructure regulation of pressed cake.

[0019] Reference Figure 1 Example 1, a method for preparing corn germ oil based on the microstructure regulation of pressed cake, includes the following steps: Step 1: Adjust the corn germ to the set target moisture content and soften it within the set temperature range; Step 2: A three-stage variable pressure pressing process is adopted. The density and temperature of the cake layer are detected online. The pressure fluctuation amplitude and frequency of the second stage pressing are adjusted in real time through a dynamic feedback algorithm to ensure that the porosity and pore connectivity of the pressed cake meet the standards. Step 3: The solvent penetration time, porosity and connectivity of the pressed cake are measured within a set time using the solvent dripping method and slice image analysis method. If the preset threshold is not met, the pressure fluctuation parameters in step 2 are automatically adjusted. Step 4: Based on the connectivity and average pore size measured in Step 3, calculate the Darcy permeability of the solvent in the cake layer, and dynamically set the leaching time and solvent ratio to carry out leaching. Step 5: Under a set low temperature range, add a compound adsorbent to the crude oil to simultaneously remove free fatty acids and pigments under vacuum conditions. Step 6: After short-path distillation to deodorize, cooling, and filtration, the finished oil is obtained.

[0020] By adopting the above technical solution, using corn germ as raw material, the processing performance of the material is improved through moisture adjustment and softening. A three-stage variable pressure pressing process combined with online monitoring is used to achieve directional shaping of the microstructure of the pressed cake. Solvent dripping and slice image analysis are used for rapid structural determination. Extraction parameters are dynamically matched based on Darcy permeability calculations. Purification is then achieved through low-temperature simultaneous refining and short-path distillation deodorization. The entire process uses the porous structure of the pressed cake as the core control carrier, linking parameters of each process to form an integrated corn germ oil processing path that optimizes structure and achieves high-efficiency preparation, ensuring simultaneous improvement in production efficiency and product quality.

[0021] In Example 2, in step 1: the target moisture content of the corn germ after adjustment is 8%-12%; the set temperature range is 70℃-85℃; and the softening time is 30-60 minutes.

[0022] By employing the above technical solutions, the moisture content of corn germ can be controlled within the range of 8% to 12%, maintaining suitable plasticity and mechanical strength. This avoids crushing during pressing due to excessively low moisture content and cake sticking due to excessively high moisture content. Softening at 70℃ to 85℃ for 30 to 60 minutes can fully disrupt the germ cell structure, reduce internal friction within the kernel, and ensure uniform softening. This provides a material basis for the formation of a stable and interconnected pore structure during subsequent pressing, while preventing oil oxidation or structural abnormalities caused by excessive softening conditions.

[0023] Example 3, the three-stage variable pressure pressing process in step 2 is specifically as follows: First stage: Pressure 5MPa-10MPa, heating rate 2℃ / min; Second segment: Pressure 15MPa-25MPa, superimposed with pressure fluctuations of frequency 0.1Hz-0.2Hz and amplitude ±2MPa-5MPa; Third stage: Pressure 30MPa-40MPa.

[0024] By adopting the above technical solution, the three-stage variable pressure pressing uses gradient pressure and temperature coordinated control. The first stage uses a pressure of 5MPa to 10MPa combined with a heating rate of 2℃ / min to preheat the germ and perform preliminary compaction, establishing a uniform cake layer. The second stage uses a pressure of 15MPa to 25MPa, superimposed with pressure fluctuations of 0.1Hz to 0.2Hz frequency and ±2MPa to 5MPa amplitude, using pressure oscillation to break down the dense layer of the cake, expand the pore channels, and improve connectivity. The third stage uses a high pressure of 30MPa to 40MPa to stabilize the cake morphology, ensuring the pre-pressed oil yield, and ultimately forming a porous pressed cake structure with high permeability.

[0025] Example 4, the dynamic feedback algorithm in step 2 includes: The real-time estimated porosity is equal to 1 minus the ratio of the online detected cake layer density to the germ skeleton density, where the online detected cake layer density is the value obtained from real-time detection, and the germ skeleton density is pre-determined using the gas replacement specific gravity bottle method. When the real-time estimated porosity is lower than the set target porosity, the pressure fluctuation amplitude of the second stage is increased by an increment value. The increment value is equal to the product of the pressure coefficient and the difference between the set target porosity and the real-time estimated porosity. The pressure coefficient ranges from 0.5 MPa / % to 1 MPa / %. When the temperature inside the cake layer detected online is greater than the set maximum temperature threshold, the heating rate is reduced to 1℃ / min.

