Cooking oil is typically extracted from plant seeds through a two-step process involving both mechanical and chemical methods. This method ensures efficient removal of oil for various uses, including salad dressing, deep fat frying, and pan frying.
Edible Oil Extraction Process
In a standard edible oil processing plant, the oil extraction process from seeds follows a specific sequence:
Step 1: Mechanical Extraction (Expeller Press)
The initial stage of oil extraction utilizes mechanical extraction, commonly performed using an expeller press.
- Process: Seeds are fed into a machine that uses intense pressure to squeeze the oil out.
- Mechanism: This process involves a screw-like shaft that compresses the seeds as they move through a confined space.
- Outcome: This method yields a significant portion of the oil but leaves some residual oil in the seed cake.
Step 2: Chemical Extraction (Hexane Extraction)
Following mechanical extraction, the remaining oil in the seed material is typically recovered through chemical extraction, often using a solvent like hexane.
- Process: The seed cake from the expeller press is washed with a solvent (like hexane) that dissolves the remaining oil.
- Mechanism: The solvent binds with the oil, separating it from the solid plant material. The solvent-oil mixture is then heated to evaporate the solvent, leaving behind the crude oil.
- Outcome: This step maximizes the yield of oil from the seeds, making the overall process more efficient.
According to the provided reference, edible oils are extracted from seeds first using mechanical extraction (expeller press) followed by chemical extraction (hexane extraction). This combined approach is standard practice for producing the edible oils we use daily in cooking and food preparation.
This dual method ensures high oil recovery rates, making the process economically viable and providing the large quantities of cooking oil needed globally.
