Optimization of ultrasonic-assisted extraction for monacolin K, antioxidant activity, pigment and citrinin of monascal waxy corn by response surface methodology
Keywords:Optimization, Ultrasonic, Monacolin K, Monascal waxy corn, Response surface methodology
This study aims to investigate the ultrasonic extraction optimization of monascal waxy corn (MWC). An optimization procedure using a central composition design with two factors (ethanol concentration and temperature) consisting of 13 experimental runs with five replicates of the central points was applied and a second-order polynomial model was used to describe the effects of these parameters on extraction for monacolin K content, antioxidant activities, pigment intensity and citrinin content. The optimized conditions were 69.91% ethanol/49.95°C (monacolin K); 69.62% ethanol/49.15°C (DPPH); 70.67%ethanol/ 49.90°C (chelating ability on Fe2+); 70.91% ethanol/50.80oC (Pigment); 85.00% ethanol/60oC (citrinin) with corresponding yields of 348.72 mg/kg dry weight; 2.65 mmol Trolox/ml; 96.76%; 4072.45 unit/g dry weight and 2.04 μg/kg dry weight, respectively. The maximal monacolin K content predicted by response surface analysis was 349.59 mg/kg dry weight. The experimental value was close to those predicted values, showing fitting of the model (R2 = 0.924) applying RSM for optimizing the ethanol concentration and temperature on monacolin K content from MWC.