[0026] By adopting the above technical solution, porosity can be estimated in real time. ,in For online detection of pie layer density, The skeletal density of the embryo was determined in advance using the gas displacement hydrostatic bottle method. when Porosity below the set target At that time, the pressure fluctuation amplitude of the second segment will be increased. , ,in ; By detecting the cake layer density online and combining it with the germ skeleton density pre-determined by the gas displacement specific gravity bottle method, the porosity of the pressed cake is calculated in real time, enabling online quantitative evaluation of the microstructure. When the real-time porosity is lower than the target value, the fluctuation increment is calculated based on a pressure coefficient of 0.5 MPa / % to 1 MPa / % to dynamically correct the second-stage pressure parameter and rapidly increase the porosity. When the internal temperature of the cake layer exceeds the upper limit threshold, the heating rate is reduced to 1℃ / min to prevent the cake from becoming excessively dense due to high temperatures, maintain the stability of the pore structure, and ensure that the structural indicators continue to meet the standards.

[0027] Example 5, the solvent dripping method judgment criterion in step 3 is: 100 μL of n-hexane is added to the surface of the pressed cake, and the complete penetration time of the droplet is recorded. ;like Then it is judged as qualified, if This will trigger the automatic adjustment of the pressure fluctuation parameters in step 2.

[0028] By adopting the above technical solution and using 100 μL of n-hexane as the detection reagent, the solvent penetration performance of the pressed cake is directly characterized by the dripping time. A penetration time of no more than 2.0 seconds indicates that the pore structure of the cake meets the requirements for rapid leaching. When the penetration time is no less than 2.5 seconds, the structure is deemed substandard, and the system automatically triggers the adjustment of pressing parameters to prevent unqualified cake from entering the leaching process, thus ensuring leaching efficiency from the source and reducing solvent waste and production time.

[0029] Example 6, the slice image analysis method in step 3 includes: freezing and slicing the pressed cake, acquiring images under a 200x microscope, and calculating the image porosity using the OTSU threshold segmentation method. The porosity was calculated using a pixel adjacency-based disjoint-set data structure algorithm. The preset threshold is and Otherwise, automatic adjustment will be triggered.

[0030] By employing the above technical solution, the pressed cake is frozen and sliced, and structural images are acquired under a 200x microscope. The OTSU threshold segmentation method is used to accurately distinguish pores from the solid matrix, and the image porosity is calculated. The pore connectivity state is identified using a pixel-adjacency-based disjoint-set data structure algorithm to obtain the pore connectivity rate. A porosity of not less than 40% and a connectivity rate of not less than 70% are used as the judgment thresholds. If these thresholds are not met, the pressing process parameters are automatically adjusted to ensure that each batch of pressed cake has a stable and efficient leaching structure.

[0031] Example 7, the formula for calculating Darcy permeability in step 4 is: ; Where K is Darcy penetration rate. The median aperture obtained from image analysis, This is the shape factor, with a value ranging from 0.7 to 0.9.

[0032] By employing the above technical solution, using pore connectivity and median pore size as core variables, and combining a shape factor correction value of 0.7 to 0.9, Darcy permeability is calculated using a formula to objectively quantify the solvent's flow capacity within the cake pores. This calculation result accurately reflects the mass transfer performance of the pressed cake, providing reliable data for the dynamic setting of leaching time and solvent ratio, and enabling precise control of the leaching process.

[0033] Example 8, step 4: dynamically setting the leaching time The formula is: ; in L is the solvent viscosity, and L is the cake layer thickness. For the leaching tank pressure differential, The initial oil content, To achieve the target oil content, When calculated When the solvent ratio is 1.2:1, reduce it by 10%-15%; otherwise, maintain the standard solvent ratio.

[0034] By adopting the above technical solution, the theoretical leaching time is calculated based on solvent viscosity, cake thickness, leaching pressure difference, initial oil content, and target oil content, combined with Darcy permeability, to match the leaching cycle with the actual mass transfer efficiency. The target oil content is set at 1% to ensure sufficient leaching. When the Darcy permeability is greater than 1×10^-12 m^2, the solvent ratio is reduced from the standard 1.2:1 by 10% to 15%, reducing solvent usage while ensuring leaching effect, and lowering solvent recovery energy consumption and residue risks.

