Pretreatment method for airflow dry enrichment of oil cake protein
By improving the structure and surface properties of oilseed cake through a combined pretreatment method, the adverse factors in the airflow dry enrichment process of oilseed cake were solved, achieving efficient, green and environmentally friendly protein separation and enrichment, and improving purity and yield.
Patent Information
- Application Number
- CN202511936915.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-22
- Publication Date
- 2026-01-27
AI Technical Summary
In existing technologies, when oilseed cakes are used for protein enrichment by airflow dry separation, there are problems such as dense cell walls that make it difficult to break cells, high residual oil rate, strong powder viscosity, strong hydrophobicity of protein molecule surfaces or uneven charge, resulting in poor protein enrichment effect. In addition, traditional wet separation has the risks of high energy consumption, use of chemical reagents and environmental pollution.
A combined pretreatment method was adopted, including coarse crushing, ultrasonic-assisted supercritical carbon dioxide extraction, low-temperature plasma treatment, and constant humidity equilibration. By improving the structure and surface properties of oilseed cake, reducing residual oil content and controlling moisture content, the efficient separation and enrichment of proteins were achieved.
It significantly improves the purity and yield of protein enrichment by airflow dry enrichment of oilseed cake, avoids wall sticking and clogging, maintains the functional properties of protein, and the process is green, environmentally friendly, low-carbon and energy-saving.
Smart Images
Figure CN121400515A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of food processing technology, and specifically relates to a pretreatment method for the dry enrichment of protein in oilseed cake by airflow. Background Technology
[0002] Oilseed cakes are important byproducts of edible vegetable oil processing, mainly including soybean cake, rapeseed cake, peanut cake, sunflower seed cake, and other types. These cakes are rich in plant protein, possessing high nutritional value and excellent functional properties such as solubility, emulsification, and gelling ability, making them a high-quality plant protein resource. Enriching and separating proteins from oilseed cakes is an important approach to the high-value utilization of these resources.
[0003] Wet separation, a traditional process for separating plant proteins, utilizes the differences in protein solubility under different pH conditions to achieve precipitation. This method boasts advantages such as high separation efficiency and high protein purity, and has been widely applied. However, wet separation processes typically involve complex operations such as multi-step acid-base adjustment, centrifugation, precipitation, and washing, resulting in high solvent and water consumption, high wastewater treatment costs, and overall high energy consumption. Furthermore, under acidic or alkaline environments and heat treatment conditions, some proteins are prone to denaturation, aggregation, or functional group destruction, leading to a decline in their nutritional value and functional properties (such as emulsifying properties, foaming properties, and solubility). In addition, this process requires the extensive use of chemical reagents, posing environmental pollution and residue risks, and failing to meet the demands of modern green, low-carbon, and sustainable processing development.
[0004] Compared to traditional wet separation processes, airflow dry enrichment technology is a physical separation method based on aerodynamic principles. This technology leverages the differences in density, particle size, and surface properties of powder particles. Through the dynamic action of high-speed airflow, proteins and non-protein components exhibit different motion characteristics in a gas-solid two-phase system, thereby achieving protein fractionation and enrichment. The enrichment process requires no organic solvents or large amounts of water, featuring a simple process flow, low energy consumption, and advantages of being environmentally friendly and controllable. Furthermore, because the entire process is carried out under mild conditions, it can maximally preserve the natural structure and functional properties of proteins, showing great promise in the field of plant protein separation and high-value utilization.
[0005] However, the effect of dry airflow enrichment of protein in oilseed cakes is closely related to the physicochemical properties of the raw materials themselves, and has obvious adaptability to raw materials. Oilseed cakes such as peanuts, sesame, cottonseeds, and sunflower seeds are not very effective in dry airflow enrichment of protein, and are prone to problems such as sticking to the wall, blockage, low protein enrichment degree or low yield. The main reasons are: (1) the dense cell wall makes it difficult for cells to break and insufficient protein release; (2) the high residual oil content of the cake, strong powder viscosity, and easy agglomeration result in poor airflow dispersion; (3) the strong hydrophobicity or uneven charge on the surface of protein molecules leads to unstable charge and uncontrollable particle movement. Summary of the Invention
[0006] The technical problem to be solved by the present invention is to provide a pretreatment method for the airflow dry enrichment of protein in oilseed cake, which addresses the shortcomings of the prior art. By designing a combined pretreatment process, the method can effectively eliminate the adverse factors in the airflow dry enrichment of protein in oilseed cake through a comprehensive approach that combines structural modification, surface regulation and moisture stabilization, and significantly promotes the efficient separation and enrichment of protein.
