Optimisation of ultrasound assisted extraction of T. hyemalis using the response surface methodology

The present study reports on the extraction of phenolic compounds from aerial parts of thymus hyemalis of morocco. box-behnken design (bbd),a widely used form of response surface methodology (rsm),was used to investigate the effect of process variables on the ultrasound-assisted extraction (uae). three independent variables including ethanol concentration (%),extraction time (min) and solvent-to-material ratio (ml/g) were studied. the results showed that the optimal uae condition was obtained with an ethanol concentration of 72%,an extraction time of 37 min and a solvent-to-material ratio of 19 ml/g for total phenols,and an ethanol concentration of 70 %,an extraction time of 38 min and solvent-to-material ratio of 20 ml/g for the yield of extraction. the experimental values under optimal conditions were in good consistent with the predicted values.