Optimisation of the Ethanol-Based Heat Reflux Extraction of Isoflavones from Pueraria lobata (Willd.) Ohwi Root

Ethanol-based heat reflux extraction has been successfully applied in extracting isoflavone compounds from the dried root of Pueraria lobata (Willd.) Ohwi. The different extraction factors including ethanol concentration, extraction temperature, extraction time, ratio of solid/liquid and number of extraction cycles has been studied on the influence of the extraction yield of isoflavone compounds. And the orthogonal experiment has been used to optimize the extracting conditions. A variety of indicators were employed to evaluate the extraction efficiency, including the yield of puerarin, daidzein and total isoflavone. The optimal extraction technology was as follows: extraction temperature 90°C, ratio of solid/liquid 1:6, ethanol concentration 90% and extraction 2 h. Under the optimal conditions extraction rates of puerarin, daidzein and total isoflavone were 37.51±0.64 mg/g, 2.63±0.03 mg/g and 117.4±0.89 mg/g. The study of this article can provide theoretical basis for large-scale production of puerarin, daidzein and total isoflavone.