Citric acid C6H8O7 (E330) is a weak organic acid contained in citrus fruits. It is a natural preservative and is also used to impart a sour taste to foods and beverages. In biochemistry it is an important intermediary in the Krebs cycle (also known as “citric acid cycle”) and is therefore involved in the metabolism almost all living beings. C6H8O7 (E330) – citric acid [/ dt_quote] It is also used as an environmentally friendly cleaning agent and acts as an antioxidant . It is used also in medicine, textiles and photography.

The acidity of citric acid is due to three carboxylic groups COOH, each of which in solution may be separated ion. Citrates are excellent buffers for adjusting the pH of acidic solutions. From a chemical point of view, citric acid has the qualities of the other carboxylic acids. When heated above 175 ° C, it decomposes, releasing carbon dioxide and water.

Citric acid is found in many fruits and vegetables, but is most concentrated in lemons, where it may constitute up to 8% by dry weight of the fruit.