Introduction
Of oil pressing from nuts, seeds, and other oil-containing materials, two dominant ruling processes are mechanical pressing and solvent extraction. Both the processes have their advantages and disadvantages, and both are chosen based on yield, cost, and efficiency of oil.
This article delves into the fundamental differences between solvent extraction and mechanical pressing, as well as the advantages and disadvantages of each process and which of these processes would be more ideally suited for certain applications. As a business trying to find the most suitable method of oil extraction or purchasing from solvent extraction equipment manufacturers, understanding these processes is important.
Understanding mechanical pressing
What is mechanical pressing?
Expeller pressing or mechanical pressing is a very old process of oil extraction in which physical pressure is applied to press out the oil from seeds or nuts. It is a chemical process and therefore a natural process for oil extraction.
How mechanical pressing works
- Seed Preparation – The seeds are cleaned and preheated at times to enable maximum oil recovery.
- Pressing – Pressure is applied from a screw press or mechanical expeller to squeeze out the oil.
- Filtration – Pressed oil is filtered to eliminate impurities.
- Cake Residue – Seed cake residue holds some of the remaining oil, typically 5-8%.
Advantages of mechanical pressing
✅ No Chemical Used – Perfect for making organic and natural oils.
✅ Preserves Natural Nutrients – Less processing = less change to the oil structure.
✅ Lower Investment Costs – Less costly than solvent extraction plant equipment.
✅ Environmentally Friendlier – No chemical solvents, reduced environmental footprint.
Disadvantages of mechanical pressing
❌ Lower Oil Recovery – Increased retention of oil by the seed cake.
❌ Increased Energy Consumption – Increased energy usage per unit of oil recovered.
❌ Limited Scaling – Most suitable for small and medium-sized enterprises.
Understanding solvent extraction
What is solvent extraction?
Solvent extraction is a highly technological process consisting of chemical solvents, mainly hexane, utilized in the process of extracting oil from oil-holding material. It is mainly practiced in large-scale operations and has higher oil recovery.
How solvent extraction works
- Seed Treatment – The seeds are milled into meal and cleaned so that solvents can penetrate more easily.
- Oil extraction is where oil is extracted from the seed meal using a chemical solvent (hexane).
- Desolventization – Heat and steam remove the solvent.
- Refining – The impurities are eliminated by processing the oil.
- Residual Cake Processing – The residual meal is also processed for animal feed or other purposes.
Advantages of solvent extraction
✅ Increased Oil Recovery – Reclaims almost 98-99% of oil, minimizing wastage.
✅ Economical for Large-Scale Production – Economically viable for mass production of oil.
✅Reduced Energy Consumed Per Unit – Reduced cost in bulk production.
✅ Can Handle More Types of Oilseeds – Can handle soybean, sunflower, canola, and other oilseeds.
Disadvantages of solvent extraction
❌ Has Chemical Solvents – Hexane is a chemical that is flammable, and therefore, precautions are needed.
❌ Higher Capital Investment – Setting up a solvent plant facility is capital-intensive.
❌ More Complicated Process – Comprises a series of steps, such as refining.
Comparing mechanical pressing and solvent extraction
| Feature | Mechanical Pressing | Solvent Extraction |
| Oil Yield | 85-90% | 98-99% |
| Investment Cost | Lower | Higher |
| Chemical Use | None | Uses solvents (hexane) |
| Best For | Small to medium operations | Large-scale production |
| Nutritional Retention | Higher | Slightly lower due to refining |
| Environmental Impact | Lower | Requires solvent management |
Conclusion
Mechanical pressing and solvent extraction are both significant in the oil industry, but for different reasons. If you desire natural, chemical-free oil with minimal investment, mechanical pressing is the way to go. But if you desire maximum oil yield and efficiency in large scale, investing in a solvent extraction plant facility is the way to go.
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FAQs
Which method is better for organic oil production?
Mechanical pressing is applied to organic oils since it does not involve the use of chemical solvents.
Is solvent extraction safe?
Yes, but should have stringent security controls in consideration of the exposure to hexane and other solvent chemicals.
Can small businesses afford solvent extraction?
Solvent extraction suits bulk production most because it requires a gigantic initial capital. Mechanical pressing suits small companies best.
Does solvent extraction affect oil quality?
Although solvent-extracted oil can be refined, new technologies guarantee the final product is of industry quality.
Which method is more environmentally friendly?
Mechanical pressing is also less harmful to the environment because it does not use chemical solvents.