Steam distillation is used to extract star anise volatile oil because star anise volatile oil contains many volatile components, which will be converted into gases at a certain temperature. During the steam distillation process, the volatile components in the star anise volatile oil will evaporate and mix with water vapor during the heating process. Then during the cooling process, the volatile components will precipitate from the water vapor and flow back to the collection container. This is water vapor. Principles of distillation.

The advantage of extracting star anise volatile oil by steam distillation is that because the temperature of water vapor is relatively low, it can avoid high temperature damage to the aromatic components in the volatile oil, thereby obtaining high-quality star anise volatile oil. In addition, steam distillation can be used to extract other volatile components, such as those in vegetable oils, spices, and pharmaceuticals.