Ultrasound Assisted Extraction UAE

Sound is transmitted through a medium by inducing vibrational motion of the molecules through which it is traveling. Sound is a series of compression waves separated by rarefaction 

Comparison Between MAE, Soxhiet Extraction (SE) and Ultrasonic-Assisted Extraction (USE) 

Advantages Fast and multiple extractions No filtration required Fast and multiple extractions 

Extraction solvent must be able to absorb microwaves Clean up step needed Waiting time for the vessels to cool down High pressure and temperature are needed (no safety) 

Long extraction time Large solvent volume Clean up step needed Thermolabile analytes are altered 

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A variety of solvent extraction techniques have been used to extract antioxidants from food matrices. The most commonly used is maceration or homogenization of the sample with an extraction solvent however, alternative procedures have been developed including pressurized fluid extraction (PFE), ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), and matrix solid-phase dispersion (MSPD), among others. The principles of each extraction technique will be briefly discussed. 

Table 2.3 Examples of extraction of antioxidant phytochemicals from various plant materials by ultrasound-assisted extraction (UAE). 

Most of the extraction techniques of phenolic compounds from vegetables are based on ultrasound-assisted extraction (UAE) [27,44,45], In addition, other techniques have been successfully applied to the pretreatment of phenolic compounds in fruits and vegetables, including pressurized liquid extraction (PLE) [46], solid-phase extraction (SPE) [47], supercritical fluid extraction (SFE) [48], microwave-assisted extraction (MAE) [49], rotary shaker-assisted extraction (RAE), [50] and QuEChERS (acronym of quick, easy, cheap, effective, rugged and safe) [51], as can be observed in Tables 16.3 and 16.4. In some cases, an acid treatment [52] was applied to hydrolyze the glycosides in order to determine the content of free and conjugated flavonoids as aglycons. 

The extraction of lycopene from tomato using ultrasonic assisted extraction (UAE) and ultrasound/microwave assisted extraction (UMAE) was also reported (Lianfu and... 

The rate of transfer of antioxidants from a solid polymer into a solvent is increased by ultrasound waves. Ultrasonic-assisted extraction (UAE) is a rather... 

Ultrasonic-assisted extraction (UAE) is the other common method that accelerates the extraction process [83]. The principle behind the UAE is similar to MAE, where the cell wall is destroyed by ultrasound that leads to active constituents being leached out from ruptured cells without modifying the polysaccharides. In general, UAE is able to extract polysaccharides at lower temperatures, which is about 25-70 °C at 120/300 W of ultrasonic power [89]. The extraction time is between 5 and 40 min. 

The UAE technique is based on the employment of the energy derived from ultrasounds that facilitate the extraction of analytes from the solid sample by the organic solvent [66]. The enhancement of extraction efficiency of organic compounds by UAE is attributed to the phenomenon of cavitation produced in the solvent by the passage of ultrasonic waves [67]. The uses of higher temperatures in UAE lead to an increase in the efficiency of the extraction process [67-69]. The ultrasound-assisted extraction of capsaicinoids from pepper has also been carried out by Barbero et al. in... 

FIGURE 8.2 Effect of ultrasonication at 230 W in a dynamic system on the extraction of oil using hexane-isopropanol mixture with a solvent to solid ratio of 8.5 (mL/g). CSE, conventional solvent extraction CSDE, conventional solvent dynamic extraction UAE, ultrasound-assisted extraction UADE, ultrasound-assisted dynamic extraction. (Adapted from Lou, Z. et al. 2010. J. Food Eng. 98 13-18, Figure 3.)... 

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