Bleaching Earths is a chemical and physical process to remove contaminants and molecular debris from edible oils and fats before deodorization. Siam Minerals supplies bleaching earths with a high surface area capable of producing quality mineral oils that are free from contaminants.

The use of bentonite in this process helps the removal of impurities, such as coloring pigments and phosphatides, as the adsorptive properties found in bentonite facilitates contaminant removal. It also supplies the necessary properties of ion exchange when removing more complex contaminants like heavy metals, soap and chlorophyll, and has acidic properties to remove hydrolysis oil. It also prevents oxidation triggered by an oil darkening reaction caused by β-carotenes and prevents the disruption of color value correlation with the inverse p-anisidine compound.