Utah Master Esthetician Practice Exam

Which essential oil extraction method involves boiling plant material?

1. Centrifugation

2. Distillation

3. Cold Pressing

4. Solvent Extraction

The correct answer is: Distillation

The extraction of essential oils through the method of distillation is based on the principle of boiling plant materials and capturing the resulting vapors. In this process, plant materials are placed in a still, and water is boiled to produce steam. As the steam passes through the plant material, it vaporizes the essential oils present. The vapor is then cooled, causing it to condense back into a liquid form, where the essential oil can be separated from the water. Distillation is widely used due to its efficiency in extracting oils while preserving their aromatic and therapeutic qualities. It is particularly valuable for extracting essential oils from delicate flowers and herbs, which might be damaged by other extraction methods. In contrast, other methods such as cold pressing are utilized specifically for citrus peels, where the oils are mechanically extracted without heat, and thus do not involve boiling. Centrifugation separates components based on density, while solvent extraction uses chemicals to dissolve oils, requiring additional purification stages. Therefore, the method that specifically involves boiling plant material to extract essential oils is indeed distillation.