Abstract: The ultrasonic-assisted extraction of polyphenols from peanut skins was optimized using response surface methodology. The extraction yield of polyphenols was investigated with respect to four process parameters including ultrasonic treatment time, ultrasonic power, ethanol concentration and solid-to-solvent ratio. As a result, a quadratic polynomial mathematical model was built. In theory, the optimal extraction conditions were determined as follows: peanut skins were suspended in 51% ethanol aqueous solution at a solid-to-solvent ratio of 1:29.6 (g/mL) and then subjected to ultrasonic treatment for 24.4 min at a power of 408 W. For practical applications, the same extraction solvent was used, but the solid-to-solvent ratio, ultrasonic treatment time and power were modified to be 1:30 (g/mL), 24 min and 410 W, respectively. Under the modified conditions, the extraction yield of polyphenols was 8.95%.

Key words: response surface methodology, ultrasonic-assisted extraction, peanut skins, polyphenols