Optimization of Ultrasound-Assisted Extraction of Flavonoids from Germinated Brown Rice Using Response Surface Methodology

Total flavonoids were extracted from geminated brown rice by ultrasound-assisted extraction method using 50% ethanol as extraction solvent.Response surface methodology was employed to optimize the extraction conditions based on extraction rate.A quadratic regression model describing the effects of four process conditions on the extraction rate of total flavonoids was developed using a Box-Behnken experimental design.The response surface analysis showed that the optimal extraction conditions were extraction for 30.5 min at 45.8 ℃ and a material/liquid ratio of 18.9:1(mL/g) after 11.7 min of ultrasound treatment.Under these conditions,the average extraction rate of total flavonoids was(0.743 ± 0.011) mg/g(n = 5),accounting for 98.5% of the predicted value,0.754 mg/g.The developed regression model showed excellent goodness of fit.