Anhydrous citric acid, molecular formula C6H8O7, is colorless translucent crystal or white granule or white crystalline powder, often contains a molecule of crystal water, odorless, very sour taste, soluble in water, alcohol and ether. Anhydrous citric acid can be obtained by controlling the appropriate temperature during crystallization. The aqueous solution is acidic. Slightly weathering in dry air, deliquescent in humid air. Mainly used in food and beverage industries as sour agent, acidity regulator, flavoring agent, preservative, and preservative. It is also used as antioxidant, plasticizer and detergent in chemical industry, cosmetic industry and washing industry.