Effect of frequency and duration of ultrasonication on the extraction efficiency of selected isoflavones and trans-resveratrol from peanuts (Arachis hypogaea).

Plant derived phytochemicals have been the focus of recent research due to their health promoting effects. Previous studies to estimate the levels of these bioactive compounds made use of traditional solvent extraction procedures such as homogenization and soxhlet (reflux) methods. Recently, the ultrasonication technique has been shown to be an efficient non-thermal extraction method. The objective of this study was to investigate the effect of frequency and duration (time) of sonication on the extraction efficiency of selected phytochemicals from peanuts and to determine optimal conditions (sample-to-solvent ratio, frequency, and time) for their extraction. The results obtained showed that sample-to-solvent ratio, frequency, and duration of sonication had significant effect on the extraction efficiency of the phytochemicals from peanut. Sonication at 80 kHz facilitated the extraction of biochanin A and trans-resveratrol while 25 kHz was effective in the extraction of daidzein and genistein. Multi-frequency extractions were more efficient than single frequency.