5. Solvent extraction

Continuous solvent extraction is a widely used technique for processing a wide range of products, particularly oleaginous materials. Extraction essentially involves washing the material with a suitable solvent, which circulates in the opposite direction to the material layer.

Fat solubilization is achieved by diffusion from the concentrated phase to the less concentrated phase. Molecular diffusion from the inside to the outside, the surface of the flakes in contact with the solvent and laminar diffusion from the surface to the moving solvent are the most important factors. The speed of extraction is limited by diffusion from the inside out, and depends directly on the internal structure of the cells, in particular the degree of wall destruction.

The oil is dissolved in the solvent and forms a miscella, which flows from the cakes (flakes,...