Solvent-Based Extraction : Solvent-based extraction involves the use of solvents to extract the desired compounds from the herbs. Common solvents used include ethanol, methanol, hexane, and supercritical carbon dioxide (CO2). The solvent is applied to the plant material, allowing it to dissolve and extract the target compounds. The resulting solution is then further processed to remove the solvent, leaving behind the concentrated extract. Solvent-based extraction methods are often efficient and yield high concentrations of desired compounds. However, they can also extract undesirable components and require careful solvent removal to ensure the final product is free of residues.

Non-Solvent-Based Extraction : Non-solvent-based extraction refers to extraction methods that do not rely on the use of solvents. Instead, they utilize physical processes or alternative mediums to extract the desired compounds from the herbs. Some common non-solvent extraction methods include:
a) Steam Distillation : This method involves passing steam through the plant material, which vaporizes the essential oils and other volatile compounds. The vapor is then condensed, resulting in the separation of the essential oil from the plant material.

b) Cold-Press Extraction : Cold-press extraction involves applying mechanical pressure to the plant material to release the oils and other compounds. This method is commonly used for extracting oils from citrus fruits, seeds, and nuts.

c) Supercritical Fluid Extraction : Supercritical fluid extraction utilizes a supercritical fluid (usually carbon dioxide) to extract the target compounds. The fluid is pressurized and heated to a state where it exhibits properties of both a liquid and a gas, making it an effective solvent for extraction.

Non-solvent-based extraction methods are often preferred when a solvent-free product is desired or when the use of solvents is not suitable for specific applications, such as food or pharmaceutical products.