Abstract: One-factor-at-a-time method and response surface methodology were used in combination to optimize the ultrasound-vacuum assisted extraction of polyphenols from apple pomace. At the same time, antioxidant assays in vitro were also carried out on the polyphenols and the polyphenol composition was analyzed by HPLC. The optimal extraction parameters that provided the maximum yield of polyphenols of 6.46?mg/g were determined as follows: 50% ethanol as extraction solvent, a solid-to-solvent ratio of 1:30 (g/mL), an extraction time of 13?min, an extraction temperature of 50 ℃, an ultrasound power of 420?W, and a vacuum degree of 0.08 MPa. Compared with traditional ultrasonic assisted extraction, the extraction time was considerably shortened by using ultrasound-vacuum assisted extraction while yielding polyphenol extracts containing more epicatechin and rutin and having stronger antioxidant activities.

Key words: apple pomace, polyphenol, ultrasound combined with vacuum treatment, response surface methodology, HPLC, antioxidant activity