Abstract: Vegetable sources and agro-industrial residues represent an important source of phenolic compounds that are useful in a wide range of applications, especially those with biological activities. Furthermore, it is easy to handle, safe, economical and reproducible due to the fact that this technology allows its development under conditions of atmospheric pressure and at an ambient temperature . UAE is based on the principle of acoustic cavitation which is capable of damaging the cell walls of the plant matrix and thereby favoring the release of bioactive compounds . This technology can be applied to obtain different phytochemicals of which phenolic compounds stand out. The integration and application of the biological properties of phenolic compounds have led to a great variety of studies focused on the recovery of these compounds from various plant sources, under the principle of implementing sustainable technologies such as UAE .
Phenolic compounds are synthesized by the shikimate, polyketide and mevalonate pathways which produce the great variety of metabolites derived from phenol. 6-carbon aromatic ring, which can be found as free glycosides and glycosidic forms, and this means that they are linked to sugars such as glucose, galactose, rhamnose, xylose and arabinose . Amplitude: maximum height of a wave. In general, several mechanisms involved in UAE have been identified. One of the positions of our mechanism is the fragmentation attributed to the collisions between particles and ultrasonic waves, which causes a reduction in the particle size, thereby facilitating mass transfer. Another is erosion which helps to improve the accessibility of the solvent by imploding the bubbles on the surface of the plant matrix. Effect of Ultrasound System Characteristics 4.
They also suggested the increase of the activity of some enzymes, such as pectinase, helps to disintegrate cell walls during cavitation. Following the drying effect, Vilkhu et al. Additionally, it has been shown that a greater contact area between the solvent and the particles favors the extraction of phenolic compounds. Hydrophilic substances are found mainly in cell vacuoles, while others such as the majority of lignins, flavonoids, and water insoluble polyphenols are deposited in the cell wall through hydrophobic bonds with proteins and polysaccharides .