Optimization of ultrasonic-assisted extraction via multiresponse surface for high antioxidant recovery from Chlorella vulgaris (Chlorophyta)

The present study reports on the extraction of antioxidant compounds from Chlorella vulgaris. Multiresponse surface methodology coupled with a central composite design was used to optimize the independent parameters for ultrasonic-assisted extraction (UAE). Four independent parameters were optimized, including extraction time (15-155 min), ethanol volume (35-95%, v/v), extraction temperature (15-75 degrees C) and liquid/solid ratio (30-150 ml g(-1\)). Total phenolic content and antioxidant capacity [2,2'-azinobis(3-ethylbenzothiazoline-6-sulphonic acid) and chromiumreducing antiaoxidant capacity methods] were considered response parameters, whereas the effects of extraction time, ethanol volume, extraction temperature and liquid/solid ratio were studied. The optimal condition was obtained with an extraction time of 146 min, ethanol volume of 71% (v/v), extraction temperature of 72 degrees C and liquid/solid ratio of 62 ml g(-1) of sample. The experimental values agreed with predicted values within a 95% confidence level. This indicates that multiresponse surface methodology is suitable for optimizing UAE of antioxidant compounds from C. vulgaris.