Bleaching earth, also known as bleaching clay or active clay, is a natural clay type with high adsorption capacity. It is specifically used during the refining of vegetable and animal oils to remove unwanted components such as coloring pigments, off-odors, soap traces, chlorophyll, free fatty acids, and phosphatides.
Bleaching earth is generally obtained from clay minerals such as bentonite (montmorillonite), sepiolite, palygorskite, or attapulgite. It is activated by special techniques to gain high surface area and pore diameter. In this way, bleaching earth adsorbs contaminants in the filtered product, ensuring a cleaner, clearer, and more stable final product. It is universally referred to as bleaching earth in international literature.