Seed oils are typically made through a two-stage process that combines mechanical and chemical methods to extract the oil from various seeds and nuts.
Understanding the process helps clarify how these common cooking oils are produced.
The Two Stages of Seed Oil Production
The extraction of oil from seeds and nuts primarily takes place in two stages: a mechanical stage and a chemical stage. These stages work in tandem to maximize the yield of oil.
Stage 1: The Mechanical Stage
The initial step in extracting seed oils involves a physical method.
- Process: This stage utilizes an expeller press.
- Action: The expeller press compresses the nuts and seeds under high pressure.
- Outcome: This compression physically squeezes out a significant portion of the oil from the raw material.
This mechanical pressing is effective for extracting a good amount of the oil content, but some oil typically remains within the seed or nut material after this step.
Stage 2: The Chemical Stage
To extract the remaining oil more efficiently, a chemical method is often employed.
- Process: This stage involves soaking the remaining seeds (or the material left after mechanical pressing).
- Chemical Used: A chemical called hexane is commonly used as a solvent.
- Action: The hexane dissolves the oil that is still present in the seed material.
- Outcome: The oil-rich hexane solution is then separated from the solid seed material, and the hexane is typically evaporated off, leaving the crude oil behind.
This chemical extraction stage allows for a higher overall yield of oil compared to mechanical pressing alone. The extracted crude oil then undergoes further processing, such as refining, bleaching, and deodorizing, to become the finished product commonly found in stores.
| Stage | Method | Key Action | Purpose |
|---|---|---|---|
| Mechanical | Expeller Press | Compresses seeds/nuts | Extracts a significant portion of oil |
| Chemical | Solvent (Hexane) | Soaks remaining material, dissolves oil | Extracts residual oil for higher yield |
In summary, seed oil production relies on both physical force from pressing and chemical action from solvents to efficiently obtain the oil from plant sources.
