Optimization of Ultrasonic-Assisted Extraction of Antioxidant Compounds in Black Shallots (Allium ascalonicum) from Vietnam using Response Surface Methodology

Abstract

Response surface methodology (RSM) was used to optimize the extraction conditions for total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity (DPPH) in black shallots (Allium ascalonicum) using ultrasonic-assisted extraction (UAE). The variables used in the process were extraction temperature (40-60oC), extraction time (60–80 min), ethanol concentration (30–70%) and power level (60–100%/600W). The results indicated that extraction temperature, extraction time, ethanol concentration and ultrasonic power level had an impact on TPC, TFC and DPPH radical scavenging activity. The optimum extraction conditions obtained from RSM were: extraction temperature of 53 oC, extraction time of 72 min, ethanol concentration of 48 % and ultrasonic power level of 84 %. The experimental values of TPC, TFC and DPPH radical scavenging activity were 17.28 ± 0.12 mg GAE/g, 5.42 ± 0.08 mg QE/g and 75.35 ± 0.15%, respectively.