Optimum Technology of Homogenated Extraction for Fresh Rehmannia by Central Composite Design-Response Surface Methodology

OBJECTIVE To optimize homogenated extraction technology for fresh rehmannia by central composite design-response surface method. METHODS Independent variables were ethanol volume fraction, solvent ratio, extracting time based on single-factor test, while dependent variables were extracting rate of catalpol and dry extract yielding rate. Multiple linear regression and multivariate binomial fit were used to estimate mathematic relationship between independent variables and dependent variables. Response surface description were based on optimum mathematical model, and than choose optimum technical conditions. RESULTS Optimum extraction conditions were as follow: volume fraction of ethanol 30%, solvent ratio 16, be extracted one time, extraction time 95 s. CONCLUSION The relationship between independent variables and dependent variables could be described by optimum model. The model has good predictability.