[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a pretreatment method for the airflow dry enrichment of protein in oilseed cake, comprising the following steps: S1. Coarse grinding: Grind the oilseed cake into powder; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction is used to remove residual fat from oilseed cake; S3. Low-temperature plasma treatment: The defatted oilseed cake is subjected to low-temperature plasma treatment; S4. Constant humidity equilibrium: The oilseed cake after low-temperature plasma treatment is placed in a constant temperature and humidity environment for constant humidity equilibrium.
[0008] Preferably, the oilseed cake in S1 includes peanuts, sunflower seeds, sesame seeds, rapeseed, flax seeds, walnuts, and soybeans, and the particle size of the oilseed cake after coarse crushing is 20-60 mesh.
[0009] Preferably, the extraction temperature of the oilseed cake extracted by ultrasound-assisted supercritical carbon dioxide in step S2 is 35-60°C, and the ultrasonic frequency is 20-40kHz. After ultrasound-assisted supercritical carbon dioxide extraction, the crude fat content of the oilseed cake is 0.5-2% (dry basis).
[0010] Preferably, the processing gas for the low-temperature plasma treatment in S3 is air, nitrogen, or a mixture thereof, with a power density of 0.1-0.5 W / cm³. 2 The processing time is 1-10 minutes.
[0011] Preferably, the temperature for constant humidity equilibrium in step S4 is 10-30°C, the relative humidity is 40-50%, and the equilibrium time is 6-24 hours. After constant humidity equilibrium, the final moisture content of the oilseed cake powder stabilizes at 3.8-4.2%.
[0012] Compared with the prior art, the present invention has the following significant technical effects: 1. This invention adopts a combined pretreatment method to eliminate the adverse factors of oilseed cake in the airflow dry enrichment process from multiple aspects, such as reducing residual oil rate, fully releasing protein, protein modification and moisture content control and homogenization. It avoids phenomena such as sticking to the wall, blockage, low protein enrichment degree or low yield caused by cake powder agglomeration, and significantly improves the purity and yield of protein enriched by airflow dry enrichment of oilseed cake.
[0013] 2. The combined pretreatment method involves only mild physical processes. By rationally controlling the process parameters, significant protein denaturation of oilseed cake due to high temperature during pretreatment is avoided, thereby ensuring that the separated oilseed cake protein retains good functional properties.
[0014] 3. The combined pretreatment method does not use chemical reagents and does not generate wastewater, waste gas or waste liquid, making it green, environmentally friendly, low-carbon and energy-saving.
[0015] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Attached Figure Description
[0016] Figure 1 This is a diagram showing pipe blockage during the airflow dry enrichment of protein from peanut cake in the comparative example of this invention.
[0017] Figure 2 This is a pipeline diagram of the process for enriching protein in peanut cake meal using the airflow dry method in an embodiment of the present invention. Detailed Implementation
[0018] The oilseed cake used in the following examples and comparative examples is peanut cake, and the peanut cake from the same manufacturer and the same batch is used as raw material, with consistent composition.
[0019] Example 1 This embodiment describes a pretreatment method for the airflow dry enrichment of protein in peanut meal, employing a combined pretreatment method, including the following steps: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 20 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake meal. A supercritical carbon dioxide extraction device with an integrated ultrasonic generator was used. The ultrasonic frequency was 20kHz, the supercritical carbon dioxide pressure was 30MPa, the extraction temperature was 35°C, and the processing time was 40min. S3. Low-Temperature Plasma Treatment: Degreased peanut cake is treated using a dielectric barrier discharge low-temperature plasma device to modify the proteins in the peanut cake, altering the functional groups and charge distribution on the protein surface. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.1W / cm³. 2 Processing time: 1 minute; S4. Humidity equilibration: Place the peanut cake meal treated with low-temperature plasma on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber at a temperature of 30°C and a relative humidity of 50% for 24 hours.
