Optimization of ultrasonic-assisted extraction of polyphenols and antioxidants from cumin (Cuminum cyminum L.)

Ultrasonic-assisted extraction (UAE) using response surface methodology (RSM) was employed for the highly efficient extraction of bioactive compounds such as polyphenols and antioxidants from cumin (Cuminum cyminum L.) seeds. A central composite design (CCD) consisting of three variables and five levels was used to estimate the significance of each process variable in the application of UAE for cumin seed extraction. Process variables optimized were ethanol concentration (0-80%, v/v), extraction time (15-75 min), and extraction temperature (15-75°C). RSM was employed to determine the optimal extraction conditions for the bioactive compounds. Four-dimensional surface plots were generated to indicate polynomial equations of good-fit models. The optimal conditions were then predicted by superimposing these four-dimensional surface plots. Based on the graph for the overlapped contour plots, the optimal UAE conditions: ethanol concentration of 40% v/v, extraction time of 51 min, and temperature of 39°C, were found to give predicted maximal values for yield (20.31%), total polyphenol content (27.11 mg GAE/g), antioxidant activity DPPH (52.47%), and ABTS (41.04%). Verification experiments were carried out under optimal conditions, and there was a good fit between the estimated and experimental values, suggesting that the model was valid and accurate for the design of UAE process. In conclusion, UAE showed effectiveness in the recovery of valuable antioxidant compounds from cumin.