[0035] In Example 9, step 5: the low temperature range is set to 40℃-60℃; the compound adsorbent is composed of activated clay, activated carbon and diatomaceous earth in a mass ratio of 70:15:15, and the amount added is 1.5%-3.0% of the oil weight; the vacuum conditions are an absolute pressure of 0.08MPa-0.095MPa, and the reaction time is 30-45 minutes.

[0036] By employing the above technical solution, under low-temperature conditions of 40℃ to 60℃, a compound adsorbent consisting of activated clay, activated carbon, and diatomaceous earth in a 70:15:15 ratio is added at an amount of 1.5% to 3.0% of the oil weight. The oil is treated in a vacuum environment with an absolute pressure of 0.08MPa to 0.095MPa for 30 to 45 minutes. Utilizing the synergistic effect of the adsorbent components, free fatty acids and pigment impurities are selectively removed simultaneously. The low temperature and vacuum environment inhibit the degradation of nutrients, reduce side reactions, and lower refining energy consumption and auxiliary agent consumption.

[0037] In Example 10, the conditions for short-path distillation deodorization in step 6 are: temperature 100℃-110℃, absolute pressure 200Pa-300Pa, and time 30-60 minutes; in the resulting finished oil, the steam consumption of the leaching process is reduced by 15-20%, the solvent turnover is reduced by more than 10%, and the unit energy consumption of the refining process is reduced by 10%-15%.

[0038] By adopting the above technical solution, short-path distillation deodorization is carried out for 30 to 60 minutes at a temperature of 100℃ to 110℃ and an absolute pressure of 200Pa to 300Pa, gently removing odors and volatile impurities from the oil and avoiding the destruction of nutrients caused by high temperatures. Combined with optimization of the front-end pressing and leaching processes, the steam consumption in the leaching process is reduced by 15% to 20%, solvent turnover is reduced by more than 10%, and unit energy consumption in the refining process is reduced by 10% to 15%, achieving energy saving and efficiency improvement throughout the entire process and enhancing product quality.

[0039] The following specific embodiments illustrate the implementation principle of the present invention: Specific Implementation Case 1: Corn germ raw material was taken and its moisture content was first adjusted to 10%, then softened at 75℃ for 45 minutes. A three-stage variable pressure pressing method was adopted: the first stage pressure was 8MPa with a heating rate of 2℃ / min; the second stage pressure was 20MPa, superimposed with pressure fluctuations at a frequency of 0.15Hz and an amplitude of ±3MPa; the third stage pressure was 35MPa. During the pressing process, the density and temperature of the cake layer were monitored online, and the pressure fluctuation amplitude was adjusted in real time according to a dynamic feedback algorithm. The pressure coefficient was set at 0.8MPa / %, and when the temperature exceeded the threshold, the heating rate was reduced to 1℃ / min.

[0040] The pressed cake was tested by adding 100 μL of n-hexane. The permeation time was measured to be 1.6 seconds. Analysis using frozen sections and 200x microscopic imaging showed a porosity of 45% and a pore connectivity of 78%, both meeting the standards. Darcy permeability was calculated using the formula, with a median pore size of 0.12 mm and a shape factor of 0.8. The calculated permeability was greater than 1 × 10⁻¹² m². Based on this, the leaching time was set, and the solvent ratio was reduced by 12% from the standard value of 1.2:1, with the target residual oil rate controlled at 1%.

[0041] A compound adsorbent with a mass ratio of 70:15:15 was added to the crude extracted oil at an amount equal to 2.0% of the oil weight. The oil was then treated under vacuum conditions of 50°C and 0.09 MPa for 40 minutes to simultaneously remove free fatty acids and pigments. Subsequently, the oil was deodorized by short-path distillation at 105°C and 250 Pa for 45 minutes, and then cooled and filtered to obtain the finished corn germ oil.

[0042] Table 1 shows a comparison of the technical indicators of the preparation method in specific implementation case 1 with those of the traditional preparation method: Table 1

[0043] Traditional preparation methods employ the industry-standard pre-pressing—leaching—high-temperature segmented refining process: The germ undergoes only simple conditioning without precise moisture content control, and softening is based on experience. Pressing is a single, fixed-pressure process, without segmentation, fluctuation, or online structural control. The structure of the pressed cake is determined visually by hand, without quantitative detection or automatic parameter adjustment. Leaching uses fixed time and solvent ratios, without dynamic adjustments based on the cake structure. Refining employs high-temperature alkali refining for deacidification, high-temperature clay decolorization, and conventional steam deodorization, with temperatures exceeding 105℃, and each process is carried out independently in segments. The entire process relies on manual experience, lacking a coordinated control mechanism linking structure, leaching, and refining.

