Vegetable oils are an essential ingredient for the human diet. No food worth taste could be prepared without the use of vegetable oils. Depending on Geographical locations different varieties of oils are popular in the different region. Nature has given distinct individual characteristics to all vegetable oils.The simplest and age-old method of obtaining edible vegetable oil has been simple mechanical extraction. The oil is squeezed out from oil seeds by applying mechanical pressure. The common equipment used now a daysis Screw Press. Peanuts i.e. Ground Nuts, Copra, Sunflower Seed, Palm Kernal, Canola seed i.e. rape seed or mustards seed yields major oil through screw presses and in a majority of the cases the oil obtained can be and is being used directly as edible oil.
However to recover the left over oil after mechanical extraction from repressed cakes and for recovery of oil from low oil content seeds like soya bean, cotton seed etc., Solvent Extraction process is adopted.Since normal Hexane a petroleum bye product is used to extract the oil, refining of oil is compulsory before using it for human consumption.