Optimization of ultrasonic extraction conditions of pigment from wolfberry residue by response surface methodology

Wolfberry residue as the research object , ultrasonic extraction as the method , with the pigment extraction rate as a measure indicator . Four extraction parameters including extraction time , extraction temperature , solid-liquid ratio (g/mL ) and extractant (ethanol ) concentration were optimized using central composite design and response surface methodology based on single factor investigations for achieving maximun the pigment extraction rate. The interaction of the respective variables and their influence on the extraction rate were studied by using Box-Benhnken central composite design and response surface analysis theory, the simulated quadratic polynomial regression equation of prediction model was set up. Under the condition of ultrasonic power 150W, the optimum extraction condition for extraction temperature 67℃ , solid-liquid ratio 1∶32 , ethanol concentration 97% , extraction time of 37min. Under these conditions , the average pigment extraction rate was 7.632% , compared to the theoretical value 7.861% , the relative error of 2.91% . Optimized by response regression equation derived some practical significance.