[0020] In this embodiment, the peanut meal after humidity equilibration was subjected to airflow dry enrichment of protein. The method was as follows: the peanut meal after humidity equilibration was placed at the inlet of the airflow dry enrichment equipment, and the peanut meal was first finely ground at a grinding wheel speed of 10,000 rpm and a classifying wheel speed of 4,000 rpm. Then, air classification was performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0021] Example 2 This embodiment describes a pretreatment method for the airflow dry enrichment of protein in peanut meal, employing a combined pretreatment method, including the following steps: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 60 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake is carried out using a supercritical carbon dioxide extraction device with an integrated ultrasonic generator. The ultrasonic frequency is 40kHz, the supercritical carbon dioxide pressure is 30MPa, the extraction temperature is 60°C, and the processing time is 20min. S3. Low-Temperature Plasma Treatment: Degreased peanut cake is treated using a dielectric barrier discharge low-temperature plasma device to modify the proteins in the peanut cake, altering the functional groups and charge distribution on the protein surface. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.5W / cm³. 2 Processing time: 10 minutes; S4. Humidity equilibration: Place the peanut cake meal treated with low-temperature plasma on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber at a temperature of 10°C and a relative humidity of 40% for equilibration time of 6 hours.
[0022] In this embodiment, the peanut meal after humidity equilibration was subjected to airflow dry enrichment of protein. The method was as follows: the peanut meal after humidity equilibration was placed at the inlet of the airflow dry enrichment equipment, and the peanut meal was first finely ground at a grinding wheel speed of 10,000 rpm and a classifying wheel speed of 4,000 rpm. Then, air classification was performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0023] Example 3 This embodiment describes a pretreatment method for the airflow dry enrichment of protein in peanut meal, employing a combined pretreatment method, including the following steps: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake meal. A supercritical carbon dioxide extraction device with an integrated ultrasonic generator was used. The ultrasonic frequency was 30kHz, the supercritical carbon dioxide pressure was 30MPa, the extraction temperature was 50°C, and the processing time was 90min. S3. Low-Temperature Plasma Treatment: Degreased peanut cake is treated using a dielectric barrier discharge low-temperature plasma device to modify the proteins in the peanut cake, altering the functional groups and charge distribution on the protein surface. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.3W / cm³. 2 Processing time: 5 minutes; S4. Humidity and temperature equilibration: Place the peanut cake meal treated with low-temperature plasma on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber at a temperature of 20°C and a relative humidity of 45% for equilibration time of 12 hours.
[0024] In this embodiment, the peanut meal after humidity equilibration was subjected to airflow dry enrichment of protein. The method was as follows: the peanut meal after humidity equilibration was placed at the inlet of the airflow dry enrichment equipment, and the peanut meal was first finely ground at a grinding wheel speed of 10,000 rpm and a classifying wheel speed of 4,000 rpm. Then, air classification was performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0025] Comparative Example 1 The peanut meal was pulverized and then directly enriched for protein using an air-flow dry method, as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh.
[0026] Airflow dry protein enrichment: Coarsely ground peanut meal is placed at the inlet of an airflow dry enrichment device. The peanut meal is first finely ground at 10,000 rpm, with the classifying wheel rotating at 4,000 rpm. Then, air classification is performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0027] Comparative Example 2 The peanut meal was crushed, defatted, and then subjected to air-flow dry enrichment of protein, as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake meal. A supercritical carbon dioxide extraction device with an integrated ultrasonic generator was used. The ultrasonic frequency was 30kHz, the supercritical carbon dioxide pressure was 30MPa, the extraction temperature was 50°C, and the processing time was 90min.
[0028] Airflow dry protein enrichment: Defatted peanut meal is placed at the inlet of an airflow dry enrichment device. The peanut meal is first finely ground at 10,000 rpm, with the classifying wheel rotating at 4,000 rpm. Then, air classification is performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0029] Comparative Example 3 The peanut meal was pulverized and then subjected to low-temperature plasma treatment, followed by protein enrichment using an airflow dry method. The steps are as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Low-Temperature Plasma Treatment: A dielectric barrier discharge low-temperature plasma device is used to treat the defatted peanut cake. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.3W / cm³. 2 Processing time: 5 minutes.
