# Anti-Breast Cancer Activity of Essential Oil:
## 3 Result
### Essential Oil
#### 3.2.1 Classification Based on the Method of Extraction  
Several extraction methods have been reported and steam distillation is the most preferred method in producing essential oils at large quantities with well-maintained purity. However, the method is not suitable for all plant parts because it is not stable at high temperatures [41]. To overcome this problem, methods such as cold pressing and solvent extraction methods have been developed. * Steam Distillation  
Steam distillation is a method that is often used for essential oil extraction [42]. The principle of steam distillation is using steam as a separation agent to separate the various component of the mixture [43], such as the separation of essential oil in the stems, leaves, and flowers. The flow of steam around these parts will cause the oil to be evaporated and carried away with the steam, which is then condensed and separated by decantation. This method is often used to make traditional or aromatherapy oils that are pure and free from impurities [44]. The quality and purity of the oil depend on various factors, such as the pressure of the steam passing through the plant material, the refrigerant used, the temperature of the closed system during oil production, as well as the skills of the distiller. The oil produced by steam distillation is of high value because of the high quality and purity of the extracts [37; 45]. * Cold Pressing Method  
The cold pressing method is used to obtain high purity oils [46]. The principle of this method is applying pressure to extract the essential oil substances present in the plant. This method is mostly used by the citrus family to extract oil from fruit peels, such as tangerines, grapefruit, lemons, oranges, and others [47]. The oil is forced out of the plant parts by mechanical pressure, and the extracted results are in liquid form or mixed with water. Thus, a filtering or distillation step is required to separate the oil and the water [48; 49; 50]. * Extraction Using Solvent  
Some plant materials are unsuitable for steam distillation due to high temperatures (in the form of steam) or cold pressing. The resulting oils following this method can be contaminated or have low purity. To avoid this, plants such as jasmine, rose, orange blossom (neroli), tuberose, and oak were extracted using solvents. This process works by passing plant materials through a hydrocarbon solvent, such as ethanol, ether, methanol, hexane, alcohol, and petroleum [38; 51]. The solvent mixture is then filtered and distilled under low pressure to obtain the essential oils [52]. Microwave-assisted hydrodistillation (MAHD), a complex distillation technique that combines conventional hydrodistillation with microwave heating, has lately gained popularity for the extraction of essential oils from medicinal plants and herbs due to its cost-effectiveness and environmentally friendly nature. A method's efficiency can be increased by increasing the yield, among other factors, through optimization of its parameter conditions. Microwave-assisted hydrodistillation (MAHD) was developed and utilized to extract some plants' essential oils in an effort to make use of microwave heating with the traditional HD. Using the MAHD approach for this extraction has several benefits. Even though the distillation takes less time than the traditional extraction method, the oil yield is slightly higher, and this would help to meet the steadily rising demand for essential oil from medicinal plants. Less time is needed to complete the extraction, resulting in less electricity being used, which lowers operating costs as well. Furthermore, MAHD does not use any chemicals. Because of this, the essential oil obtained using this technique is virtually pure and secure. Given their widespread use in both food preparation and medicine, these requirements are crucial for medicinal essential oils [53]. Ohmic-assisted hydrodistillation (OAHD) is a newly proposed extraction technique that has been utilized to separate essential oils and makes use of the benefits of ohmic heating.