Abstract

In this study, ultrasonication was used to extract antioxidant compounds such as polyphenols, flavonoids, and curcuminoids from turmeric (Curcuma longa L.) The influences of time, ethanol concentration and temperature as three independent factors on the extraction of the total phenolic content were evaluated by the Folin-Ciocalteu method and the antioxidant capacities by the ABTS and chromium reducing antioxidant capacity (CHROMAC) methods. The central composite design (CCD) with a multi-response surface methodology (MRSM) was used for the statistical modeling of the response data followed by the regression and analysis of variance (ANOVA) to determine the significance of the model and the factors. The response predictions obtained at optimum extraction conditions of an extraction time of 64min, an ethanol concentration of 82% (v/v) and an extraction temperature of 32°C were 47.32mg GAE/g (for Folin-Ciocalteu), 29.15 (for ABTS) and 5.17mg TE/g (for CHROMAC). The predicted values obtained from the multi-response surface methodology agreed with the experimental values data 95% confidence level. These data indicate that the multi-response surface methodology is applicable for optimizing the ultrasonic-assisted extraction of antioxidant compounds from C. longa.