Citric acid is a colorless, water-soluble solid acid. The term refers to a citrate salt of citric acid and generally deprotonated forms. In biochemistry, it is often also of citrate when occurring in the aqueous environment of a cell dissociated ionic form of citric acid is meant. In addition to the citric acid anhydrous variant (C6H8O7 • H2O) containing one molecule of water of crystallization per molecule of citric acid exists.