[0044] This invention significantly improves the porosity and connectivity of the pressed cake through precise conditioning, three-stage pressure variation, and dynamic feedback algorithms, solving the core problems of random structure and poor permeability in traditional pressing, and providing a stable structural foundation for efficient leaching.

[0045] Based on quantitative structural detection and dynamic setting of leaching parameters using Darcy permeability, the leaching time is shorter, steam and solvent consumption is lower, and residual oil rate is lower, resulting in significantly better production efficiency and economy than the traditional fixed parameter mode.

[0046] Low-temperature simultaneous refining and low-temperature short-path distillation avoid high-temperature damage, significantly improve the retention rate of vitamin E and phytosterols, result in lower acid value of finished oil, and make the flavor and nutrition closer to the natural state, which is significantly better than traditional high-temperature refining.

[0047] With full-process online detection, automatic adjustment, and parameter linkage, batch stability is higher, manual intervention is less, and overall energy consumption and production costs are lower, making it more suitable for large-scale continuous production.

[0048] Specific Implementation Case 2: 1. Select corn germ as raw material, adjust the moisture content to 11%, and soften it at 80℃ for 50 minutes.

[0049] 2. Three-stage variable pressure pressing: First stage: Pressure 9MPa, heating rate 2℃ / min Second section: Pressure 22MPa, plus pressure fluctuation of 0.18Hz and ±4MPa. Third section: Pressure 38MPa Online monitoring of density and temperature, with a pressure coefficient of 0.9 MPa / %, and a heating rate reduced to 1℃ / min when the temperature exceeds the limit.

[0050] 3. Press cake structure inspection: 100 μL of n-hexane permeation time was 1.5 seconds; 200x image analysis of frozen sections showed a porosity of 47% and a connectivity of 80%.

[0051] 4. Dynamic leaching: The Darcy permeability was calculated to be >1×10⁻¹²m², the solvent ratio was reduced by 14% from 1.2:1, the leaching time was calculated and set according to the formula, and the target residual oil rate was 1%.

[0052] 5. Low-temperature simultaneous refining: Temperature 55℃, compound adsorbent ratio 70:15:15, addition amount 2.5%, vacuum 0.092MPa, treatment time 42 minutes.

[0053] 6. Short-path distillation deodorization: Temperature 108℃, vacuum 280Pa, time 50 minutes, cooling and filtration to obtain the finished oil.

[0054] Table 2 shows a comparison of the technical indicators of the preparation method in specific implementation case 2 with those of the traditional preparation method: Table 2

[0055] This embodiment further improves the porosity and connectivity of the pressed cake by using a higher softening temperature, greater pressure fluctuation, and a higher pressure coefficient. The solvent penetration rate is shortened by more than 50% compared with the traditional method, fundamentally improving the leaching mass transfer conditions.

[0056] Based on dynamic optimization of leaching parameters by permeability, leaching time is shortened by 24%, steam consumption is reduced by 19%, solvent consumption is reduced by 13%, and residual oil rate is reduced to 0.9%, with resource utilization and production efficiency significantly better than traditional processes.

[0057] Low-temperature simultaneous refining combined with gentle short-path distillation increases the retention rate of vitamin E and phytosterols by more than 25%, resulting in a lower acid value, purer flavor, and complete nutrient retention in the finished oil, which is significantly superior to traditional high-temperature refined products.

[0058] The closed-loop control of parameters throughout the entire process ensures high batch consistency, shortens the production cycle by 20%, and further reduces overall energy consumption and production costs, making it more suitable for continuous, automated, and large-scale production line operation.

[0059] The preferred embodiments of the invention are not intended to limit the scope of protection of the invention. Therefore, all equivalent changes made in accordance with the structure, shape and principle of the invention should be covered within the scope of protection of the invention.

