Citric acid is an important organic acid, also known as citric acid. It is a colorless crystal that often contains one molecule of crystalline water. It is odorless, has a strong sour taste, and is easily soluble in water. Its calcium salt is more soluble in cold water than in hot water, and this property is often used to identify and separate citric acid. Controlling the appropriate temperature during crystallization can obtain anhydrous citric acid. It has a wide range of applications in industries such as food and cosmetics.