Optimal Enzyme-Assisted Ethanol Extraction of Flavonoids from Broccoli by RSM and Research on Antioxidant Effect

Enzyme-assisted ethanol extraction of total flavonoids from broccoli and research on its antioxidant effect, were studied in this paper. Enzyme concentration, solid-liquid ratio, extraction temperature and time were determined as four single-factor in the experiment. According to the single-factor experimental results, the extract process was further optimized by RSM and Box-Benhnken design. The optimum extract conditions were enzyme concentration of 0.15%, solid-liquid ratio of 5:30 (g/mL), extraction temperature of 70°C and time of 2 h, the experimental responding extraction ratio was 0.935% corresponding to the theoretical predictions of 0.953%. The experimental extraction ratio matched well with the theoretical value by solving the multiple regression equation. RSM has been proved to be an effective technique for optimization of extraction process and the fitted quadratic model has a predictive effect on target extracts. The scavenging effect of broccoli extracts on hydroxyl radicals displayed a significant dose-effect relationship.