Optimization conditions for anthocyanin and phenolic content extraction form purple sweet potato using response surface methodology.

Purple sweet potato flour could be used to enhance the bioactive components such as phenolic compounds and anthocyanin content that might be used as nutraceutical ingredients for formulated foods. Optimization of anthocyanin and phenolic contents of purple sweet potato were investigated using response surface methodology. A face-centered cube design was used to investigate the effects of three independent variables: namely, drying temperature 55-65°C, citric acid concentration 1-3% w/v and soaking time 1-3 min. The optimal conditions for anthocyanin and phenolic contents were 62.91°C, 1.38%, 2.53 min and 60.94°C, 1.04% and 2.24 min, respectively. However, optimal conditions of anthocyanin content were not apparent. The experimental value of anthocyanin content was 19.78 mg/100 g and total phenolic content was 61.55 mg/g. These data showed that the experimental responses were reasonably close to the predicted responses. Therefore, the results showed that treated flours could be used to enhance the antioxidant activities of functional foods.