Citric acid is a weak organic acid naturally found in all citrus fruits, such as lemons and limes. It has the chemical formula C6H8O7 and appears as a colorless, odorless solid with a pleasantly sour taste. In nature, it plays a crucial role as an intermediate in the metabolic pathway that converts food into energy, known as the citric acid cycle or Krebs cycle. Commercially, citric acid is mostly produced by fermenting sugars using a mold called Aspergillus niger, rather than extracting it from fruit, due to efficiency and cost. It is widely used in the food and beverage industry as a flavoring agent to add a tart taste, and as a preservative to keep products fresh by lowering pH and inhibiting bacterial growth. Beyond food, citric acid is found in pharmaceuticals, helping to treat conditions like kidney stones and to stabilize medicines. It's also used in personal care products, cosmetics, and household cleaners because of its antioxidant, chelating, and antimicrobial properties. In summary, citric acid is a versatile, naturally occurring acid important in biochemistry and industrial applications, especially in food preservation, flavoring, and health products. It is safe and commonly used worldwide in a variety of products.
