Optimization of ultrasound-microwave assisted extraction of selenium-containing polysaccharides from Se-enriched Cordyceps militaris by response surface methodology

Response surface methodology was used to optimize the ultrasound-microwave assisted extraction (UME) of selenium-containing polysaccharides from Se-enriched Cordyceps militaris (SCMP) based on single factor experiments. The yield, selenium content and antioxidant activities in vitro of SCMP were compared with those obtained with hot water extraction (HWE) and ultrasonic extraction (UE). The results indicated that the optimum conditions for UME extraction were as follows: ultrasonication time, 26.0 min; subsequent microwave treatment, 3.20 min; microwave power, 350 W; and ratio of liquor to solvent, 32.00:1 (mL/g). Under these conditions, the extraction yield of SCMP was 5.05%, which was increased by 19.96% and 3.70% compared with UE and HWE, respectively. Furthermore, the SCMP prepared by UME exhibited the strongest antioxidant activity and contained the highest level of organic selenium, and its selenium content was 360.37 mg/kg, which was increased by 4.47% and 12.92% as compared with those obtained with UE and HWE. © 2016, China Food Publishing Company. All right reserved.