Moreover there is a large domestic and export market for De-oiled Cakes. The Solvent Extraction process is more efficient than the traditional kolhu, hydraulic press, ghani or continuous screw process, since only 0.7% or less is left as a residual in this process.

Solvent extraction is essentially a process of diffusion of solvent into oil bearing cells of the material to be extracted resulting in a solution of the oil into solvent. For a successful and efficient extraction, it is therefore, necessary to ensure that each and every cell is brought in contact with the solvent.

After the oil is extracted from oilseeds by mechanical means, percentage of oil normally retained in the cakes is about 7-9% and it is not possible to further extract the oil economically by mechanical means. If further extraction (by mechanical means) is attempted, the quality of oil goes down and also it is very uneconomical too. The only method possible to extract the oil from cakes is by solvent extraction process. The solvent extraction is essentially a process of diffusion of the solvent into oil bearing material as well as into the material to be extracted resulting in a solution of oil in the solvent.

For successful and efficient extraction, it is therefore necessary to ensure that each and every oil cell is brought into contact with the solvent. For this purpose two conditions are to be fulfilled
i) The raw material should be prepared to make it easy for the solvent penetrate the oil cell and
ii) The solvent is spread over uniformly. Whereas the mechanical expulsion with expellers submits the oil to high temperature and pressure, which causes hydrolysis and colour fixation of oil, the continuous solvent extraction, on the other hand, does not cause any harm to the oil which is recovered with the same characteristics as were present in the oil bearing material.

Indeed, the outstanding and rich advantages of continuous solvent extraction are such that it has become and viable factor in determining the survival of the vegetable oil industry in many parts of the world.