Abstract: Polyphenol and catechin were extracted from lotus root by using acetic ester as solvent. The optimum conditions were obtained by the response surface methodology (RSM) tests. In this test based on three test factors, pH(X1), phase ratio (X2), countercurrent extraction times(X3), the dynamic models gave quantitative parameters for the extraction of polyphenol and catechin. The results showed that the optimal extraction conditions are as follows: pH3.2, phase ratio 1:1.5 and countercurrent extraction 3 times. Under these conditions the content of polyphenol is 283.5 mg/kg and regressions of the model of catechin extraction significant. The results indicated that there are other factors which can affect the content of the catechin, and further studies should be done later for the optimal conditions of catechin extraction.

Key words: lotus root, polyphenol, extraction, response surface methodology (RSM)