Density 1.8± 0.1g /cm3 Boiling point 667.9±55.0 °C at 760 mmHg Melting point 222.8°C Molecular formula C12H22O11 Molecular weight 342.297 Flash point 357.8±31.5 °C Accurate mass 342.116211 PSA 197.37000 LogP minus 3.41 Appearance properties White crystalline or crystalline powder. It is sweet and has about 70% of the sweetness of sucrose. Odorless or slightly characteristic odor. Relative density d4201.525(water content). It is reductive and right-handed. There are two isomers, ±-type and ²-type. ±-lactose can be broken down into glucose and galactose by acid and lactase, and can be acted on by lactic acid bacteria to become lactic acid, but yeast cannot use it. The crystalline precipitates in water as monohydrate C12 H22O11? H2O, if heated at 120 ° C, can become anhydrous. The melting point of anhydrous substance is 201 ~ 202, 1g can be dissolved in 5ml water or 2.6ml hot water, slightly soluble in ethanol, insoluble in ether. ²-lactose is precipitated in hot water above 93 ° C, and the solubility is different from that of ±-type, 1g is dissolved in 2.2ml water or Vapor pressure 0.0±4.6 mmHg at 25°C Refractive index 1.652 Storage conditions Room temperature Water solubility 5-10 g/100 mL at 20 ºC Molecular structure 1, molar refractive index: 71.47 2, molar volume (cm3/mol) : 202.7 3. Isotropic specific volume (90.2K) : 648.4 4, surface tension (dyne/cm) : 104.5 5. Polarizability (10-24cm3) : 28.33