Citric acid is a weak organic acid with the formula C6H8O7. It is a natural preservative/conservative and is also used to add an acidic or sour taste to foods and soft drinks.
The citric acid cycle _ also known as the tricarboxylic acid cycle (TCA cycle), the Krebs cycle, or the Szent-Gyorgyi_Krebs cycle _ is a series of chemical reactions used by all aerobic organisms to generate energy through the oxidization of acetate derived from carbohydrates, fats and proteins into carbon dioxide and water. In addition, the cycle provides precursors including certain amino acids as well as the reducing agent NADH that is used in numerous biochemical reactions for the biosynthesis of compounds including certain amino acids. Its central importance to many biochemical pathways suggests that it was one of the earliest established components of cellular metabolism and may have originated abiogenically. The name of this metabolic pathway is derived from citric acid (a type of tricarboxylic acid) that is first consumed and then regenerated by this sequence of reactions to complete the cycle.
Contributions by Johner, ClockworkSoul, and David D..