Optimization of Flash Extraction Process of Total Flavonoids from Fig (Ficus carica L.) and Its Antioxidant Activities

Flash extraction of total flavonoids from Ficus carica L. was investigated in this study. Based on the single factor experiments, four extraction parameters including ethanol concentration, extraction voltage, liquid-to-liquid ratio and extraction time were tested and optimized by Box-Behnken design (BBD) experiments. The results showed that the optimal extraction conditions were:Ethanol concentration of 50%, liquid-to-liquid ratio of 50:1 (mL/g), extraction time of 80 s, and extraction voltage of 150 V. The extraction yield of total flavonoids reached (36.94±0.02) mg/g under the optimized conditions, which was much close to the predicted value (36.98 mg/g), which confirmed the accuracy and reliability of the BBD. The antioxidant experiments showed that fig flavonoids had better scavenging effect on DPPH radicals than ascorbic acid, while the capacity on scavenging ABTS⁺ free radicals was less effective than ascorbic acid. The IC₅₀ of total flavonoids on scavenging OH free radicals was 0.098 mg/mL, compared with ascorbic acid (IC₅₀ was 0.159 mg/mL), the total flavonoids had a better scavenging effect on the OH free radicals. As compared to conventional method, flash extraction may serve as a better extraction technology for recovery of flavonoids from figs on considering both the extraction yield and extraction time. Furthermore, fig flavonoids revealed strong antioxidant activity and could provide a theoretical basis for the clevelopment of functional foods and ingredients.