Response surface optimization of polyphenol extraction from petals of Hibiscus-rosa sinensis

Edible flowers of Hibiscus rosa-sinensis have been identified as a source of antioxidant phenolics. Thus, effective extraction of phenolics is important to efficiently utilize these flowers. The present study aims to make use of a central composite design, to investigate the effects of extraction variables on the three response variables; total phenolic content, total anthocyanin content and antioxidant activity. Central composite design with four independent variables including solid: liquid ratio, ethanol concentration, temperature and time were used for the simultaneous optimization of response variables. The optimum process parameters generated were 24.0% ethanol, 1:40 solid: liquid ratio, 44°C temperature and 41 minutes of extraction. The experimental values obtained for the response variables under the generated optimum conditions confirmed the validity of the proposed second-order polynomial model. The results from the simultaneous optimization demonstrated the application of feasible process parameters for the extraction of phenolics from Hibiscus rosa-sinensis flowers and the effective utilization of these flowers in food as well as the pharmaceutical industry.