Plant extraction is harvesting plant oil or substance usually for medicinal purpose. There are various methods of plant extraction depending the plant or desired extracts. The most common methods use solvents such as alcohol, CO2, or butane. Essential oil, resins, waxes, and other plant materials are extracted using butane and are called concretes. They can be highly fragrant and concentrated although they still contain unwanted plant materials. Most of the time ethyl alcohol is used to purify concretes. The concretes and ethyl alcohol is mixed then it will be chilled at 0°F for 2 days. This excess waxes and lipids will then precipitate, this is called winterization. The precipitates will then be filtered and ethanol will be removed through evaporation, vacuum purging, or both. The final output is called absolute. This method usually leaves trace amounts of the solvents used so testing is necessary to determine if the remaining solvent is acceptable. If the desired purity of the absolute is not achieved, the extraction and filtering can be done several times to achieve absolute purity. Keep in mind that multiple extraction and filtering may reduce the flavor and aroma of the extract. At this time the concentration of the absolute has increased proportional to the materials that was extracted.
Essential oils extracts are of high value as they highly concentrated and are able to maintain its consistency during the production process. They are also very easy to store and transport with negligible loss. Because of this, plant extract are becoming widely used when it comes to medicinal plants.
For quality and health concerns, the plant extraction process have standards that needs to be followed. Recapturing the solvents such as butane and CO2 is necessary as both are harmful to our health, proper equipment to recapture these solvents are important. Laboratory vacuums and ovens should always be contained.