[0030] Airflow dry protein enrichment: Peanut meal treated with low-temperature plasma was placed at the inlet of an airflow dry enrichment device. The peanut meal was first finely ground at 10,000 rpm and the classifying wheel at 4,000 rpm. Then, air classification was performed at an airflow velocity of 50 m³ / h. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0031] Comparative Example 4 After crushing the peanut meal, it was subjected to constant humidity equilibrium, and then the protein was enriched by airflow dry method, as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Constant humidity equilibration: Place peanut cake meal on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber. Set the temperature to 20°C, the relative humidity to 45%, and the equilibration time to 12 hours. Airflow dry protein enrichment: Peanut meal, after being equilibrated to constant humidity, is placed at the inlet of an airflow dry enrichment device. The peanut meal is first finely ground at 10,000 rpm, with the classifying wheel rotating at 4,000 rpm. Then, air classification is performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0032] Comparative Example 5 After crushing and defatting the peanut cake, it was subjected to constant humidity equilibrium and then enriched with protein by airflow dry method, as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake meal. A supercritical carbon dioxide extraction device with an integrated ultrasonic generator was used. The ultrasonic frequency was 20kHz, the supercritical carbon dioxide pressure was 30MPa, the extraction temperature was 50°C, and the processing time was 90min. S3. Humidity equilibration: Place the defatted peanut cake on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber. Set the temperature to 20°C, the relative humidity to 45%, and the equilibration time to 12 hours.
[0033] Airflow dry protein enrichment: Peanut meal, after being equilibrated to constant humidity, is placed at the inlet of an airflow dry enrichment device. The peanut meal is first finely ground at 10,000 rpm, with the classifying wheel rotating at 4,000 rpm. Then, air classification is performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0034] Comparative Example 6 After crushing and defatting, peanut cake meal is subjected to low-temperature plasma treatment, followed by protein enrichment via airflow dry method. The steps are as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake meal to 30 mesh; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction of residual fat in peanut cake meal. A supercritical carbon dioxide extraction device with an integrated ultrasonic generator was used. The ultrasonic frequency was 30kHz, the supercritical carbon dioxide pressure was 30MPa, the extraction temperature was 50°C, and the processing time was 90min. S3. Low-Temperature Plasma Treatment: A dielectric barrier discharge low-temperature plasma device is used to treat the defatted peanut cake. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.3W / cm³. 2 Processing time: 5 minutes.
[0035] Airflow dry protein enrichment: Peanut meal treated with low-temperature plasma was placed at the inlet of an airflow dry enrichment device. The peanut meal was first finely ground at 10,000 rpm and the classifying wheel at 4,000 rpm. Then, air classification was performed at an airflow velocity of 50 m³ / h. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0036] Comparative Example 7 After the peanut meal is crushed, it is subjected to low-temperature plasma treatment, constant humidity equilibration, and then protein enrichment by airflow dry method. The steps are as follows: S1. Coarse grinding: Use a universal grinder to grind the lumpy peanut cake to 40 mesh; S2. Low-Temperature Plasma Treatment: Peanut cake is treated using a dielectric barrier discharge low-temperature plasma device. The gas source is nitrogen, the generation voltage is 15kV, the power frequency is 20kHz, and the power density is 0.3W / cm³. 2 Processing time: 5 minutes; S3. Constant humidity equilibration: Place the peanut cake meal treated with low temperature plasma on a tray, spread it into a thin layer, and put it into a constant temperature and humidity chamber. The temperature is set to 20°C, the relative humidity is set to 45%, and the equilibration time is 12 hours.
[0037] Airflow dry protein enrichment: Peanut meal, after being equilibrated to constant humidity, is placed at the inlet of an airflow dry enrichment device. The peanut meal is first finely ground at 10,000 rpm, with the classifying wheel rotating at 4,000 rpm. Then, air classification is performed at an airflow velocity of 50 m / s. 3 The grading wheel rotates at 10,000 rpm per hour, collecting the fine fraction, which is peanut meal protein.
[0038] The protein, fat, and moisture content of the peanut meal raw material before processing in this invention is shown in Table 1.