Claims

1. A method for preparing corn germ oil based on the microstructure regulation of pressed cake, characterized in that, Includes the following steps: Step 1: Adjust the corn germ to the set target moisture content and soften it within the set temperature range; Step 2: A three-stage variable pressure pressing process is adopted. The density and temperature of the cake layer are detected online. The pressure fluctuation amplitude and frequency of the second stage pressing are adjusted in real time through a dynamic feedback algorithm to ensure that the porosity and pore connectivity of the pressed cake meet the standards. Step 3: The solvent penetration time, porosity and connectivity of the pressed cake are measured within a set time using the solvent dripping method and slice image analysis method. If the preset threshold is not met, the pressure fluctuation parameters in step 2 are automatically adjusted. Step 4: Based on the connectivity and average pore size measured in Step 3, calculate the Darcy permeability of the solvent in the cake layer, and dynamically set the leaching time and solvent ratio to carry out leaching. Step 5: Under a set low temperature range, add a compound adsorbent to the crude oil to simultaneously remove free fatty acids and pigments under vacuum conditions. Step 6: After short-path distillation to deodorize, cooling, and filtration, the finished oil is obtained.

2. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 1, characterized in that, In step 1: the target moisture content of the corn germ after adjustment is 8%-12%; the set temperature range is 70℃-85℃; and the softening time is 30-60 minutes.

3. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 2, characterized in that, The three-stage variable pressure pressing process in step 2 is as follows: First stage: Pressure 5MPa-10MPa, heating rate 2℃ / min; Second segment: Pressure 15MPa-25MPa, superimposed with pressure fluctuations of frequency 0.1Hz-0.2Hz and amplitude ±2MPa-5MPa; Third stage: Pressure 30MPa-40MPa.

4. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 3, characterized in that, The dynamic feedback algorithm in step 2 includes: The real-time estimated porosity is equal to 1 minus the ratio of the online detected cake layer density to the germ skeleton density, where the online detected cake layer density is the value obtained from real-time detection, and the germ skeleton density is pre-determined using the gas replacement specific gravity bottle method. When the real-time estimated porosity is lower than the set target porosity, the pressure fluctuation amplitude of the second stage is increased by an increment value. The increment value is equal to the product of the pressure coefficient and the difference between the set target porosity and the real-time estimated porosity. The pressure coefficient ranges from 0.5 MPa / % to 1 MPa / %. When the temperature inside the cake layer detected online is greater than the set maximum temperature threshold, the heating rate is reduced to 1℃ / min.

5. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 4, characterized in that, The criterion for determining the solvent dripping method in step 3 is as follows: 100 μL of n-hexane is added to the surface of the pressed cake, and the time for complete penetration of the droplet is recorded. ;like Then it is judged as qualified, if This will trigger the automatic adjustment of the pressure fluctuation parameters in step 2.

6. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 5, characterized in that, Step 3, the slice image analysis method, includes: freezing and slicing the pressed cake, acquiring images under a 200x microscope, and calculating the image porosity using the OTSU threshold segmentation method. The porosity was calculated using a pixel adjacency-based disjoint-set data structure algorithm. The preset threshold is and Otherwise, automatic adjustment will be triggered.

7. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 6, characterized in that, The formula for calculating Darcy permeability in step 4 is: ； Where K is Darcy penetration rate. The median aperture obtained from image analysis, This is the shape factor, with a value ranging from 0.7 to 0.

9.

8. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 7, characterized in that, In step 4, the leaching time is dynamically set. The formula is: ； in L is the solvent viscosity, and L is the cake layer thickness. For the leaching tank pressure differential, The initial oil content, To achieve the target oil content, When calculated When the solvent ratio is 1.2:1, reduce it by 10%-15%; otherwise, maintain the standard solvent ratio.

9. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 8, characterized in that, In step 5: the low temperature range is set to 40℃-60℃; the compound adsorbent is composed of activated clay, activated carbon and diatomaceous earth in a mass ratio of 70:15:15, and the amount added is 1.5%-3.0% of the oil weight; the vacuum conditions are an absolute pressure of 0.08MPa-0.095MPa, and the reaction time is 30-45 minutes.

10. The method for preparing corn germ oil based on the microstructure regulation of pressed cake according to claim 9, characterized in that, The conditions for short-path distillation deodorization in step 6 are: temperature 100℃-110℃, absolute pressure 200Pa-300Pa, and time 30-60 minutes; in the resulting finished oil, the steam consumption of the leaching process is reduced by 15-20%, the solvent turnover is reduced by more than 10%, and the unit energy consumption of the refining process is reduced by 10%-15%.

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