Pretreatment & Pressure Strategies for Oil Pressing
During the oil extraction process with a hydraulic oil press, precise pressure regulation significantly impacts both the yield and quality of the oil. The optimal pressure required for different oilseed crops (such as rapeseed, peanuts, soybeans, etc.) varies during the extraction process. For example, in rapeseed oil extraction, a lower pressure may be needed initially to cause preliminary deformation of the oilseeds, and as the extraction process advances, the pressure should be gradually increased to fully extract the oil.
Improper pressure regulation may lead to a series of problems. Excessive pressure can increase the impurity content in the extracted oil and damage the oil extraction equipment, shortening the lifespan of the equipment; conversely, insufficient pressure may fail to fully extract the oil, reducing the oil yield and causing waste of raw materials.
Customizable pressure control & process optimization
SIMEC oil press machine is equipped with an advanced pressure control system that can automatically adjust the pressure based on the set parameters and real-time monitored data. The system includes components such as pressure sensor, controller, and actuator, enabling precise and stable pressure regulation.
In addition to the precision of pressure regulation, SIMEC oil press can also provide customizable pressure and time control schemes. However, the optimal pressure and time control schemes for each type of oilseed, as well as the best pretreatment methods, are not determined by the machine. Instead, users need to conduct repeated experiments, accumulate data, and analyze and summarize the results to figure them out.
Pretreatment & pressure strategies for oil pressing
While pressure regulation is a key factor in oil extraction, material pretreatment plays an equally vital role in determining both extraction efficiency and final oil quality. Different oil-bearing materials require customized pretreatment workflows, which typically involve:
Dehydration (moisture control)
Size reduction (crushing/grinding)
Thermal processing (steaming/roasting)
Next, let’s analyze the recommended set pressure variation for the following materials: soybean seeds, coriander seeds, almond seeds, nutmeg (jaiphal) seeds, boswellia and senna extract cake.
There is no universal set pressure variation for these materials when using a hydraulic oil press, as it can be affected by multiple factors such as the material characteristics (oil content, hardness, moisture), pretreatment effectiveness, target oil yield vs. quality balance. For most of the raw material, it’s important to start from low pressure, then increase gradually. Now, let’s apply these principles to six target materials, starting with their unique pretreatment needs and corresponding pressing strategies.
 |  |
| Soybean Seeds | Coriander Seeds |
1. Soybean Seeds
| Raw Material Pretreatment | |
| Cleaning | Remove foreign materials (stones, dirt, broken seeds) using a sieve or air classifier. |
| Drying | Reduce moisture content to 8-10% via air-drying or low-temperature drying (40-50°C) to prevent mold and improve oil yield. |
| Crushing | Use a roller mill or hammer mill to break seeds into coarse particles (3-5mm) to expose oil cells. |
| Conditioning (Optional) | Steam for 10-15 minutes at 80-90°C to soften cell walls and enhance oil flow during pressing. |
| Pressing Parameters & Operation | |
| Pressure Setting | Start at 30 MPa, gradually increasing to 40-45 MPa (long-term safe range) to avoid over-stressing the press. |
| Pressing Time | 2-3 minutes for steady compression, allowing gradual oil release. |
| Retention Time | 5-8 minutes to ensure full oil drainage; longer retention helps extract residual oil from dense soybean cakes. |
2. Coriander Seeds
| Raw Material Pretreatment | |
| Cleaning & Sorting | Use a vibrating sieve to remove debris and undersized seeds. |
| Moisture Adjustment | If moisture >12%, dry at 35-40°C until moisture is 8-10%. |
| Cracking | Gently crush seeds with a roller mill to split them into halves (avoid excessive powder to prevent clogging). |
| Roasting (Optional) | Roast at 100-110°C for 15-20 minutes to enhance oil flavor and release oils more easily. |
| Pressing Parameters & Operation | |
| Pressure Setting | Maintain 35-40 MPa to handle small, brittle seeds without generating excessive fines. |
| Pressing Time | 1.5-2 minutes for quick compression, suitable for small seeds. |
| Retention Time | 4-6 minutes to allow oil to flow through the compacted seed bed. |
 |  |
| Almond Seeds | Nutmeg (Jaiphal) Seeds |
3. Almond Seeds
| Raw Material Pretreatment | |
| Shell Removal | Mechanically remove hard shells; use a nutcracker for uniform splitting. |
| Blanching (Optional) | Soak in hot water (80°C) for 1-2 minutes to remove skins, improving oil clarity. |
| Drying | Ensure moisture <8% (air-dry or low-temperature drying at 40°C). |
| Chopping | Cut almonds into 4-5mm pieces to increase surface area for oil extraction. |
| Pressing Parameters & Operation | |
| Pressure Setting | Start at 25 MPa, gradually increasing to 35-40 MPa (almonds have high oil content; lower pressure prevents excessive cake fines). |
| Pressing Time | 2-2.5 minutes for gentle compression. |
| Retention Time | 6-8 minutes to allow slow drainage of viscous almond oil. |
4. Nutmeg (Jaiphal) Seeds
| Raw Material Pretreatment | |
| Shell Removal | Crack hard outer shells using a specialized nutcracker; discard shells. |
| Grinding | Use a disc mill to grind kernels into a coarse powder (2-3mm particles) to break oil-rich tissues. |
| Conditioning | Warm at 60-70°C for 10 minutes to soften oils (nutmeg oil has a low melting point, ~30°C). |
| Pressing Parameters & Operation | |
| Pressure Setting | 40-45 MPa to handle the dense structure of nutmeg kernels. |
| Pressing Time | 2.5-3 minutes for steady compression of granular material. |
| Retention Time | 5-7 minutes to ensure full extraction of aromatic nutmeg oil. |
 |  |
| Boswellia Extract Cake | Senna Extract Cake |
Boswellia/senna extract cakes are byproducts with residual oils, not primary oilseeds. Pretreatment focuses on moisture reduction and structure modification for oil recovery.
5. Boswellia Extract Cake
| Raw Material Pretreatment | |
| Dehydration | Reduce high moisture (75% → <15%) via forced-air drying at 50-60°C for 4-6 hours to prevent bacterial growth and improve press efficiency. |
| Crushing | Break cake into 1-2cm chunks using a jaw crusher; grind into a coarse meal to expose residual oil pockets. |
| Mixing (Optional) | Blend with dry rice hulls (10% by weight) to create a porous structure for better oil flow. |
| Pressing Parameters & Operation | |
| Pressure Setting | The pressure needs to be gradually increased to 45-50 MPa (high pressure needed to extract residual oils from compacted cake). |
| Pressing Time | 3-4 minutes for slow, firm compression. |
| Retention Time | 8-10 minutes to allow oil to drain through the dense, moisture-reduced cake. |
6. Senna Extract Cake
| Raw Material Pretreatment | |
| Drying | Reduce moisture from 75% to 12-15% using a tray dryer at 50°C (6-8 hours) to improve pressability. |
| Shredding | Use a hammer mill to shred cake into fine strips (5-10mm) to increase surface area. |
| Conditioning | Mix with 5% calcium oxide to absorb excess moisture and prevent cake sticking during pressing. |
| Pressing Parameters & Operation | |
| Pressure Setting | Gradually increase to 45-50 MPa (similar to Boswellia cake). |
| Pressing Time | 3-4 minutes for gradual compression. |
| Retention Time | 8-10 minutes to maximize oil extraction from the low-oil cake. |
In actual operation, it is necessary to conduct preliminary tests according to the specific characteristics of the raw materials, equipment performance, and the desired product quality to determine the most suitable set pressure variation range, pressing time and retention time.