Optimization of extraction time and temperature for antioxidant activity of edible wild mushroom, Pleurotus porrigens

The extraction time and temperature of Pleurotus porrigens were optimized for the maximization of 2,2-diphenyl-1-picryhydrazyl (DPPH) radical scavenging and 2,2'-azino-bis(3-ethylbenzthiazoline-6-sulfonate) (ABTS) radical cation inhibition activities, ferric reducing/antioxidant power (FRAP) and total phenolic content (TPC) using response surface methodology (RSM). A rotatable central composite design consisting of 14 experimental runs with three replicates at the central points was applied and second-order polynomial models were used to describe the experimental data regarding the responses. The experimental results adequately fitted into the second-order polynomial models with significant linear, quadratic and interaction effects of the independent variables. The optimized conditions were 372.8 min/32.0 degrees C (DPPH); 340.9 min/36.8 degrees C (ABTS); 240.0 min/38.1 degrees C (FRAP); and 310.1 min/43.6 degrees C (TPC) with corresponding yields of 32.65%; 91.21%; 7.91 mM Fe2+ equivalent/100 g; and 494 mg gallic acid equivalent/100 g, respectively. The experimental values were close with those predicted values, indicating suitability of the model employing RSM for optimizing the extraction time and temperature on antioxidant activity from P. porrigens. (C) 2011 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.