Citric acid (CA), also known as citric acid, molecular formula for C H O, is an important organic acid, colorless crystal, odorless, has a strong sour taste, soluble in water, is a natural preservative and food additive.
At room temperature, citric acid is a white crystalline powder, odourless and extremely acidic , with a density of 1.542g/cm3 and a melting point of 153-159, and water and carbon dioxide released after decomposition above 175. Citric acid is easily soluble in water and ethanol, and its solubility is 59% at 20, and the pH of its 2% aqueous solution is 2.1Crystal morphology of citric acid varies due to different crystallization conditions. It has weathering property in dry air and hygroscopic property in wet air. It can be decompose into a variety of products by heating, which can react with acid, base and glycerol .