# Green Extraction of Valuable Compounds from Rubber Seed Trees: A Path to Sustainability
## 7 Green Extraction of Rubber Seed Oil
### Microwave Assisted Extraction (MAE)
#### 7.2.1 Microwave Extraction Mechanism  
MAE is a specialized approach that employs microwave energy to expedite the extraction process. This is achieved by subjecting the sample matrix to regulated microwave radiation, as seen in Table 3 and Figure 5. The process of MAE encompasses the collaborative action of thermal and non-thermal factors, which together contribute to the improved extraction of bioactive constituents from various botanical sources such as rubber seed trees. The primary mechanisms involved in microwave extraction are described below.  
1. Thermal Effects: Microwave radiation is used to achieve rapid and uniform heating of both the solvent and the sample matrix. The occurrence of localized heating leads to an increase in temperature inside the matrix, hence enhancing the solubility and diffusion of bioactive substances. Increased temperatures might potentially lead to a degradation of cell walls, hence facilitating the subsequent liberation of chemicals into the extraction solvent. The use of this thermal phenomenon demonstrates significant advantages in the extraction procedure of heat-sensitive compounds from rubber seed plants, as it efficiently mitigates the amount of their degradation [90].
2. Non-Thermal Effects (Dielectric Heating): The phenomenon of microwave radiation is known to cause interactions with polar molecules present in the sample matrix, resulting in the induction of molecular rotations and the generation of frictional heating [91]. The occurrence referred to as dielectric heating leads to fast generation of heat inside the matrix itself. The enhanced extraction efficiency of non-polar molecules, such as lipids and essential oils, may be attributed to the preferential heating of polar  
Figure 5: The extraction mechanism of rubber seed trees with the use of microwave-assisted extraction (MAE).  
constituents (e.g., water) present in the matrix. The non-thermal phenomenon in question plays a significant role in facilitating the extraction process by disrupting cellular structures and facilitating the liberation of bioactive compounds [92].
* Cavitation and Microbubbles: Another result linked with microwave extraction is the production of cavitation and microbubbles inside the solvent [93]. As microwave radiation warms the solvent, vaporization may occur, leading to the production and subsequent collapse of microbubbles. These bubbles generate mechanical disturbance inside the sample matrix, assisting in the extraction process by increasing the contact area between the matrix and the solvent [94].  
The simultaneous operation of these processes expedites the extraction process, diminishes extraction durations, and amplifies the production of bioactive chemicals from rubber seed plants. MAE is considered a highly efficient and ecologically sustainable alternative to traditional extraction techniques due to its ability to provide regulated and fast heating, which leads to the rupture of cell structures and enhanced solubility. Nevertheless, it is essential to acknowledge that the optimization of microwave power, extraction duration, and several other factors plays a pivotal role in attaining the necessary level of extraction efficiency, all the while ensuring the preservation of the extracted compounds' purity.