Optimization of Extraction of Bioactive Compounds from Black Carrot Using Response Surface Methodology (RSM)

In this study, optimum conditions for the extraction of black carrot anthocyanins were determined by response surface methodology. Central composite design of extraction factors (pH 2.5–6.5, temperature 4–72 °C, solvent/solid ratio 5:1–25:1 v/w, ethanol/water ratio 0:100–100:0 v/v) was generated as two replicates. Total phenolic content, total monomeric anthocyanin content, polymeric color, total antioxidant activity, and anthocyanin composition determined by high-performance liquid chromatography were used as responses. Except for color analysis, higher temperature, solid/solvent ratio, and ethanol concentration were observed to increase the extraction yield. However, polymeric color results were found to have minimum values at lower pH and solid/solvent ratio, lower or moderate temperature, and higher ethanol concentration. Optimum extraction conditions were found as follows: 50 °C, pH 3.5, solvent solid ratio 10:1 (v/w), and ethanol/water ratio 75:25 (v/v) when all responses were considered. The validation of the optimum conditions for black carrot extraction was performed at specified values.