Optimization of Ultrasound-Assisted Extraction of Antioxidants from Apium graveolens L. Seeds using Response Surface Methodology

In this study, optimum conditions for ultrasound-assisted extraction (UAE) of antioxidants from Apium graveolens L. seeds were investigated by Response Surface Methodology (RSM). A Box-Behnken Design (BBD) was used to evaluate the effect of sonication time (5, 10, 15 min), ultrasound power (60, 120, 180 W) and the ratio of extraction solvent in terms of methanol (0, 50, 100%) on antioxidant capacity. The optimal UAE conditions for the parameters investigated were 11 min of sonication time, ultrasound power of 131 W and 100% methanol as an extraction solvent. Under these conditions, UAE of antioxidants from the seeds achieved a maximum of 95.08% in respect to 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical scavenging activity. Additionally, the high value of the adjusted coefficient of determination ( R 2 adj = 0.9192) and the non-significant difference between experimental and predicted values confirmed the validity of the quadratic polynomial model. Hence, UAE is a suitable, fast, economical and practical technique for the extraction of antioxidants from Apium graveolens  L. seeds.