What is screw oil press?
A screw oil press, also known as an oil expeller or screw press, is a machine used to extract oil from various seeds, nuts, and other oil-bearing materials. It operates by squeezing the oil-containing materials with the help of a screw or worm shaft. The pressing process typically involves the following steps:
Feeding: The oil-bearing seeds or nuts are fed into the press.
Pressing: The material is compressed as it moves along the screw shaft. The pressure and friction generated during this process cause the oil to be released from the seeds/nuts.
Oil Extraction: The extracted oil flows out through small openings or gaps in the press cage, leaving behind the pressed and de-oiled cake.
Screw oil presses are commonly used for processing a variety of oilseeds such as soybeans, sunflower seeds, rapeseeds, peanuts, and more. They are widely employed in the oil extraction industry due to their efficiency and simplicity of operation. The choice of the specific type of screw press depends on the type of oilseed being processed and the desired oil extraction efficiency.
The difference between pressing and leaching
Different processing techniques
The processing technology of pressed oil is “physical pressing method”, while the processing technology of leached oil is “chemical leaching method”. The production process of the physical pressing method requires the raw materials to be carefully selected. After the soybean is removed from impurities and stones, it is crushed, steamed, fried, and squeezed to separate the oil from the soybean. During the pressing process, fried seeds are added, and after being squeezed by the press, using high-tech natural filtration and purification technology. It maintains the original taste of soybeans, has a mellow aroma, is rich in vitamin E, has a long shelf life, and does not contain any additives, solvent residues and soap content. It is a pure natural green food produced by a combination of modern technology and traditional technology. The leaching method adopts an organic solvent extraction method. The oil is fully combined with organic solvents such as “No. 6 light gasoline” (common name for “No. 6 solvent oil”) and then extracted. Therefore, n-ethane and other organic substances that are toxic to the human body, which is difficult to completely remove. Only after the refining reaches very strict standards can it be safely consumed. Otherwise, it will easily cause harm to the human body. However, during high-temperature refining, some vitamin nutrients will inevitably be lost. Due to the high oil yield of the leaching method, most corn oil, soybean oil, cottonseed oil, etc. are basically processed and manufactured using the “No. 6 light gasoline” leaching method.
Which method is best for oil extraction?
The choice of the best method for oil extraction depends on various factors, including the type of oilseed, the scale of production, the desired oil quality, and economic considerations. Both hydraulic and screw press methods have their advantages and are suitable for different applications. Here are some considerations to help you determine which method might be more suitable for your needs:
Hydraulic Oil Press:
Advantages:
Generally higher extraction efficiency, especially for hard and large oilseeds.
Suitable for processing oilseeds with a higher oil content.
Can handle materials with larger particles.
Considerations:
Higher initial cost and potential maintenance requirements.
May require more manual operation.
Screw Oil Press:
Advantages:
Versatile and suitable for a wide range of oilseeds.
More cost-effective and simpler in design.
Can be operated manually or with some degree of automation.
Considerations:
Extraction efficiency may vary depending on the specific model and type of oilseed.
May not be as efficient for hard or large oilseeds compared to hydraulic presses.
Solvent Extraction:
Advantages:
Generally higher extraction efficiency, especially for oilseeds with lower oil content.
Can extract a higher percentage of oil from the material.
Suitable for large-scale commercial operations.
Considerations:
Involves the use of chemical solvents, which may raise concerns about the final oil quality.
Higher initial investment in equipment.
Cold Pressing:
Advantages:
Preserves the natural flavors and nutritional qualities of the oil.
Does not involve the use of heat, preserving heat-sensitive compounds.
Considerations:
Generally lower extraction efficiency compared to solvent extraction or mechanical pressing.
May not be suitable for all types of oilseeds.
The “best” method depends on your specific requirements and constraints. For small-scale or artisanal operations, a screw press might be a practical choice. Large-scale commercial operations might opt for solvent extraction for its high efficiency. It’s crucial to consider factors such as the type of oilseed you’re working with, the desired oil quality, production scale, and budget when choosing an oil extraction method.