The prime focus in modern bleaching processes is now on the removal of a wide range of different impurities, of which pigmentation is only one. Such impurities can virtually all be removed using new processes in which combinations of different bleaching agents are used to bind specific impurities. These are then removed when the bleaching agent is subsequently filtered out.
Efficient bleaching makes it possible to
remove certain pigments such as carotinoids and chlorophyll
decompose and partially remove oxidation products
remove contaminants such as soaps and trace metals
remove traces of phosphatides
remove polycyclic aromatic hydrocarbons and other pollutants.
All these substances can have adverse effects on both the quality and stability of your final product, and therefore have to be removed to ensure that the product is commercially attractive.