Citric acid is a weak organic acid found in citrus fruits. This is a natural preservative and is also used to add acid taste (acid) to food and soft drinks. In biochemistry, it is important as an intermediate in the citric acid cycle and therefore occurs in the metabolism of almost all living things.
It also functions as an environmentally friendly cleaning agent and acts as an antioxidant. Citric acid is in various fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8 percent of the dry weight of the fruit. Citric acid is found in powder form and is white in color. You can also find hydrated citric acid for sale online.
The concentrations of citric acid in citrus fruits range from 0.005 mol for oranges and grapefruits to 0.30 mol for lemons and limes and these values vary within species depending upon the cultivar and the circumstances in which the fruit was grown. Citric acid was first isolated in 1784 by the chemist Carl Wilhelm Scheele, who crystallized it from lemon juice.
Industrial-scale citric acid production first began in 1890 based on the Italian citrus fruit industry, where the juice was treated with hydrated lime (calcium hydroxide) to precipitate calcium citrate, which was isolated and converted back to the acid using diluted sulfuric acid.