Fermentative Production of citric acid, and its crude liquid yellow and red pigment, most of activated carbon to remove red pigment more easily, and very difficult to remove the yellow pigment. Special charcoal to remove yellow pigment has the ability to vote in the amount of carbon in less than 1% can be achieved colorless. Sodium citrate-specific characteristics of carbon is extremely adapt decoloration under alkaline conditions, so that a clear solution, as well as the crystallization of white, this could also have a dedicated carbon removed from the solution molysite trace function.