[0039] Table 1. Protein, fat, and moisture content of peanut meal raw material before processing Table 2 shows the fat and moisture content of peanut meal after treatment by different methods in Examples 1-3 and Comparative Examples 1-7: Table 2. Fat and moisture content of peanut meal after pretreatment by different methods As shown in Table 2, the peanut meal in Examples 1-3, after undergoing a combination of ultrasound-assisted supercritical carbon dioxide extraction, low-temperature plasma treatment, and constant humidity equilibrium pretreatment, exhibited low fat and moisture content. Comparative Examples 1 and 3 exhibited high fat and moisture content. Due to the ability to entrain some moisture during ultrasound-assisted supercritical carbon dioxide extraction of residual oil, Comparative Examples 2 and 6 exhibited low fat and moderate moisture content. Comparative Examples 4 and 7 exhibited high fat and low moisture content. Comparative Example 5, after undergoing both ultrasound-assisted supercritical carbon dioxide extraction and constant humidity equilibrium treatment, also exhibited low fat and moisture content.
[0040] Table 3 shows the purity, yield, and enrichment rate of proteins obtained by airflow drying enrichment of peanut meal treated by different methods in Examples 1-3 and Comparative Examples 1-7: Table 3. Purity, yield, and enrichment rate of protein enriched by airflow drying method from peanut meal. In Comparative Examples 1, 3, and 4, the pipelines were severely blocked during the airflow dry enrichment of protein from peanut meal, such as... Figure 1 As shown; in Examples 1, 2, and 3, the pipelines were functioning normally and were not blocked during the airflow dry enrichment of protein from peanut meal, allowing for effective protein enrichment. Figure 2 As shown.
[0041] Through multiple experiments, it was found that in the pretreatment method of the present invention for the dry enrichment of protein in oilseed cake by airflow, after ultrasonic-assisted supercritical carbon dioxide extraction in step S2, the crude fat content of the oilseed cake is 0.5-2% dry basis, and after constant humidity equilibrium in step S4, the final moisture content of the oilseed cake powder is stabilized at 3.8-4.2%, which can achieve the effect of improving protein enrichment.
[0042] The above results demonstrate that the combined pretreatment method of ultrasound-assisted supercritical carbon dioxide extraction, low-temperature plasma treatment, and constant humidity equilibrium provided by this invention can eliminate adverse factors in the airflow dry enrichment process of oilseed cake from multiple aspects, including reducing residual oil content, fully releasing protein, protein modification, and controlling and homogenizing moisture content. It avoids phenomena such as wall adhesion, blockage, low protein enrichment degree, or low yield caused by cake powder agglomeration, thereby improving the purity and yield of protein in the airflow dry enrichment process of oilseed cake and significantly increasing the protein enrichment rate. Simultaneously, the process is green, environmentally friendly, low-carbon, and energy-saving, exhibiting significant technical advantages.
[0043] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.
Claims
1. A pretreatment method for the airflow dry enrichment of protein in oilseed cake, characterized in that, Includes the following steps: S1. Coarse crushing: Crush the oilseed cake; S2. Degreasing: Ultrasonic-assisted supercritical carbon dioxide extraction is used to remove residual fat from oilseed cake; S3. Low-temperature plasma treatment: The defatted oilseed cake is subjected to low-temperature plasma treatment; S4. Constant humidity equilibrium: The oilseed cake after low-temperature plasma treatment is placed in a constant temperature and humidity environment for constant humidity equilibrium.
2. The method according to claim 1, characterized in that, The oilseed cakes mentioned in S1 include peanuts, sunflower seeds, sesame seeds, rapeseed, flax seeds, walnuts, and soybeans. The coarsely ground oilseed cakes have a particle size of 20-60 mesh.
3. The method according to claim 1, characterized in that, The extraction temperature for ultrasonic-assisted supercritical carbon dioxide extraction of oilseed cake described in S2 is 35-60°C, and the ultrasonic frequency is 20-40kHz.
4. The method according to claim 1, characterized in that, The oilseed cake described in S2, after ultrasonic-assisted supercritical carbon dioxide extraction, has a crude fat content of 0.5-2% (dry basis).
5. The method according to claim 1, characterized in that, The processing gas for the low-temperature plasma treatment described in S3 is air, nitrogen, or a mixture thereof, with a power density of 0.1-0.5 W / cm² and a processing time of 1-10 min.
6. The method according to claim 1, characterized in that, The constant humidity equilibrium temperature described in S4 is 10-30°C, the relative humidity is 40-50%, and the equilibrium time is 6-24h.
7. The method according to claim 1, characterized in that, After constant humidity equilibrium in S4, the final moisture content of oilseed cake powder stabilizes at 3.8-4.2%.