At room temperature, citric acid is a white crystalline powder, odorless, very sour in taste [2], density 1.542g/cm3, melting point 153-159℃, above 175℃, it will release water and carbon dioxide. Ethanol has a solubility of 59% at 20°C, and the pH of its 2% aqueous solution is 2.1. The crystal shape of citric acid is different due to different crystallization conditions. It is slightly weathered in dry air and hygroscopic in air. It can be differentiated into a variety of products when heated, and it can react with acids, alkalis, glycerol, etc.